Code:
/ Dotnetfx_Win7_3.5.1 / Dotnetfx_Win7_3.5.1 / 3.5.1 / DEVDIV / depot / DevDiv / releases / Orcas / NetFXw7 / wpf / src / Framework / System / Windows / Controls / ItemContainerGenerator.cs / 1 / ItemContainerGenerator.cs
//----------------------------------------------------------------------------
//
//
// Copyright (C) Microsoft Corporation. All rights reserved.
//
//
// Description: ItemContainerGenerator object
//
// Specs: http://avalon/connecteddata/M5%20General%20Docs/Data%20Styling.mht
//
//---------------------------------------------------------------------------
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Globalization; // for CultureInfo.InvariantCulture (event tracing)
using System.Windows.Media;
using System.Windows.Controls.Primitives; // IItemContainerGenerator
using System.Windows.Data;
using System.Windows.Markup;
using System.Diagnostics;
using MS.Internal;
using MS.Internal.Controls;
using MS.Internal.KnownBoxes;
using MS.Internal.Utility;
using MS.Utility;
namespace System.Windows.Controls
{
///
/// An ItemContainerGenerator is responsible for generating the UI on behalf of
/// its host (e.g. ItemsControl). It maintains the association between the items in
/// the control's data view and the corresponding
/// UIElements. The control's item-host can ask the ItemContainerGenerator for
/// a Generator, which does the actual generation of UI.
///
public sealed class ItemContainerGenerator : IRecyclingItemContainerGenerator, IWeakEventListener
{
//-----------------------------------------------------
//
// Constructors
//
//-----------------------------------------------------
/// Constructor
/// the control that owns the items
internal ItemContainerGenerator(IGeneratorHost host)
: this(null, host, host as DependencyObject, 0)
{
// The top-level generator always listens to changes from ItemsCollection.
// It needs to get these events before anyone else, so that other listeners
// can call the generator's mapping functions with correct results.
CollectionChangedEventManager.AddListener(host.View, this);
}
private ItemContainerGenerator(ItemContainerGenerator parent, GroupItem groupItem)
: this(parent, parent.Host, groupItem, parent.Level + 1)
{
}
private ItemContainerGenerator(ItemContainerGenerator parent, IGeneratorHost host, DependencyObject peer, int level)
{
_parent = parent;
_host = host;
_peer = peer;
_level = level;
OnRefresh();
}
//------------------------------------------------------
//
// Public Properties
//
//-----------------------------------------------------
/// The status of the generator
public GeneratorStatus Status
{
get { return _status; }
}
//[CodeAnalysis("AptcaMethodsShouldOnlyCallAptcaMethods")] //Tracking Bug: 29647
private void SetStatus(GeneratorStatus value)
{
if (value != _status)
{
_status = value;
switch (_status)
{
case GeneratorStatus.GeneratingContainers:
if (EventTrace.IsEnabled(EventTrace.Flags.performance, EventTrace.Level.normal))
{
EventTrace.EventProvider.TraceEvent(EventTrace.GuidFromId(EventTraceGuidId.GENERICSTRINGGUID), MS.Utility.EventType.StartEvent, "ItemsControl.Generator");
_itemsGenerated = 0;
}
else
_itemsGenerated = Int32.MinValue;
#if GENERATOR_TRACE
_creationTimer.Reset();
_timer.Begin();
#endif
break;
case GeneratorStatus.ContainersGenerated:
string label = null;
if (_itemsGenerated >= 0) // this implies that tracing is enabled
{
DependencyObject d = Host as DependencyObject;
if (d != null)
label = (string)d.GetValue(FrameworkElement.NameProperty);
if (label == null || label.Length == 0)
label = Host.GetHashCode().ToString(CultureInfo.InvariantCulture);
EventTrace.EventProvider.TraceEvent(EventTrace.GuidFromId(EventTraceGuidId.GENERICSTRINGGUID),
MS.Utility.EventType.EndEvent,
String.Format(CultureInfo.InvariantCulture, "ItemContainerGenerator for {0} {1} - {2} items", Host.GetType().Name, label, _itemsGenerated));
}
#if GENERATOR_TRACE
_timer.End();
if (_itemsGenerated > 0)
{
Console.WriteLine("Generator for {0} {1} did {2} items in {3:f2} msec - {4:f2} msec/item",
Host.GetType().Name, label, _itemsGenerated, _timer.TimeOfLastPeriod, _timer.TimeOfLastPeriod/_itemsGenerated);
Console.WriteLine(" this excludes time for element creation: {0:f2} msec - {1:f2} msec/item",
_creationTimer.OverallTimeInMilliseconds, _creationTimer.OverallTimeInMilliseconds/_itemsGenerated);
}
#endif
break;
}
if (StatusChanged != null)
StatusChanged(this, EventArgs.Empty);
}
}
//------------------------------------------------------
//
// Public Methods
//
//------------------------------------------------------
#region IItemContainerGenerator
///
/// Return the ItemContainerGenerator appropriate for use by the given panel
///
ItemContainerGenerator IItemContainerGenerator.GetItemContainerGeneratorForPanel(Panel panel)
{
if (!panel.IsItemsHost)
throw new ArgumentException(SR.Get(SRID.PanelIsNotItemsHost), "panel");
// if panel came from an ItemsPresenter, use its generator
ItemsPresenter ip = ItemsPresenter.FromPanel(panel);
if (ip != null)
return ip.Generator;
// if panel came from a style, use the main generator
if (panel.TemplatedParent != null)
return this;
// otherwise the panel doesn't have a generator
return null;
}
/// Begin generating at the given position and direction
///
/// This method must be called before calling GenerateNext. It returns an
/// IDisposable object that tracks the lifetime of the generation loop.
/// This method sets the generator's status to GeneratingContent; when
/// the IDisposable is disposed, the status changes to ContentReady or
/// Error, as appropriate.
///
IDisposable IItemContainerGenerator.StartAt(GeneratorPosition position, GeneratorDirection direction)
{
return ((IItemContainerGenerator)this).StartAt(position, direction, false);
}
/// Begin generating at the given position and direction
///
/// This method must be called before calling GenerateNext. It returns an
/// IDisposable object that tracks the lifetime of the generation loop.
/// This method sets the generator's status to GeneratingContent; when
/// the IDisposable is disposed, the status changes to ContentReady or
/// Error, as appropriate.
///
IDisposable IItemContainerGenerator.StartAt(GeneratorPosition position, GeneratorDirection direction, bool allowStartAtRealizedItem)
{
if (_generator != null)
throw new InvalidOperationException(SR.Get(SRID.GenerationInProgress));
_generator = new Generator(this, position, direction, allowStartAtRealizedItem);
return _generator;
}
DependencyObject IItemContainerGenerator.GenerateNext()
{
bool isNewlyRealized;
if (_generator == null)
throw new InvalidOperationException(SR.Get(SRID.GenerationNotInProgress));
return _generator.GenerateNext(true, out isNewlyRealized);
}
DependencyObject IItemContainerGenerator.GenerateNext(out bool isNewlyRealized)
{
if (_generator == null)
throw new InvalidOperationException(SR.Get(SRID.GenerationNotInProgress));
return _generator.GenerateNext(false, out isNewlyRealized);
}
///
/// Prepare the given element to act as the container for the
/// corresponding item. This includes applying the container style,
/// forwarding information from the host control (ItemTemplate, etc.),
/// and other small adjustments.
///
///
/// This method must be called after the element has been added to the
/// visual tree, so that resource references and inherited properties
/// work correctly.
///
/// The container to prepare.
/// Normally this is the result of the previous call to GenerateNext.
///
void IItemContainerGenerator.PrepareItemContainer(DependencyObject container)
{
object item = container.ReadLocalValue(ItemForItemContainerProperty);
Host.PrepareItemContainer(container, item);
}
///
/// Remove generated elements.
///
void IItemContainerGenerator.Remove(GeneratorPosition position, int count)
{
Remove(position, count, /*isRecycling = */ false);
}
///
/// Remove generated elements.
///
private void Remove(GeneratorPosition position, int count, bool isRecycling)
{
if (position.Offset != 0)
throw new ArgumentException(SR.Get(SRID.RemoveRequiresOffsetZero, position.Index, position.Offset), "position");
if (count <= 0)
throw new ArgumentException(SR.Get(SRID.RemoveRequiresPositiveCount, count), "count");
int index = position.Index;
ItemBlock block;
// find the leftmost item to remove
int offsetL = index;
for (block = _itemMap.Next; block != _itemMap; block = block.Next)
{
if (offsetL < block.ContainerCount)
break;
offsetL -= block.ContainerCount;
}
RealizedItemBlock blockL = block as RealizedItemBlock;
// find the rightmost item to remove
int offsetR = offsetL + count - 1;
for (; block != _itemMap; block = block.Next)
{
if (!(block is RealizedItemBlock))
throw new InvalidOperationException(SR.Get(SRID.CannotRemoveUnrealizedItems, index, count));
if (offsetR < block.ContainerCount)
break;
offsetR -= block.ContainerCount;
}
RealizedItemBlock blockR = block as RealizedItemBlock;
// de-initialize the containers that are being removed
RealizedItemBlock rblock = blockL;
int offset = offsetL;
while (rblock != blockR || offset <= offsetR)
{
DependencyObject container = rblock.ContainerAt(offset);
UnlinkContainerFromItem(container, rblock.ItemAt(offset), isRecycling);
if (isRecycling)
{
Debug.Assert(!_recyclableContainers.Contains(container), "trying to add a container to the collection twice");
if (_containerType == null)
{
_containerType = container.GetType();
}
else if (_containerType != container.GetType())
{
throw new InvalidOperationException(SR.Get(SRID.CannotRecyleHeterogeneousTypes));
}
_recyclableContainers.Enqueue(container);
}
if (++offset >= rblock.ContainerCount && rblock != blockR)
{
rblock = rblock.Next as RealizedItemBlock;
offset = 0;
}
}
// see whether the range hits the edge of a block on either side,
// and whether the a`butting block is an unrealized gap
bool edgeL = (offsetL == 0);
bool edgeR = (offsetR == blockR.ItemCount-1);
bool abutL = edgeL && (blockL.Prev is UnrealizedItemBlock);
bool abutR = edgeR && (blockR.Next is UnrealizedItemBlock);
// determine the target (unrealized) block,
// the offset within the target at which to insert items,
// and the intial change in cumulative item count
UnrealizedItemBlock blockT;
ItemBlock predecessor = null;
int offsetT;
int deltaCount;
if (abutL)
{
blockT = (UnrealizedItemBlock)blockL.Prev;
offsetT = blockT.ItemCount;
deltaCount = -blockT.ItemCount;
}
else if (abutR)
{
blockT = (UnrealizedItemBlock)blockR.Next;
offsetT = 0;
deltaCount = offsetL;
}
else
{
blockT = new UnrealizedItemBlock();
offsetT = 0;
deltaCount = offsetL;
// remember where the new block goes, so we can insert it later
predecessor = (edgeL) ? blockL.Prev : blockL;
}
// move items within the range to the target block
for (block = blockL; block != blockR; block = block.Next)
{
int itemCount = block.ItemCount;
MoveItems(block, offsetL, itemCount-offsetL,
blockT, offsetT, deltaCount);
offsetT += itemCount-offsetL;
offsetL = 0;
deltaCount -= itemCount;
if (block.ItemCount == 0)
block.Remove();
}
// the last block in the range is a little special...
// Move the last unrealized piece.
int remaining = block.ItemCount - 1 - offsetR;
MoveItems(block, offsetL, offsetR - offsetL + 1,
blockT, offsetT, deltaCount);
// Move the remaining realized items
RealizedItemBlock blockX = blockR;
if (!edgeR)
{
if (blockL == blockR && !edgeL)
{
blockX = new RealizedItemBlock();
}
MoveItems(block, offsetR+1, remaining,
blockX, 0, offsetR+1);
}
// if we created any new blocks, insert them in the list
if (predecessor != null)
blockT.InsertAfter(predecessor);
if (blockX != blockR)
blockX.InsertAfter(blockT);
RemoveAndCoalesceBlocksIfNeeded(block);
}
///
/// Remove all generated elements.
///
void IItemContainerGenerator.RemoveAll()
{
// Take _itemMap offline, to protect against reentrancy (bug 1285179)
ItemBlock itemMap = _itemMap;
_itemMap = null;
try
{
// de-initialize the containers that are being removed
if (itemMap != null)
{
for (ItemBlock block = itemMap.Next; block != itemMap; block = block.Next)
{
RealizedItemBlock rib = block as RealizedItemBlock;
if (rib != null)
{
for (int offset = 0; offset < rib.ContainerCount; ++offset)
{
UnlinkContainerFromItem(rib.ContainerAt(offset), rib.ItemAt(offset));
}
}
}
}
}
finally
{
PrepareGrouping();
// re-initialize the data structure
_itemMap = new ItemBlock();
_itemMap.Prev = _itemMap.Next = _itemMap;
UnrealizedItemBlock uib = new UnrealizedItemBlock();
uib.InsertAfter(_itemMap);
uib.ItemCount = Items.Count;
_recyclableContainers = new Queue();
SetAlternationCount();
// tell generators what happened
if (MapChanged != null)
{
MapChanged(null, -1, 0, uib, 0, 0);
}
}
}
void IRecyclingItemContainerGenerator.Recycle(GeneratorPosition position, int count)
{
Remove(position, count, /*isRecyling = */ true);
}
///
/// Map an index into the items collection to a GeneratorPosition.
///
GeneratorPosition IItemContainerGenerator.GeneratorPositionFromIndex(int itemIndex)
{
GeneratorPosition position;
ItemBlock itemBlock;
int offsetFromBlockStart;
GetBlockAndPosition(itemIndex, out position, out itemBlock, out offsetFromBlockStart);
if (itemBlock == _itemMap && position.Index == -1)
++position.Offset;
return position;
}
///
/// Map a GeneratorPosition to an index into the items collection.
///
int IItemContainerGenerator.IndexFromGeneratorPosition(GeneratorPosition position)
{
int index = position.Index;
if (index == -1)
{
// offset is relative to the fictitious boundary item
if (position.Offset >= 0)
{
return position.Offset - 1;
}
else
{
return Items.Count + position.Offset;
}
}
if (_itemMap != null)
{
int itemIndex = 0; // number of items we've skipped over
// locate container at the given index
for (ItemBlock block = _itemMap.Next; block != _itemMap; block = block.Next)
{
if (index < block.ContainerCount)
{
// container is within this block. return the answer
return itemIndex + index + position.Offset;
}
else
{
// skip over this block
itemIndex += block.ItemCount;
index -= block.ContainerCount;
}
}
}
return -1;
}
#endregion IItemContainerGenerator
///
/// Return the item corresponding to the given UI element.
/// If the element was not generated as a container for this generator's
/// host, the method returns DependencyProperty.UnsetValue.
///
public object ItemFromContainer(DependencyObject container)
{
if (container == null)
throw new ArgumentNullException("container");
object item = container.ReadLocalValue(ItemForItemContainerProperty);
if (item != DependencyProperty.UnsetValue)
{
// verify that the element really belongs to the host
if (!Host.IsHostForItemContainer(container))
item = DependencyProperty.UnsetValue;
}
return item;
}
///
/// Return the UI element corresponding to the given item.
/// Returns null if the item does not belong to the item collection,
/// or if no UI has been generated for it.
///
public DependencyObject ContainerFromItem(object item)
{
DependencyObject container = null;
int index;
DoLinearSearch(ref container, ref item, out index);
return container;
}
///
/// Given a generated UI element, return the index of the corresponding item
/// within the ItemCollection.
///
public int IndexFromContainer(DependencyObject container)
{
if (container == null)
{
throw new ArgumentNullException("container");
}
object item = null;
int index;
DoLinearSearch(ref container, ref item, out index);
return index;
}
///
/// Performs a linear search.
///
///
/// There's no avoiding a linear search, which leads to O(n^2) performance
/// if someone calls ContainerFromItem or IndexFromContainer for every item.
/// To mitigate this, we start each search at _startIndexForUIFromItem, and
/// heuristically set this in various places to where we expect the next
/// call to occur.
///
/// For example, after a successul search, we set it to the resulting
/// index, hoping that the next call will query either the same item or
/// the one after it. And after inserting a new item, we expect a query
/// about the new item. Etc.
///
/// Saving this as an index instead of a (block, offset) pair, makes it
/// more robust during insertions/deletions. If the index ends up being
/// wrong, the worst that happens is a full search (as opposed to following
/// a reference to a block that's no longer in use).
///
/// To re-use the search code for two methods, please read the description
/// of the parameters.
///
///
/// If non-null, then searches for the container.
/// Otherwise, updated with container for the item.
///
///
/// If non-null, then searches for the item.
/// Otherwise, updated with the item that the container represents.
///
///
/// If a container or item is found, then updated with its index.
/// Otherwise, set to -1.
///
///
/// true if found, false otherwise.
///
private bool DoLinearSearch(ref DependencyObject container, ref object item, out int itemIndex)
{
itemIndex = 0;
if (_itemMap == null)
{
// _itemMap can be null if we re-enter the generator. Scenario: user calls RemoveAll(), we Unlink every container, fire
// ClearContainerForItem for each, and someone overriding ClearContainerForItem decides to look up the container.
return false;
}
// Move to the starting point of the search
ItemBlock startBlock = _itemMap.Next;
int index = 0; // index of first item in current block
RealizedItemBlock rib;
int startOffset;
while (index <= _startIndexForUIFromItem && startBlock != _itemMap)
{
index += startBlock.ItemCount;
startBlock = startBlock.Next;
}
startBlock = startBlock.Prev;
index -= startBlock.ItemCount;
rib = startBlock as RealizedItemBlock;
if (rib != null)
{
startOffset = _startIndexForUIFromItem - index;
if (startOffset >= rib.ItemCount)
{
// we can get here if items get removed since the last
// time we saved _startIndexForUIFromItem - so the
// saved offset is no longer meaningful. To make the
// search work, we need to make sure the first loop
// does at least one iteration. Setting startOffset to 0
// does exactly that.
startOffset = 0;
}
}
else
{
startOffset = 0;
}
// search for the desired item, wrapping around the end
ItemBlock block = startBlock;
int offset = startOffset;
int endOffset = startBlock.ItemCount;
while (true)
{
// search the current block (only need to search realized blocks)
if (rib != null)
{
for (; offset < endOffset; ++offset)
{
CollectionViewGroup group;
bool found = false;
if (container != null)
{
if (rib.ContainerAt(offset) == container)
{
found = true;
item = rib.ItemAt(offset);
}
}
else
{
if (Object.Equals(item, rib.ItemAt(offset)))
{
found = true;
container = rib.ContainerAt(offset);
}
}
if (IsGrouping && !found && ((group = rib.ItemAt(offset) as CollectionViewGroup) != null))
{
// found a group; see if the group contains the item
GroupItem groupItem = (GroupItem)rib.ContainerAt(offset);
found = groupItem.Generator.DoLinearSearch(ref container, ref item, out itemIndex);
}
if (found)
{
// found the item; update state and return
_startIndexForUIFromItem = index + offset;
itemIndex += GetRealizedItemBlockCount(rib, offset) + GetCount(block);
return true;
}
}
// check for termination
if (block == startBlock && offset == startOffset)
{
itemIndex = -1;
return false;
}
}
// advance to next block
index += block.ItemCount;
offset = 0;
block = block.Next;
// if we've reached the end, wrap around
if (block == _itemMap)
{
block = block.Next;
index = 0;
}
// prepare to search the block
endOffset = block.ItemCount;
rib = block as RealizedItemBlock;
// check for termination
if (block == startBlock)
{
if (rib != null)
{
endOffset = startOffset; // search first part of block
}
else
{
itemIndex = -1;
return false;
}
}
}
}
private int GetCount()
{
return GetCount(_itemMap);
}
private int GetCount(ItemBlock stop)
{
int count = 0;
ItemBlock start = _itemMap;
ItemBlock block = start.Next;
while (block != stop)
{
RealizedItemBlock rib = block as RealizedItemBlock;
if (rib != null)
{
// Search for groups within realized blocks
count += GetRealizedItemBlockCount(rib, rib.ItemCount);
}
else
{
count += block.ItemCount;
}
block = block.Next;
}
return count;
}
private int GetRealizedItemBlockCount(RealizedItemBlock rib, int end)
{
if (!IsGrouping)
{
// when the UI is not grouping, each item counts as 1, even
// groups (bug 1761421)
return end;
}
int count = 0;
for (int offset = 0; offset < end; ++offset)
{
CollectionViewGroup group;
if ((group = rib.ItemAt(offset) as CollectionViewGroup) != null)
{
// found a group, count the group
GroupItem groupItem = (GroupItem)rib.ContainerAt(offset);
count += groupItem.Generator.GetCount();
}
else
{
count++;
}
}
return count;
}
///
/// Return the UI element corresponding to the item at the given index
/// within the ItemCollection.
///
public DependencyObject ContainerFromIndex(int index)
{
#if DEBUG
object target = (Parent == null) && (0 <= index && index < Host.View.Count) ? Host.View[index] : null;
#endif
int subIndex = 0;
// if we're grouping, determine the appropriate child
if (IsGrouping)
{
int n;
subIndex = index;
for (index=0, n=Items.Count; index < n; ++index)
{
CollectionViewGroup group = Items[index] as CollectionViewGroup;
int size = (group == null) ? 1 : group.ItemCount;
if (subIndex < size)
break;
else
subIndex -= size;
}
}
// search the table for the item
for (ItemBlock block = _itemMap.Next; block != _itemMap; block = block.Next)
{
if (index < block.ItemCount)
{
DependencyObject container = block.ContainerAt(index);
GroupItem groupItem = container as GroupItem;
if (groupItem != null)
{
container = groupItem.Generator.ContainerFromIndex(subIndex);
}
#if DEBUG
object item = (Parent == null) && (container != null) ?
container.ReadLocalValue(ItemForItemContainerProperty) : null;
Debug.Assert(item == null || Object.Equals(item, target),
"Generator's data structure is corrupt - ContainerFromIndex found wrong item");
#endif
return container;
}
index -= block.ItemCount;
}
return null; // *not* throw new IndexOutOfRangeException(); - bug 890195
}
//-----------------------------------------------------
//
// Public Events
//
//------------------------------------------------------
///
/// The ItemsChanged event is raised by a ItemContainerGenerator to inform
/// layouts that the items collection has changed.
///
public event ItemsChangedEventHandler ItemsChanged;
///
/// The StatusChanged event is raised by a ItemContainerGenerator to inform
/// controls that its status has changed.
///
public event EventHandler StatusChanged;
//-----------------------------------------------------
//
// Internal methods
//
//-----------------------------------------------------
// regenerate everything
internal void Refresh()
{
OnRefresh();
}
// called when this generator is no longer needed
internal void Release()
{
((IItemContainerGenerator)this).RemoveAll();
}
// called when the host's AlternationCount changes
internal void ChangeAlternationCount()
{
// update my AlternationCount and adjust my containers
SetAlternationCount();
// propagate to subgroups, if necessary
if (IsGrouping && GroupStyle != null)
{
ItemBlock block = _itemMap.Next;
while (block != _itemMap)
{
for (int offset = 0; offset < block.ContainerCount; ++offset)
{
GroupItem gi = ((RealizedItemBlock)block).ContainerAt(offset) as GroupItem;
if (gi != null)
{
gi.Generator.ChangeAlternationCount();
}
}
block = block.Next;
}
}
}
// update AlternationIndex on each container to reflect the new AlternationCount
void ChangeAlternationCount(int newAlternationCount)
{
if (_alternationCount == newAlternationCount)
return;
// find the first realized container (need this regardless of what happens)
ItemBlock block = _itemMap.Next;
int offset = 0;
while (offset == block.ContainerCount)
{
block = block.Next;
}
// if there are no realized containers, there's nothing to do
if (block != _itemMap)
{
// if user is requesting alternation, reset each container's AlternationIndex
if (newAlternationCount > 0)
{
_alternationCount = newAlternationCount;
SetAlternationIndex((RealizedItemBlock)block, offset, GeneratorDirection.Forward);
}
// otherwise, clear each container's AlternationIndex
else if (_alternationCount > 0)
{
while (block != _itemMap)
{
for (offset = 0; offset < block.ContainerCount; ++offset)
{
ItemsControl.ClearAlternationIndex(((RealizedItemBlock)block).ContainerAt(offset));
}
block = block.Next;
}
}
}
_alternationCount = newAlternationCount;
}
//-----------------------------------------------------
//
// Internal properties
//
//------------------------------------------------------
internal ItemContainerGenerator Parent
{
get { return _parent;}
}
internal int Level
{
get { return _level;}
}
// The group style that governs the generation of UI for the items.
internal GroupStyle GroupStyle
{
get { return _groupStyle; }
set
{
if (_groupStyle != value)
{
if (_groupStyle is INotifyPropertyChanged)
{
PropertyChangedEventManager.RemoveListener(_groupStyle, this, String.Empty);
}
_groupStyle = value;
if (_groupStyle is INotifyPropertyChanged)
{
PropertyChangedEventManager.AddListener(_groupStyle, this, String.Empty);
}
}
}
}
// The collection of items, as IList
internal IList Items
{
get { return _items; }
set
{
if (_items != value)
{
INotifyCollectionChanged incc = _items as INotifyCollectionChanged;
if (_items != Host.View && incc != null)
{
CollectionChangedEventManager.RemoveListener(incc, this);
}
_items = value;
incc = _items as INotifyCollectionChanged;
if (_items != Host.View && incc != null)
{
CollectionChangedEventManager.AddListener(incc, this);
}
}
}
}
///
/// ItemForItemContainer DependencyProperty
///
// This is an attached property that the generator sets on each container
// (generated or direct) to point back to the item.
internal static readonly DependencyProperty ItemForItemContainerProperty =
DependencyProperty.RegisterAttached("ItemForItemContainer", typeof(object), typeof(ItemContainerGenerator),
new FrameworkPropertyMetadata((object)null));
//-----------------------------------------------------
//
// Internal events
//
//------------------------------------------------------
internal event EventHandler PanelChanged;
internal void OnPanelChanged()
{
if (PanelChanged != null)
PanelChanged(this, EventArgs.Empty);
}
//------------------------------------------------------
//
// Private Nested Class - ItemContainerGenerator.Generator
//
//-----------------------------------------------------
///
/// Generator is the object that generates UI on behalf of an ItemsControl,
/// working under the supervision of an ItemContainerGenerator.
///
private class Generator : IDisposable
{
//------------------------------------------------------
//
// Constructors
//
//-----------------------------------------------------
internal Generator(ItemContainerGenerator factory, GeneratorPosition position, GeneratorDirection direction, bool allowStartAtRealizedItem)
{
_factory = factory;
_direction = direction;
_factory.MapChanged += new MapChangedHandler(OnMapChanged);
_factory.MoveToPosition(position, direction, allowStartAtRealizedItem, ref _cachedState);
_done = (_factory.Items.Count == 0);
_factory.SetStatus(GeneratorStatus.GeneratingContainers);
}
//-----------------------------------------------------
//
// Public Properties
//
//-----------------------------------------------------
/* This method was requested for virtualization. It's not being used right now
(bug 1079525) but it probably will be when UI virtualization comes back.
///
/// returns false if a call to GenerateNext is known to return null (indicating
/// that the generator is done). Does not generate anything or change the
/// generator's state; cheaper than GenerateNext. Returning true does not
/// necessarily mean GenerateNext will produce anything.
///
public bool IsActive
{
get { return !_done; }
}
*/
//------------------------------------------------------
//
// Public Methods
//
//-----------------------------------------------------
/// Generate UI for the next item or group
public DependencyObject GenerateNext(bool stopAtRealized, out bool isNewlyRealized)
{
DependencyObject container = null;
isNewlyRealized = false;
while (container == null)
{
UnrealizedItemBlock uBlock = _cachedState.Block as UnrealizedItemBlock;
IList items = _factory.Items;
int itemIndex = _cachedState.ItemIndex;
int incr = (_direction == GeneratorDirection.Forward) ? +1 : -1;
if (_cachedState.Block == _factory._itemMap)
_done = true; // we've reached the end of the list
if (uBlock == null && stopAtRealized)
_done = true;
if (!(0 <= itemIndex && itemIndex < items.Count))
_done = true;
if (_done)
{
isNewlyRealized = false;
return null;
}
object item = items[itemIndex];
if (uBlock != null)
{
// We don't have a realized container for this item. Try to use a recycled container
// if possible, otherwise generate a new container.
isNewlyRealized = true;
CollectionViewGroup group = item as CollectionViewGroup;
if (group == null || !_factory.IsGrouping)
{
if (_factory._recyclableContainers.Count > 0 && !_factory.Host.IsItemItsOwnContainer(item))
{
container = _factory._recyclableContainers.Dequeue();
isNewlyRealized = false;
}
else
{
// generate container for an item
container = _factory.Host.GetContainerForItem(item);
}
ItemContainerGenerator.LinkContainerToItem(container, item, /* isRecycled = */ !isNewlyRealized);
}
else
{
// generate container for a group
container = _factory.ContainerForGroup(group);
}
// add the (item, container) to the current block
if (container != null)
{
_factory.Realize(uBlock, _cachedState.Offset, item, container);
// set AlternationIndex on the container (and possibly others)
_factory.SetAlternationIndex(_cachedState.Block, _cachedState.Offset, _direction);
}
}
else
{
// return existing realized container
isNewlyRealized = false;
RealizedItemBlock rib = (RealizedItemBlock)_cachedState.Block;
container = rib.ContainerAt(_cachedState.Offset);
}
// advance to the next item
_cachedState.ItemIndex = itemIndex;
if (_direction == GeneratorDirection.Forward)
{
_cachedState.Block.MoveForward(ref _cachedState, true);
}
else
{
_cachedState.Block.MoveBackward(ref _cachedState, true);
}
}
return container;
}
//------------------------------------------------------
//
// Interfaces - IDisposable
//
//------------------------------------------------------
/// Dispose this generator.
void IDisposable.Dispose()
{
if (_factory != null)
{
_factory.MapChanged -= new MapChangedHandler(OnMapChanged);
_done = true;
_factory.SetStatus(GeneratorStatus.ContainersGenerated);
_factory._generator = null;
_factory = null;
}
}
//-----------------------------------------------------
//
// Private methods
//
//------------------------------------------------------
// The map data structure has changed, so the state must change accordingly.
// This is called in various different ways.
// A. Items were moved within the data structure, typically because
// items were realized or un-realized. In this case, the args are:
// block - the block from where the items were moved
// offset - the offset within the block of the first item moved
// count - how many items moved
// newBlock - the block to which the items were moved
// newOffset - the offset within the new block of the first item moved
// deltaCount - the difference between the cumululative item counts
// of newBlock and block
// B. An item was added or removed from the data structure. In this
// case the args are:
// block - null (to distinguish case B from case A)
// offset - the index of the changed item, w.r.t. the entire item list
// count - +1 for insertion, -1 for deletion
// others - unused
// C. Refresh: all items are returned to a single unrealized block.
// In this case, the args are:
// block - null
// offset - -1 (to distinguish case C from case B)
// newBlock = the single unrealized block
// others - unused
void OnMapChanged(ItemBlock block, int offset, int count,
ItemBlock newBlock, int newOffset, int deltaCount)
{
// Case A. Items were moved within the map data structure
if (block != null)
{
// if the move affects this generator, update the cached state
if (block == _cachedState.Block && offset <= _cachedState.Offset &&
_cachedState.Offset < offset + count)
{
_cachedState.Block = newBlock;
_cachedState.Offset += newOffset - offset;
_cachedState.Count += deltaCount;
}
}
// Case B. An item was inserted or deleted
else if (offset >= 0)
{
// if the item occurs before my block, update my item count
if (offset < _cachedState.Count)
{
_cachedState.Count += count;
_cachedState.ItemIndex += count;
}
// if the item occurs within my block before my item, update my offset
else if (offset < _cachedState.Count + _cachedState.Offset)
{
_cachedState.Offset += count;
_cachedState.ItemIndex += count;
}
// if an insert occurs at my position, update my offset
else if (offset == _cachedState.Count + _cachedState.Offset &&
count > 0)
{
_cachedState.Offset += count;
_cachedState.ItemIndex += count;
}
}
// Case C. Refresh
else
{
_cachedState.Block = newBlock;
_cachedState.Offset += _cachedState.Count;
_cachedState.Count = 0;
}
}
//-----------------------------------------------------
//
// Private Fields
//
//-----------------------------------------------------
ItemContainerGenerator _factory;
GeneratorDirection _direction;
bool _done;
GeneratorState _cachedState;
}
//-----------------------------------------------------
//
// Private Properties
//
//------------------------------------------------------
IGeneratorHost Host { get { return _host; } }
// The DO for which this generator was created. For normal generators,
// this is the ItemsControl. For subgroup generators, this is
// the GroupItem.
DependencyObject Peer
{
get { return _peer; }
}
bool IsGrouping
{
get { return (Items != Host.View); }
}
//-----------------------------------------------------
//
// Private Methods
//
//------------------------------------------------------
void MoveToPosition(GeneratorPosition position, GeneratorDirection direction, bool allowStartAtRealizedItem, ref GeneratorState state)
{
ItemBlock block = _itemMap;
int itemIndex = 0;
// first move to the indexed (realized) item
if (position.Index != -1)
{
// find the right block
int itemCount = 0;
int index = position.Index;
block = block.Next;
while (index >= block.ContainerCount)
{
itemCount += block.ItemCount;
index -= block.ContainerCount;
itemIndex += block.ItemCount;
block = block.Next;
}
// set the position
state.Block = block;
state.Offset = index;
state.Count = itemCount;
state.ItemIndex = itemIndex + index;
}
else
{
state.Block = block;
state.Offset = 0;
state.Count = 0;
state.ItemIndex = itemIndex - 1;
}
// adjust the offset - we always set the state so it points to the next
// item to be generated.
int offset = position.Offset;
if (offset == 0 && (!allowStartAtRealizedItem || state.Block == _itemMap))
{
offset = (direction == GeneratorDirection.Forward) ? 1 : -1;
}
// advance the state according to the offset
if (offset > 0)
{
state.Block.MoveForward(ref state, true);
while (--offset > 0)
{
state.Block.MoveForward(ref state, allowStartAtRealizedItem);
}
}
else if (offset < 0)
{
if (state.Block == _itemMap)
{
state.ItemIndex = state.Count = Items.Count;
}
state.Block.MoveBackward(ref state, true);
while (++offset < 0)
{
state.Block.MoveBackward(ref state, allowStartAtRealizedItem);
}
}
}
// "Realize" the item in a block at the given offset, to be
// the given item with corresponding container. This means updating
// the item map data structure so that the item belongs to a Realized block.
// It also requires updating the state of every generator to track the
// changes we make here.
void Realize(UnrealizedItemBlock block, int offset, object item, DependencyObject container)
{
RealizedItemBlock prevR, nextR;
RealizedItemBlock newBlock; // new location of the target item
int newOffset; // its offset within the new block
int deltaCount; // diff between cumulative item count of block and newBlock
// if we're realizing the leftmost item and there's room in the
// previous block, move it there
if (offset == 0 &&
(prevR = block.Prev as RealizedItemBlock) != null &&
prevR.ItemCount < ItemBlock.BlockSize)
{
newBlock = prevR;
newOffset = prevR.ItemCount;
MoveItems(block, offset, 1, newBlock, newOffset, -prevR.ItemCount);
MoveItems(block, 1, block.ItemCount, block, 0, +1);
}
// if we're realizing the rightmost item and there's room in the
// next block, move it there
else if (offset == block.ItemCount - 1 &&
(nextR = block.Next as RealizedItemBlock) != null &&
nextR.ItemCount < ItemBlock.BlockSize)
{
newBlock = nextR;
newOffset = 0;
MoveItems(newBlock, 0, newBlock.ItemCount, newBlock, 1, -1);
MoveItems(block, offset, 1, newBlock, newOffset, offset);
}
// otherwise we need a new block for the target item
else
{
newBlock = new RealizedItemBlock();
newOffset = 0;
deltaCount = offset;
// if target is leftmost item, insert it before remaining items
if (offset == 0)
{
newBlock.InsertBefore(block);
MoveItems(block, offset, 1, newBlock, newOffset, 0);
MoveItems(block, 1, block.ItemCount, block, 0, +1);
}
// if target is rightmost item, insert it after remaining items
else if (offset == block.ItemCount - 1)
{
newBlock.InsertAfter(block);
MoveItems(block, offset, 1, newBlock, newOffset, offset);
}
// otherwise split the block into two, with the target in the middle
else
{
UnrealizedItemBlock newUBlock = new UnrealizedItemBlock();
newUBlock.InsertAfter(block);
newBlock.InsertAfter(block);
MoveItems(block, offset+1, block.ItemCount-offset-1, newUBlock, 0, offset+1);
MoveItems(block, offset, 1, newBlock, 0, offset);
}
}
RemoveAndCoalesceBlocksIfNeeded(block);
// add the new target to the map
newBlock.RealizeItem(newOffset, item, container);
}
void RemoveAndCoalesceBlocksIfNeeded(ItemBlock block)
{
if (block != null && block != _itemMap && block.ItemCount == 0)
{
block.Remove();
// coalesce adjacent unrealized blocks
if (block.Prev is UnrealizedItemBlock && block.Next is UnrealizedItemBlock)
{
MoveItems(block.Next, 0, block.Next.ItemCount, block.Prev, block.Prev.ItemCount, -block.Prev.ItemCount-1);
block.Next.Remove();
}
}
}
// Move 'count' items starting at position 'offset' in block 'block'
// to position 'newOffset' in block 'newBlock'. The difference between
// the cumulative item counts of newBlock and block is given by 'deltaCount'.
void MoveItems(ItemBlock block, int offset, int count,
ItemBlock newBlock, int newOffset, int deltaCount)
{
RealizedItemBlock ribSrc = block as RealizedItemBlock;
RealizedItemBlock ribDst = newBlock as RealizedItemBlock;
// when both blocks are Realized, entries must be physically copied
if (ribSrc != null && ribDst != null)
{
ribDst.CopyEntries(ribSrc, offset, count, newOffset);
}
// when the source block is Realized, clear the vacated entries -
// to avoid leaks. (No need if it's now empty - the block will get GC'd).
else if (ribSrc != null && ribSrc.ItemCount > count)
{
ribSrc.ClearEntries(offset, count);
}
// update block information
block.ItemCount -= count;
newBlock.ItemCount += count;
// tell generators what happened
if (MapChanged != null)
MapChanged(block, offset, count, newBlock, newOffset, deltaCount);
}
// Set the AlternationIndex on a newly-realized container. Also, reset
// the AlternationIndex on other containers to maintain the adjacency
// criterion.
void SetAlternationIndex(ItemBlock block, int offset, GeneratorDirection direction)
{
// If user doesn't request alternation, don't do anything
if (_alternationCount <= 0)
return;
int index;
RealizedItemBlock rib;
// Proceed in the direction of generation. This tends to reach the
// end sooner (often in one step).
if (direction != GeneratorDirection.Backward)
{
// Forward. Back up one container to determine the starting index
-- offset;
while (offset < 0 || block is UnrealizedItemBlock)
{
block = block.Prev;
offset = block.ContainerCount - 1;
}
rib = block as RealizedItemBlock;
index = (block == _itemMap) ? -1 : ItemsControl.GetAlternationIndex(rib.ContainerAt(offset));
// loop through the remaining containers, resetting each AlternationIndex
for (;;)
{
// advance to next realized container
++offset;
while (offset == block.ContainerCount)
{
block = block.Next;
offset = 0;
}
// exit if we've reached the end
if (block == _itemMap)
break;
// advance the AlternationIndex
index = (index + 1) % _alternationCount;
// assign it to the container
rib = block as RealizedItemBlock;
ItemsControl.SetAlternationIndex(rib.ContainerAt(offset), index);
}
}
else
{
// Backward. Advance one container to determine the starting index
++ offset;
while (offset >= block.ContainerCount || block is UnrealizedItemBlock)
{
block = block.Next;
offset = 0;
}
rib = block as RealizedItemBlock;
index = (block == _itemMap) ? _alternationCount : ItemsControl.GetAlternationIndex(rib.ContainerAt(offset));
// loop through the remaining containers, resetting each AlternationIndex
for (;;)
{
// retreat to next realized container
--offset;
while (offset == 0)
{
block = block.Prev;
offset = block.ContainerCount;
}
// exit if we've reached the end
if (block == _itemMap)
break;
// retreat the AlternationIndex
index = (index - 1) % _alternationCount;
// assign it to the container
rib = block as RealizedItemBlock;
ItemsControl.SetAlternationIndex(rib.ContainerAt(offset), index);
}
}
}
// create a group item for the given group
DependencyObject ContainerForGroup(CollectionViewGroup group)
{
if (!ShouldHide(group))
{
// normal group - link a new GroupItem
GroupItem groupItem = new GroupItem();
LinkContainerToItem(groupItem, group);
// create the generator
groupItem.Generator = new ItemContainerGenerator(this, groupItem);
return groupItem;
}
else
{
// hidden empty group - link a new EmptyGroupItem
AddEmptyGroupItem(group);
// but don't return it to layout
return null;
}
}
// prepare the grouping information. Called from RemoveAll.
void PrepareGrouping()
{
GroupStyle groupStyle;
IList items;
if (Level == 0)
{
groupStyle = Host.GetGroupStyle(null, 0);
if (groupStyle == null)
{
items = Host.View;
}
else
{
CollectionView cv = Host.View.CollectionView;
items = (cv == null) ? null : cv.Groups;
if (items == null)
{
items = Host.View;
}
}
}
else
{
GroupItem groupItem = (GroupItem)Peer;
CollectionViewGroup group = groupItem.ReadLocalValue(ItemForItemContainerProperty) as CollectionViewGroup;
if (group != null)
{
if (group.IsBottomLevel)
{
groupStyle = null;
}
else
{
groupStyle = Host.GetGroupStyle(group, Level);
}
items = group.Items;
}
else
{
groupStyle = null;
items = Host.View;
}
}
GroupStyle = groupStyle;
Items = items;
if ((Level == 0) && (Host != null))
{
// Notify the host of a change in IsGrouping
Host.SetIsGrouping(IsGrouping);
}
}
void SetAlternationCount()
{
int alternationCount;
if (IsGrouping && GroupStyle != null)
{
if (GroupStyle.IsAlternationCountSet)
{
alternationCount = GroupStyle.AlternationCount;
}
else if (_parent != null)
{
alternationCount = _parent._alternationCount;
}
else
{
alternationCount = Host.AlternationCount;
}
}
else
{
alternationCount = Host.AlternationCount;
}
ChangeAlternationCount(alternationCount);
}
// should the given group be hidden?
bool ShouldHide(CollectionViewGroup group)
{
return GroupStyle.HidesIfEmpty && // user asked to hide
group.ItemCount == 0; // group is empty
}
// create an empty-group placeholder item
void AddEmptyGroupItem(CollectionViewGroup group)
{
EmptyGroupItem emptyGroupItem = new EmptyGroupItem();
LinkContainerToItem(emptyGroupItem, group);
emptyGroupItem.SetGenerator(new ItemContainerGenerator(this, emptyGroupItem));
// add it to the list of placeholder items (this keeps it from being GC'd)
if (_emptyGroupItems == null)
_emptyGroupItems = new ArrayList();
_emptyGroupItems.Add(emptyGroupItem);
}
// notification that a subgroup has become non-empty
void OnSubgroupBecameNonEmpty(EmptyGroupItem groupItem, CollectionViewGroup group)
{
// Discard placeholder container.
UnlinkContainerFromItem(groupItem, group);
if (_emptyGroupItems != null)
_emptyGroupItems.Remove(groupItem);
// inform layout as if the group just got added
if (ItemsChanged != null)
{
GeneratorPosition position = PositionFromIndex(Items.IndexOf(group));
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Add, position, 1, 0));
}
}
// notification that a subgroup has become empty
void OnSubgroupBecameEmpty(CollectionViewGroup group)
{
if (ShouldHide(group))
{
GeneratorPosition position = PositionFromIndex(Items.IndexOf(group));
// if the group is realized, un-realize it and notify layout
if (position.Offset == 0 && position.Index >= 0)
{
// un-realize
((IItemContainerGenerator)this).Remove(position, 1);
// inform layout as if the group just got removed
if (ItemsChanged != null)
{
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Remove, position, 1, 1));
}
// create the placeholder
AddEmptyGroupItem(group);
}
}
}
// convert an index (into Items) into a GeneratorPosition
GeneratorPosition PositionFromIndex(int itemIndex)
{
GeneratorPosition position;
ItemBlock itemBlock;
int offsetFromBlockStart;
GetBlockAndPosition(itemIndex, out position, out itemBlock, out offsetFromBlockStart);
return position;
}
void GetBlockAndPosition(object item, int itemIndex, bool deletedFromItems, out GeneratorPosition position, out ItemBlock block, out int offsetFromBlockStart, out int correctIndex)
{
if (itemIndex >= 0)
{
GetBlockAndPosition(itemIndex, out position, out block, out offsetFromBlockStart);
correctIndex = itemIndex;
}
else
{
GetBlockAndPosition(item, deletedFromItems, out position, out block, out offsetFromBlockStart, out correctIndex);
}
}
void GetBlockAndPosition(int itemIndex, out GeneratorPosition position, out ItemBlock block, out int offsetFromBlockStart)
{
position = new GeneratorPosition(-1, 0);
block = null;
offsetFromBlockStart = itemIndex;
if (_itemMap == null || itemIndex < 0)
return;
int containerIndex = 0;
for (block = _itemMap.Next; block != _itemMap; block = block.Next)
{
if (offsetFromBlockStart >= block.ItemCount)
{
// item belongs to a later block, increment the containerIndex
containerIndex += block.ContainerCount;
offsetFromBlockStart -= block.ItemCount;
}
else
{
// item belongs to this block. Determine the container index and offset
if (block.ContainerCount > 0)
{
// block has realized items
position = new GeneratorPosition(containerIndex + offsetFromBlockStart, 0);
}
else
{
// block has unrealized items
position = new GeneratorPosition(containerIndex-1, offsetFromBlockStart+1);
}
break;
}
}
}
void GetBlockAndPosition(object item, bool deletedFromItems, out GeneratorPosition position, out ItemBlock block, out int offsetFromBlockStart, out int correctIndex)
{
correctIndex = 0;
int containerIndex = 0;
offsetFromBlockStart = 0;
int deletionOffset = deletedFromItems ? 1 : 0;
position = new GeneratorPosition(-1, 0);
for (block = _itemMap.Next; block != _itemMap; block = block.Next)
{
UnrealizedItemBlock uib;
RealizedItemBlock rib = block as RealizedItemBlock;
if (rib != null)
{
// compare realized items with item for which we are searching
offsetFromBlockStart = rib.OffsetOfItem(item);
if (offsetFromBlockStart >= 0)
{
position = new GeneratorPosition(containerIndex + offsetFromBlockStart, 0);
correctIndex += offsetFromBlockStart;
break;
}
}
else if ((uib = block as UnrealizedItemBlock) != null)
{
// if the item isn't realized, we can't find it
// directly. Instead, look for indirect evidence that it
// belongs to this block by checking the indices of
// nearby realized items.
#if DEBUG
// Sanity check - make sure data structure is OK so far.
rib = block.Prev as RealizedItemBlock;
if (rib != null && rib.ContainerCount > 0)
{
Debug.Assert(Object.Equals(rib.ItemAt(rib.ContainerCount - 1),
Items[correctIndex - 1]),
"Generator data structure is corrupt");
}
#endif
bool itemIsInCurrentBlock = false;
rib = block.Next as RealizedItemBlock;
if (rib != null && rib.ContainerCount > 0)
{
// if the index of the next realized item is off by one,
// the deleted item likely comes from the current
// unrealized block.
itemIsInCurrentBlock =
Object.Equals(rib.ItemAt(0),
Items[correctIndex + block.ItemCount - deletionOffset]);
}
else if (block.Next == _itemMap)
{
// similarly if we're at the end of the list and the
// overall count is off by one, or if the current block
// is the only block, the deleted item likely
// comes from the current (last) unrealized block
itemIsInCurrentBlock = block.Prev == _itemMap ||
(Items.Count == correctIndex + block.ItemCount - deletionOffset);
}
if (itemIsInCurrentBlock)
{
// we don't know where it is in this block, so assume
// it's the very first item.
offsetFromBlockStart = 0;
position = new GeneratorPosition(containerIndex-1, 1);
break;
}
}
correctIndex += block.ItemCount;
containerIndex += block.ContainerCount;
}
if (block == _itemMap)
{
// There's no way of knowing which unrealized block it belonged to, so
// the data structure can't be updated correctly. Sound the alarm.
throw new InvalidOperationException(SR.Get(SRID.CannotFindRemovedItem));
}
}
private void LinkContainerToItem(DependencyObject container, object item)
{
LinkContainerToItem(container, item, false);
}
// establish the link from the container to the corresponding item
static void LinkContainerToItem(DependencyObject container, object item, bool isRecycled)
{
// always set the ItemForItemContainer property
container.ClearValue(ItemForItemContainerProperty);
container.SetValue(ItemForItemContainerProperty, item);
// for non-direct items, set the DataContext property
if (container != item)
{
if (!isRecycled)
{
// We already cleared recycled containers in UnlinkContainerFromItem
container.ClearValue(FrameworkElement.DataContextProperty);
}
container.SetValue(FrameworkElement.DataContextProperty, item);
}
}
private void UnlinkContainerFromItem(DependencyObject container, object item)
{
UnlinkContainerFromItem(container, item, false);
}
// unlink the container from the corresponding item
private void UnlinkContainerFromItem(DependencyObject container, object item, bool isRecycled)
{
container.ClearValue(ItemForItemContainerProperty);
// There are two ways to view the properties set by PrepareItemContainer:
//
// a) these properties are added by the generator/host so that
// the container can function correctly in the generated tree.
//
// b) these properties are part of the container's initial state,
// independent of whether the container belongs to the tree.
//
// If you take the first point of view, then the generator should remove
// these properties when the container is removed from the tree. If
// you take the second point of view, then the generator should not do this.
//
// In response to bug 1445288 and independent discussions, we take the
// second point of view. This saves the cost of clearing all those
// properties, which can add up to quite a lot. As long as no one expects
// to use a container after it has been removed, there should be no harm.
//
// We make a small exception for the ItemForItemContainer property, since
// that is an internal property that only makes sense for an active container.
//
// When we're in Recycling mode, the above doesn't apply; we need to clear off
// the DataContext property on the container since it will get re-used. The
// issue here is that if we don't clear it off we can alias DataContexts; we
// could get a container on the recycled list with the same DataContext as a
// live container -- that causes all sorts of subtle issues.
//
if (isRecycled && container != item)
{
// ClearValue has a perf problem because the DataContext will be inherited by the recycled container's
// parent. That will cause us to resolve a binding that we really don't care about. This can be insanely expensive
// depending on the structure of the data.
//
// In the rare case that the DataContext property has an expression on it we have to do ClearValue to get rid of it
// so that the SetValue later in LinkContainerToItem will work.
DependencyProperty dp = FrameworkElement.DataContextProperty;
EntryIndex entryIndex = container.LookupEntry(dp.GlobalIndex);
if (container.HasExpression(entryIndex, dp))
{
container.ClearValue(dp);
}
else
{
container.SetValue(dp, null);
}
}
_host.ClearContainerForItem(container, item);
}
///
/// Handle events from the centralized event table
///
bool IWeakEventListener.ReceiveWeakEvent(Type managerType, object sender, EventArgs e)
{
if (managerType == typeof(PropertyChangedEventManager))
{
PropertyChangedEventArgs pce = (PropertyChangedEventArgs)e;
if (sender == GroupStyle)
{
if (pce.PropertyName == "Panel")
{
OnPanelChanged();
}
else
{
OnRefresh();
}
}
}
else if (managerType == typeof(CollectionChangedEventManager))
{
OnCollectionChanged(sender, (NotifyCollectionChangedEventArgs)e);
}
else
{
return false; // unrecognized event
}
return true;
}
void ValidateAndCorrectIndex(object item, ref int index)
{
if (index >= 0)
{
// this check is expensive - Items[index] potentially iterates through
// the collection. So trust the sender to tell us the truth in retail bits.
Debug.Assert(Object.Equals(item, Items[index]), "Event contains the wrong index");
}
else
{
index = Items.IndexOf(item);
if (index < 0)
throw new InvalidOperationException(SR.Get(SRID.CollectionAddEventMissingItem, item));
}
}
///
/// Forward a CollectionChanged event
///
// Called when items collection changes.
void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs args)
{
// get the affected item
object item;
int startingIndex = -1;
switch (args.Action)
{
case NotifyCollectionChangedAction.Add:
case NotifyCollectionChangedAction.Remove:
if (sender != Items)
return; // ignore events from ItemsCollection when we're listening to group's items.
if (args.Action == NotifyCollectionChangedAction.Add)
{
if (args.NewItems.Count != 1)
throw new NotSupportedException(SR.Get(SRID.RangeActionsNotSupported));
item = args.NewItems[0];
startingIndex = args.NewStartingIndex;
}
else
{
if (args.OldItems.Count != 1)
throw new NotSupportedException(SR.Get(SRID.RangeActionsNotSupported));
item = args.OldItems[0];
startingIndex = args.OldStartingIndex;
}
break;
case NotifyCollectionChangedAction.Replace:
case NotifyCollectionChangedAction.Move:
case NotifyCollectionChangedAction.Reset:
item = null;
break;
default:
throw new NotSupportedException(SR.Get(SRID.UnexpectedCollectionChangeAction, args.Action));
}
if (_traceLog != null)
_traceLog.Add("Received collection change from {0} action = {1} item={2}",
TraceLog.IdFor(sender), args.Action, item);
switch (args.Action)
{
case NotifyCollectionChangedAction.Add:
OnItemAdded(item, startingIndex);
break;
case NotifyCollectionChangedAction.Remove:
OnItemRemoved(item, startingIndex);
break;
case NotifyCollectionChangedAction.Replace:
OnItemReplaced(args.OldItems[0], args.NewItems[0], args.NewStartingIndex);
break;
case NotifyCollectionChangedAction.Move:
OnItemMoved(args.OldItems[0], args.OldStartingIndex, args.NewStartingIndex);
break;
case NotifyCollectionChangedAction.Reset:
OnRefresh();
break;
}
}
// Called when an item is added to the items collection
void OnItemAdded(object item, int index)
{
ValidateAndCorrectIndex(item, ref index);
GeneratorPosition position = new GeneratorPosition(-1,0);
// find the block containing the new item
ItemBlock block = _itemMap.Next;
int offset = index;
while (block != _itemMap && offset >= block.ItemCount)
{
offset -= block.ItemCount;
position.Index += block.ContainerCount;
block = block.Next;
}
position.Offset = offset + 1;
// if it's an unrealized block, add the item by bumping the count
UnrealizedItemBlock uib = block as UnrealizedItemBlock;
if (uib != null)
{
MoveItems(uib, offset, 1, uib, offset+1, 0);
++ uib.ItemCount;
}
// if the item can be added to a previous unrealized block, do so
else if ((offset == 0 || block == _itemMap) &&
((uib = block.Prev as UnrealizedItemBlock) != null))
{
++ uib.ItemCount;
}
// otherwise, create a new unrealized block
else
{
uib = new UnrealizedItemBlock();
uib.ItemCount = 1;
// split the current realized block, if necessary
RealizedItemBlock rib;
if (offset > 0 && (rib = block as RealizedItemBlock) != null)
{
RealizedItemBlock newBlock = new RealizedItemBlock();
MoveItems(rib, offset, rib.ItemCount - offset, newBlock, 0, offset);
newBlock.InsertAfter(rib);
position.Index += block.ContainerCount;
position.Offset = 1;
block = newBlock;
}
uib.InsertBefore(block);
}
if (_traceLog != null)
_traceLog.Add("OnItemAdded {0} index = {1}", TraceLog.IdFor(item), index);
// tell generators what happened
if (MapChanged != null)
{
MapChanged(null, index, +1, null, 0, 0);
}
// tell layout what happened
if (ItemsChanged != null)
{
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Add, position, 1, 0));
}
}
// Called when an item is removed from the items collection
void OnItemRemoved(object item, int itemIndex)
{
DependencyObject container = null; // the corresponding container
int containerCount = 0;
// search for the deleted item
GeneratorPosition position;
ItemBlock block;
int offsetFromBlockStart;
int correctIndex;
GetBlockAndPosition(item, itemIndex, true, out position, out block, out offsetFromBlockStart, out correctIndex);
RealizedItemBlock rib = block as RealizedItemBlock;
if (rib != null)
{
containerCount = 1;
container = rib.ContainerAt(offsetFromBlockStart);
}
// remove the item, and remove the block if it's now empty
MoveItems(block, offsetFromBlockStart + 1, block.ItemCount - offsetFromBlockStart - 1, block, offsetFromBlockStart, 0);
--block.ItemCount;
if (rib != null)
{
// fix up the alternation index before removing an empty block, while
// we still have a valid block and offset
SetAlternationIndex(block, offsetFromBlockStart, GeneratorDirection.Forward);
}
RemoveAndCoalesceBlocksIfNeeded(block);
if (_traceLog != null)
_traceLog.Add("OnItemRemoved {0} index = {1}", TraceLog.IdFor(item), itemIndex);
// tell generators what happened
if (MapChanged != null)
{
MapChanged(null, itemIndex, -1, null, 0, 0);
}
// tell layout what happened
if (ItemsChanged != null)
{
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Remove, position, 1, containerCount));
}
// unhook the container. Do this after layout has (presumably) removed it from
// the UI, so that it doesn't inherit DataContext falsely.
if (container != null)
{
UnlinkContainerFromItem(container, item);
}
// detect empty groups, so they can be hidden if necessary
if (Level > 0 && Items.Count == 0)
{
GroupItem groupItem = (GroupItem)Peer;
CollectionViewGroup group = groupItem.ReadLocalValue(ItemForItemContainerProperty) as CollectionViewGroup;
// the group could be null if the parent generator has already
// unhooked its container
if (group != null)
{
Parent.OnSubgroupBecameEmpty(group);
}
}
}
void OnItemReplaced(object oldItem, object newItem, int index)
{
// search for the replaced item
GeneratorPosition position;
ItemBlock block;
int offsetFromBlockStart;
int correctIndex;
GetBlockAndPosition(oldItem, index, false, out position, out block, out offsetFromBlockStart, out correctIndex);
// If the item is in an UnrealizedItemBlock, then this change need not
// be made to the _itemsMap as we are replacing an unrealized item with another unrealized
// item in the same place.
RealizedItemBlock rib = block as RealizedItemBlock;
if (rib != null)
{
DependencyObject container = rib.ContainerAt(offsetFromBlockStart);
// replace the old item with the new one
rib.RealizeItem(offsetFromBlockStart, newItem, container);
// hook up the container to the new item
LinkContainerToItem(container, newItem);
_host.PrepareItemContainer(container, newItem);
}
if (_traceLog != null)
_traceLog.Add("OnItemReplaced {0} index = {1}", TraceLog.IdFor(oldItem), index);
}
void OnItemMoved(object item, int oldIndex, int newIndex)
{
DependencyObject container = null; // the corresponding container
int containerCount = 0;
UnrealizedItemBlock uib;
// search for the moved item
GeneratorPosition position;
ItemBlock block;
int offsetFromBlockStart;
int correctIndex;
GetBlockAndPosition(item, oldIndex, true, out position, out block, out offsetFromBlockStart, out correctIndex);
GeneratorPosition oldPosition = position;
RealizedItemBlock rib = block as RealizedItemBlock;
if (rib != null)
{
containerCount = 1;
container = rib.ContainerAt(offsetFromBlockStart);
}
// remove the item, and remove the block if it's now empty
MoveItems(block, offsetFromBlockStart + 1, block.ItemCount - offsetFromBlockStart - 1, block, offsetFromBlockStart, 0);
--block.ItemCount;
RemoveAndCoalesceBlocksIfNeeded(block);
//
// now insert into the new spot.
//
position = new GeneratorPosition(-1,0);
block = _itemMap.Next;
offsetFromBlockStart = newIndex;
while (block != _itemMap && offsetFromBlockStart >= block.ItemCount)
{
offsetFromBlockStart -= block.ItemCount;
if (block.ContainerCount > 0)
{
position.Index += block.ContainerCount;
position.Offset = 0;
}
else
{
position.Offset += block.ItemCount;
}
block = block.Next;
}
position.Offset += offsetFromBlockStart + 1;
// if it's an unrealized block, add the item by bumping the count
uib = block as UnrealizedItemBlock;
if (uib != null)
{
MoveItems(uib, offsetFromBlockStart, 1, uib, offsetFromBlockStart+1, 0);
++ uib.ItemCount;
}
// if the item can be added to a previous unrealized block, do so
else if ((offsetFromBlockStart == 0 || block == _itemMap) &&
((uib = block.Prev as UnrealizedItemBlock) != null))
{
++ uib.ItemCount;
}
// otherwise, create a new unrealized block
else
{
uib = new UnrealizedItemBlock();
uib.ItemCount = 1;
// split the current realized block, if necessary
if (offsetFromBlockStart > 0 && (rib = block as RealizedItemBlock) != null)
{
RealizedItemBlock newBlock = new RealizedItemBlock();
MoveItems(rib, offsetFromBlockStart, rib.ItemCount - offsetFromBlockStart, newBlock, 0, offsetFromBlockStart);
newBlock.InsertAfter(rib);
position.Index += block.ContainerCount;
position.Offset = 1;
offsetFromBlockStart = 0;
block = newBlock;
}
uib.InsertBefore(block);
}
if (_traceLog != null)
_traceLog.Add("OnItemMoved {0} oldIndex = {1}", TraceLog.IdFor(item), oldIndex);
DependencyObject parent = VisualTreeHelper.GetParentInternal(container);
// tell layout what happened
if (ItemsChanged != null)
{
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Move, position, oldPosition, 1, containerCount));
}
// unhook the container. Do this after layout has (presumably) removed it from
// the UI, so that it doesn't inherit DataContext falsely.
if (container != null)
{
if (parent == null || VisualTreeHelper.GetParentInternal(container) != parent)
{
UnlinkContainerFromItem(container, item);
}
else
{
// If the container has the same visual parent as before then that means that
// the container was just repositioned within the parent's VisualCollection.
// we don't need to unlink the container, but we do need to re-realize the block.
Realize(uib, offsetFromBlockStart, item, container);
}
}
// fix up the AlternationIndex on containers affected by the move
if (_alternationCount > 0)
{
// start with the smaller of the two positions, and proceed forward.
// This tends to preserve the AlternatonIndex on containers at the
// front of the list, as users expect
int index = Math.Min(oldIndex, newIndex);
GetBlockAndPosition(index, out position, out block, out offsetFromBlockStart);
SetAlternationIndex(block, offsetFromBlockStart, GeneratorDirection.Forward);
}
}
// Called when the items collection is refreshed
void OnRefresh()
{
((IItemContainerGenerator)this).RemoveAll();
if (_traceLog != null)
_traceLog.Add("OnRefresh count = {0}", Items.Count);
// tell layout what happened
if (ItemsChanged != null)
{
GeneratorPosition position = new GeneratorPosition(0, 0);
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Reset, position, 0, 0));
}
}
// this method is here just to avoid the compiler error
// error CS0649: Warning as Error: Field '..._traceLog' is never assigned to, and will always have its default value null
void InitializeTraceLog()
{
_traceLog = new TraceLog(20);
}
//------------------------------------------------------
//
// Private Fields
//
//-----------------------------------------------------
private TraceLog _traceLog;
private Generator _generator;
private IGeneratorHost _host;
private ItemBlock _itemMap;
private GeneratorStatus _status;
private int _itemsGenerated;
private int _startIndexForUIFromItem;
private DependencyObject _peer;
private int _level;
private IList _items;
private GroupStyle _groupStyle;
private ItemContainerGenerator _parent;
private ArrayList _emptyGroupItems;
private int _alternationCount;
private Type _containerType; // type of containers on the recycle queue
private Queue _recyclableContainers = new Queue();
event MapChangedHandler MapChanged;
delegate void MapChangedHandler(ItemBlock block, int offset, int count,
ItemBlock newBlock, int newOffset, int deltaCount);
#if GENERATOR_TRACE
MS.Internal.Utility.HFTimer _timer = new MS.Internal.Utility.HFTimer();
MS.Internal.Utility.HFTimer _creationTimer = new MS.Internal.Utility.HFTimer();
#endif
//------------------------------------------------------
//
// Private Nested Classes
//
//-----------------------------------------------------
// The ItemContainerGenerator uses the following data structure to maintain
// the correspondence between items and their containers. It's a doubly-linked
// list of ItemBlocks, with a sentinel node serving as the header.
// Each node maintains two counts: the number of items it holds, and
// the number of containers.
//
// There are two kinds of blocks - one holding only "realized" items (i.e.
// items that have been generated into containers) and one holding only
// unrealized items. The container count of a realized block is the same
// as its item count (one container per item); the container count of an
// unrealized block is zero.
//
// Unrealized blocks can hold any number of items. We only need to know
// the count. Realized blocks have a fixed-sized array (BlockSize) so
// they hold up to that many items and their corresponding containers. When
// a realized block fills up, it inserts a new (empty) realized block into
// the list and carries on.
//
// This data structure was chosen with virtualization in mind. The typical
// state is a long block of unrealized items (the ones that have scrolled
// off the top), followed by a moderate number (<50?) of realized items
// (the ones in view), followed by another long block of unrealized items
// (the ones that have not yet scrolled into view). So the list will contain
// an unrealized block, followed by 3 or 4 realized blocks, followed by
// another unrealized block. Fewer than 10 blocks altogether, so linear
// searching won't cost that much. Thus we don't need a more sophisticated
// data structure. (If profiling reveals that we do, we can always replace
// this one. It's totally private to the ItemContainerGenerator and its
// Generators.)
// represents a block of items
private class ItemBlock
{
public const int BlockSize = 16;
public int ItemCount { get { return _count; } set { _count = value; } }
public ItemBlock Prev { get { return _prev; } set { _prev = value; } }
public ItemBlock Next { get { return _next; } set { _next = value; } }
public virtual int ContainerCount { get { return Int32.MaxValue; } }
public virtual DependencyObject ContainerAt(int index) { return null; }
public virtual object ItemAt(int index) { return null; }
public void InsertAfter(ItemBlock prev)
{
Next = prev.Next;
Prev = prev;
Prev.Next = this;
Next.Prev = this;
}
public void InsertBefore(ItemBlock next)
{
InsertAfter(next.Prev);
}
public void Remove()
{
Prev.Next = Next;
Next.Prev = Prev;
}
public void MoveForward(ref GeneratorState state, bool allowMovePastRealizedItem)
{
if (IsMoveAllowed(allowMovePastRealizedItem))
{
state.ItemIndex += 1;
if (++state.Offset >= ItemCount)
{
state.Block = Next;
state.Offset = 0;
state.Count += ItemCount;
}
}
}
public void MoveBackward(ref GeneratorState state, bool allowMovePastRealizedItem)
{
if (IsMoveAllowed(allowMovePastRealizedItem))
{
if (--state.Offset < 0)
{
state.Block = Prev;
state.Offset = state.Block.ItemCount - 1;
state.Count -= state.Block.ItemCount;
}
state.ItemIndex -= 1;
}
}
protected virtual bool IsMoveAllowed(bool allowMovePastRealizedItem)
{
return allowMovePastRealizedItem;
}
int _count;
ItemBlock _prev, _next;
}
// represents a block of unrealized (ungenerated) items
private class UnrealizedItemBlock : ItemBlock
{
public override int ContainerCount { get { return 0; } }
protected override bool IsMoveAllowed(bool allowMovePastRealizedItem)
{
return true;
}
}
// represents a block of realized (generated) items
private class RealizedItemBlock : ItemBlock
{
public override int ContainerCount { get { return ItemCount; } }
public override DependencyObject ContainerAt(int index)
{
return _entry[index].Container;
}
public override object ItemAt(int index)
{
return _entry[index].Item;
}
public void CopyEntries(RealizedItemBlock src, int offset, int count, int newOffset)
{
int k;
// choose which direction to copy so as not to clobber existing
// entries (in case the source and destination blocks are the same)
if (offset < newOffset)
{
// copy right-to-left
for (k = count - 1; k >= 0; --k)
{
_entry[newOffset + k] = src._entry[offset + k];
}
// clear vacated entries, to avoid leak
if (src != this)
{
src.ClearEntries(offset, count);
}
else
{
src.ClearEntries(offset, newOffset - offset);
}
}
else
{
// copy left-to-right
for (k = 0; k < count; ++k)
{
_entry[newOffset + k] = src._entry[offset + k];
}
// clear vacated entries, to avoid leak
if (src != this)
{
src.ClearEntries(offset, count);
}
else
{
src.ClearEntries(newOffset + count, offset - newOffset);
}
}
}
public void ClearEntries(int offset, int count)
{
for (int i=0; i 0)
{
ItemContainerGenerator generator = Generator;
generator.ItemsChanged -= new ItemsChangedEventHandler(OnItemsChanged);
generator.Parent.OnSubgroupBecameNonEmpty(this, group);
}
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
//----------------------------------------------------------------------------
//
//
// Copyright (C) Microsoft Corporation. All rights reserved.
//
//
// Description: ItemContainerGenerator object
//
// Specs: http://avalon/connecteddata/M5%20General%20Docs/Data%20Styling.mht
//
//---------------------------------------------------------------------------
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Globalization; // for CultureInfo.InvariantCulture (event tracing)
using System.Windows.Media;
using System.Windows.Controls.Primitives; // IItemContainerGenerator
using System.Windows.Data;
using System.Windows.Markup;
using System.Diagnostics;
using MS.Internal;
using MS.Internal.Controls;
using MS.Internal.KnownBoxes;
using MS.Internal.Utility;
using MS.Utility;
namespace System.Windows.Controls
{
///
/// An ItemContainerGenerator is responsible for generating the UI on behalf of
/// its host (e.g. ItemsControl). It maintains the association between the items in
/// the control's data view and the corresponding
/// UIElements. The control's item-host can ask the ItemContainerGenerator for
/// a Generator, which does the actual generation of UI.
///
public sealed class ItemContainerGenerator : IRecyclingItemContainerGenerator, IWeakEventListener
{
//-----------------------------------------------------
//
// Constructors
//
//-----------------------------------------------------
/// Constructor
/// the control that owns the items
internal ItemContainerGenerator(IGeneratorHost host)
: this(null, host, host as DependencyObject, 0)
{
// The top-level generator always listens to changes from ItemsCollection.
// It needs to get these events before anyone else, so that other listeners
// can call the generator's mapping functions with correct results.
CollectionChangedEventManager.AddListener(host.View, this);
}
private ItemContainerGenerator(ItemContainerGenerator parent, GroupItem groupItem)
: this(parent, parent.Host, groupItem, parent.Level + 1)
{
}
private ItemContainerGenerator(ItemContainerGenerator parent, IGeneratorHost host, DependencyObject peer, int level)
{
_parent = parent;
_host = host;
_peer = peer;
_level = level;
OnRefresh();
}
//------------------------------------------------------
//
// Public Properties
//
//-----------------------------------------------------
/// The status of the generator
public GeneratorStatus Status
{
get { return _status; }
}
//[CodeAnalysis("AptcaMethodsShouldOnlyCallAptcaMethods")] //Tracking Bug: 29647
private void SetStatus(GeneratorStatus value)
{
if (value != _status)
{
_status = value;
switch (_status)
{
case GeneratorStatus.GeneratingContainers:
if (EventTrace.IsEnabled(EventTrace.Flags.performance, EventTrace.Level.normal))
{
EventTrace.EventProvider.TraceEvent(EventTrace.GuidFromId(EventTraceGuidId.GENERICSTRINGGUID), MS.Utility.EventType.StartEvent, "ItemsControl.Generator");
_itemsGenerated = 0;
}
else
_itemsGenerated = Int32.MinValue;
#if GENERATOR_TRACE
_creationTimer.Reset();
_timer.Begin();
#endif
break;
case GeneratorStatus.ContainersGenerated:
string label = null;
if (_itemsGenerated >= 0) // this implies that tracing is enabled
{
DependencyObject d = Host as DependencyObject;
if (d != null)
label = (string)d.GetValue(FrameworkElement.NameProperty);
if (label == null || label.Length == 0)
label = Host.GetHashCode().ToString(CultureInfo.InvariantCulture);
EventTrace.EventProvider.TraceEvent(EventTrace.GuidFromId(EventTraceGuidId.GENERICSTRINGGUID),
MS.Utility.EventType.EndEvent,
String.Format(CultureInfo.InvariantCulture, "ItemContainerGenerator for {0} {1} - {2} items", Host.GetType().Name, label, _itemsGenerated));
}
#if GENERATOR_TRACE
_timer.End();
if (_itemsGenerated > 0)
{
Console.WriteLine("Generator for {0} {1} did {2} items in {3:f2} msec - {4:f2} msec/item",
Host.GetType().Name, label, _itemsGenerated, _timer.TimeOfLastPeriod, _timer.TimeOfLastPeriod/_itemsGenerated);
Console.WriteLine(" this excludes time for element creation: {0:f2} msec - {1:f2} msec/item",
_creationTimer.OverallTimeInMilliseconds, _creationTimer.OverallTimeInMilliseconds/_itemsGenerated);
}
#endif
break;
}
if (StatusChanged != null)
StatusChanged(this, EventArgs.Empty);
}
}
//------------------------------------------------------
//
// Public Methods
//
//------------------------------------------------------
#region IItemContainerGenerator
///
/// Return the ItemContainerGenerator appropriate for use by the given panel
///
ItemContainerGenerator IItemContainerGenerator.GetItemContainerGeneratorForPanel(Panel panel)
{
if (!panel.IsItemsHost)
throw new ArgumentException(SR.Get(SRID.PanelIsNotItemsHost), "panel");
// if panel came from an ItemsPresenter, use its generator
ItemsPresenter ip = ItemsPresenter.FromPanel(panel);
if (ip != null)
return ip.Generator;
// if panel came from a style, use the main generator
if (panel.TemplatedParent != null)
return this;
// otherwise the panel doesn't have a generator
return null;
}
/// Begin generating at the given position and direction
///
/// This method must be called before calling GenerateNext. It returns an
/// IDisposable object that tracks the lifetime of the generation loop.
/// This method sets the generator's status to GeneratingContent; when
/// the IDisposable is disposed, the status changes to ContentReady or
/// Error, as appropriate.
///
IDisposable IItemContainerGenerator.StartAt(GeneratorPosition position, GeneratorDirection direction)
{
return ((IItemContainerGenerator)this).StartAt(position, direction, false);
}
/// Begin generating at the given position and direction
///
/// This method must be called before calling GenerateNext. It returns an
/// IDisposable object that tracks the lifetime of the generation loop.
/// This method sets the generator's status to GeneratingContent; when
/// the IDisposable is disposed, the status changes to ContentReady or
/// Error, as appropriate.
///
IDisposable IItemContainerGenerator.StartAt(GeneratorPosition position, GeneratorDirection direction, bool allowStartAtRealizedItem)
{
if (_generator != null)
throw new InvalidOperationException(SR.Get(SRID.GenerationInProgress));
_generator = new Generator(this, position, direction, allowStartAtRealizedItem);
return _generator;
}
DependencyObject IItemContainerGenerator.GenerateNext()
{
bool isNewlyRealized;
if (_generator == null)
throw new InvalidOperationException(SR.Get(SRID.GenerationNotInProgress));
return _generator.GenerateNext(true, out isNewlyRealized);
}
DependencyObject IItemContainerGenerator.GenerateNext(out bool isNewlyRealized)
{
if (_generator == null)
throw new InvalidOperationException(SR.Get(SRID.GenerationNotInProgress));
return _generator.GenerateNext(false, out isNewlyRealized);
}
///
/// Prepare the given element to act as the container for the
/// corresponding item. This includes applying the container style,
/// forwarding information from the host control (ItemTemplate, etc.),
/// and other small adjustments.
///
///
/// This method must be called after the element has been added to the
/// visual tree, so that resource references and inherited properties
/// work correctly.
///
/// The container to prepare.
/// Normally this is the result of the previous call to GenerateNext.
///
void IItemContainerGenerator.PrepareItemContainer(DependencyObject container)
{
object item = container.ReadLocalValue(ItemForItemContainerProperty);
Host.PrepareItemContainer(container, item);
}
///
/// Remove generated elements.
///
void IItemContainerGenerator.Remove(GeneratorPosition position, int count)
{
Remove(position, count, /*isRecycling = */ false);
}
///
/// Remove generated elements.
///
private void Remove(GeneratorPosition position, int count, bool isRecycling)
{
if (position.Offset != 0)
throw new ArgumentException(SR.Get(SRID.RemoveRequiresOffsetZero, position.Index, position.Offset), "position");
if (count <= 0)
throw new ArgumentException(SR.Get(SRID.RemoveRequiresPositiveCount, count), "count");
int index = position.Index;
ItemBlock block;
// find the leftmost item to remove
int offsetL = index;
for (block = _itemMap.Next; block != _itemMap; block = block.Next)
{
if (offsetL < block.ContainerCount)
break;
offsetL -= block.ContainerCount;
}
RealizedItemBlock blockL = block as RealizedItemBlock;
// find the rightmost item to remove
int offsetR = offsetL + count - 1;
for (; block != _itemMap; block = block.Next)
{
if (!(block is RealizedItemBlock))
throw new InvalidOperationException(SR.Get(SRID.CannotRemoveUnrealizedItems, index, count));
if (offsetR < block.ContainerCount)
break;
offsetR -= block.ContainerCount;
}
RealizedItemBlock blockR = block as RealizedItemBlock;
// de-initialize the containers that are being removed
RealizedItemBlock rblock = blockL;
int offset = offsetL;
while (rblock != blockR || offset <= offsetR)
{
DependencyObject container = rblock.ContainerAt(offset);
UnlinkContainerFromItem(container, rblock.ItemAt(offset), isRecycling);
if (isRecycling)
{
Debug.Assert(!_recyclableContainers.Contains(container), "trying to add a container to the collection twice");
if (_containerType == null)
{
_containerType = container.GetType();
}
else if (_containerType != container.GetType())
{
throw new InvalidOperationException(SR.Get(SRID.CannotRecyleHeterogeneousTypes));
}
_recyclableContainers.Enqueue(container);
}
if (++offset >= rblock.ContainerCount && rblock != blockR)
{
rblock = rblock.Next as RealizedItemBlock;
offset = 0;
}
}
// see whether the range hits the edge of a block on either side,
// and whether the a`butting block is an unrealized gap
bool edgeL = (offsetL == 0);
bool edgeR = (offsetR == blockR.ItemCount-1);
bool abutL = edgeL && (blockL.Prev is UnrealizedItemBlock);
bool abutR = edgeR && (blockR.Next is UnrealizedItemBlock);
// determine the target (unrealized) block,
// the offset within the target at which to insert items,
// and the intial change in cumulative item count
UnrealizedItemBlock blockT;
ItemBlock predecessor = null;
int offsetT;
int deltaCount;
if (abutL)
{
blockT = (UnrealizedItemBlock)blockL.Prev;
offsetT = blockT.ItemCount;
deltaCount = -blockT.ItemCount;
}
else if (abutR)
{
blockT = (UnrealizedItemBlock)blockR.Next;
offsetT = 0;
deltaCount = offsetL;
}
else
{
blockT = new UnrealizedItemBlock();
offsetT = 0;
deltaCount = offsetL;
// remember where the new block goes, so we can insert it later
predecessor = (edgeL) ? blockL.Prev : blockL;
}
// move items within the range to the target block
for (block = blockL; block != blockR; block = block.Next)
{
int itemCount = block.ItemCount;
MoveItems(block, offsetL, itemCount-offsetL,
blockT, offsetT, deltaCount);
offsetT += itemCount-offsetL;
offsetL = 0;
deltaCount -= itemCount;
if (block.ItemCount == 0)
block.Remove();
}
// the last block in the range is a little special...
// Move the last unrealized piece.
int remaining = block.ItemCount - 1 - offsetR;
MoveItems(block, offsetL, offsetR - offsetL + 1,
blockT, offsetT, deltaCount);
// Move the remaining realized items
RealizedItemBlock blockX = blockR;
if (!edgeR)
{
if (blockL == blockR && !edgeL)
{
blockX = new RealizedItemBlock();
}
MoveItems(block, offsetR+1, remaining,
blockX, 0, offsetR+1);
}
// if we created any new blocks, insert them in the list
if (predecessor != null)
blockT.InsertAfter(predecessor);
if (blockX != blockR)
blockX.InsertAfter(blockT);
RemoveAndCoalesceBlocksIfNeeded(block);
}
///
/// Remove all generated elements.
///
void IItemContainerGenerator.RemoveAll()
{
// Take _itemMap offline, to protect against reentrancy (bug 1285179)
ItemBlock itemMap = _itemMap;
_itemMap = null;
try
{
// de-initialize the containers that are being removed
if (itemMap != null)
{
for (ItemBlock block = itemMap.Next; block != itemMap; block = block.Next)
{
RealizedItemBlock rib = block as RealizedItemBlock;
if (rib != null)
{
for (int offset = 0; offset < rib.ContainerCount; ++offset)
{
UnlinkContainerFromItem(rib.ContainerAt(offset), rib.ItemAt(offset));
}
}
}
}
}
finally
{
PrepareGrouping();
// re-initialize the data structure
_itemMap = new ItemBlock();
_itemMap.Prev = _itemMap.Next = _itemMap;
UnrealizedItemBlock uib = new UnrealizedItemBlock();
uib.InsertAfter(_itemMap);
uib.ItemCount = Items.Count;
_recyclableContainers = new Queue();
SetAlternationCount();
// tell generators what happened
if (MapChanged != null)
{
MapChanged(null, -1, 0, uib, 0, 0);
}
}
}
void IRecyclingItemContainerGenerator.Recycle(GeneratorPosition position, int count)
{
Remove(position, count, /*isRecyling = */ true);
}
///
/// Map an index into the items collection to a GeneratorPosition.
///
GeneratorPosition IItemContainerGenerator.GeneratorPositionFromIndex(int itemIndex)
{
GeneratorPosition position;
ItemBlock itemBlock;
int offsetFromBlockStart;
GetBlockAndPosition(itemIndex, out position, out itemBlock, out offsetFromBlockStart);
if (itemBlock == _itemMap && position.Index == -1)
++position.Offset;
return position;
}
///
/// Map a GeneratorPosition to an index into the items collection.
///
int IItemContainerGenerator.IndexFromGeneratorPosition(GeneratorPosition position)
{
int index = position.Index;
if (index == -1)
{
// offset is relative to the fictitious boundary item
if (position.Offset >= 0)
{
return position.Offset - 1;
}
else
{
return Items.Count + position.Offset;
}
}
if (_itemMap != null)
{
int itemIndex = 0; // number of items we've skipped over
// locate container at the given index
for (ItemBlock block = _itemMap.Next; block != _itemMap; block = block.Next)
{
if (index < block.ContainerCount)
{
// container is within this block. return the answer
return itemIndex + index + position.Offset;
}
else
{
// skip over this block
itemIndex += block.ItemCount;
index -= block.ContainerCount;
}
}
}
return -1;
}
#endregion IItemContainerGenerator
///
/// Return the item corresponding to the given UI element.
/// If the element was not generated as a container for this generator's
/// host, the method returns DependencyProperty.UnsetValue.
///
public object ItemFromContainer(DependencyObject container)
{
if (container == null)
throw new ArgumentNullException("container");
object item = container.ReadLocalValue(ItemForItemContainerProperty);
if (item != DependencyProperty.UnsetValue)
{
// verify that the element really belongs to the host
if (!Host.IsHostForItemContainer(container))
item = DependencyProperty.UnsetValue;
}
return item;
}
///
/// Return the UI element corresponding to the given item.
/// Returns null if the item does not belong to the item collection,
/// or if no UI has been generated for it.
///
public DependencyObject ContainerFromItem(object item)
{
DependencyObject container = null;
int index;
DoLinearSearch(ref container, ref item, out index);
return container;
}
///
/// Given a generated UI element, return the index of the corresponding item
/// within the ItemCollection.
///
public int IndexFromContainer(DependencyObject container)
{
if (container == null)
{
throw new ArgumentNullException("container");
}
object item = null;
int index;
DoLinearSearch(ref container, ref item, out index);
return index;
}
///
/// Performs a linear search.
///
///
/// There's no avoiding a linear search, which leads to O(n^2) performance
/// if someone calls ContainerFromItem or IndexFromContainer for every item.
/// To mitigate this, we start each search at _startIndexForUIFromItem, and
/// heuristically set this in various places to where we expect the next
/// call to occur.
///
/// For example, after a successul search, we set it to the resulting
/// index, hoping that the next call will query either the same item or
/// the one after it. And after inserting a new item, we expect a query
/// about the new item. Etc.
///
/// Saving this as an index instead of a (block, offset) pair, makes it
/// more robust during insertions/deletions. If the index ends up being
/// wrong, the worst that happens is a full search (as opposed to following
/// a reference to a block that's no longer in use).
///
/// To re-use the search code for two methods, please read the description
/// of the parameters.
///
///
/// If non-null, then searches for the container.
/// Otherwise, updated with container for the item.
///
///
/// If non-null, then searches for the item.
/// Otherwise, updated with the item that the container represents.
///
///
/// If a container or item is found, then updated with its index.
/// Otherwise, set to -1.
///
///
/// true if found, false otherwise.
///
private bool DoLinearSearch(ref DependencyObject container, ref object item, out int itemIndex)
{
itemIndex = 0;
if (_itemMap == null)
{
// _itemMap can be null if we re-enter the generator. Scenario: user calls RemoveAll(), we Unlink every container, fire
// ClearContainerForItem for each, and someone overriding ClearContainerForItem decides to look up the container.
return false;
}
// Move to the starting point of the search
ItemBlock startBlock = _itemMap.Next;
int index = 0; // index of first item in current block
RealizedItemBlock rib;
int startOffset;
while (index <= _startIndexForUIFromItem && startBlock != _itemMap)
{
index += startBlock.ItemCount;
startBlock = startBlock.Next;
}
startBlock = startBlock.Prev;
index -= startBlock.ItemCount;
rib = startBlock as RealizedItemBlock;
if (rib != null)
{
startOffset = _startIndexForUIFromItem - index;
if (startOffset >= rib.ItemCount)
{
// we can get here if items get removed since the last
// time we saved _startIndexForUIFromItem - so the
// saved offset is no longer meaningful. To make the
// search work, we need to make sure the first loop
// does at least one iteration. Setting startOffset to 0
// does exactly that.
startOffset = 0;
}
}
else
{
startOffset = 0;
}
// search for the desired item, wrapping around the end
ItemBlock block = startBlock;
int offset = startOffset;
int endOffset = startBlock.ItemCount;
while (true)
{
// search the current block (only need to search realized blocks)
if (rib != null)
{
for (; offset < endOffset; ++offset)
{
CollectionViewGroup group;
bool found = false;
if (container != null)
{
if (rib.ContainerAt(offset) == container)
{
found = true;
item = rib.ItemAt(offset);
}
}
else
{
if (Object.Equals(item, rib.ItemAt(offset)))
{
found = true;
container = rib.ContainerAt(offset);
}
}
if (IsGrouping && !found && ((group = rib.ItemAt(offset) as CollectionViewGroup) != null))
{
// found a group; see if the group contains the item
GroupItem groupItem = (GroupItem)rib.ContainerAt(offset);
found = groupItem.Generator.DoLinearSearch(ref container, ref item, out itemIndex);
}
if (found)
{
// found the item; update state and return
_startIndexForUIFromItem = index + offset;
itemIndex += GetRealizedItemBlockCount(rib, offset) + GetCount(block);
return true;
}
}
// check for termination
if (block == startBlock && offset == startOffset)
{
itemIndex = -1;
return false;
}
}
// advance to next block
index += block.ItemCount;
offset = 0;
block = block.Next;
// if we've reached the end, wrap around
if (block == _itemMap)
{
block = block.Next;
index = 0;
}
// prepare to search the block
endOffset = block.ItemCount;
rib = block as RealizedItemBlock;
// check for termination
if (block == startBlock)
{
if (rib != null)
{
endOffset = startOffset; // search first part of block
}
else
{
itemIndex = -1;
return false;
}
}
}
}
private int GetCount()
{
return GetCount(_itemMap);
}
private int GetCount(ItemBlock stop)
{
int count = 0;
ItemBlock start = _itemMap;
ItemBlock block = start.Next;
while (block != stop)
{
RealizedItemBlock rib = block as RealizedItemBlock;
if (rib != null)
{
// Search for groups within realized blocks
count += GetRealizedItemBlockCount(rib, rib.ItemCount);
}
else
{
count += block.ItemCount;
}
block = block.Next;
}
return count;
}
private int GetRealizedItemBlockCount(RealizedItemBlock rib, int end)
{
if (!IsGrouping)
{
// when the UI is not grouping, each item counts as 1, even
// groups (bug 1761421)
return end;
}
int count = 0;
for (int offset = 0; offset < end; ++offset)
{
CollectionViewGroup group;
if ((group = rib.ItemAt(offset) as CollectionViewGroup) != null)
{
// found a group, count the group
GroupItem groupItem = (GroupItem)rib.ContainerAt(offset);
count += groupItem.Generator.GetCount();
}
else
{
count++;
}
}
return count;
}
///
/// Return the UI element corresponding to the item at the given index
/// within the ItemCollection.
///
public DependencyObject ContainerFromIndex(int index)
{
#if DEBUG
object target = (Parent == null) && (0 <= index && index < Host.View.Count) ? Host.View[index] : null;
#endif
int subIndex = 0;
// if we're grouping, determine the appropriate child
if (IsGrouping)
{
int n;
subIndex = index;
for (index=0, n=Items.Count; index < n; ++index)
{
CollectionViewGroup group = Items[index] as CollectionViewGroup;
int size = (group == null) ? 1 : group.ItemCount;
if (subIndex < size)
break;
else
subIndex -= size;
}
}
// search the table for the item
for (ItemBlock block = _itemMap.Next; block != _itemMap; block = block.Next)
{
if (index < block.ItemCount)
{
DependencyObject container = block.ContainerAt(index);
GroupItem groupItem = container as GroupItem;
if (groupItem != null)
{
container = groupItem.Generator.ContainerFromIndex(subIndex);
}
#if DEBUG
object item = (Parent == null) && (container != null) ?
container.ReadLocalValue(ItemForItemContainerProperty) : null;
Debug.Assert(item == null || Object.Equals(item, target),
"Generator's data structure is corrupt - ContainerFromIndex found wrong item");
#endif
return container;
}
index -= block.ItemCount;
}
return null; // *not* throw new IndexOutOfRangeException(); - bug 890195
}
//-----------------------------------------------------
//
// Public Events
//
//------------------------------------------------------
///
/// The ItemsChanged event is raised by a ItemContainerGenerator to inform
/// layouts that the items collection has changed.
///
public event ItemsChangedEventHandler ItemsChanged;
///
/// The StatusChanged event is raised by a ItemContainerGenerator to inform
/// controls that its status has changed.
///
public event EventHandler StatusChanged;
//-----------------------------------------------------
//
// Internal methods
//
//-----------------------------------------------------
// regenerate everything
internal void Refresh()
{
OnRefresh();
}
// called when this generator is no longer needed
internal void Release()
{
((IItemContainerGenerator)this).RemoveAll();
}
// called when the host's AlternationCount changes
internal void ChangeAlternationCount()
{
// update my AlternationCount and adjust my containers
SetAlternationCount();
// propagate to subgroups, if necessary
if (IsGrouping && GroupStyle != null)
{
ItemBlock block = _itemMap.Next;
while (block != _itemMap)
{
for (int offset = 0; offset < block.ContainerCount; ++offset)
{
GroupItem gi = ((RealizedItemBlock)block).ContainerAt(offset) as GroupItem;
if (gi != null)
{
gi.Generator.ChangeAlternationCount();
}
}
block = block.Next;
}
}
}
// update AlternationIndex on each container to reflect the new AlternationCount
void ChangeAlternationCount(int newAlternationCount)
{
if (_alternationCount == newAlternationCount)
return;
// find the first realized container (need this regardless of what happens)
ItemBlock block = _itemMap.Next;
int offset = 0;
while (offset == block.ContainerCount)
{
block = block.Next;
}
// if there are no realized containers, there's nothing to do
if (block != _itemMap)
{
// if user is requesting alternation, reset each container's AlternationIndex
if (newAlternationCount > 0)
{
_alternationCount = newAlternationCount;
SetAlternationIndex((RealizedItemBlock)block, offset, GeneratorDirection.Forward);
}
// otherwise, clear each container's AlternationIndex
else if (_alternationCount > 0)
{
while (block != _itemMap)
{
for (offset = 0; offset < block.ContainerCount; ++offset)
{
ItemsControl.ClearAlternationIndex(((RealizedItemBlock)block).ContainerAt(offset));
}
block = block.Next;
}
}
}
_alternationCount = newAlternationCount;
}
//-----------------------------------------------------
//
// Internal properties
//
//------------------------------------------------------
internal ItemContainerGenerator Parent
{
get { return _parent;}
}
internal int Level
{
get { return _level;}
}
// The group style that governs the generation of UI for the items.
internal GroupStyle GroupStyle
{
get { return _groupStyle; }
set
{
if (_groupStyle != value)
{
if (_groupStyle is INotifyPropertyChanged)
{
PropertyChangedEventManager.RemoveListener(_groupStyle, this, String.Empty);
}
_groupStyle = value;
if (_groupStyle is INotifyPropertyChanged)
{
PropertyChangedEventManager.AddListener(_groupStyle, this, String.Empty);
}
}
}
}
// The collection of items, as IList
internal IList Items
{
get { return _items; }
set
{
if (_items != value)
{
INotifyCollectionChanged incc = _items as INotifyCollectionChanged;
if (_items != Host.View && incc != null)
{
CollectionChangedEventManager.RemoveListener(incc, this);
}
_items = value;
incc = _items as INotifyCollectionChanged;
if (_items != Host.View && incc != null)
{
CollectionChangedEventManager.AddListener(incc, this);
}
}
}
}
///
/// ItemForItemContainer DependencyProperty
///
// This is an attached property that the generator sets on each container
// (generated or direct) to point back to the item.
internal static readonly DependencyProperty ItemForItemContainerProperty =
DependencyProperty.RegisterAttached("ItemForItemContainer", typeof(object), typeof(ItemContainerGenerator),
new FrameworkPropertyMetadata((object)null));
//-----------------------------------------------------
//
// Internal events
//
//------------------------------------------------------
internal event EventHandler PanelChanged;
internal void OnPanelChanged()
{
if (PanelChanged != null)
PanelChanged(this, EventArgs.Empty);
}
//------------------------------------------------------
//
// Private Nested Class - ItemContainerGenerator.Generator
//
//-----------------------------------------------------
///
/// Generator is the object that generates UI on behalf of an ItemsControl,
/// working under the supervision of an ItemContainerGenerator.
///
private class Generator : IDisposable
{
//------------------------------------------------------
//
// Constructors
//
//-----------------------------------------------------
internal Generator(ItemContainerGenerator factory, GeneratorPosition position, GeneratorDirection direction, bool allowStartAtRealizedItem)
{
_factory = factory;
_direction = direction;
_factory.MapChanged += new MapChangedHandler(OnMapChanged);
_factory.MoveToPosition(position, direction, allowStartAtRealizedItem, ref _cachedState);
_done = (_factory.Items.Count == 0);
_factory.SetStatus(GeneratorStatus.GeneratingContainers);
}
//-----------------------------------------------------
//
// Public Properties
//
//-----------------------------------------------------
/* This method was requested for virtualization. It's not being used right now
(bug 1079525) but it probably will be when UI virtualization comes back.
///
/// returns false if a call to GenerateNext is known to return null (indicating
/// that the generator is done). Does not generate anything or change the
/// generator's state; cheaper than GenerateNext. Returning true does not
/// necessarily mean GenerateNext will produce anything.
///
public bool IsActive
{
get { return !_done; }
}
*/
//------------------------------------------------------
//
// Public Methods
//
//-----------------------------------------------------
/// Generate UI for the next item or group
public DependencyObject GenerateNext(bool stopAtRealized, out bool isNewlyRealized)
{
DependencyObject container = null;
isNewlyRealized = false;
while (container == null)
{
UnrealizedItemBlock uBlock = _cachedState.Block as UnrealizedItemBlock;
IList items = _factory.Items;
int itemIndex = _cachedState.ItemIndex;
int incr = (_direction == GeneratorDirection.Forward) ? +1 : -1;
if (_cachedState.Block == _factory._itemMap)
_done = true; // we've reached the end of the list
if (uBlock == null && stopAtRealized)
_done = true;
if (!(0 <= itemIndex && itemIndex < items.Count))
_done = true;
if (_done)
{
isNewlyRealized = false;
return null;
}
object item = items[itemIndex];
if (uBlock != null)
{
// We don't have a realized container for this item. Try to use a recycled container
// if possible, otherwise generate a new container.
isNewlyRealized = true;
CollectionViewGroup group = item as CollectionViewGroup;
if (group == null || !_factory.IsGrouping)
{
if (_factory._recyclableContainers.Count > 0 && !_factory.Host.IsItemItsOwnContainer(item))
{
container = _factory._recyclableContainers.Dequeue();
isNewlyRealized = false;
}
else
{
// generate container for an item
container = _factory.Host.GetContainerForItem(item);
}
ItemContainerGenerator.LinkContainerToItem(container, item, /* isRecycled = */ !isNewlyRealized);
}
else
{
// generate container for a group
container = _factory.ContainerForGroup(group);
}
// add the (item, container) to the current block
if (container != null)
{
_factory.Realize(uBlock, _cachedState.Offset, item, container);
// set AlternationIndex on the container (and possibly others)
_factory.SetAlternationIndex(_cachedState.Block, _cachedState.Offset, _direction);
}
}
else
{
// return existing realized container
isNewlyRealized = false;
RealizedItemBlock rib = (RealizedItemBlock)_cachedState.Block;
container = rib.ContainerAt(_cachedState.Offset);
}
// advance to the next item
_cachedState.ItemIndex = itemIndex;
if (_direction == GeneratorDirection.Forward)
{
_cachedState.Block.MoveForward(ref _cachedState, true);
}
else
{
_cachedState.Block.MoveBackward(ref _cachedState, true);
}
}
return container;
}
//------------------------------------------------------
//
// Interfaces - IDisposable
//
//------------------------------------------------------
/// Dispose this generator.
void IDisposable.Dispose()
{
if (_factory != null)
{
_factory.MapChanged -= new MapChangedHandler(OnMapChanged);
_done = true;
_factory.SetStatus(GeneratorStatus.ContainersGenerated);
_factory._generator = null;
_factory = null;
}
}
//-----------------------------------------------------
//
// Private methods
//
//------------------------------------------------------
// The map data structure has changed, so the state must change accordingly.
// This is called in various different ways.
// A. Items were moved within the data structure, typically because
// items were realized or un-realized. In this case, the args are:
// block - the block from where the items were moved
// offset - the offset within the block of the first item moved
// count - how many items moved
// newBlock - the block to which the items were moved
// newOffset - the offset within the new block of the first item moved
// deltaCount - the difference between the cumululative item counts
// of newBlock and block
// B. An item was added or removed from the data structure. In this
// case the args are:
// block - null (to distinguish case B from case A)
// offset - the index of the changed item, w.r.t. the entire item list
// count - +1 for insertion, -1 for deletion
// others - unused
// C. Refresh: all items are returned to a single unrealized block.
// In this case, the args are:
// block - null
// offset - -1 (to distinguish case C from case B)
// newBlock = the single unrealized block
// others - unused
void OnMapChanged(ItemBlock block, int offset, int count,
ItemBlock newBlock, int newOffset, int deltaCount)
{
// Case A. Items were moved within the map data structure
if (block != null)
{
// if the move affects this generator, update the cached state
if (block == _cachedState.Block && offset <= _cachedState.Offset &&
_cachedState.Offset < offset + count)
{
_cachedState.Block = newBlock;
_cachedState.Offset += newOffset - offset;
_cachedState.Count += deltaCount;
}
}
// Case B. An item was inserted or deleted
else if (offset >= 0)
{
// if the item occurs before my block, update my item count
if (offset < _cachedState.Count)
{
_cachedState.Count += count;
_cachedState.ItemIndex += count;
}
// if the item occurs within my block before my item, update my offset
else if (offset < _cachedState.Count + _cachedState.Offset)
{
_cachedState.Offset += count;
_cachedState.ItemIndex += count;
}
// if an insert occurs at my position, update my offset
else if (offset == _cachedState.Count + _cachedState.Offset &&
count > 0)
{
_cachedState.Offset += count;
_cachedState.ItemIndex += count;
}
}
// Case C. Refresh
else
{
_cachedState.Block = newBlock;
_cachedState.Offset += _cachedState.Count;
_cachedState.Count = 0;
}
}
//-----------------------------------------------------
//
// Private Fields
//
//-----------------------------------------------------
ItemContainerGenerator _factory;
GeneratorDirection _direction;
bool _done;
GeneratorState _cachedState;
}
//-----------------------------------------------------
//
// Private Properties
//
//------------------------------------------------------
IGeneratorHost Host { get { return _host; } }
// The DO for which this generator was created. For normal generators,
// this is the ItemsControl. For subgroup generators, this is
// the GroupItem.
DependencyObject Peer
{
get { return _peer; }
}
bool IsGrouping
{
get { return (Items != Host.View); }
}
//-----------------------------------------------------
//
// Private Methods
//
//------------------------------------------------------
void MoveToPosition(GeneratorPosition position, GeneratorDirection direction, bool allowStartAtRealizedItem, ref GeneratorState state)
{
ItemBlock block = _itemMap;
int itemIndex = 0;
// first move to the indexed (realized) item
if (position.Index != -1)
{
// find the right block
int itemCount = 0;
int index = position.Index;
block = block.Next;
while (index >= block.ContainerCount)
{
itemCount += block.ItemCount;
index -= block.ContainerCount;
itemIndex += block.ItemCount;
block = block.Next;
}
// set the position
state.Block = block;
state.Offset = index;
state.Count = itemCount;
state.ItemIndex = itemIndex + index;
}
else
{
state.Block = block;
state.Offset = 0;
state.Count = 0;
state.ItemIndex = itemIndex - 1;
}
// adjust the offset - we always set the state so it points to the next
// item to be generated.
int offset = position.Offset;
if (offset == 0 && (!allowStartAtRealizedItem || state.Block == _itemMap))
{
offset = (direction == GeneratorDirection.Forward) ? 1 : -1;
}
// advance the state according to the offset
if (offset > 0)
{
state.Block.MoveForward(ref state, true);
while (--offset > 0)
{
state.Block.MoveForward(ref state, allowStartAtRealizedItem);
}
}
else if (offset < 0)
{
if (state.Block == _itemMap)
{
state.ItemIndex = state.Count = Items.Count;
}
state.Block.MoveBackward(ref state, true);
while (++offset < 0)
{
state.Block.MoveBackward(ref state, allowStartAtRealizedItem);
}
}
}
// "Realize" the item in a block at the given offset, to be
// the given item with corresponding container. This means updating
// the item map data structure so that the item belongs to a Realized block.
// It also requires updating the state of every generator to track the
// changes we make here.
void Realize(UnrealizedItemBlock block, int offset, object item, DependencyObject container)
{
RealizedItemBlock prevR, nextR;
RealizedItemBlock newBlock; // new location of the target item
int newOffset; // its offset within the new block
int deltaCount; // diff between cumulative item count of block and newBlock
// if we're realizing the leftmost item and there's room in the
// previous block, move it there
if (offset == 0 &&
(prevR = block.Prev as RealizedItemBlock) != null &&
prevR.ItemCount < ItemBlock.BlockSize)
{
newBlock = prevR;
newOffset = prevR.ItemCount;
MoveItems(block, offset, 1, newBlock, newOffset, -prevR.ItemCount);
MoveItems(block, 1, block.ItemCount, block, 0, +1);
}
// if we're realizing the rightmost item and there's room in the
// next block, move it there
else if (offset == block.ItemCount - 1 &&
(nextR = block.Next as RealizedItemBlock) != null &&
nextR.ItemCount < ItemBlock.BlockSize)
{
newBlock = nextR;
newOffset = 0;
MoveItems(newBlock, 0, newBlock.ItemCount, newBlock, 1, -1);
MoveItems(block, offset, 1, newBlock, newOffset, offset);
}
// otherwise we need a new block for the target item
else
{
newBlock = new RealizedItemBlock();
newOffset = 0;
deltaCount = offset;
// if target is leftmost item, insert it before remaining items
if (offset == 0)
{
newBlock.InsertBefore(block);
MoveItems(block, offset, 1, newBlock, newOffset, 0);
MoveItems(block, 1, block.ItemCount, block, 0, +1);
}
// if target is rightmost item, insert it after remaining items
else if (offset == block.ItemCount - 1)
{
newBlock.InsertAfter(block);
MoveItems(block, offset, 1, newBlock, newOffset, offset);
}
// otherwise split the block into two, with the target in the middle
else
{
UnrealizedItemBlock newUBlock = new UnrealizedItemBlock();
newUBlock.InsertAfter(block);
newBlock.InsertAfter(block);
MoveItems(block, offset+1, block.ItemCount-offset-1, newUBlock, 0, offset+1);
MoveItems(block, offset, 1, newBlock, 0, offset);
}
}
RemoveAndCoalesceBlocksIfNeeded(block);
// add the new target to the map
newBlock.RealizeItem(newOffset, item, container);
}
void RemoveAndCoalesceBlocksIfNeeded(ItemBlock block)
{
if (block != null && block != _itemMap && block.ItemCount == 0)
{
block.Remove();
// coalesce adjacent unrealized blocks
if (block.Prev is UnrealizedItemBlock && block.Next is UnrealizedItemBlock)
{
MoveItems(block.Next, 0, block.Next.ItemCount, block.Prev, block.Prev.ItemCount, -block.Prev.ItemCount-1);
block.Next.Remove();
}
}
}
// Move 'count' items starting at position 'offset' in block 'block'
// to position 'newOffset' in block 'newBlock'. The difference between
// the cumulative item counts of newBlock and block is given by 'deltaCount'.
void MoveItems(ItemBlock block, int offset, int count,
ItemBlock newBlock, int newOffset, int deltaCount)
{
RealizedItemBlock ribSrc = block as RealizedItemBlock;
RealizedItemBlock ribDst = newBlock as RealizedItemBlock;
// when both blocks are Realized, entries must be physically copied
if (ribSrc != null && ribDst != null)
{
ribDst.CopyEntries(ribSrc, offset, count, newOffset);
}
// when the source block is Realized, clear the vacated entries -
// to avoid leaks. (No need if it's now empty - the block will get GC'd).
else if (ribSrc != null && ribSrc.ItemCount > count)
{
ribSrc.ClearEntries(offset, count);
}
// update block information
block.ItemCount -= count;
newBlock.ItemCount += count;
// tell generators what happened
if (MapChanged != null)
MapChanged(block, offset, count, newBlock, newOffset, deltaCount);
}
// Set the AlternationIndex on a newly-realized container. Also, reset
// the AlternationIndex on other containers to maintain the adjacency
// criterion.
void SetAlternationIndex(ItemBlock block, int offset, GeneratorDirection direction)
{
// If user doesn't request alternation, don't do anything
if (_alternationCount <= 0)
return;
int index;
RealizedItemBlock rib;
// Proceed in the direction of generation. This tends to reach the
// end sooner (often in one step).
if (direction != GeneratorDirection.Backward)
{
// Forward. Back up one container to determine the starting index
-- offset;
while (offset < 0 || block is UnrealizedItemBlock)
{
block = block.Prev;
offset = block.ContainerCount - 1;
}
rib = block as RealizedItemBlock;
index = (block == _itemMap) ? -1 : ItemsControl.GetAlternationIndex(rib.ContainerAt(offset));
// loop through the remaining containers, resetting each AlternationIndex
for (;;)
{
// advance to next realized container
++offset;
while (offset == block.ContainerCount)
{
block = block.Next;
offset = 0;
}
// exit if we've reached the end
if (block == _itemMap)
break;
// advance the AlternationIndex
index = (index + 1) % _alternationCount;
// assign it to the container
rib = block as RealizedItemBlock;
ItemsControl.SetAlternationIndex(rib.ContainerAt(offset), index);
}
}
else
{
// Backward. Advance one container to determine the starting index
++ offset;
while (offset >= block.ContainerCount || block is UnrealizedItemBlock)
{
block = block.Next;
offset = 0;
}
rib = block as RealizedItemBlock;
index = (block == _itemMap) ? _alternationCount : ItemsControl.GetAlternationIndex(rib.ContainerAt(offset));
// loop through the remaining containers, resetting each AlternationIndex
for (;;)
{
// retreat to next realized container
--offset;
while (offset == 0)
{
block = block.Prev;
offset = block.ContainerCount;
}
// exit if we've reached the end
if (block == _itemMap)
break;
// retreat the AlternationIndex
index = (index - 1) % _alternationCount;
// assign it to the container
rib = block as RealizedItemBlock;
ItemsControl.SetAlternationIndex(rib.ContainerAt(offset), index);
}
}
}
// create a group item for the given group
DependencyObject ContainerForGroup(CollectionViewGroup group)
{
if (!ShouldHide(group))
{
// normal group - link a new GroupItem
GroupItem groupItem = new GroupItem();
LinkContainerToItem(groupItem, group);
// create the generator
groupItem.Generator = new ItemContainerGenerator(this, groupItem);
return groupItem;
}
else
{
// hidden empty group - link a new EmptyGroupItem
AddEmptyGroupItem(group);
// but don't return it to layout
return null;
}
}
// prepare the grouping information. Called from RemoveAll.
void PrepareGrouping()
{
GroupStyle groupStyle;
IList items;
if (Level == 0)
{
groupStyle = Host.GetGroupStyle(null, 0);
if (groupStyle == null)
{
items = Host.View;
}
else
{
CollectionView cv = Host.View.CollectionView;
items = (cv == null) ? null : cv.Groups;
if (items == null)
{
items = Host.View;
}
}
}
else
{
GroupItem groupItem = (GroupItem)Peer;
CollectionViewGroup group = groupItem.ReadLocalValue(ItemForItemContainerProperty) as CollectionViewGroup;
if (group != null)
{
if (group.IsBottomLevel)
{
groupStyle = null;
}
else
{
groupStyle = Host.GetGroupStyle(group, Level);
}
items = group.Items;
}
else
{
groupStyle = null;
items = Host.View;
}
}
GroupStyle = groupStyle;
Items = items;
if ((Level == 0) && (Host != null))
{
// Notify the host of a change in IsGrouping
Host.SetIsGrouping(IsGrouping);
}
}
void SetAlternationCount()
{
int alternationCount;
if (IsGrouping && GroupStyle != null)
{
if (GroupStyle.IsAlternationCountSet)
{
alternationCount = GroupStyle.AlternationCount;
}
else if (_parent != null)
{
alternationCount = _parent._alternationCount;
}
else
{
alternationCount = Host.AlternationCount;
}
}
else
{
alternationCount = Host.AlternationCount;
}
ChangeAlternationCount(alternationCount);
}
// should the given group be hidden?
bool ShouldHide(CollectionViewGroup group)
{
return GroupStyle.HidesIfEmpty && // user asked to hide
group.ItemCount == 0; // group is empty
}
// create an empty-group placeholder item
void AddEmptyGroupItem(CollectionViewGroup group)
{
EmptyGroupItem emptyGroupItem = new EmptyGroupItem();
LinkContainerToItem(emptyGroupItem, group);
emptyGroupItem.SetGenerator(new ItemContainerGenerator(this, emptyGroupItem));
// add it to the list of placeholder items (this keeps it from being GC'd)
if (_emptyGroupItems == null)
_emptyGroupItems = new ArrayList();
_emptyGroupItems.Add(emptyGroupItem);
}
// notification that a subgroup has become non-empty
void OnSubgroupBecameNonEmpty(EmptyGroupItem groupItem, CollectionViewGroup group)
{
// Discard placeholder container.
UnlinkContainerFromItem(groupItem, group);
if (_emptyGroupItems != null)
_emptyGroupItems.Remove(groupItem);
// inform layout as if the group just got added
if (ItemsChanged != null)
{
GeneratorPosition position = PositionFromIndex(Items.IndexOf(group));
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Add, position, 1, 0));
}
}
// notification that a subgroup has become empty
void OnSubgroupBecameEmpty(CollectionViewGroup group)
{
if (ShouldHide(group))
{
GeneratorPosition position = PositionFromIndex(Items.IndexOf(group));
// if the group is realized, un-realize it and notify layout
if (position.Offset == 0 && position.Index >= 0)
{
// un-realize
((IItemContainerGenerator)this).Remove(position, 1);
// inform layout as if the group just got removed
if (ItemsChanged != null)
{
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Remove, position, 1, 1));
}
// create the placeholder
AddEmptyGroupItem(group);
}
}
}
// convert an index (into Items) into a GeneratorPosition
GeneratorPosition PositionFromIndex(int itemIndex)
{
GeneratorPosition position;
ItemBlock itemBlock;
int offsetFromBlockStart;
GetBlockAndPosition(itemIndex, out position, out itemBlock, out offsetFromBlockStart);
return position;
}
void GetBlockAndPosition(object item, int itemIndex, bool deletedFromItems, out GeneratorPosition position, out ItemBlock block, out int offsetFromBlockStart, out int correctIndex)
{
if (itemIndex >= 0)
{
GetBlockAndPosition(itemIndex, out position, out block, out offsetFromBlockStart);
correctIndex = itemIndex;
}
else
{
GetBlockAndPosition(item, deletedFromItems, out position, out block, out offsetFromBlockStart, out correctIndex);
}
}
void GetBlockAndPosition(int itemIndex, out GeneratorPosition position, out ItemBlock block, out int offsetFromBlockStart)
{
position = new GeneratorPosition(-1, 0);
block = null;
offsetFromBlockStart = itemIndex;
if (_itemMap == null || itemIndex < 0)
return;
int containerIndex = 0;
for (block = _itemMap.Next; block != _itemMap; block = block.Next)
{
if (offsetFromBlockStart >= block.ItemCount)
{
// item belongs to a later block, increment the containerIndex
containerIndex += block.ContainerCount;
offsetFromBlockStart -= block.ItemCount;
}
else
{
// item belongs to this block. Determine the container index and offset
if (block.ContainerCount > 0)
{
// block has realized items
position = new GeneratorPosition(containerIndex + offsetFromBlockStart, 0);
}
else
{
// block has unrealized items
position = new GeneratorPosition(containerIndex-1, offsetFromBlockStart+1);
}
break;
}
}
}
void GetBlockAndPosition(object item, bool deletedFromItems, out GeneratorPosition position, out ItemBlock block, out int offsetFromBlockStart, out int correctIndex)
{
correctIndex = 0;
int containerIndex = 0;
offsetFromBlockStart = 0;
int deletionOffset = deletedFromItems ? 1 : 0;
position = new GeneratorPosition(-1, 0);
for (block = _itemMap.Next; block != _itemMap; block = block.Next)
{
UnrealizedItemBlock uib;
RealizedItemBlock rib = block as RealizedItemBlock;
if (rib != null)
{
// compare realized items with item for which we are searching
offsetFromBlockStart = rib.OffsetOfItem(item);
if (offsetFromBlockStart >= 0)
{
position = new GeneratorPosition(containerIndex + offsetFromBlockStart, 0);
correctIndex += offsetFromBlockStart;
break;
}
}
else if ((uib = block as UnrealizedItemBlock) != null)
{
// if the item isn't realized, we can't find it
// directly. Instead, look for indirect evidence that it
// belongs to this block by checking the indices of
// nearby realized items.
#if DEBUG
// Sanity check - make sure data structure is OK so far.
rib = block.Prev as RealizedItemBlock;
if (rib != null && rib.ContainerCount > 0)
{
Debug.Assert(Object.Equals(rib.ItemAt(rib.ContainerCount - 1),
Items[correctIndex - 1]),
"Generator data structure is corrupt");
}
#endif
bool itemIsInCurrentBlock = false;
rib = block.Next as RealizedItemBlock;
if (rib != null && rib.ContainerCount > 0)
{
// if the index of the next realized item is off by one,
// the deleted item likely comes from the current
// unrealized block.
itemIsInCurrentBlock =
Object.Equals(rib.ItemAt(0),
Items[correctIndex + block.ItemCount - deletionOffset]);
}
else if (block.Next == _itemMap)
{
// similarly if we're at the end of the list and the
// overall count is off by one, or if the current block
// is the only block, the deleted item likely
// comes from the current (last) unrealized block
itemIsInCurrentBlock = block.Prev == _itemMap ||
(Items.Count == correctIndex + block.ItemCount - deletionOffset);
}
if (itemIsInCurrentBlock)
{
// we don't know where it is in this block, so assume
// it's the very first item.
offsetFromBlockStart = 0;
position = new GeneratorPosition(containerIndex-1, 1);
break;
}
}
correctIndex += block.ItemCount;
containerIndex += block.ContainerCount;
}
if (block == _itemMap)
{
// There's no way of knowing which unrealized block it belonged to, so
// the data structure can't be updated correctly. Sound the alarm.
throw new InvalidOperationException(SR.Get(SRID.CannotFindRemovedItem));
}
}
private void LinkContainerToItem(DependencyObject container, object item)
{
LinkContainerToItem(container, item, false);
}
// establish the link from the container to the corresponding item
static void LinkContainerToItem(DependencyObject container, object item, bool isRecycled)
{
// always set the ItemForItemContainer property
container.ClearValue(ItemForItemContainerProperty);
container.SetValue(ItemForItemContainerProperty, item);
// for non-direct items, set the DataContext property
if (container != item)
{
if (!isRecycled)
{
// We already cleared recycled containers in UnlinkContainerFromItem
container.ClearValue(FrameworkElement.DataContextProperty);
}
container.SetValue(FrameworkElement.DataContextProperty, item);
}
}
private void UnlinkContainerFromItem(DependencyObject container, object item)
{
UnlinkContainerFromItem(container, item, false);
}
// unlink the container from the corresponding item
private void UnlinkContainerFromItem(DependencyObject container, object item, bool isRecycled)
{
container.ClearValue(ItemForItemContainerProperty);
// There are two ways to view the properties set by PrepareItemContainer:
//
// a) these properties are added by the generator/host so that
// the container can function correctly in the generated tree.
//
// b) these properties are part of the container's initial state,
// independent of whether the container belongs to the tree.
//
// If you take the first point of view, then the generator should remove
// these properties when the container is removed from the tree. If
// you take the second point of view, then the generator should not do this.
//
// In response to bug 1445288 and independent discussions, we take the
// second point of view. This saves the cost of clearing all those
// properties, which can add up to quite a lot. As long as no one expects
// to use a container after it has been removed, there should be no harm.
//
// We make a small exception for the ItemForItemContainer property, since
// that is an internal property that only makes sense for an active container.
//
// When we're in Recycling mode, the above doesn't apply; we need to clear off
// the DataContext property on the container since it will get re-used. The
// issue here is that if we don't clear it off we can alias DataContexts; we
// could get a container on the recycled list with the same DataContext as a
// live container -- that causes all sorts of subtle issues.
//
if (isRecycled && container != item)
{
// ClearValue has a perf problem because the DataContext will be inherited by the recycled container's
// parent. That will cause us to resolve a binding that we really don't care about. This can be insanely expensive
// depending on the structure of the data.
//
// In the rare case that the DataContext property has an expression on it we have to do ClearValue to get rid of it
// so that the SetValue later in LinkContainerToItem will work.
DependencyProperty dp = FrameworkElement.DataContextProperty;
EntryIndex entryIndex = container.LookupEntry(dp.GlobalIndex);
if (container.HasExpression(entryIndex, dp))
{
container.ClearValue(dp);
}
else
{
container.SetValue(dp, null);
}
}
_host.ClearContainerForItem(container, item);
}
///
/// Handle events from the centralized event table
///
bool IWeakEventListener.ReceiveWeakEvent(Type managerType, object sender, EventArgs e)
{
if (managerType == typeof(PropertyChangedEventManager))
{
PropertyChangedEventArgs pce = (PropertyChangedEventArgs)e;
if (sender == GroupStyle)
{
if (pce.PropertyName == "Panel")
{
OnPanelChanged();
}
else
{
OnRefresh();
}
}
}
else if (managerType == typeof(CollectionChangedEventManager))
{
OnCollectionChanged(sender, (NotifyCollectionChangedEventArgs)e);
}
else
{
return false; // unrecognized event
}
return true;
}
void ValidateAndCorrectIndex(object item, ref int index)
{
if (index >= 0)
{
// this check is expensive - Items[index] potentially iterates through
// the collection. So trust the sender to tell us the truth in retail bits.
Debug.Assert(Object.Equals(item, Items[index]), "Event contains the wrong index");
}
else
{
index = Items.IndexOf(item);
if (index < 0)
throw new InvalidOperationException(SR.Get(SRID.CollectionAddEventMissingItem, item));
}
}
///
/// Forward a CollectionChanged event
///
// Called when items collection changes.
void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs args)
{
// get the affected item
object item;
int startingIndex = -1;
switch (args.Action)
{
case NotifyCollectionChangedAction.Add:
case NotifyCollectionChangedAction.Remove:
if (sender != Items)
return; // ignore events from ItemsCollection when we're listening to group's items.
if (args.Action == NotifyCollectionChangedAction.Add)
{
if (args.NewItems.Count != 1)
throw new NotSupportedException(SR.Get(SRID.RangeActionsNotSupported));
item = args.NewItems[0];
startingIndex = args.NewStartingIndex;
}
else
{
if (args.OldItems.Count != 1)
throw new NotSupportedException(SR.Get(SRID.RangeActionsNotSupported));
item = args.OldItems[0];
startingIndex = args.OldStartingIndex;
}
break;
case NotifyCollectionChangedAction.Replace:
case NotifyCollectionChangedAction.Move:
case NotifyCollectionChangedAction.Reset:
item = null;
break;
default:
throw new NotSupportedException(SR.Get(SRID.UnexpectedCollectionChangeAction, args.Action));
}
if (_traceLog != null)
_traceLog.Add("Received collection change from {0} action = {1} item={2}",
TraceLog.IdFor(sender), args.Action, item);
switch (args.Action)
{
case NotifyCollectionChangedAction.Add:
OnItemAdded(item, startingIndex);
break;
case NotifyCollectionChangedAction.Remove:
OnItemRemoved(item, startingIndex);
break;
case NotifyCollectionChangedAction.Replace:
OnItemReplaced(args.OldItems[0], args.NewItems[0], args.NewStartingIndex);
break;
case NotifyCollectionChangedAction.Move:
OnItemMoved(args.OldItems[0], args.OldStartingIndex, args.NewStartingIndex);
break;
case NotifyCollectionChangedAction.Reset:
OnRefresh();
break;
}
}
// Called when an item is added to the items collection
void OnItemAdded(object item, int index)
{
ValidateAndCorrectIndex(item, ref index);
GeneratorPosition position = new GeneratorPosition(-1,0);
// find the block containing the new item
ItemBlock block = _itemMap.Next;
int offset = index;
while (block != _itemMap && offset >= block.ItemCount)
{
offset -= block.ItemCount;
position.Index += block.ContainerCount;
block = block.Next;
}
position.Offset = offset + 1;
// if it's an unrealized block, add the item by bumping the count
UnrealizedItemBlock uib = block as UnrealizedItemBlock;
if (uib != null)
{
MoveItems(uib, offset, 1, uib, offset+1, 0);
++ uib.ItemCount;
}
// if the item can be added to a previous unrealized block, do so
else if ((offset == 0 || block == _itemMap) &&
((uib = block.Prev as UnrealizedItemBlock) != null))
{
++ uib.ItemCount;
}
// otherwise, create a new unrealized block
else
{
uib = new UnrealizedItemBlock();
uib.ItemCount = 1;
// split the current realized block, if necessary
RealizedItemBlock rib;
if (offset > 0 && (rib = block as RealizedItemBlock) != null)
{
RealizedItemBlock newBlock = new RealizedItemBlock();
MoveItems(rib, offset, rib.ItemCount - offset, newBlock, 0, offset);
newBlock.InsertAfter(rib);
position.Index += block.ContainerCount;
position.Offset = 1;
block = newBlock;
}
uib.InsertBefore(block);
}
if (_traceLog != null)
_traceLog.Add("OnItemAdded {0} index = {1}", TraceLog.IdFor(item), index);
// tell generators what happened
if (MapChanged != null)
{
MapChanged(null, index, +1, null, 0, 0);
}
// tell layout what happened
if (ItemsChanged != null)
{
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Add, position, 1, 0));
}
}
// Called when an item is removed from the items collection
void OnItemRemoved(object item, int itemIndex)
{
DependencyObject container = null; // the corresponding container
int containerCount = 0;
// search for the deleted item
GeneratorPosition position;
ItemBlock block;
int offsetFromBlockStart;
int correctIndex;
GetBlockAndPosition(item, itemIndex, true, out position, out block, out offsetFromBlockStart, out correctIndex);
RealizedItemBlock rib = block as RealizedItemBlock;
if (rib != null)
{
containerCount = 1;
container = rib.ContainerAt(offsetFromBlockStart);
}
// remove the item, and remove the block if it's now empty
MoveItems(block, offsetFromBlockStart + 1, block.ItemCount - offsetFromBlockStart - 1, block, offsetFromBlockStart, 0);
--block.ItemCount;
if (rib != null)
{
// fix up the alternation index before removing an empty block, while
// we still have a valid block and offset
SetAlternationIndex(block, offsetFromBlockStart, GeneratorDirection.Forward);
}
RemoveAndCoalesceBlocksIfNeeded(block);
if (_traceLog != null)
_traceLog.Add("OnItemRemoved {0} index = {1}", TraceLog.IdFor(item), itemIndex);
// tell generators what happened
if (MapChanged != null)
{
MapChanged(null, itemIndex, -1, null, 0, 0);
}
// tell layout what happened
if (ItemsChanged != null)
{
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Remove, position, 1, containerCount));
}
// unhook the container. Do this after layout has (presumably) removed it from
// the UI, so that it doesn't inherit DataContext falsely.
if (container != null)
{
UnlinkContainerFromItem(container, item);
}
// detect empty groups, so they can be hidden if necessary
if (Level > 0 && Items.Count == 0)
{
GroupItem groupItem = (GroupItem)Peer;
CollectionViewGroup group = groupItem.ReadLocalValue(ItemForItemContainerProperty) as CollectionViewGroup;
// the group could be null if the parent generator has already
// unhooked its container
if (group != null)
{
Parent.OnSubgroupBecameEmpty(group);
}
}
}
void OnItemReplaced(object oldItem, object newItem, int index)
{
// search for the replaced item
GeneratorPosition position;
ItemBlock block;
int offsetFromBlockStart;
int correctIndex;
GetBlockAndPosition(oldItem, index, false, out position, out block, out offsetFromBlockStart, out correctIndex);
// If the item is in an UnrealizedItemBlock, then this change need not
// be made to the _itemsMap as we are replacing an unrealized item with another unrealized
// item in the same place.
RealizedItemBlock rib = block as RealizedItemBlock;
if (rib != null)
{
DependencyObject container = rib.ContainerAt(offsetFromBlockStart);
// replace the old item with the new one
rib.RealizeItem(offsetFromBlockStart, newItem, container);
// hook up the container to the new item
LinkContainerToItem(container, newItem);
_host.PrepareItemContainer(container, newItem);
}
if (_traceLog != null)
_traceLog.Add("OnItemReplaced {0} index = {1}", TraceLog.IdFor(oldItem), index);
}
void OnItemMoved(object item, int oldIndex, int newIndex)
{
DependencyObject container = null; // the corresponding container
int containerCount = 0;
UnrealizedItemBlock uib;
// search for the moved item
GeneratorPosition position;
ItemBlock block;
int offsetFromBlockStart;
int correctIndex;
GetBlockAndPosition(item, oldIndex, true, out position, out block, out offsetFromBlockStart, out correctIndex);
GeneratorPosition oldPosition = position;
RealizedItemBlock rib = block as RealizedItemBlock;
if (rib != null)
{
containerCount = 1;
container = rib.ContainerAt(offsetFromBlockStart);
}
// remove the item, and remove the block if it's now empty
MoveItems(block, offsetFromBlockStart + 1, block.ItemCount - offsetFromBlockStart - 1, block, offsetFromBlockStart, 0);
--block.ItemCount;
RemoveAndCoalesceBlocksIfNeeded(block);
//
// now insert into the new spot.
//
position = new GeneratorPosition(-1,0);
block = _itemMap.Next;
offsetFromBlockStart = newIndex;
while (block != _itemMap && offsetFromBlockStart >= block.ItemCount)
{
offsetFromBlockStart -= block.ItemCount;
if (block.ContainerCount > 0)
{
position.Index += block.ContainerCount;
position.Offset = 0;
}
else
{
position.Offset += block.ItemCount;
}
block = block.Next;
}
position.Offset += offsetFromBlockStart + 1;
// if it's an unrealized block, add the item by bumping the count
uib = block as UnrealizedItemBlock;
if (uib != null)
{
MoveItems(uib, offsetFromBlockStart, 1, uib, offsetFromBlockStart+1, 0);
++ uib.ItemCount;
}
// if the item can be added to a previous unrealized block, do so
else if ((offsetFromBlockStart == 0 || block == _itemMap) &&
((uib = block.Prev as UnrealizedItemBlock) != null))
{
++ uib.ItemCount;
}
// otherwise, create a new unrealized block
else
{
uib = new UnrealizedItemBlock();
uib.ItemCount = 1;
// split the current realized block, if necessary
if (offsetFromBlockStart > 0 && (rib = block as RealizedItemBlock) != null)
{
RealizedItemBlock newBlock = new RealizedItemBlock();
MoveItems(rib, offsetFromBlockStart, rib.ItemCount - offsetFromBlockStart, newBlock, 0, offsetFromBlockStart);
newBlock.InsertAfter(rib);
position.Index += block.ContainerCount;
position.Offset = 1;
offsetFromBlockStart = 0;
block = newBlock;
}
uib.InsertBefore(block);
}
if (_traceLog != null)
_traceLog.Add("OnItemMoved {0} oldIndex = {1}", TraceLog.IdFor(item), oldIndex);
DependencyObject parent = VisualTreeHelper.GetParentInternal(container);
// tell layout what happened
if (ItemsChanged != null)
{
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Move, position, oldPosition, 1, containerCount));
}
// unhook the container. Do this after layout has (presumably) removed it from
// the UI, so that it doesn't inherit DataContext falsely.
if (container != null)
{
if (parent == null || VisualTreeHelper.GetParentInternal(container) != parent)
{
UnlinkContainerFromItem(container, item);
}
else
{
// If the container has the same visual parent as before then that means that
// the container was just repositioned within the parent's VisualCollection.
// we don't need to unlink the container, but we do need to re-realize the block.
Realize(uib, offsetFromBlockStart, item, container);
}
}
// fix up the AlternationIndex on containers affected by the move
if (_alternationCount > 0)
{
// start with the smaller of the two positions, and proceed forward.
// This tends to preserve the AlternatonIndex on containers at the
// front of the list, as users expect
int index = Math.Min(oldIndex, newIndex);
GetBlockAndPosition(index, out position, out block, out offsetFromBlockStart);
SetAlternationIndex(block, offsetFromBlockStart, GeneratorDirection.Forward);
}
}
// Called when the items collection is refreshed
void OnRefresh()
{
((IItemContainerGenerator)this).RemoveAll();
if (_traceLog != null)
_traceLog.Add("OnRefresh count = {0}", Items.Count);
// tell layout what happened
if (ItemsChanged != null)
{
GeneratorPosition position = new GeneratorPosition(0, 0);
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Reset, position, 0, 0));
}
}
// this method is here just to avoid the compiler error
// error CS0649: Warning as Error: Field '..._traceLog' is never assigned to, and will always have its default value null
void InitializeTraceLog()
{
_traceLog = new TraceLog(20);
}
//------------------------------------------------------
//
// Private Fields
//
//-----------------------------------------------------
private TraceLog _traceLog;
private Generator _generator;
private IGeneratorHost _host;
private ItemBlock _itemMap;
private GeneratorStatus _status;
private int _itemsGenerated;
private int _startIndexForUIFromItem;
private DependencyObject _peer;
private int _level;
private IList _items;
private GroupStyle _groupStyle;
private ItemContainerGenerator _parent;
private ArrayList _emptyGroupItems;
private int _alternationCount;
private Type _containerType; // type of containers on the recycle queue
private Queue _recyclableContainers = new Queue();
event MapChangedHandler MapChanged;
delegate void MapChangedHandler(ItemBlock block, int offset, int count,
ItemBlock newBlock, int newOffset, int deltaCount);
#if GENERATOR_TRACE
MS.Internal.Utility.HFTimer _timer = new MS.Internal.Utility.HFTimer();
MS.Internal.Utility.HFTimer _creationTimer = new MS.Internal.Utility.HFTimer();
#endif
//------------------------------------------------------
//
// Private Nested Classes
//
//-----------------------------------------------------
// The ItemContainerGenerator uses the following data structure to maintain
// the correspondence between items and their containers. It's a doubly-linked
// list of ItemBlocks, with a sentinel node serving as the header.
// Each node maintains two counts: the number of items it holds, and
// the number of containers.
//
// There are two kinds of blocks - one holding only "realized" items (i.e.
// items that have been generated into containers) and one holding only
// unrealized items. The container count of a realized block is the same
// as its item count (one container per item); the container count of an
// unrealized block is zero.
//
// Unrealized blocks can hold any number of items. We only need to know
// the count. Realized blocks have a fixed-sized array (BlockSize) so
// they hold up to that many items and their corresponding containers. When
// a realized block fills up, it inserts a new (empty) realized block into
// the list and carries on.
//
// This data structure was chosen with virtualization in mind. The typical
// state is a long block of unrealized items (the ones that have scrolled
// off the top), followed by a moderate number (<50?) of realized items
// (the ones in view), followed by another long block of unrealized items
// (the ones that have not yet scrolled into view). So the list will contain
// an unrealized block, followed by 3 or 4 realized blocks, followed by
// another unrealized block. Fewer than 10 blocks altogether, so linear
// searching won't cost that much. Thus we don't need a more sophisticated
// data structure. (If profiling reveals that we do, we can always replace
// this one. It's totally private to the ItemContainerGenerator and its
// Generators.)
// represents a block of items
private class ItemBlock
{
public const int BlockSize = 16;
public int ItemCount { get { return _count; } set { _count = value; } }
public ItemBlock Prev { get { return _prev; } set { _prev = value; } }
public ItemBlock Next { get { return _next; } set { _next = value; } }
public virtual int ContainerCount { get { return Int32.MaxValue; } }
public virtual DependencyObject ContainerAt(int index) { return null; }
public virtual object ItemAt(int index) { return null; }
public void InsertAfter(ItemBlock prev)
{
Next = prev.Next;
Prev = prev;
Prev.Next = this;
Next.Prev = this;
}
public void InsertBefore(ItemBlock next)
{
InsertAfter(next.Prev);
}
public void Remove()
{
Prev.Next = Next;
Next.Prev = Prev;
}
public void MoveForward(ref GeneratorState state, bool allowMovePastRealizedItem)
{
if (IsMoveAllowed(allowMovePastRealizedItem))
{
state.ItemIndex += 1;
if (++state.Offset >= ItemCount)
{
state.Block = Next;
state.Offset = 0;
state.Count += ItemCount;
}
}
}
public void MoveBackward(ref GeneratorState state, bool allowMovePastRealizedItem)
{
if (IsMoveAllowed(allowMovePastRealizedItem))
{
if (--state.Offset < 0)
{
state.Block = Prev;
state.Offset = state.Block.ItemCount - 1;
state.Count -= state.Block.ItemCount;
}
state.ItemIndex -= 1;
}
}
protected virtual bool IsMoveAllowed(bool allowMovePastRealizedItem)
{
return allowMovePastRealizedItem;
}
int _count;
ItemBlock _prev, _next;
}
// represents a block of unrealized (ungenerated) items
private class UnrealizedItemBlock : ItemBlock
{
public override int ContainerCount { get { return 0; } }
protected override bool IsMoveAllowed(bool allowMovePastRealizedItem)
{
return true;
}
}
// represents a block of realized (generated) items
private class RealizedItemBlock : ItemBlock
{
public override int ContainerCount { get { return ItemCount; } }
public override DependencyObject ContainerAt(int index)
{
return _entry[index].Container;
}
public override object ItemAt(int index)
{
return _entry[index].Item;
}
public void CopyEntries(RealizedItemBlock src, int offset, int count, int newOffset)
{
int k;
// choose which direction to copy so as not to clobber existing
// entries (in case the source and destination blocks are the same)
if (offset < newOffset)
{
// copy right-to-left
for (k = count - 1; k >= 0; --k)
{
_entry[newOffset + k] = src._entry[offset + k];
}
// clear vacated entries, to avoid leak
if (src != this)
{
src.ClearEntries(offset, count);
}
else
{
src.ClearEntries(offset, newOffset - offset);
}
}
else
{
// copy left-to-right
for (k = 0; k < count; ++k)
{
_entry[newOffset + k] = src._entry[offset + k];
}
// clear vacated entries, to avoid leak
if (src != this)
{
src.ClearEntries(offset, count);
}
else
{
src.ClearEntries(newOffset + count, offset - newOffset);
}
}
}
public void ClearEntries(int offset, int count)
{
for (int i=0; i 0)
{
ItemContainerGenerator generator = Generator;
generator.ItemsChanged -= new ItemsChangedEventHandler(OnItemsChanged);
generator.Parent.OnSubgroupBecameNonEmpty(this, group);
}
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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