Code:
/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / System / Windows / EventTrigger.cs / 1305600 / EventTrigger.cs
/****************************************************************************\
*
* File: EventTrigger.cs
*
* An event trigger is a set of actions that will be activated in response to
* the specified event fired elsewhere.
*
* Copyright (C) by Microsoft Corporation. All rights reserved.
*
\***************************************************************************/
using System.Collections;
using System.Diagnostics;
using System.Windows.Markup;
using System.Collections.Specialized;
using System.ComponentModel;
namespace System.Windows
{
///
/// A class that controls a set of actions to activate in response to an event
///
[ContentProperty("Actions")]
public class EventTrigger : TriggerBase, IAddChild
{
///////////////////////////////////////////////////////////////////////
// Public members
///
/// Build an empty instance of the EventTrigger object
///
public EventTrigger()
{
}
///
/// Build an instance of EventTrigger associated with the given event
///
public EventTrigger( RoutedEvent routedEvent )
{
RoutedEvent = routedEvent;
}
///
/// Add an object child to this trigger's Actions
///
void IAddChild.AddChild(object value)
{
AddChild(value);
}
///
/// Add an object child to this trigger's Actions
///
protected virtual void AddChild(object value)
{
TriggerAction action = value as TriggerAction;
if (action == null)
{
throw new ArgumentException(SR.Get(SRID.EventTriggerBadAction, value.GetType().Name));
}
Actions.Add(action);
}
///
/// Add a text string to this trigger's Actions. Note that this
/// is not supported and will result in an exception.
///
void IAddChild.AddText(string text)
{
AddText(text);
}
///
/// Add a text string to this trigger's Actions. Note that this
/// is not supported and will result in an exception.
///
protected virtual void AddText(string text)
{
XamlSerializerUtil.ThrowIfNonWhiteSpaceInAddText(text, this);
}
///
/// The Event that will activate this trigger - one must be specified
/// before an event trigger is meaningful.
///
public RoutedEvent RoutedEvent
{
get
{
return _routedEvent;
}
set
{
if ( value == null )
{
throw new ArgumentNullException("value");
}
if( IsSealed )
{
throw new InvalidOperationException(SR.Get(SRID.CannotChangeAfterSealed, "EventTrigger"));
}
// When used as an element trigger, we don't actually need to seal
// to ensure cross-thread usability. However, if we *are* fixed on
// listening to an event already, don't allow this change.
if( _routedEventHandler != null )
{
// Recycle the Seal error message.
throw new InvalidOperationException(SR.Get(SRID.CannotChangeAfterSealed, "EventTrigger"));
}
_routedEvent = value;
}
}
///
/// The x:Name of the object whose event shall trigger this
/// EventTrigger. If null, then this is the object being Styled
/// and not anything under its Style.VisualTree.
///
[DefaultValue(null)]
public string SourceName
{
get
{
return _sourceName;
}
set
{
if( IsSealed )
{
throw new InvalidOperationException(SR.Get(SRID.CannotChangeAfterSealed, "EventTrigger"));
}
_sourceName = value;
}
}
///
/// Internal method to get the childId corresponding to the public
/// sourceId.
///
internal int TriggerChildIndex
{
get
{
return _childId;
}
set
{
_childId = value;
}
}
///
/// The collection of actions to activate when the Event occurs.
/// At least one action is required for the trigger to be meaningful.
///
[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
public TriggerActionCollection Actions
{
get
{
if( _actions == null )
{
_actions = new TriggerActionCollection();
// Give the collection a back-link, this is used for the inheritance context
_actions.Owner = this;
}
return _actions;
}
}
///
/// If we get a new inheritance context (or it goes to null)
/// we need to tell actions about it.
///
internal override void OnInheritanceContextChangedCore(EventArgs args)
{
base.OnInheritanceContextChangedCore(args);
if (_actions == null)
{
return;
}
for (int i=0; i<_actions.Count; i++)
{
DependencyObject action = _actions[i] as DependencyObject;
if (action != null && action.InheritanceContext == this)
{
action.OnInheritanceContextChanged(args);
}
}
}
///
/// This method is used by TypeDescriptor to determine if this property should
/// be serialized.
///
[EditorBrowsable(EditorBrowsableState.Never)]
public bool ShouldSerializeActions()
{
return ( _actions != null && _actions.Count > 0 );
}
///////////////////////////////////////////////////////////////////////
// Internal members
internal sealed override void Seal()
{
if( PropertyValues.Count > 0 )
{
throw new InvalidOperationException(SR.Get(SRID.EventTriggerDoNotSetProperties));
}
// EnterActions/ExitActions aren't meaningful on event triggers.
if( HasEnterActions || HasExitActions )
{
throw new InvalidOperationException(SR.Get(SRID.EventTriggerDoesNotEnterExit));
}
if (_routedEvent != null && _actions != null && _actions.Count > 0)
{
_actions.Seal(this); // TriggerActions need a link back to me to fetch the childId corresponding the sourceId string.
}
base.Seal(); // Should be almost a no-op given lack of PropertyValues
}
///////////////////////////////////////////////////////////////////////
// Private members
// Event that will fire this trigger
private RoutedEvent _routedEvent = null;
// Name of the Style.VisualTree node whose event to listen to.
// May remain the default value of null, which means the object being
// Styled is the target instead of something within the Style.VisualTree.
private string _sourceName = null;
// Style childId corresponding to the SourceName string
private int _childId = 0;
// Actions to invoke when this trigger is fired
private TriggerActionCollection _actions = null;
///////////////////////////////////////////////////////////////////////
// Storage attached to other objects to support triggers
// Some of these can be moved to base class as necessary.
// Exists on objects that have information in their [Class].Triggers collection property. (Currently root FrameworkElement only.)
internal static readonly UncommonField TriggerCollectionField = new UncommonField(null);
// This is the listener that we hook up to the SourceId element.
RoutedEventHandler _routedEventHandler = null;
// This is the SourceId-ed element.
FrameworkElement _source;
///////////////////////////////////////////////////////////////////////
// Internal static methods to process event trigger information stored
// in attached storage of other objects.
//
// Called when the FrameworkElement and the tree structure underneath it has been
// built up. This is the earliest point we can resolve all the child
// node identification that may exist in a Trigger object.
// This should be moved to base class if PropertyTrigger support is added.
internal static void ProcessTriggerCollection( FrameworkElement triggersHost )
{
TriggerCollection triggerCollection = TriggerCollectionField.GetValue(triggersHost);
if( triggerCollection != null )
{
// Don't seal the collection, because we allow it to change. We will,
// however, seal each of the triggers.
for( int i = 0; i < triggerCollection.Count; i++ )
{
ProcessOneTrigger( triggersHost, triggerCollection[i] );
}
}
}
////////////////////////////////////////////////////////////////////////
// ProcessOneTrigger
//
// Find the target element for this trigger, and set a listener for
// the event into (pointing back to the trigger).
internal static void ProcessOneTrigger( FrameworkElement triggersHost, TriggerBase triggerBase )
{
// This code path is used in the element trigger case. We don't actually
// need these guys to be usable cross-thread, so we don't really need
// to freeze/seal these objects. The only one expected to cause problems
// is a change to the RoutedEvent. At the same time we remove this
// Seal(), the RoutedEvent setter will check to see if the handler has
// already been created and refuse an update if so.
// triggerBase.Seal();
EventTrigger eventTrigger = triggerBase as EventTrigger;
if( eventTrigger != null )
{
Debug.Assert( eventTrigger._routedEventHandler == null && eventTrigger._source == null);
// PERF: Cache this result if it turns out we're doing a lot of lookups on the same name.
eventTrigger._source = FrameworkElement.FindNamedFrameworkElement( triggersHost, eventTrigger.SourceName );
// Create a statefull event delegate (which keeps a ref to the FE).
EventTriggerSourceListener listener = new EventTriggerSourceListener( eventTrigger, triggersHost );
// Store the RoutedEventHandler & target for use in DisconnectOneTrigger
eventTrigger._routedEventHandler = new RoutedEventHandler(listener.Handler);
eventTrigger._source.AddHandler( eventTrigger.RoutedEvent, eventTrigger._routedEventHandler,
false /* HandledEventsToo */ );
}
else
{
throw new InvalidOperationException(SR.Get(SRID.TriggersSupportsEventTriggersOnly));
}
}
////////////////////////////////////////////////////////////////////////
//
// DisconnectAllTriggers
//
// Call DisconnectOneTrigger for each trigger in the Triggers collection.
internal static void DisconnectAllTriggers( FrameworkElement triggersHost )
{
TriggerCollection triggerCollection = TriggerCollectionField.GetValue(triggersHost);
if( triggerCollection != null )
{
for( int i = 0; i < triggerCollection.Count; i++ )
{
DisconnectOneTrigger( triggersHost, triggerCollection[i] );
}
}
}
////////////////////////////////////////////////////////////////////////
//
// DisconnectOneTrigger
//
// In ProcessOneTrigger, we connect an event trigger to the element
// which it targets. Here, we remove the event listener to clean up.
internal static void DisconnectOneTrigger( FrameworkElement triggersHost, TriggerBase triggerBase )
{
EventTrigger eventTrigger = triggerBase as EventTrigger;
if( eventTrigger != null )
{
eventTrigger._source.RemoveHandler( eventTrigger.RoutedEvent, eventTrigger._routedEventHandler);
eventTrigger._routedEventHandler = null;
}
else
{
throw new InvalidOperationException(SR.Get(SRID.TriggersSupportsEventTriggersOnly));
}
}
internal class EventTriggerSourceListener
{
internal EventTriggerSourceListener( EventTrigger trigger, FrameworkElement host )
{
_owningTrigger = trigger;
_owningTriggerHost = host;
}
internal void Handler(object sender, RoutedEventArgs e)
{
// Invoke all actions of the associated EventTrigger object.
TriggerActionCollection actions = _owningTrigger.Actions;
for( int j = 0; j < actions.Count; j++ )
{
actions[j].Invoke(_owningTriggerHost);
}
}
private EventTrigger _owningTrigger;
private FrameworkElement _owningTriggerHost;
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
/****************************************************************************\
*
* File: EventTrigger.cs
*
* An event trigger is a set of actions that will be activated in response to
* the specified event fired elsewhere.
*
* Copyright (C) by Microsoft Corporation. All rights reserved.
*
\***************************************************************************/
using System.Collections;
using System.Diagnostics;
using System.Windows.Markup;
using System.Collections.Specialized;
using System.ComponentModel;
namespace System.Windows
{
///
/// A class that controls a set of actions to activate in response to an event
///
[ContentProperty("Actions")]
public class EventTrigger : TriggerBase, IAddChild
{
///////////////////////////////////////////////////////////////////////
// Public members
///
/// Build an empty instance of the EventTrigger object
///
public EventTrigger()
{
}
///
/// Build an instance of EventTrigger associated with the given event
///
public EventTrigger( RoutedEvent routedEvent )
{
RoutedEvent = routedEvent;
}
///
/// Add an object child to this trigger's Actions
///
void IAddChild.AddChild(object value)
{
AddChild(value);
}
///
/// Add an object child to this trigger's Actions
///
protected virtual void AddChild(object value)
{
TriggerAction action = value as TriggerAction;
if (action == null)
{
throw new ArgumentException(SR.Get(SRID.EventTriggerBadAction, value.GetType().Name));
}
Actions.Add(action);
}
///
/// Add a text string to this trigger's Actions. Note that this
/// is not supported and will result in an exception.
///
void IAddChild.AddText(string text)
{
AddText(text);
}
///
/// Add a text string to this trigger's Actions. Note that this
/// is not supported and will result in an exception.
///
protected virtual void AddText(string text)
{
XamlSerializerUtil.ThrowIfNonWhiteSpaceInAddText(text, this);
}
///
/// The Event that will activate this trigger - one must be specified
/// before an event trigger is meaningful.
///
public RoutedEvent RoutedEvent
{
get
{
return _routedEvent;
}
set
{
if ( value == null )
{
throw new ArgumentNullException("value");
}
if( IsSealed )
{
throw new InvalidOperationException(SR.Get(SRID.CannotChangeAfterSealed, "EventTrigger"));
}
// When used as an element trigger, we don't actually need to seal
// to ensure cross-thread usability. However, if we *are* fixed on
// listening to an event already, don't allow this change.
if( _routedEventHandler != null )
{
// Recycle the Seal error message.
throw new InvalidOperationException(SR.Get(SRID.CannotChangeAfterSealed, "EventTrigger"));
}
_routedEvent = value;
}
}
///
/// The x:Name of the object whose event shall trigger this
/// EventTrigger. If null, then this is the object being Styled
/// and not anything under its Style.VisualTree.
///
[DefaultValue(null)]
public string SourceName
{
get
{
return _sourceName;
}
set
{
if( IsSealed )
{
throw new InvalidOperationException(SR.Get(SRID.CannotChangeAfterSealed, "EventTrigger"));
}
_sourceName = value;
}
}
///
/// Internal method to get the childId corresponding to the public
/// sourceId.
///
internal int TriggerChildIndex
{
get
{
return _childId;
}
set
{
_childId = value;
}
}
///
/// The collection of actions to activate when the Event occurs.
/// At least one action is required for the trigger to be meaningful.
///
[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
public TriggerActionCollection Actions
{
get
{
if( _actions == null )
{
_actions = new TriggerActionCollection();
// Give the collection a back-link, this is used for the inheritance context
_actions.Owner = this;
}
return _actions;
}
}
///
/// If we get a new inheritance context (or it goes to null)
/// we need to tell actions about it.
///
internal override void OnInheritanceContextChangedCore(EventArgs args)
{
base.OnInheritanceContextChangedCore(args);
if (_actions == null)
{
return;
}
for (int i=0; i<_actions.Count; i++)
{
DependencyObject action = _actions[i] as DependencyObject;
if (action != null && action.InheritanceContext == this)
{
action.OnInheritanceContextChanged(args);
}
}
}
///
/// This method is used by TypeDescriptor to determine if this property should
/// be serialized.
///
[EditorBrowsable(EditorBrowsableState.Never)]
public bool ShouldSerializeActions()
{
return ( _actions != null && _actions.Count > 0 );
}
///////////////////////////////////////////////////////////////////////
// Internal members
internal sealed override void Seal()
{
if( PropertyValues.Count > 0 )
{
throw new InvalidOperationException(SR.Get(SRID.EventTriggerDoNotSetProperties));
}
// EnterActions/ExitActions aren't meaningful on event triggers.
if( HasEnterActions || HasExitActions )
{
throw new InvalidOperationException(SR.Get(SRID.EventTriggerDoesNotEnterExit));
}
if (_routedEvent != null && _actions != null && _actions.Count > 0)
{
_actions.Seal(this); // TriggerActions need a link back to me to fetch the childId corresponding the sourceId string.
}
base.Seal(); // Should be almost a no-op given lack of PropertyValues
}
///////////////////////////////////////////////////////////////////////
// Private members
// Event that will fire this trigger
private RoutedEvent _routedEvent = null;
// Name of the Style.VisualTree node whose event to listen to.
// May remain the default value of null, which means the object being
// Styled is the target instead of something within the Style.VisualTree.
private string _sourceName = null;
// Style childId corresponding to the SourceName string
private int _childId = 0;
// Actions to invoke when this trigger is fired
private TriggerActionCollection _actions = null;
///////////////////////////////////////////////////////////////////////
// Storage attached to other objects to support triggers
// Some of these can be moved to base class as necessary.
// Exists on objects that have information in their [Class].Triggers collection property. (Currently root FrameworkElement only.)
internal static readonly UncommonField TriggerCollectionField = new UncommonField(null);
// This is the listener that we hook up to the SourceId element.
RoutedEventHandler _routedEventHandler = null;
// This is the SourceId-ed element.
FrameworkElement _source;
///////////////////////////////////////////////////////////////////////
// Internal static methods to process event trigger information stored
// in attached storage of other objects.
//
// Called when the FrameworkElement and the tree structure underneath it has been
// built up. This is the earliest point we can resolve all the child
// node identification that may exist in a Trigger object.
// This should be moved to base class if PropertyTrigger support is added.
internal static void ProcessTriggerCollection( FrameworkElement triggersHost )
{
TriggerCollection triggerCollection = TriggerCollectionField.GetValue(triggersHost);
if( triggerCollection != null )
{
// Don't seal the collection, because we allow it to change. We will,
// however, seal each of the triggers.
for( int i = 0; i < triggerCollection.Count; i++ )
{
ProcessOneTrigger( triggersHost, triggerCollection[i] );
}
}
}
////////////////////////////////////////////////////////////////////////
// ProcessOneTrigger
//
// Find the target element for this trigger, and set a listener for
// the event into (pointing back to the trigger).
internal static void ProcessOneTrigger( FrameworkElement triggersHost, TriggerBase triggerBase )
{
// This code path is used in the element trigger case. We don't actually
// need these guys to be usable cross-thread, so we don't really need
// to freeze/seal these objects. The only one expected to cause problems
// is a change to the RoutedEvent. At the same time we remove this
// Seal(), the RoutedEvent setter will check to see if the handler has
// already been created and refuse an update if so.
// triggerBase.Seal();
EventTrigger eventTrigger = triggerBase as EventTrigger;
if( eventTrigger != null )
{
Debug.Assert( eventTrigger._routedEventHandler == null && eventTrigger._source == null);
// PERF: Cache this result if it turns out we're doing a lot of lookups on the same name.
eventTrigger._source = FrameworkElement.FindNamedFrameworkElement( triggersHost, eventTrigger.SourceName );
// Create a statefull event delegate (which keeps a ref to the FE).
EventTriggerSourceListener listener = new EventTriggerSourceListener( eventTrigger, triggersHost );
// Store the RoutedEventHandler & target for use in DisconnectOneTrigger
eventTrigger._routedEventHandler = new RoutedEventHandler(listener.Handler);
eventTrigger._source.AddHandler( eventTrigger.RoutedEvent, eventTrigger._routedEventHandler,
false /* HandledEventsToo */ );
}
else
{
throw new InvalidOperationException(SR.Get(SRID.TriggersSupportsEventTriggersOnly));
}
}
////////////////////////////////////////////////////////////////////////
//
// DisconnectAllTriggers
//
// Call DisconnectOneTrigger for each trigger in the Triggers collection.
internal static void DisconnectAllTriggers( FrameworkElement triggersHost )
{
TriggerCollection triggerCollection = TriggerCollectionField.GetValue(triggersHost);
if( triggerCollection != null )
{
for( int i = 0; i < triggerCollection.Count; i++ )
{
DisconnectOneTrigger( triggersHost, triggerCollection[i] );
}
}
}
////////////////////////////////////////////////////////////////////////
//
// DisconnectOneTrigger
//
// In ProcessOneTrigger, we connect an event trigger to the element
// which it targets. Here, we remove the event listener to clean up.
internal static void DisconnectOneTrigger( FrameworkElement triggersHost, TriggerBase triggerBase )
{
EventTrigger eventTrigger = triggerBase as EventTrigger;
if( eventTrigger != null )
{
eventTrigger._source.RemoveHandler( eventTrigger.RoutedEvent, eventTrigger._routedEventHandler);
eventTrigger._routedEventHandler = null;
}
else
{
throw new InvalidOperationException(SR.Get(SRID.TriggersSupportsEventTriggersOnly));
}
}
internal class EventTriggerSourceListener
{
internal EventTriggerSourceListener( EventTrigger trigger, FrameworkElement host )
{
_owningTrigger = trigger;
_owningTriggerHost = host;
}
internal void Handler(object sender, RoutedEventArgs e)
{
// Invoke all actions of the associated EventTrigger object.
TriggerActionCollection actions = _owningTrigger.Actions;
for( int j = 0; j < actions.Count; j++ )
{
actions[j].Invoke(_owningTriggerHost);
}
}
private EventTrigger _owningTrigger;
private FrameworkElement _owningTriggerHost;
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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