AdornedElementPlaceholder.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / System / Windows / Controls / AdornedElementPlaceholder.cs / 1305600 / AdornedElementPlaceholder.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) 2005 by Microsoft Corporation.  All rights reserved.
//  
//
// 
// Description: 
//      AdornedElementPlaceholder is an element used in a Binding.ErrorTemplate.
//      Its purpose is to mimic the height and width of the AdornedElement so that 
//      other elements in Template can be arranged around or within it.
//
// See specs at http://avalon/connecteddata/Specs/Validation.mht
// 
// History:
//  02/01/2005       mharper: created. 
// 
//---------------------------------------------------------------------------
 
using System;
using System.Collections;
using System.Collections.Specialized;
using System.ComponentModel; 
using System.Diagnostics;
using System.Windows.Media; 
using System.Windows; 
using System.Windows.Data;
using System.Windows.Documents; 
using System.Windows.Markup;
using MS.Internal.Controls;
using MS.Utility;
 

namespace System.Windows.Controls 
{ 
    /// 
    ///     The base class for all controls. 
    /// 
    [ContentProperty("Child")]
    public class AdornedElementPlaceholder : FrameworkElement, IAddChild
    { 
        #region Constructors
 
        ///  
        ///     Default Control constructor
        ///  
        /// 
        ///     Automatic determination of current Dispatcher. Use alternative constructor
        ///     that accepts a Dispatcher for best performance.
        ///  
        public AdornedElementPlaceholder() : base()
        { 
        } 

        #endregion Constructors 


        ///
        /// This method is called to Add the object as a child.  This method is used primarily 
        /// by the parser; a more direct way of adding a child is to use the 
        /// property. 
        /// 
        ///
        /// The object to add as a child; it must be a UIElement. 
        ///
        void IAddChild.AddChild (Object value)
        {
            // keeping consistent with other elements:  adding null is a no-op. 
            if (value == null)
                return; 
 
            if (!(value is UIElement))
                throw new ArgumentException (SR.Get(SRID.UnexpectedParameterType, value.GetType(), typeof(UIElement)), "value"); 

            if (this.Child != null)
                throw new ArgumentException(SR.Get(SRID.CanOnlyHaveOneChild, this.GetType(), value.GetType()));
 
            this.Child = (UIElement)value;
        } 
 
        ///
        /// This method is called by the parser when text appears under the tag in markup. 
        /// Calling this method has no effect if text is just whitespace.  If text is not
        /// just whitespace, throw an exception.
        ///
        /// 
        /// Text to add as a child.
        /// 
        void IAddChild.AddText (string text) 
        {
            XamlSerializerUtil.ThrowIfNonWhiteSpaceInAddText(text, this); 
        }


        /// 
        /// Element for which the AdornedElementPlaceholder is reserving space.
        /// 
        public UIElement AdornedElement 
        {
            get 
            {
                TemplatedAdorner adorner = TemplatedAdorner;
                return adorner == null ? null : TemplatedAdorner.AdornedElement;
            } 
        }
 
 
        /// 
        /// The single child of an  
        /// 
        [DefaultValue(null)]
        public virtual UIElement Child
        { 
            get
            { 
                return _child; 
            }
 
            set
            {
                UIElement old = _child;
 
                if (old != value)
                { 
                    RemoveVisualChild(old); 
                    //need to remove old element from logical tree
                    RemoveLogicalChild(old); 
                    _child = value;

                    AddVisualChild(_child);
                    AddLogicalChild(value); 

                    InvalidateMeasure(); 
                } 
            }
        } 

        /// 
        /// Gets the Visual children count.
        ///  
        protected override int VisualChildrenCount
        { 
            get 
            {
                return (_child == null) ? 0 : 1; 
            }
        }

        ///  
        /// Gets the Visual child at the specified index.
        ///  
        protected override Visual GetVisualChild(int index) 
        {
            if (_child == null || index != 0) 
            {
                throw new ArgumentOutOfRangeException("index", index, SR.Get(SRID.Visual_ArgumentOutOfRange));
            }
            return _child; 
        }
 
        ///  
        /// Returns enumerator to logical children.
        ///  
        protected internal override IEnumerator LogicalChildren
        {
            get
            { 
                // Could optimize this code by returning EmptyEnumerator.Instance if _child == null.
                return new SingleChildEnumerator(_child); 
            } 
        }
 
        /// 
        ///     This virtual method in called when IsInitialized is set to true and it raises an Initialized event
        /// 
        protected override void OnInitialized(EventArgs e) 
        {
            if (TemplatedParent == null) 
                throw new InvalidOperationException(SR.Get(SRID.AdornedElementPlaceholderMustBeInTemplate)); 

            base.OnInitialized(e); 
        }


        ///  
        ///     AdornedElementPlaceholder measure behavior is to measure
        ///     only the first visual child.  Note that the return value 
        ///     of Measure on this child is ignored as the purpose of this 
        ///     class is to match the size of the element for which this
        ///     is a placeholder. 
        /// 
        /// The measurement constraints.
        /// The desired size of the control.
        protected override Size MeasureOverride(Size constraint) 
        {
            if (TemplatedParent == null) 
                throw new InvalidOperationException(SR.Get(SRID.AdornedElementPlaceholderMustBeInTemplate)); 

            if (AdornedElement == null) 
                return new Size(0,0);

            Size desiredSize = AdornedElement.RenderSize;
            UIElement child = Child; 

            if (child != null) 
                child.Measure(desiredSize); 

            return desiredSize; 
        }

        /// 
        ///     Default AdornedElementPlaceholder arrangement is to only arrange 
        ///     the first visual child. No transforms will be applied.
        ///  
        /// The computed size. 
        protected override Size ArrangeOverride(Size arrangeBounds)
        { 
            UIElement child = Child;

            if (child != null)
                child.Arrange(new Rect(arrangeBounds)); 

            return arrangeBounds; 
        } 

 
        private TemplatedAdorner TemplatedAdorner
        {
            get
            { 
                if (_templatedAdorner == null)
                { 
                    // find the TemplatedAdorner 
                    FrameworkElement templateParent = this.TemplatedParent as FrameworkElement;
 
                    if (templateParent != null)
                    {
                        _templatedAdorner = VisualTreeHelper.GetParent(templateParent) as TemplatedAdorner;
 
                        if (_templatedAdorner != null && _templatedAdorner.ReferenceElement == null)
                        { 
                            _templatedAdorner.ReferenceElement = this; 
                        }
                    } 
                }
                return _templatedAdorner;
            }
        } 

        private UIElement _child; 
        private TemplatedAdorner _templatedAdorner; 
    }
} 



 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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