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//---------------------------------------------------------------------------
//
// Copyright (C) Microsoft Corporation. All rights reserved.
//
// File: Canvas.cs
//
// Description: Contains the Canvas class.
// Spec at http://avalon/layout/Specs/Canvas.xml
//
// History:
// 06/02/2003 : greglett - Added to WCP branch (was APEContainer.cs in old branch)
//
//---------------------------------------------------------------------------
using MS.Internal;
using MS.Internal.Telemetry.PresentationFramework;
using MS.Utility;
using System.ComponentModel;
using System.Diagnostics;
using System.Reflection;
using System.Windows.Threading;
using System.Windows.Media;
using System;
using MS.Internal.PresentationFramework;
namespace System.Windows.Controls
{
/// <summary>
/// Canvas is used to place child UIElements at arbitrary positions or to draw children in multiple
/// layers.
///
/// Child positions are computed from the Left, Top properties. These properties do
/// not contribute to the size of the Canvas. To position children in a way that affects the Canvas' size,
/// use the Margin properties.
///
/// The order that children are drawn (z-order) is determined exclusively by child order.
/// </summary>
public class Canvas : Panel
{
//-------------------------------------------------------------------
//
// Constructors
//
//-------------------------------------------------------------------
#region Constructors
static Canvas()
{
ControlsTraceLogger.AddControl(TelemetryControls.Canvas);
}
/// <summary>
/// Default DependencyObject constructor
/// </summary>
/// <remarks>
/// Automatic determination of current Dispatcher. Use alternative constructor
/// that accepts a Dispatcher for best performance.
/// </remarks>
public Canvas() : base()
{
}
#endregion
//-------------------------------------------------------------------
//
// Public Methods
//
//-------------------------------------------------------------------
#region Public Methods
/// <summary>
/// Reads the attached property Left from the given element.
/// </summary>
/// <param name="element">The element from which to read the Left attached property.</param>
/// <returns>The property's value.</returns>
/// <seealso cref="Canvas.LeftProperty" />
[TypeConverter("System.Windows.LengthConverter, PresentationFramework, Version=" + BuildInfo.WCP_VERSION + ", Culture=neutral, PublicKeyToken=" + BuildInfo.WCP_PUBLIC_KEY_TOKEN + ", Custom=null")]
[AttachedPropertyBrowsableForChildren()]
public static double GetLeft(UIElement element)
{
if (element == null) { throw new ArgumentNullException("element"); }
return (double)element.GetValue(LeftProperty);
}
/// <summary>
/// Writes the attached property Left to the given element.
/// </summary>
/// <param name="element">The element to which to write the Left attached property.</param>
/// <param name="length">The length to set</param>
/// <seealso cref="Canvas.LeftProperty" />
public static void SetLeft(UIElement element, double length)
{
if (element == null) { throw new ArgumentNullException("element"); }
element.SetValue(LeftProperty, length);
}
/// <summary>
/// Reads the attached property Top from the given element.
/// </summary>
/// <param name="element">The element from which to read the Top attached property.</param>
/// <returns>The property's value.</returns>
/// <seealso cref="Canvas.TopProperty" />
[TypeConverter("System.Windows.LengthConverter, PresentationFramework, Version=" + BuildInfo.WCP_VERSION + ", Culture=neutral, PublicKeyToken=" + BuildInfo.WCP_PUBLIC_KEY_TOKEN + ", Custom=null")]
[AttachedPropertyBrowsableForChildren()]
public static double GetTop(UIElement element)
{
if (element == null) { throw new ArgumentNullException("element"); }
return (double)element.GetValue(TopProperty);
}
/// <summary>
/// Writes the attached property Top to the given element.
/// </summary>
/// <param name="element">The element to which to write the Top attached property.</param>
/// <param name="length">The length to set</param>
/// <seealso cref="Canvas.TopProperty" />
public static void SetTop(UIElement element, double length)
{
if (element == null) { throw new ArgumentNullException("element"); }
element.SetValue(TopProperty, length);
}
/// <summary>
/// Reads the attached property Right from the given element.
/// </summary>
/// <param name="element">The element from which to read the Right attached property.</param>
/// <returns>The property's Length value.</returns>
/// <seealso cref="Canvas.RightProperty" />
[TypeConverter("System.Windows.LengthConverter, PresentationFramework, Version=" + BuildInfo.WCP_VERSION + ", Culture=neutral, PublicKeyToken=" + BuildInfo.WCP_PUBLIC_KEY_TOKEN + ", Custom=null")]
[AttachedPropertyBrowsableForChildren()]
public static double GetRight(UIElement element)
{
if (element == null) { throw new ArgumentNullException("element"); }
return (double)element.GetValue(RightProperty);
}
/// <summary>
/// Writes the attached property Right to the given element.
/// </summary>
/// <param name="element">The element to which to write the Right attached property.</param>
/// <param name="length">The Length to set</param>
/// <seealso cref="Canvas.RightProperty" />
public static void SetRight(UIElement element, double length)
{
if (element == null) { throw new ArgumentNullException("element"); }
element.SetValue(RightProperty, length);
}
/// <summary>
/// Reads the attached property Bottom from the given element.
/// </summary>
/// <param name="element">The element from which to read the Bottom attached property.</param>
/// <returns>The property's Length value.</returns>
/// <seealso cref="Canvas.BottomProperty" />
[TypeConverter("System.Windows.LengthConverter, PresentationFramework, Version=" + BuildInfo.WCP_VERSION + ", Culture=neutral, PublicKeyToken=" + BuildInfo.WCP_PUBLIC_KEY_TOKEN + ", Custom=null")]
[AttachedPropertyBrowsableForChildren()]
public static double GetBottom(UIElement element)
{
if (element == null) { throw new ArgumentNullException("element"); }
return (double)element.GetValue(BottomProperty);
}
/// <summary>
/// Writes the attached property Bottom to the given element.
/// </summary>
/// <param name="element">The element to which to write the Bottom attached property.</param>
/// <param name="length">The Length to set</param>
/// <seealso cref="Canvas.BottomProperty" />
public static void SetBottom(UIElement element, double length)
{
if (element == null) { throw new ArgumentNullException("element"); }
element.SetValue(BottomProperty, length);
}
#endregion
//-------------------------------------------------------------------
//
// Public Properties + Dependency Properties's
//
//-------------------------------------------------------------------
#region Public Properties
//having this invalidate callback allows to host UIElements in Canvas and still
//receive invalidations when Left/Top/Bottom/Right properties change -
//registering the attached properties with AffectsParentArrange flag would be a mistake
//because those flags only work for FrameworkElements
private static void OnPositioningChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
UIElement uie = d as UIElement;
if(uie != null)
{
Canvas p = VisualTreeHelper.GetParent(uie) as Canvas;
if(p != null)
p.InvalidateArrange();
}
}
/// <summary>
/// This is the dependency property registered for the Canvas' Left attached property.
///
/// The Left property is read by a Canvas on its children to determine where to position them.
/// The child's offset from this property does not have an effect on the Canvas' own size.
/// Conflict between the Left and Right properties is resolved in favor of Left.
/// </summary>
public static readonly DependencyProperty LeftProperty
= DependencyProperty.RegisterAttached("Left", typeof(double), typeof(Canvas),
new FrameworkPropertyMetadata(Double.NaN, new PropertyChangedCallback(OnPositioningChanged)),
new ValidateValueCallback(System.Windows.Shapes.Shape.IsDoubleFiniteOrNaN));
/// <summary>
/// This is the dependency property registered for the Canvas' Top attached property.
///
/// The Top property is read by a Canvas on its children to determine where to position them.
/// The child's offset from this property does not have an effect on the Canvas' own size.
/// </summary>
public static readonly DependencyProperty TopProperty
= DependencyProperty.RegisterAttached("Top", typeof(double), typeof(Canvas),
new FrameworkPropertyMetadata(Double.NaN, new PropertyChangedCallback(OnPositioningChanged)),
new ValidateValueCallback(System.Windows.Shapes.Shape.IsDoubleFiniteOrNaN));
/// <summary>
/// This is the dependency property registered for the Canvas' Right attached property.
///
/// The Right property is read by a Canvas on its children to determine where to position them.
/// The child's offset from this property does not have an effect on the Canvas' own size.
/// Conflict between the Left and Right properties is resolved in favor of Left.
/// </summary>
public static readonly DependencyProperty RightProperty
= DependencyProperty.RegisterAttached("Right", typeof(double), typeof(Canvas),
new FrameworkPropertyMetadata(Double.NaN, new PropertyChangedCallback(OnPositioningChanged)),
new ValidateValueCallback(System.Windows.Shapes.Shape.IsDoubleFiniteOrNaN));
/// <summary>
/// This is the dependency property registered for the Canvas' Bottom attached property.
///
/// The Bottom property is read by a Canvas on its children to determine where to position them.
/// The child's offset from this property does not have an effect on the Canvas' own size.
/// </summary>
public static readonly DependencyProperty BottomProperty
= DependencyProperty.RegisterAttached("Bottom", typeof(double), typeof(Canvas),
new FrameworkPropertyMetadata(Double.NaN, new PropertyChangedCallback(OnPositioningChanged)),
new ValidateValueCallback(System.Windows.Shapes.Shape.IsDoubleFiniteOrNaN));
#endregion
//-------------------------------------------------------------------
//
// Protected Methods
//
//-------------------------------------------------------------------
#region Protected Methods
/// <summary>
/// Updates DesiredSize of the Canvas. Called by parent UIElement. This is the first pass of layout.
/// </summary>
/// <param name="constraint">Constraint size is an "upper limit" that Canvas should not exceed.</param>
/// <returns>Canvas' desired size.</returns>
protected override Size MeasureOverride(Size constraint)
{
Size childConstraint = new Size(Double.PositiveInfinity, Double.PositiveInfinity);
foreach (UIElement child in InternalChildren)
{
if (child == null) { continue; }
child.Measure(childConstraint);
}
return new Size();
}
/// <summary>
/// Canvas computes a position for each of its children taking into account their margin and
/// attached Canvas properties: Top, Left.
///
/// Canvas will also arrange each of its children.
/// </summary>
/// <param name="arrangeSize">Size that Canvas will assume to position children.</param>
protected override Size ArrangeOverride(Size arrangeSize)
{
//Canvas arranges children at their DesiredSize.
//This means that Margin on children is actually respected and added
//to the size of layout partition for a child.
//Therefore, is Margin is 10 and Left is 20, the child's ink will start at 30.
foreach (UIElement child in InternalChildren)
{
if (child == null) { continue; }
double x = 0;
double y = 0;
//Compute offset of the child:
//If Left is specified, then Right is ignored
//If Left is not specified, then Right is used
//If both are not there, then 0
double left = GetLeft(child);
if(!DoubleUtil.IsNaN(left))
{
x = left;
}
else
{
double right = GetRight(child);
if(!DoubleUtil.IsNaN(right))
{
x = arrangeSize.Width - child.DesiredSize.Width - right;
}
}
double top = GetTop(child);
if(!DoubleUtil.IsNaN(top))
{
y = top;
}
else
{
double bottom = GetBottom(child);
if(!DoubleUtil.IsNaN(bottom))
{
y = arrangeSize.Height - child.DesiredSize.Height - bottom;
}
}
child.Arrange(new Rect(new Point(x, y), child.DesiredSize));
}
return arrangeSize;
}
/// <summary>
/// Override of <seealso cref="UIElement.GetLayoutClip"/>.
/// </summary>
/// <returns>Geometry to use as additional clip if LayoutConstrained=true</returns>
protected override Geometry GetLayoutClip(Size layoutSlotSize)
{
//Canvas only clips to bounds if ClipToBounds is set,
// no automatic clipping
if(ClipToBounds)
return new RectangleGeometry(new Rect(RenderSize));
else
return null;
}
//
// This property
// 1. Finds the correct initial size for the _effectiveValues store on the current DependencyObject
// 2. This is a performance optimization
//
internal override int EffectiveValuesInitialSize
{
get { return 9; }
}
#endregion Protected Methods
}
}
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