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using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
namespace DiagramDesigner.Controls
{
public class RelativePositionPanel : Panel
{
public static readonly DependencyProperty RelativePositionProperty =
DependencyProperty.RegisterAttached("RelativePosition", typeof(Point), typeof(RelativePositionPanel),
new FrameworkPropertyMetadata(new Point(0, 0),
new PropertyChangedCallback(RelativePositionPanel.OnRelativePositionChanged)));
public static Point GetRelativePosition(UIElement element)
{
if (element == null)
{
throw new ArgumentNullException("element");
}
return (Point)element.GetValue(RelativePositionProperty);
}
public static void SetRelativePosition(UIElement element, Point value)
{
if (element == null)
{
throw new ArgumentNullException("element");
}
element.SetValue(RelativePositionProperty, value);
}
private static void OnRelativePositionChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
UIElement reference = d as UIElement;
if (reference != null)
{
RelativePositionPanel parent = VisualTreeHelper.GetParent(reference) as RelativePositionPanel;
if (parent != null)
{
parent.InvalidateArrange();
}
}
}
protected override Size ArrangeOverride(Size arrangeSize)
{
foreach (UIElement element in base.InternalChildren)
{
if (element != null)
{
Point relPosition = GetRelativePosition(element);
double x = (arrangeSize.Width - element.DesiredSize.Width) * relPosition.X;
double y = (arrangeSize.Height - element.DesiredSize.Height) * relPosition.Y;
if (double.IsNaN(x)) x = 0;
if (double.IsNaN(y)) y = 0;
element.Arrange(new Rect(new Point(x, y), element.DesiredSize));
}
}
return arrangeSize;
}
protected override Size MeasureOverride(Size availableSize)
{
Size size = new Size(double.PositiveInfinity, double.PositiveInfinity);
// SDK docu says about InternalChildren Property: 'Classes that are derived from Panel
// should use this property, instead of the Children property, for internal overrides
// such as MeasureCore and ArrangeCore.
foreach (UIElement element in this.InternalChildren)
{
if (element != null)
element.Measure(size);
}
return base.MeasureOverride(availableSize);
}
}
}
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