元の一連のブログ投稿に基づいた実用的なコードがいくつかあります。完全なコードは長すぎてここに投稿できません。PasteBinに投稿しました。
のコードDragAdorner
は非常に単純です。
internal sealed class DragAdorner : Adorner
{
private readonly UIElement _child;
private readonly double _xCenter;
private readonly double _yCenter;
private double _leftOffset;
private double _topOffset;
public DragAdorner(UIElement owner, UIElement child, bool useVisualBrush, double opacity) : base(owner)
{
if (!useVisualBrush)
{
_child = child;
}
else
{
var size = GetRealSize(child);
_xCenter = size.Width / 2;
_yCenter = size.Height / 2;
_child = new Rectangle
{
RadiusX = 3,
RadiusY = 3,
Width = size.Width,
Height = size.Height,
Fill = new VisualBrush(child)
{
Opacity = opacity,
AlignmentX = AlignmentX.Left,
AlignmentY = AlignmentY.Top,
Stretch = Stretch.None,
},
};
}
}
protected override int VisualChildrenCount
{
get { return 1; }
}
public double LeftOffset
{
get
{
return _leftOffset + _xCenter;
}
set
{
_leftOffset = value - _xCenter;
UpdatePosition();
}
}
public double TopOffset
{
get
{
return _topOffset + _yCenter;
}
set
{
_topOffset = value - _yCenter;
UpdatePosition();
}
}
private static Size GetRealSize(UIElement child)
{
return child == null ? Size.Empty : child.RenderSize;
}
public void UpdatePosition(Point point)
{
_leftOffset = point.X;
_topOffset = point.Y;
UpdatePosition();
}
public void UpdatePosition()
{
var adorner = Parent as AdornerLayer;
if (adorner != null) adorner.Update(AdornedElement);
}
protected override Visual GetVisualChild(int index)
{
if (0 != index) throw new ArgumentOutOfRangeException("index");
return _child;
}
protected override Size MeasureOverride(Size availableSize)
{
_child.Measure(availableSize);
return _child.DesiredSize;
}
protected override Size ArrangeOverride(Size finalSize)
{
_child.Arrange(new Rect(_child.DesiredSize));
return finalSize;
}
public override GeneralTransform GetDesiredTransform(GeneralTransform transform)
{
var result = new GeneralTransformGroup();
result.Children.Add(new TranslateTransform(_leftOffset, _topOffset));
var baseTransform = base.GetDesiredTransform(transform);
if (baseTransform != null) result.Children.Add(baseTransform);
return result;
}
}