private void RotateThumb_DragStarted(object sender, DragStartedEventArgs e)
{
_designerItem = DataContext as ContentControl;
if (_designerItem != null)
{
_canvas = _designerItem.FindParentControl<Canvas>();
var annoyingRectangle = _designerItem.DataContext as AnnoyingRectangle;
if (_canvas != null)
{
_centerPoint = _designerItem.TranslatePoint(
new Point((double)annoyingRectangle.Width * _designerItem.RenderTransformOrigin.X,
(double)annoyingRectangle.Height * _designerItem.RenderTransformOrigin.Y),
_canvas);
Point startPoint = Mouse.GetPosition(_canvas);
_startVector = Point.Subtract(startPoint, _centerPoint);
_offset = annoyingRectangle.Angle;
AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(this._canvas);
if (adornerLayer != null)
{
adorner = new RotateAdorner(this._designerItem);
adornerLayer.Add(this.adorner);
}
}
}
}
