private void ExecuteHandleDrag(ResizingThumb hitThumb, double horizontalChange, double verticalChange)
{
double currentScale = Scale;
double offsetX = hitThumb.IsLeft ? Math.Min(Canvas.GetLeft(adornedElement), -horizontalChange) : horizontalChange;
double offsetY = hitThumb.IsTop ? Math.Min(Canvas.GetTop(adornedElement), -verticalChange) : verticalChange;
double scaleX = (adornedElement.ActualWidth * Scale + offsetX) / adornedElement.ActualWidth;
double scaleY = (adornedElement.ActualHeight * Scale + offsetY) / adornedElement.ActualHeight;
Scale = Math.Min(scaleX, scaleY);
Scale = Math.Max(0.5, Scale);
if (hitThumb.IsLeft)
{
double move = (Scale - currentScale) * adornedElement.ActualWidth;
Canvas.SetLeft(adornedElement, Canvas.GetLeft(adornedElement) - move);
}
if (hitThumb.IsTop)
{
double move = (Scale - currentScale) * adornedElement.ActualHeight;
Canvas.SetTop(adornedElement, Canvas.GetTop(adornedElement) - move);
}
adornedElement.LayoutTransform = new ScaleTransform(Scale, Scale);
OnWidgetDragging(new Point(
Canvas.GetLeft(adornedElement) + adornedElement.ActualWidth * Scale,
Canvas.GetTop(adornedElement) + adornedElement.ActualHeight * Scale));
}
/// <summary>
/// Initialize the ResizingAdorner
/// </summary>
/// <param name="adornedElement"></param>
public ResizingAdorner(FrameworkElement adornedElement)
: base(adornedElement)
{
visualChildren = new VisualCollection(this);
// Call a helper method to initialize the Thumbs
// with a customized cursors.
topLeft = BuildAdornerCorner(true, true, Cursors.SizeNWSE);
topRight = BuildAdornerCorner(true, false, Cursors.SizeNESW);
bottomLeft = BuildAdornerCorner(false, true, Cursors.SizeNESW);
bottomRight = BuildAdornerCorner(false, false, Cursors.SizeNWSE);
}
protected override void HandleDrag(ResizingThumb hitThumb, DragDeltaEventArgs args)
{
ExecuteHandleDrag(hitThumb, args.HorizontalChange,args.VerticalChange);
}
private void HandleDragMethod(ResizingThumb hitThumb, double argsHorizontalChange, double argsVerticalChange)
{
// Ensure that the Width and Height are properly initialized after the resize.
EnforceSize();
// Change the size by the amount the user drags the mouse, as long as it's larger
// than the width or height of an adorner, respectively.
if (hitThumb.IsLeft)
{
double widthCanChange = adornedElement.Width - hitThumb.DesiredSize.Width;
double horizontalChange = Math.Min(argsHorizontalChange, widthCanChange);
Canvas.SetLeft(adornedElement, Canvas.GetLeft(adornedElement) + horizontalChange);
adornedElement.Width -= horizontalChange;
}
else
{
adornedElement.Width = Math.Max(adornedElement.Width + argsHorizontalChange, hitThumb.DesiredSize.Width);
}
if (hitThumb.IsTop)
{
double heightCanChange = adornedElement.Height - hitThumb.DesiredSize.Height;
double verticalChange = Math.Min(argsVerticalChange, heightCanChange);
Canvas.SetTop(adornedElement, Canvas.GetTop(adornedElement) + verticalChange);
adornedElement.Height -= verticalChange;
}
else
{
adornedElement.Height = Math.Max(adornedElement.Height + argsVerticalChange, hitThumb.DesiredSize.Height);
}
OnWidgetDragging(new Point(
Canvas.GetLeft(adornedElement) + adornedElement.Width,
Canvas.GetTop(adornedElement) + adornedElement.Height));
}
// Helper method to instantiate the corner Thumbs, set the Cursor property,
// set some appearance properties, and add the elements to the visual tree.
private ResizingThumb BuildAdornerCorner(bool isTop, bool isLeft, Cursor customizedCursor)
{
ResizingThumb cornerThumb = new ResizingThumb(isTop, isLeft);
cornerThumb.Cursor = customizedCursor;
cornerThumb.BorderBrush = Brushes.Black;
cornerThumb.Background = Brushes.White;
cornerThumb.BorderThickness = new Thickness(1);
cornerThumb.Height = cornerThumb.Width = 5;
cornerThumb.DragDelta += HandleDrag;
visualChildren.Add(cornerThumb);
return cornerThumb;
}
protected virtual void HandleDrag(ResizingThumb hitThumb, DragDeltaEventArgs args)
{
HandleDragMethod(hitThumb, args.HorizontalChange,args.VerticalChange);
}
