Hi,

Looks like there's actually no category for this stuff yet. Question is about WPF graphics /C#2008 /.NET 3.5. Below is a snippet lifted from a MS code sample and is the ArrangeOverride for an Adorner:

        protected override Size ArrangeOverride(Size finalSize)
        {
            // desiredWidth and desiredHeight are the width and height of the element that's being adorned.  
            // These will be used to place the ResizingAdorner at the corners of the adorned element.  
            double desiredWidth = AdornedElement.DesiredSize.Width;
            double desiredHeight = AdornedElement.DesiredSize.Height;
            // adornerWidth & adornerHeight are used for placement as well.

            double adornerWidth = this.DesiredSize.Width;
            double adornerHeight = this.DesiredSize.Height;

            topLeft.Arrange(new Rect(-adornerWidth / 2, -adornerHeight / 2, adornerWidth, adornerHeight));
            topRight.Arrange(new Rect(desiredWidth - adornerWidth / 2, -adornerHeight / 2, adornerWidth, adornerHeight));
            bottomLeft.Arrange(new Rect(-adornerWidth / 2, desiredHeight - adornerHeight / 2, adornerWidth, adornerHeight));
            bottomRight.Arrange(new Rect(desiredWidth - adornerWidth / 2, desiredHeight - adornerHeight / 2, adornerWidth, adornerHeight));

            // Return the final size.
            return finalSize;
        }

I don't understand why the example uses Desired.X properties of both the Adorner and its AdornedElement. AFAICS they are always identical at runtime.
The AdornedElement in this case is a Rectangle. topLeft,topRight etc. are Thumbs.

I should mention that other sections of the sample were pretty sloppy and gave erroneous results so I've no great faith in this snippet actually demonstrating best practice...

TIA,
Viv