Can you attach an adorner's position to anywhere other than the upper-left of the adorned element?

I can't find any way of fixing an adorner to another point of the adorned element, other than the upper-left point. I know you can move the adorner relative to this point, by implementing ArrangeOverride, but the co-ord system is always based on the top-left.

Any ideas?

Solution

Not that I know of. But there is one more possibility to position the Adorner content than ArrangeOverride: AdornerPanel Class. With it's AdornerPlacementCollection Methods

PositionRelativeToAdornerHeight Method
PositionRelativeToAdornerWidth Method
PositionRelativeToContentHeight Method
PositionRelativeToContentWidth Method
SizeRelativeToAdornerDesiredHeight Method
SizeRelativeToAdornerDesiredWidth Method
SizeRelativeToContentHeight Method
SizeRelativeToContentWidth Method

you can determine the position and size of your Adorner relative to adorner or content e.g. with a factor and an offset. See this sample to place the Adorner above the adorned control:

// create AdornerPanel and add your adorner content
AdornerPanel adornerPanel = new AdornerPanel();
adornerPanel.Children.Add(yourAdornerContent);

// set placements on AdornerPanel
AdornerPlacementCollection placement = new AdornerPlacementCollection();
placement.PositionRelativeToAdornerHeight(-1, 0);
placement.PositionRelativeToAdornerWidth(1, 0);
AdornerPanel.SetPlacements(adornerPanel, placement);

// create Adorner with AdornerPanel inside
Adorner adorner = new YourAdorner(adornedElement)
{
    Child = adornerPanel
};