Adorners in Silverlight - Move, Size, Rotate, Custom Mouse Cursor

Dec 13, 2009

This adorner took me few days to get right!

Edit Dec, 15: Andrej Tozon created an updated source supporting Behaviours (and drag-drop without code in Blend). Here's a link to his version. Thanks Andrej!

This is work in progress, but the base functionality is there and stable!

Download source code

View Sample


The adorner currently has the following features:

  • Shows custom mouse cursors that get rotated and aligned to the object being rotated/sized in realtime. The cursors are Path elements, so this makes the cursor rotation possible. To see the effect in action, try rotating a window and then sizing: the size cursor is always perpendicular to the sizing edges.
  • Move. It also does click detection on activation - so that you can click a non-adorned object and immediately start dragging.
  • Two resize modes: center-preserving and edge-preserving (currently set via private bool property).
  • Rotate: hover outside any corner with the mouse to see the rotating adorner
  • Extension panel: allows to add additional adorner controls (e.g. "send backwards" icon on top of adorner). This is currently private, but will become properly exposed in later versions
  • The element being adorned can choose any algorithm to rotate/move itself (e.g. use TranslateTransform vs Canvas.Left and Canvas.Top). The functionality with the element being adorned is loosely coupled with the adorner through a simple IAdornedOject interface.
  • Nice glass border (from

Turns out, properly doing rotation, translation and all those adorner-specific things, wasn't easy for fact it took me quite a bit of time! I'm glad it's done for now! :)

Here is a quick extract of the source and how to use the interfaces:

     public interface IAdornedObject
        double Angle { get; set; }
        double X { get; set; }
        double Y { get; set; }
        double Width { get; set; }
        double Height { get; set; }

Usage is straight-forward:

Adorner adorner = new Adorner();
AdornedObject item = new AdornedObject(testImage);

To avoid hassles with Thumbs moving around, the core of the move/size/rotate code is in thumb_MouseMove() - giving it nice absolute mouse coordinates!

What do you think this adorner?

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