Search code examples
c#wpfadorner

Accessing data from an Adorner

I'm writing a 2D graphics tool in C# and WPF, and I'm using Adorners on the Shapes drawn to Canvas.

I'd like the adorners to highlight when a shape is considered "selected", which I'm currently doing using MouseDown and MouseUp events.

However, the user can select multiple shapes, so not all of the shapes will receive both of the mouse events.

I have a class that manages the drawing, which holds a List of the selected shapes. What is the best way to give the adorners access to this data, so they can see if their adorned element is selected?

Some thing's I've considered:

  • Making the List global - bad idea
  • Sub-classing each shape to add a "selected" property - would require changing all references to the shapes in my class
Solution

  • You can make an attached dependencyproperty you set on your shape - then you can set that property when you select one. The adorner can have a visibility binding to the property on the shape so you get visibility set automatic.

    You can also use the Tag property on the shape to store values - that is the old way of doing it :)