Question

I need to create a custom combo box that display shapes. I created the shapes by extending the Shape class, and implementing the DefiningGeometry function like this:

public abstract class MyShape : Shape
{


    public static readonly DependencyProperty SizeProperty = DependencyProperty.Register("Size", typeof(Double), typeof(MapShape));
    public static readonly DependencyProperty RotationAngleProperty = DependencyProperty.Register("RotationAngle", typeof(Double), typeof(MapShape), new PropertyMetadata(0.0d));

    public double Size
    {
        get { return (double)this.GetValue(SizeProperty); }
        set { this.SetValue(SizeProperty, value); }
    }

    public double RotationAngle
    {
        get { return (double)this.GetValue(RotationAngleProperty); }
        set { this.SetValue(RotationAngleProperty, value); }
    }

    protected override Geometry DefiningGeometry
    {
        get
        { return null; }
    }
}

I can extend that class and create any other shape I want. for instance, I have one that looks like an arrow:

public class Arrow : MyShape
{
    public Arrow() { 
    }

    protected override Geometry DefiningGeometry
    {
        get
        {
            double oneThird = this.Size / 3;
            double twoThirds = (this.Size * 2) / 3;
            double oneHalf = this.Size / 2;

            Point p1 = new Point(0.0d, oneThird);
            Point p2 = new Point(0.0d, twoThirds);
            Point p3 = new Point(oneHalf, twoThirds);
            Point p4 = new Point(oneHalf, this.Size);

            Point p5 = new Point(this.Size, oneHalf);
            Point p6 = new Point(oneHalf, 0);
            Point p7 = new Point(oneHalf, oneThird);


            List<PathSegment> segments = new List<PathSegment>(3);
            segments.Add(new LineSegment(p1, true));
            segments.Add(new LineSegment(p2, true));
            segments.Add(new LineSegment(p3, true));
            segments.Add(new LineSegment(p4, true));

            segments.Add(new LineSegment(p5, true));
            segments.Add(new LineSegment(p6, true));
            segments.Add(new LineSegment(p7, true));

            List<PathFigure> figures = new List<PathFigure>(1);
            PathFigure pf = new PathFigure(p1, segments, true);
            figures.Add(pf);
            RotateTransform rt = new RotateTransform(this.RotationAngle);

            Geometry g = new PathGeometry(figures, FillRule.EvenOdd, rt);

            return g;
        }
    }
}

I can add this shapes on XAML or code and they work just fine.

Now, those shapes are displayed on a graphics object somewhere in my form which is no relevant. The requirement I have is for the shapes on the graphic object in the form to be changed by the client from a ComboBox. So, basically I need to display the shapes inside the combo box as well. I really don’t need to use these classes I am showing here, it is just for clarification I add them to this note. But I do need to customize the combobox to show shapes in the items. One way I thought is using the ControlTemplate, Any other ideas, code, readings?
Thanks!

Answer 1

If I understood, what you want can be achieved by customizing the ItemTemplate property of the ComboBox.

 <ComboBox ...>
      <ComboBox.ItemTemplate>
          <DataTemplate>
             <!-- Whatever UI -->
          </DataTemplate>
      </ComboBox.ItemTemplate>
 </ComboBox>