12.5. Designing Irregularly Shaped Controls

The UserControl object has a rectangular shape by default. However, a custom control need not be rectangular. It's possible to create irregularly shaped forms, too, but unlike irregularly shaped controls, an irregularly shaped form is still quite uncommon. Irregularly shaped controls are used in fancy interfaces, and they usually react to movement of the mouse. (They may change color when the mouse is over them or when they're clicked, for example.)

To change the default shape of a custom control, you must use the Region object, which is another graphics-related object that specifies a closed area. You can even use Bezier curves to make highly unusual and smooth shapes for your controls. In this section, we'll do something less ambitious: We'll create controls with the shape of an ellipse, as shown in the upper half of Figure 12.7. To follow the code presented in this section, open the NonRectangularControl project; the custom control is the RoundControl Windows Control Library project, and Form1 is the test form for the control.