CompositeFigures are collections of existing figures organised together into a single figure using the Composite design pattern. In JHotDraw this functionality is represented in the abstract CompositeFigure class and its subclass GroupFigure.

When creating a custom composite figure there are several issues to consider: selecting which classes are going to be composed, positioning those classes in the composite and finally defining how the composite will react to movement and resize events?

• For further information on the Figure inheritance hierarchy see [The Figure Hierarchy]
• To reuse existing figures in your composite see [Identifying Existing Figures]
  

Figures can be added to a composite by calling its add(Figure) method  When adding figures to a composite each figure's position relative to the others has to be defined before composing them together (see example below for details). When figures overlap in a composite It is also important to add the figures in a back to front ordering (i.e. the figure at the back of the composite should be added first).

The GroupFigure class provides a default implementation of composite functionality; it provides support for moving the composite around the drawing but prevents resize behaviour.

• How to create a composite figure (example creates composite figure shown above)
  

        ...
    TriangleFigure triangle1 = new TriangleFigure(new Point(0,0), new Point(20,20));
    TriangleFigure triangle2 = new TriangleFigure(new Point(20,0), new Point(40,20));

    GroupFigure group = new GroupFigure();

    group.add(triangle1);
    group.add(triangle2);
    //GroupFigure group can now be added to the drawing or used to create a tool
        ...

•     To create construction tools for figures see [Using CreationTool]