PaintBox
PaintBox is a free open source painting program with built in shapes.
PaintBox is a painting program that allows the user to draw and color lines, rectangles, ovals, polylines, polygons, and text. The program also allows the user to create customs shapes and then save them for quick use in other drawings. Also the program allows users to export the image form the custom .drw format to either a .png, .jpg, or .gif.
PaintBox is coded in Java and the code can be downloaded at SourceForge or found in the installation folder (the src folder).