Using Drawing Tools
Go Up to Handling Multiple Drawing Objects in Your Application
Now that you can tell what tool to use, you must indicate how to draw the different shapes. The only methods that perform any drawing are the mouse-move and mouse-up handlers, and the only drawing code draws lines, no matter what tool is selected.
To use different drawing tools, your code needs to specify how to draw, based on the selected tool. You add this instruction to each tool's event handler.