Programming Python, 3rd Edition

PyDraw: Painting and Moving Graphics

Chapter 10 introduced simple Tkinter animation techniques (see the tour’s canvasDraw variants). The PyDraw program listed here builds upon those ideas to implement a more feature-rich painting program in Python. It adds new trails and scribble drawing modes, object and background color fills, embedded photos, and more. In addition, it implements object movement and animation techniques—drawn objects may be moved around the canvas by clicking and dragging, and any drawn object can be gradually moved across the screen to a target location clicked with the mouse.

Running PyDraw

PyDraw is essentially a Tkinter canvas with lots of keyboard and mouse event bindings to allow users to perform common drawing operations. This isn’t a professional-grade paint program by any definition, but it’s fun to play with. In fact, you really should—it is impossible to capture things such as object motion in the medium afforded by this book. Start PyDraw from the launcher bars (or run the file movingpics.py from Example 12-8 directly). Press the ? key to view a help message giving available commands (or read the help string in the code listings).

Figure 12-13 shows PyDraw after a few objects have been drawn on the canvas. To move any object shown here, either click it with the middle mouse button and drag to move it with the mouse cursor, or middle-click the object, and then right-click in the spot you want it to move toward. In the latter case, PyDraw performs an ...