Basic Graphics Programming

As always, feel free to ask lots of questions, and feel free to work together as well!

The Canvas class

In your c:\CSTI folder, create a subfolder called graphicsIntro to hold your work for this lab.

Copy the file Canvas.java to the graphicsLab directory that you just created. To do so, right click on the link and choose "Save Link As..."

You can open up the file and look at it if you'd like. However, we won't be paying much attention for a while to what's in this class. Instead, we're going to use this class in our own programs.

Now copy the file MyArtwork.java to your directory and open it up in DrJava. Read through the code and see if you can figure out what it will do.

Compile and run MyArtwork. What do you see? Try modifying the program to accomplish the following:

• Make the graphics window tall and skinny. What happens to the square when you run your new version? Why?
• Change the background color. Can you make it white?
• Make the square green.

The documentation for the Canvas class is at this web page. Notice that the page has distinct sections: a general description of the class, a summary of fields and constructors (we'll talk about those later), and a more detailed description of all the methods available to you. Take a few minutes to skim the methods and to familiarize yourself with the documentation format. Then try picking out a few methods that look like they might be interesting, and try them out. Modify your program to use other methods from this documentation page. (Note that the polygon methods require ideas we haven't covered yet, so you might want to stay away from them unless you feel particularly daring.)

Your Own Design

Write a Java application named MyDrawing.java. Your program should create a Canvas object and, using the methods in the Canvas class, draw a picture. Spend a little bit of time experimenting with the different methods, and then figure out how to combine these methods to draw more complex shapes or pictures. Use the arithmetic operations that you learned in the last assignment as part of your program.

Some suggestions:

• Use arithmetic to create a "scalable" shape. For example, you might ask the user to enter how long each edge of a square should be, and the program should draw a square accordingly.
• Combine simple shapes in more complex ways. For example, combine triangles to form a star, or circles to generate different patterns, or rectangles to create a tic-tac-toe board.
• Draw a picture, and then use the wait() and erase() methods to erase part of the picture. (If you're really feeling ambitious, you might want to figure out how you could use these methods to make it appear as if something is moving across your canvas.)

Be creative, and have fun!

Written by Amy Csizmar Dalal, Dave Musicant, and Jeff Ondich.