CS 6395: Assignment 3: Paint!

Summary

Implement a paint program. You program is to support a selection of drawing primitives and colors. It is also to support move/copy of rectangular regions and region fill.

The purpose of this assignment is to deal with interactivity issues, not to create a full featured paint program.

Due

This assignment is due the last day of class. You are to implement it in Java and Swing.

Details

You are to create a simple paint program. The program should support the following main features:

• drawing primitive: you should support a few different primitives, including (at least) two sizes of paint brushes (a single pixel and 10 pixels wide) and the ability to draw lines (and rectangles) by specifying their endpoints (corners).
• colors: you should support a palette of at least 8 colors. These are used for the "paint color". The "background" color is always white.
• move/copy of rectangular regions: you should support the ability to select a rectangular region and then copy it or move it. In both cases, moving or copying is performed by grabbing the selected region and dragging it to a new position, where it is painted onto the destination position. The difference is that if the region is copied, then the original region is not changed, but if the region is moved, then the original region is filled with white, the background color.
• region fill: you should be able to grab a paint color from the palette and "drop" it on the paint surface, where it will fill the region around the pixel that was "dropped" on. A region is defined as the connected set of pixels of the same color.
• at least one other feature of your choice.

Your interface should support multiple access to the modal commands. In particular, the drawing primitives and the action to select the copy/move region should be in a palette, a menu, and have keyboard shortcuts.

The colors should only be available from a palette. Clicking on a color should change the current color. Clicking and dragging onto the paint region should perform a fill.

Move and copy are implicit: if the current command is to select a copy/move region, dragging inside an existing region performs copy, and dragging with a shift key held does a move. Dragging outside the region replaces the region replaces the region. Clicking anywhere clears the region.

The palettes for the colors and tools can be in their own subwindow, or in the side of the main paint window, whichever you prefer. They should all be within one top-level window.

Feedback

• The cursor should unambiguously indicate what action is being performed, especially if the effect of clicking changes as the mouse moves.
• Feedback should be adjusted to be as detailed as possible, given the constraints of the current operation. For example, when dragging a rectangular image being copied, if the program cannot smoothly drag the image, you should switch to using an outline. But, for small images, you can draw the real image.
• When doing drag and drop filling, it would be desirable to give an indication of what will happen when the button is released. Ideally, you would show an outline of the affected area, but that will be to slow to compute as you move the mouse around. However, when the user pauses (doesn't move the mouse for a small amount of time) you could provide that feedback.

Extra Credit

You may obtain extra credit (up to 20% of the assignment value) for implementing extra features that lead to interesting interactivity problems and solutions. Please send the Professor email (blair@cc) if you would like to attempt to do something for extra credit, and want to make sure it is reasonable.