Programming assignment 3

Ask questions about this assignment at http://pbl.cc.gatech.edu:8080/cs2390.24

Implement an object-oriented drawing tool for Squeak. Make sure that it has these capabilities:

• Draw lines, rectangles, and circles, of any color that I want. (Support at least four colors).
• Draw polygons -- let me click out points, connect the points. (Note: I still want to be able to drag these things around!) For ease of use and implementation, simply accept four points and connect them.
• Be able to drag these objects around the screen.
• Be able to delete these objects.
• Choose between tools.
• Choose a tool that says "Quit the Editor"
• Choose a tool that says "Save this Form to Disk" (Hint: Forms understand storeOn:, e.g., given a form to write out named myForm, fred := FileStream fileNamed: 'fred'. myForm storeOn: fred. fred close.

I want to test your tool by executing DrawingEditor new.

In your Scenarios section, be sure to answer these questions:

• How do you figure out which object is being clicked upon?
• How do you figure out which tool is active when somebody clicks down on the drawing surface?
• How do you show the user that they're drawing a new object or resizing an object or dragging an object?
• How do you redraw things after an object is moved so that things get redrawn appropriately (e.g., the old one is deleted, the tracked one is deleted)?

RECOMMENDED: Don't just implement your Design Assignment! You've learned a lot about design since then. Re-think it.

STRONGLY RECOMMENDED: Don't try to just assemble components. This ain't Visual Basic -- I want you to actually think through how buttons, canvases, etc. are implemented! If you want, you can reuse Squeak windows, buttons, controllers, etc., but I don't recommend it. I suggest that you implement from scratch: Blast graphics onto the Display instead of using windows, and track user events with Sensor.

WARNING: Beware of overwriting the existing Squeak classes for Rectangle, etc. (Note: But you can, and should, reuse these!)

What you don't have to worry about: Don't bother with clipping, with having multiple editors at once, with having resizable editor areas.

Ask questions about this assignment at http://pbl.cc.gatech.edu:8080/cs2390.24