CS 345: Spring 2025

Programming Assignment 1

Building Blocks

We are now ready to begin creating our graphics library.

    class GCanvas {
    public:
        virtual ~GCanvas() {}
    
        /**
         *  Fill the entire canvas with the specified color, using SRC porter-duff mode.
         */
        virtual void clear(const GColor&) = 0;
        
        /**
         *  Fill the rectangle with the color, using SRC_OVER porter-duff mode.
         *
         *  The affected pixels are those whose centers are "contained" inside the rectangle:
         *      e.g. contained == center > min_edge && center <= max_edge
         *
         *  Any area in the rectangle that is outside of the bounds of the canvas is ignored.
         */
        virtual void fillRect(const GRect&, const GColor&) = 0;
    };

    /**
     *  Implemnt this, returning an instance of your subclass of GCanvas.
     */
    std::unique_ptr<GCanvas> GCreateCanvas(const GBitmap&);

    /**
     *  Implement this, drawing into the provided canvas, and returning the title of your artwork.
     */
    std::string GDrawSomething(GCanvas*, GISize dimension);

You have 3 tasks:

Create a subclass of GCanvas, and override these methods:
- clear(...)
- fillRect(...)
Implement GCreateCanvas to return an instance of your subclass.
Implement GDrawSomething
- draw something into the canvas
- return a title for your artwork
- Inspirations

The pa1 directory will look something like this:

apps contains the code for testing your code.
expected contains sample output from the image tool to compare with your output.
include contains class headers that your code can use.
src contains common implementations needed for the tools.
DO NOT EDIT/ADD/REMOVE anything in these sub-directories. You should only add files to the root of the directory.

Add your files as needed at the root level (whatever .cpp or .h files you need). e.g.

my_canvas.cpp

my_draw_something.cpp

my_utils.h

To test your code...

    > make
    > ./image -e expected
    > ./tests
    > ./bench
    > ./dbench

For more details when testing...

    > mkdir diff
    > ./image -e expected -d diff
    > open diff/index.html
    >
    > ./tests -v
    >
    > ./bench -m substring-to-match

Bench scores on the VM

   clear         2.01
   rects_blend   6.3
   rects_opaque  0.66
   rect_big      0.35
   rect_tiny     0.34