4.32: Drawing the Icon, and Syntactic Sugar

def drawIcon(shape, color, boxx, boxy):
    quarter = int(BOXSIZE * 0.25) # syntactic sugar
    half =    int(BOXSIZE * 0.5)  # syntactic sugar

    left, top = leftTopCoordsOfBox(boxx, boxy) # get pixel coords from board coords
    # Draw the shapes
    if shape == DONUT:
        pygame.draw.circle(DISPLAYSURF, color, (left + half, top + half), half - 5)
        pygame.draw.circle(DISPLAYSURF, BGCOLOR, (left + half, top + half), quarter - 5)
    elif shape == SQUARE:
        pygame.draw.rect(DISPLAYSURF, color, (left + quarter, top + quarter, BOXSIZE - half, BOXSIZE - half))
    elif shape == DIAMOND:
        pygame.draw.polygon(DISPLAYSURF, color, ((left + half, top), (left + BOXSIZE - 1, top + half), (left + half, top + BOXSIZE - 1), (left, top + half)))
    elif shape == LINES:
        for i in range(0, BOXSIZE, 4):
            pygame.draw.line(DISPLAYSURF, color, (left, top + i), (left + i, top))
            pygame.draw.line(DISPLAYSURF, color, (left + i, top + BOXSIZE - 1), (left + BOXSIZE - 1, top + i))
    elif shape == OVAL:
        pygame.draw.ellipse(DISPLAYSURF, color, (left, top + quarter, BOXSIZE, half))

The drawIcon() function will draw an icon (with the specified shape and color) at the space whose coordinates are given in the boxx and boxy parameters. Each possible shape has a different set of Pygame drawing function calls for it, so we must have a large set of if and elif statements to differentiate between them. (These statements are on lines 7 [187] to 18 [198].)

The X and Y coordinates of the left and top edge of the box can be obtained by calling the leftTopCoordsOfBox() function. The width and height of the box are both set in the BOXSIZE constant. However, many of the shape drawing function calls use the midpoint and quarter-point of the box as well. We can calculate this and store it in the variables quarter and half. We could just as easily have the code int(BOXSIZE * 0.25) instead of the variable quarter, but this way the code becomes easier to read since it is more obvious what quarter means rather than int(BOXSIZE * 0.25).

Such variables are an example of syntactic sugar. Syntactic sugar is when we add code that could have been written in another way (probably with less actual code and variables), but does make the source code easier to read. Constant variables are one form of syntactic sugar. Pre-calculating a value and storing it in a variable is another type of syntactic sugar. (For example, in the getRandomizedBoard() function, we could have easily made the code on lines 140 and line 141 into a single line of code. But it’s easier to read as two separate lines.) We don’t need to have the extra quarter and half variables, but having them makes the code easier to read. Code that is easy to read is easy to debug and upgrade in the future.

Note

Each of the donut, square, diamond, lines, and oval functions require different drawing primitive function calls to make.