A little Python CoreGraphics scaffolding.

coregraphics_scaffold.py

#!/usr/bin/python

from Quartz.CoreGraphics import *
from Quartz.ImageIO import *

def write_image_to_file(ctx, path):
    img = CGBitmapContextCreateImage(ctx)
    url = CFURLCreateWithFileSystemPath(None, path, kCFURLPOSIXPathStyle, True)
    dest = CGImageDestinationCreateWithURL(url, "public.png", 1, None);
    CGImageDestinationAddImage(dest, img, None);
    if not CGImageDestinationFinalize(dest):
        print("Failed to write image to ", path);

w = 100
h = 100

ctx = CGBitmapContextCreate(None, w, h, 8, (4 * w), 
                            CGColorSpaceCreateDeviceRGB(), 
                            kCGImageAlphaPremultipliedFirst)

# fill bg white
CGContextSetRGBFillColor(ctx, 1, 1, 1, 1)
CGContextFillRect(ctx, CGRectMake(0, 0, w, h))

# set colors & line width
CGContextSetRGBFillColor(ctx, 1, 0, 0, 1)
CGContextSetRGBStrokeColor(ctx, 1, 1, 0, 1)
CGContextSetLineWidth(ctx, 10)

# stroke and fill a rect
r = CGRectMake(w/4, h/4, w/2, h/2)
CGContextAddRect(ctx, r)
CGContextDrawPath(ctx, kCGPathFillStroke)

# write to an image file on disk
write_image_to_file(ctx, "/Users/itod/Desktop/testimage.png")