From Forum Nokia Wiki

ID		Creation date	March 19, 2007
Platform	S60 2nd Edition, S60 3rd Edition	Tested on devices	Nokia N96
Category	Python	Subcategory	UI

Keywords (APIs, classes, methods, functions): graphics, image

Overview

Image class of Python will load a transparent gif/png image just like a non-transparent one. But its blit() method accept a mask parameter ! The missing link is to create a mask automatically from the Image. It's typically the top-left pixel. You can use Image's getpixel() and combine them all as shown below.

Code

The automask function

def automask(im):
    width, height = im.size        # get image size
    mask = Image.new(im.size, '1') # black and white
    tran = im.getpixel((0,0))[0]   # transparent top-left
    for y in range(height):
        line = im.getpixel([(x, y) for x in range(width)])
        for x in range(width):
            if line[x] == tran:
                mask.point((x,y), 0)  # mask on the point
    return mask

Example usage

# import modules
from graphics import Image
import appuifw, e32
# define quit function
def quit():
  a.signal()
appuifw.app.exit_key_handler = quit
 
# open image
img = Image.open('E:\\Images\\img.gif')
# create mask
mask = automask(img)
# create canvas on application body
appuifw.app.body = canvas = appuifw.Canvas()
# clear canvas with yellow color
canvas.clear(0xDBDB70)
# show transparent image
canvas.blit(img, mask=mask)
 
a = e32.Ao_lock()
a.wait()       # wait for exit

Postconditions

Following screenshots show the result of above code.

Origional Image

Normal blit method

Transparent Image