Python bitmap

bmp.py

import struct, random, sys
from PIL import Image


class Bitmap(object):


    def __gen_radom_pixel__(self):
        return 111
        return random.randint(0, 255)


    def __init__(self, header=None, filename=None):

        self.default_header = { 'importantcolors':0, 'filesize':0,'undef1':0,
                                'undef2':0, 'offset':54, 'headerlength':40, 'mn1':66, 
                                'width':20, 'height':20, 'colorplanes':8, 
                                'colordepth':24, 'compression':0, 'imagesize':0,
                                'res_hor':0, 'res_vert':0,'palette':0, 'mn2':77 }

        self.header = header or self.default_header
        self.filename = filename


    def __make_pixels__(self):


        im = Image.open(self.filename)
        pixels = list(im.getdata())
        width, height = im.size
        
        self.header['width'] = width
        self.header['height'] = height

        pixels = [pixels[i * width:(i + 1) * width] for i in xrange(height)]

        p = ''
        for row in pixels:
            for column in row:
                r = column[0]
                g = column[1]
                b = column[2]
                p += self.binary_color(r, g, b)
            p += self.padding(self.header['width'], self.header['colordepth'])

        return p


    def __make_header__(self):

        header = self.header
        header_str = ""

        header_str += struct.pack('<B', header['mn1'])
        header_str += struct.pack('<B', header['mn2'])        
        header_str += struct.pack('<L', header['filesize'])
        header_str += struct.pack('<H', header['undef1'])
        header_str += struct.pack('<H', header['undef2'])
        header_str += struct.pack('<L', header['offset'])
        header_str += struct.pack('<L', header['headerlength'])
        header_str += struct.pack('<L', header['width'])
        header_str += struct.pack('<L', header['height'])
        header_str += struct.pack('<H', header['colorplanes'])
        header_str += struct.pack('<H', header['colordepth'])
        header_str += struct.pack('<L', header['compression'])
        header_str += struct.pack('<L', header['imagesize'])
        header_str += struct.pack('<L', header['res_hor'])
        header_str += struct.pack('<L', header['res_vert'])
        header_str += struct.pack('<L', header['palette'])
        header_str += struct.pack('<L', header['importantcolors'])

        return header_str


    def binary_color(self, red, green, blue):

        assert red >= 0 and red <= 255,     "Red value should be 0-255, and its %s" % red
        assert green >= 0 and green <= 255, "Green value should be 0-255, and its %s" % green
        assert blue >= 0 and blue <= 255,   "Blue value should be 0-255, and its %s" % blue

        return struct.pack('<BBB', blue, green, red)


    def set_w_h(self, width, height):

        self.header['width'] = width
        self.header['height'] = height


    def padding(self, width, depth):
        
        byte_len = width * depth / 8
        pad = (4 - byte_len) % 4
        pad_byte = ''

        for index in range(pad):
          val = struct.pack("<B", 0)
          pad_byte += val

        return pad_byte


    def write_to_file(self, filename, header, pixels):

        try:
            out = open(filename, 'wb')
            out.write(header + pixels)
            out.close()
        except:
            pass


    def make_bmp(self, filename):

        pixels = self.__make_pixels__()
        header_binary = self.__make_header__()
        self.write_to_file(filename, header_binary, pixels)


if __name__ == '__main__':

    if len(sys.argv) != 2:
        sys.exit(1)

    bmp = Bitmap(None, sys.argv[1])
    bmp.make_bmp("/tmp/test.bmp")