diff options
Diffstat (limited to 'util/png.py')
| -rw-r--r-- | util/png.py | 45 |
1 files changed, 23 insertions, 22 deletions
diff --git a/util/png.py b/util/png.py index 0936cf0..3a750c0 100644 --- a/util/png.py +++ b/util/png.py @@ -1,32 +1,33 @@ import struct import zlib + def encode(buf, width, height): - """ buf: must be bytes or a bytearray in py3, a regular string in py2. formatted RGBRGB... """ - assert (width * height * 3 == len(buf)) - bpp = 3 + """ buf: must be bytes or a bytearray in py3, a regular string in py2. formatted RGBRGB... """ + assert (width * height * 3 == len(buf)) + bpp = 3 - def raw_data(): - # reverse the vertical line order and add null bytes at the start - row_bytes = width * bpp - for row_start in range((height - 1) * width * bpp, -1, -row_bytes): - yield b'\x00' - yield buf[row_start:row_start + row_bytes] + def raw_data(): + # reverse the vertical line order and add null bytes at the start + row_bytes = width * bpp + for row_start in range((height - 1) * width * bpp, -1, -row_bytes): + yield b'\x00' + yield buf[row_start:row_start + row_bytes] - def chunk(tag, data): - return [ - struct.pack("!I", len(data)), - tag, - data, - struct.pack("!I", 0xFFFFFFFF & zlib.crc32(data, zlib.crc32(tag))) - ] + def chunk(tag, data): + return [ + struct.pack("!I", len(data)), + tag, + data, + struct.pack("!I", 0xFFFFFFFF & zlib.crc32(data, zlib.crc32(tag))) + ] - SIGNATURE = b'\x89PNG\r\n\x1a\n' - COLOR_TYPE_RGB = 2 - COLOR_TYPE_RGBA = 6 - bit_depth = 8 - return b''.join( - [ SIGNATURE ] + + SIGNATURE = b'\x89PNG\r\n\x1a\n' + COLOR_TYPE_RGB = 2 + COLOR_TYPE_RGBA = 6 + bit_depth = 8 + return b''.join( + [SIGNATURE] + chunk(b'IHDR', struct.pack("!2I5B", width, height, bit_depth, COLOR_TYPE_RGB, 0, 0, 0)) + chunk(b'IDAT', zlib.compress(b''.join(raw_data()), 9)) + chunk(b'IEND', b'') |