naive python gif crop

main.py

from os import listdir
from os.path import splitext, isfile, join

import gif


def optimizeImage(source_file):
    target_file = source_file.replace("data", "data2")

    file = open(source_file, 'rb')
    file2 = open(target_file, 'wb')

    reader = gif.Reader()
    writer = gif.Writer(file2)
    writer.write_header()

    reader.feed(file.read())

    if reader.has_screen_descriptor():
        writer.write_screen_descriptor(reader.width, reader.height, has_color_table=len(reader.color_table) > 0,
                                       depth=reader.original_depth)
        writer.write_color_table(reader.color_table, reader.original_depth)

        print('Processing %s' % source_file)
        isFirst = 1
        for block in reader.blocks:
            if isinstance(block, gif.Image):
                if isFirst:
                    isFirst = 0
                    writer.write_image(block.width, block.height, reader.original_depth, block.get_pixels(),
                                       block.left,
                                       block.top,
                                       block.color_table, block.interlace, block.color_table_sorted)
                else:
                    new_left_offset, new_top_offset, new_height, new_width, pixels = trimBlock(block, reader)

                    writer.write_image(new_width, new_height, reader.original_depth, pixels,
                                       new_left_offset,
                                       new_top_offset,
                                       block.color_table, block.interlace, block.color_table_sorted)
            elif isinstance(block, gif.NetscapeExtension):
                writer.write_netscape_extension(block.loop_count, block.buffer_size or 0)
            elif isinstance(block, gif.XMPDataExtension):
                pass  # writer.write_xmp_data_extension(block.get_metadata())
            elif isinstance(block, gif.GraphicControlExtension):
                writer.write_graphic_control_extension(block.disposal_method, block.delay_time, block.user_input,
                                                       block.has_transparent, block.transparent_color)
            elif isinstance(block, gif.Trailer):
                writer.write_trailer()
            else:
                raise "Fail"
        if reader.has_unknown_block():
            print('Encountered unknown block')
        elif not reader.is_complete():
            print('Missing trailer')
    else:
        print('Not a valid GIF file')
    file.close()
    file2.close()


def trimBlock(block, reader):
    pixels = block.get_pixels()
    len_pixels = len(pixels)
    two_dimensional_array = [pixels[i:i + block.width] for i in range(0, len(pixels), block.width)]
    left, lower, right, upper = findBoundaries(block, reader, two_dimensional_array)
    new_left_offset, new_top_offset, new_height, new_width, trimmed_array = trimPixels(block, left, right, upper, lower,
                                                                                       two_dimensional_array)
    pixels = [pixel for row in trimmed_array for pixel in row]
    print("from %i x %i to %i x %i, pixels %i to %i" % (
        block.width, block.height, new_width, new_height, len_pixels, len(pixels)))
    return new_left_offset, new_top_offset, new_height, new_width, pixels


def trimPixels(block, left, right, upper, lower, two_dimensional_array):
    # Calculate new dimensions
    new_height = len(two_dimensional_array) - upper - lower
    new_width = len(two_dimensional_array[0]) - left - right
    new_left_offset = block.left + left
    new_top_offset = block.top + upper
    # Remove columns and rows
    trimmed_array = [row[left:new_width + left] for row in
                     two_dimensional_array[upper:new_height + upper]]
    return new_left_offset, new_top_offset, new_height, new_width, trimmed_array


def findBoundaries(block, reader, two_dimensional_array):
    # Initialize variables to store corner positions
    left, upper, right, lower = 0, 0, 0, 0

    for x in range(block.width):
        all_black = 1
        for y in range(block.height):
            pixel = two_dimensional_array[y][x]
            color = (block.color_table or reader.color_table)[pixel]
            if color != (0, 0, 0) and color != (255, 255, 255):
                all_black = 0
                break
        if all_black:
            left += 1
        else:
            break

    for x in range(block.width):
        all_black = 1
        for y in range(block.height):
            pixel = two_dimensional_array[y][block.width - x - 1]
            color = (block.color_table or reader.color_table)[pixel]
            if color != (0, 0, 0) and color != (255, 255, 255):
                all_black = 0
                break
        if all_black:
            right += 1
        else:
            break

    for y in range(block.height):
        all_black = 1
        for x in range(block.width):
            pixel = two_dimensional_array[y][x]
            color = (block.color_table or reader.color_table)[pixel]
            if color != (0, 0, 0) and color != (255, 255, 255):
                all_black = 0
                break
        if all_black:
            upper += 1
        else:
            break

    for y in range(block.height):
        all_black = 1
        for x in range(block.width):
            pixel = two_dimensional_array[block.height - y - 1][x]
            color = (block.color_table or reader.color_table)[pixel]
            if color != (0, 0, 0) and color != (255, 255, 255):
                all_black = 0
                break
        if all_black:
            lower += 1
        else:
            break

    if left + right >= block.width:
        left = block.width - 1
        right = 0

    if lower + upper >= block.height:
        upper = block.height - 1
        lower = 0

    return left, lower, right, upper


def optimizeImagesInFolder(folder):
    gifs = [f for f in listdir(folder) if isfile(join(folder, f)) and splitext(f)[1] == ".gif"]
    gifs.sort()

    for file in gifs:
        optimizeImage(join(folder, file))


optimizeImage("c:\\work\\Repository\\Knomi\\Firmware\\data\\cp.gif")
#optimizeImagesInFolder("c:\\work\\Repository\\Knomi\\Firmware\\data")

requirements.txt

pygif