128 lines
4 KiB
GDScript
128 lines
4 KiB
GDScript
@tool
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extends RefCounted
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class_name GifReader
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var lzw_module = preload("./gif-lzw/lzw.gd")
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var lzw = lzw_module.new()
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func read(source_file) -> SpriteFrames:
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var file = FileAccess.open(source_file, FileAccess.READ)
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if file == null:
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return null
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var data = file.get_buffer(file.get_length())
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file.close()
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return load_gif(data)
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func load_gif(data):
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var pos = 0
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# Header 'GIF89a'
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pos = pos + 6
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# Logical Screen Descriptor
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var width = get_int(data, pos)
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var height = get_int(data, pos + 2)
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var packed_info = data[pos + 4]
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var background_color_index = data[pos + 5]
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pos = pos + 7
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# Global color table
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var global_lut
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if (packed_info & 0x80) != 0:
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var lut_size = 1 << (1 + (packed_info & 0x07))
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global_lut = get_lut(data, pos, lut_size)
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pos = pos + 3 * lut_size
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# Frames
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var repeat = -1
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var img = Image.new()
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var frame_number = 0
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var frame_delay = -1
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var frame_anim_packed_info = -1
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var frame_transparent_color = -1
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var sprite_frame = SpriteFrames.new()
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img = Image.create(width, height, false, Image.FORMAT_RGBA8)
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while pos < data.size():
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if data[pos] == 0x21: # Extension block
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var ext_type = data[pos + 1]
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pos = pos + 2 # 21 xx ...
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match ext_type:
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0xF9: # Graphic extension
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var subblock = get_subblock(data, pos)
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frame_anim_packed_info = subblock[0]
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frame_delay = get_int(subblock, 1)
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frame_transparent_color = subblock[3]
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0xFF: # Application extension
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var subblock = get_subblock(data, pos)
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if subblock != null and subblock.get_string_from_ascii() == "NETSCAPE2.0":
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subblock = get_subblock(data, pos + 1 + subblock.size())
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repeat = get_int(subblock, 1)
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_: # Miscelaneous extension
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#print("extension ", data[pos + 1])
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pass
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var block_len = 0
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while data[pos + block_len] != 0:
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block_len = block_len + data[pos + block_len] + 1
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pos = pos + block_len + 1
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elif data[pos] == 0x2C: # Image data
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var img_left = get_int(data, pos + 1)
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var img_top = get_int(data, pos + 3)
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var img_width = get_int(data, pos + 5)
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var img_height = get_int(data, pos + 7)
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var img_packed_info = get_int(data, pos + 9)
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pos = pos + 10
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# Local color table
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var local_lut = global_lut
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if (img_packed_info & 0x80) != 0:
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var lut_size = 1 << (1 + (img_packed_info & 0x07))
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local_lut = get_lut(data, pos, lut_size)
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pos = pos + 3 * lut_size
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# Image data
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var min_code_size = data[pos]
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pos = pos + 1
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var colors = []
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for i in range(0, 1 << min_code_size):
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colors.append(i)
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var block = PackedByteArray()
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while data[pos] != 0:
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block.append_array(data.slice(pos + 1, pos + data[pos] + 1))
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pos = pos + data[pos] + 1
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pos = pos + 1
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var decompressed = lzw.decompress_lzw(block, min_code_size, colors)
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var disposal = (frame_anim_packed_info >> 2) & 7 # 1 = Keep, 2 = Clear
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var transparency = frame_anim_packed_info & 1
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if disposal == 2:
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if transparency == 0 and background_color_index != frame_transparent_color:
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img.fill(local_lut[background_color_index])
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else:
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img.fill(Color(0,0,0,0))
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var p = 0
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for y in range(0, img_height):
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for x in range(0, img_width):
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var c = decompressed[p]
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if transparency == 0 or c != frame_transparent_color:
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img.set_pixel(img_left + x, img_top + y, local_lut[c])
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p = p + 1
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var frame = ImageTexture.create_from_image(img);
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sprite_frame.add_frame(&"default", frame, frame_delay / 100.0);
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frame_anim_packed_info = -1
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frame_transparent_color = -1
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frame_delay = -1
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frame_number = frame_number + 1
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elif data[pos] == 0x3B: # Trailer
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pos = pos + 1
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sprite_frame.set_animation_speed(&"default", 1);
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return sprite_frame
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func get_subblock(data: PackedByteArray, pos):
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if data[pos] == 0:
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return null
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else:
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return data.slice(pos + 1, pos + data[pos] + 1)
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func get_lut(data, pos, size):
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var colors = Array()
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for i in range(0, size):
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colors.append(Color(data[pos + i * 3] / 255.0, data[pos + 1 + i * 3] / 255.0, data[pos + 2 + i * 3] / 255.0))
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return colors
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func get_int(data, pos):
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return data[pos] + (data[pos + 1] << 8)
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