江苏省建设工程考试网站,网站域名绑定ip,北京服务器租用,群晖nas做网站Python #xff5c;GIF 解析与构建#xff08;2#xff09;#xff1a;状态机解析
目录
Python #xff5c;GIF 解析与构建#xff08;2#xff09;#xff1a;状态机解析
引言
一、状态机概述
状态机的优势与改进方向
总结 引言
在《Python #xff5c;GIF 解…Python GIF 解析与构建2状态机解析
目录
Python GIF 解析与构建2状态机解析
引言
一、状态机概述
状态机的优势与改进方向
总结 引言
在《Python GIF 解析与构建1初步解析》中我们初步进行解析gif文件。
本文将深入探讨如何使用 ** 状态机State Machine** 实现 GIF 文件的解析通过分阶段处理数据流逐步提取关键信息如版本、颜色表、图像数据等。状态机的优势在于将复杂的解析逻辑拆解为多个可管理的状态每个状态专注于处理特定的数据流片段从而提高代码的可读性和可维护性。
一、状态机概述
GIF 文件由一系列区块Block组成每个区块包含特定类型的数据如文件头、颜色表、图像数据、扩展指令等。状态机的核心思想是根据当前解析进度将程序划分为多个状态State每个状态负责解析某一类区块或数据片段并根据输入数据决定下一步跳转的状态。 GIF 解析的主要状态包括
开头Header验证 GIF 文件签名GIF87a或GIF89a。逻辑屏幕标识符Logical Screen Descriptor解析画布尺寸、颜色表标志等基础信息。全局颜色表Global Color Table提取全局调色板若存在。区块检测Block Detection识别后续区块类型如图像标识符、扩展块等。扩展块处理Extension Blocks解析图形控制扩展如动画延迟、应用程序扩展如循环参数。图像标识符Image Descriptor解析图像位置、尺寸、局部颜色表若存在及压缩数据。结束符检测Trailer Detection验证文件结束符0x3B。
状态机的优势与改进方向
优势 模块化每个状态职责单一便于调试和扩展。容错性通过状态转移控制数据流可优雅处理无效数据如提前终止解析。 改进方向 支持更多扩展块类型如注释扩展、文本扩展。优化 LZW 解码性能如使用更高效的数据结构存储字典。添加动画帧时序处理结合图形控制扩展中的延迟时间。
总结
本文通过状态机实现了 GIF 文件的逐步解析将复杂的格式解析拆解为可管理的状态转移过程。状态机模型不仅适用于 GIF 解析还可推广到其他二进制格式如 PNG、BMP的解析场景。下一篇文章将探讨如何基于状态机构建 GIF 文件实现从像素数据到 GIF 动画的生成。
from PIL import Image
import struct# 读取文件
gif_path 1.gif
for _ in range(2):try:with open(gif_path, rb) as f:data f.read()breakexcept:# 创建全白帧 50x50white_frame Image.new(RGB, (5, 5), color(255, 255, 255))# 创建全黑帧 50x50black_frame Image.new(RGB, (5, 5), color(0, 0, 0))# 保存为无限循环的GIF动画white_frame.save(gif_path,save_allTrue,append_images[black_frame],duration200,loop0)# 解码
def lzw_decode(compressed):# 初始化字典dictionary {i: bytes([i]) for i in range(256)}next_code 258result bytearray()# 处理压缩数据buffer 0bits_in_buffer 0code_size 9prev_code Nonefor byte in compressed:buffer | byte bits_in_bufferbits_in_buffer 8while bits_in_buffer code_size:code buffer ((1 code_size) - 1)buffer code_sizebits_in_buffer - code_sizeif code 256: # 清除码dictionary {i: bytes([i]) for i in range(256)}next_code 258code_size 9prev_code Nonecontinueelif code 257: # 结束码return bytes(result)if prev_code is None:result.extend(dictionary[code])prev_code codecontinueif code in dictionary:entry dictionary[code]result.extend(entry)dictionary[next_code] dictionary[prev_code] entry[:1]else:entry dictionary[prev_code] dictionary[prev_code][:1]result.extend(entry)dictionary[next_code] entrynext_code 1prev_code codeif next_code (1 code_size) and code_size 12:code_size 1return bytes(result)# 压缩
def lzw_decompress(compressed):dictionary {i: bytes([i]) for i in range(256)}next_code 258result bytearray()buffer 0bits 0code_size 9prev Nonefor byte in compressed:buffer | byte bitsbits 8while bits code_size:code buffer ((1 code_size) - 1)buffer code_sizebits - code_sizeif code 256:dictionary {i: bytes([i]) for i in range(256)}next_code 258code_size 9prev Nonecontinueelif code 257:return bytes(result)if prev is None:result.extend(dictionary[code])prev codecontinueif code in dictionary:entry dictionary[code]result.extend(entry)dictionary[next_code] dictionary[prev] entry[:1]else:entry dictionary[prev] dictionary[prev][:1]result.extend(entry)dictionary[next_code] entrynext_code 1prev codeif next_code (1 code_size) - 1 and code_size 12:code_size 1return bytes(result)# 按照分块处理
print(data)
print(data.hex( ))# dict_ex {ff:应用程序扩展,f9:图形控制扩展}# 状态机
class GIFDecode:def __init__(self):self.state 开头 # 状态self.state_child 开始 # 子状态self.global_color [] # 全局颜色self.local_color_all [] # 局部颜色(全部)self.local_color_one [] # 局部颜色(单个)self.image_data []self.version # 版本self.buffer bytearray() # 缓冲字节self.screen_width 0 # 宽度self.screen_height 0 # 长度self.has_global_color 0 # 存在全局颜色表self.color_resolution 3 # 颜色深度self.sort_flag 0 # 分类标志self.global_color_table_size 0 # 全局颜色数量self.bg_color_index 0 # 背景颜色索引self.color_block_size 0 # 颜色块长度self.pixel_aspect_ratio 0 # 像素高宽比self.application_size 0 # 应用程序扩展字节长度self.application_text 0 # 应用程序扩展文本self.application_child_size 0 # 应用程序扩展子块字节长度self.loop_type 0 # 循环类型self.loop_parameter 0 # 循环参数self.graphic_control_size 0 # 图像控制字符长度self.graphic_control_sign_transparent 0 # 图像控制标志位透明色self.graphic_control_sign_dispose 0 # 图像控制标志位处置方法 # 0不使用 1把图形移去 2恢复到背景色 3恢复到先前状态 4-7自定义self.graphic_control_sign_input 0 # 图像控制标志位用户输入self.graphic_control_sign_customize 0 # 图像控制标志位自定义self.graphic_control_delay 0 # 图像控制延迟时间self.graphic_control_sign_transparent_index 0 # 图像控制透明色索引self.image_offset_x 0 # 图像左偏移量 即X轴self.image_offset_y 0 # 图像顶部偏移量 即Y轴self.image_width 0 # 画布宽度self.image_length 0 # 画布长度self.local_color_sign_number 0 # 0-2颜色多少self.local_color_sign_retain 0 # 3-4保留位self.image_local_color_sign_sort 0 # 5排序self.local_color_sign_interwoven 0 # 6交织self.local_color_sign_has_color_table 0 # 7局部颜色表标志self.local_color_size 0 # 局部颜色表字节self.image_compressed_bit 0 # 压缩位self.image_block_size 0 # 图像子块字节self.image_bytes_data b # 图片压缩字节数据def feed(self, byte):print(self.buffer)if self.state 开头:self.buffer.append(byte)if len(self.buffer) 6:if self.buffer bGIF87a or self.buffer bGIF89a:self.state 逻辑屏幕标识符self.version self.buffer.decode(ascii)self.buffer.clear()else:raise ValueError(f无效的GIF版本: {bytes(self.buffer)})elif self.state 逻辑屏幕标识符:self.buffer.append(byte)if len(self.buffer) 7:# 解析逻辑屏幕描述符self.screen_width int.from_bytes(self.buffer[0:2], little)self.screen_height int.from_bytes(self.buffer[2:4], little)# 解析标志字节flags self.buffer[4]假设m 1存在全局颜色表cr 3颜色深度为 3二进制 011s 0不使用分类标志pixel 4全局颜色列表大小为 4二进制 100。计算各字段的位位置m 占位 7 → 需左移 7 位m 7cr 占位 6-4 → 需左移 4 位cr 4s 占位 3 → 需左移 3 位s 3pixel 占位 2-0 → 无需位移直接取 pixelself.has_global_color (flags 0b10000000)self.color_resolution (flags 0b01110000)self.sort_flag (flags 0b00001000) ! 0self.global_color_table_size 2 ** ((flags 0b00000111) 1)self.bg_color_index self.buffer[5]self.pixel_aspect_ratio self.buffer[6]if self.has_global_color:self.state 全局颜色表self.color_block_size self.global_color_table_size * 3self.buffer.clear()else:self.state 区块检测self.buffer.clear()elif self.state 全局颜色表:self.buffer.append(byte)if len(self.buffer) self.color_block_size:# 解析全局颜色表self.global_color [(self.buffer[i], self.buffer[i 1], self.buffer[i 2]) for i inrange(0, len(self.buffer), 3)]self.state 区块检测self.buffer.clear()elif self.state 结束符检测:self.state_child 开始 # 重置子状态if byte 0x00:self.state 区块检测else:raise ValueError(f无效的结束符: {bytes(byte)})elif self.state 区块检测:self.buffer.append(byte)if byte 0x3B: # 检测结束return Trueif self.state_child 开始:if len(self.buffer) 1:if self.buffer[0] 0x21:self.state_child 拓展块self.buffer.clear()elif self.buffer[0] 0x2C:self.state 图像标识符self.state_child 开始 # 重置子状态self.buffer.clear()else:raise ValueError(f无效的区块: {bytes(self.buffer)})elif self.state_child 拓展块:if self.buffer[0] 0xFF:self.state 应用程序扩展elif self.buffer[0] 0xF9:self.state 图形控制扩展self.state_child 开始 # 重置子状态self.buffer.clear()else:raise ValueError(f无效的区块: {bytes(self.buffer)})elif self.state 应用程序扩展:self.buffer.append(byte)if self.state_child 开始:if len(self.buffer) 1:self.application_size struct.unpack(B, self.buffer)[0]self.state_child 解析self.buffer.clear()elif self.state_child 解析:if len(self.buffer) self.application_size:self.application_text self.buffer[0:self.application_size].decode(ascii, errorsreplace)self.state_child 子块长度self.buffer.clear()elif self.state_child 子块长度:if len(self.buffer) 1:self.application_child_size struct.unpack(B, self.buffer)[0]self.state_child 子块解析self.buffer.clear()elif self.state_child 子块解析:if len(self.buffer) self.application_child_size:self.loop_type self.buffer[0]self.loop_parameter self.buffer[1:2]self.state 结束符检测self.buffer.clear()elif self.state 图形控制扩展:self.buffer.append(byte)if self.state_child 开始:if len(self.buffer) 1:self.graphic_control_size struct.unpack(B, self.buffer)[0]self.state_child 解析self.buffer.clear()elif self.state_child 解析:if len(self.buffer) self.graphic_control_size:sign self.buffer[0]# 解析标志位self.graphic_control_sign_transparent (sign 0b00000001)self.graphic_control_sign_dispose (sign 0b00000010)self.graphic_control_sign_input (sign 0b00011100)self.graphic_control_sign_customize (sign 0b11100000)self.graphic_control_delay struct.unpack(H, self.buffer[1:3])[0] * 0.01self.graphic_control_sign_transparent_index self.buffer[3]self.state 结束符检测self.buffer.clear()elif self.state 图像标识符:self.buffer.append(byte)if self.state_child 开始:if len(self.buffer) 9:self.image_offset_x struct.unpack(H, self.buffer[0:2])[0]self.image_offset_y struct.unpack(H, self.buffer[2:4])[0]self.image_width struct.unpack(H, self.buffer[4:6])[0]self.image_length struct.unpack(H, self.buffer[6:8])[0]sign self.buffer[8]- 第 0-2 位局部颜色表大小0 无局部颜色表- 第 3-4 位保留位0- 第 5 位排序标志0 未排序- 第 6 位交织标志0 非交织- 第 7 位局部颜色表标志0 无局部颜色表self.local_color_sign_number (sign 0b00000111)self.local_color_sign_retain (sign 0b00011000)self.image_local_color_sign_sort (sign 0b00100000)self.local_color_sign_interwoven (sign 0b01000000)self.local_color_sign_has_color_table (sign 0b10000000)# 检测是否存在局部颜色表格if self.local_color_sign_has_color_table 128:self.local_color_size 2 ** (self.local_color_sign_number 1) * 3self.state_child 获取局部颜色表self.buffer.clear()else:self.state_child 解析图像self.buffer.clear()elif self.state_child 获取局部颜色表:if len(self.buffer) self.local_color_size:# 获取局部颜色表放入局部颜色中self.local_color_one [(self.buffer[i], self.buffer[i 1], self.buffer[i 2]) for i inrange(0, len(self.buffer), 3)]self.local_color_all.append(self.local_color_one)self.state_child 解析图像self.buffer.clear()elif self.state_child 解析图像:if len(self.buffer) 2:self.image_compressed_bit self.buffer[0]self.image_block_size self.buffer[1]self.state_child 获取数据self.buffer.clear()elif self.state_child 获取数据:if len(self.buffer) self.image_block_size:self.image_bytes_data bytes(self.buffer) # 转换字节而非对象self.state_child 检测获取结束self.buffer.clear()elif self.state_child 检测获取结束:if self.buffer[0] 0x00:image_data self.lzw_decode(self.image_bytes_data)if self.local_color_one: # 如果局部存在 则按照局部生成 如果局部不存在则按照全局生成self.image_data.append([self.local_color_one[image_data[i]] for i in range(len(image_data))])else:self.image_data.append([self.global_color[image_data[i]] for i in range(len(image_data))])self.state 区块检测self.state_child 开始# 重置数据self.image_bytes_data bself.local_color_one.clear()self.buffer.clear()else:self.image_block_size self.buffer[0]self.state_child 获取数据self.buffer.clear()# 解码def lzw_decode(self, compressed):# 初始化字典dictionary {i: bytes([i]) for i in range(256)}next_code 258result bytearray()# 处理压缩数据buffer 0bits_in_buffer 0code_size 9prev_code Nonefor byte in compressed:buffer | byte bits_in_bufferbits_in_buffer 8while bits_in_buffer code_size:code buffer ((1 code_size) - 1)buffer code_sizebits_in_buffer - code_sizeif code 256: # 清除码dictionary {i: bytes([i]) for i in range(256)}next_code 258code_size 9prev_code Nonecontinueelif code 257: # 结束码return bytes(result)if prev_code is None:result.extend(dictionary[code])prev_code codecontinueif code in dictionary:entry dictionary[code]result.extend(entry)dictionary[next_code] dictionary[prev_code] entry[:1]else:entry dictionary[prev_code] dictionary[prev_code][:1]result.extend(entry)dictionary[next_code] entrynext_code 1prev_code codeif next_code (1 code_size) and code_size 12:code_size 1return bytes(result)passdecoder GIFDecode()
for byte in data:decoder.feed(byte)print(decoder.version)
print(decoder.image_data)
print(decoder) from PIL import Image
import struct# 读取文件
gif_path 1.gif
for _ in range(2):try:with open(gif_path, rb) as f:data f.read()breakexcept:# 创建全白帧 50x50white_frame Image.new(RGB, (5, 5), color(255, 255, 255))# 创建全黑帧 50x50black_frame Image.new(RGB, (5, 5), color(0, 0, 0))# 保存为无限循环的GIF动画white_frame.save(gif_path,save_allTrue,append_images[black_frame],duration200,loop0)# 解码
def lzw_decode(compressed):# 初始化字典dictionary {i: bytes([i]) for i in range(256)}next_code 258result bytearray()# 处理压缩数据buffer 0bits_in_buffer 0code_size 9prev_code Nonefor byte in compressed:buffer | byte bits_in_bufferbits_in_buffer 8while bits_in_buffer code_size:code buffer ((1 code_size) - 1)buffer code_sizebits_in_buffer - code_sizeif code 256: # 清除码dictionary {i: bytes([i]) for i in range(256)}next_code 258code_size 9prev_code Nonecontinueelif code 257: # 结束码return bytes(result)if prev_code is None:result.extend(dictionary[code])prev_code codecontinueif code in dictionary:entry dictionary[code]result.extend(entry)dictionary[next_code] dictionary[prev_code] entry[:1]else:entry dictionary[prev_code] dictionary[prev_code][:1]result.extend(entry)dictionary[next_code] entrynext_code 1prev_code codeif next_code (1 code_size) and code_size 12:code_size 1return bytes(result)# 压缩
def lzw_decompress(compressed):dictionary {i: bytes([i]) for i in range(256)}next_code 258result bytearray()buffer 0bits 0code_size 9prev Nonefor byte in compressed:buffer | byte bitsbits 8while bits code_size:code buffer ((1 code_size) - 1)buffer code_sizebits - code_sizeif code 256:dictionary {i: bytes([i]) for i in range(256)}next_code 258code_size 9prev Nonecontinueelif code 257:return bytes(result)if prev is None:result.extend(dictionary[code])prev codecontinueif code in dictionary:entry dictionary[code]result.extend(entry)dictionary[next_code] dictionary[prev] entry[:1]else:entry dictionary[prev] dictionary[prev][:1]result.extend(entry)dictionary[next_code] entrynext_code 1prev codeif next_code (1 code_size) - 1 and code_size 12:code_size 1return bytes(result)# 按照分块处理
print(data)
print(data.hex( ))# dict_ex {ff:应用程序扩展,f9:图形控制扩展}# 状态机
class GIFDecode:def __init__(self):self.state 开头 # 状态self.state_child 开始 # 子状态self.global_color [] # 全局颜色self.local_color_all [] # 局部颜色(全部)self.local_color_one [] # 局部颜色(单个)self.image_data []self.version # 版本self.buffer bytearray() # 缓冲字节self.screen_width 0 # 宽度self.screen_height 0 # 长度self.has_global_color 0 # 存在全局颜色表self.color_resolution 3 # 颜色深度self.sort_flag 0 # 分类标志self.global_color_table_size 0 # 全局颜色数量self.bg_color_index 0 # 背景颜色索引self.color_block_size 0 # 颜色块长度self.pixel_aspect_ratio 0 # 像素高宽比self.application_size 0 # 应用程序扩展字节长度self.application_text 0 # 应用程序扩展文本self.application_child_size 0 # 应用程序扩展子块字节长度self.loop_type 0 # 循环类型self.loop_parameter 0 # 循环参数self.graphic_control_size 0 # 图像控制字符长度self.graphic_control_sign_transparent 0 # 图像控制标志位透明色self.graphic_control_sign_dispose 0 # 图像控制标志位处置方法 # 0不使用 1把图形移去 2恢复到背景色 3恢复到先前状态 4-7自定义self.graphic_control_sign_input 0 # 图像控制标志位用户输入self.graphic_control_sign_customize 0 # 图像控制标志位自定义self.graphic_control_delay 0 # 图像控制延迟时间self.graphic_control_sign_transparent_index 0 # 图像控制透明色索引self.image_offset_x 0 # 图像左偏移量 即X轴self.image_offset_y 0 # 图像顶部偏移量 即Y轴self.image_width 0 # 画布宽度self.image_length 0 # 画布长度self.local_color_sign_number 0 # 0-2颜色多少self.local_color_sign_retain 0 # 3-4保留位self.image_local_color_sign_sort 0 # 5排序self.local_color_sign_interwoven 0 # 6交织self.local_color_sign_has_color_table 0 # 7局部颜色表标志self.local_color_size 0 # 局部颜色表字节self.image_compressed_bit 0 # 压缩位self.image_block_size 0 # 图像子块字节self.image_bytes_data b # 图片压缩字节数据def feed(self, byte):print(self.buffer)if self.state 开头:self.buffer.append(byte)if len(self.buffer) 6:if self.buffer bGIF87a or self.buffer bGIF89a:self.state 逻辑屏幕标识符self.version self.buffer.decode(ascii)self.buffer.clear()else:raise ValueError(f无效的GIF版本: {bytes(self.buffer)})elif self.state 逻辑屏幕标识符:self.buffer.append(byte)if len(self.buffer) 7:# 解析逻辑屏幕描述符self.screen_width int.from_bytes(self.buffer[0:2], little)self.screen_height int.from_bytes(self.buffer[2:4], little)# 解析标志字节flags self.buffer[4]假设m 1存在全局颜色表cr 3颜色深度为 3二进制 011s 0不使用分类标志pixel 4全局颜色列表大小为 4二进制 100。计算各字段的位位置m 占位 7 → 需左移 7 位m 7cr 占位 6-4 → 需左移 4 位cr 4s 占位 3 → 需左移 3 位s 3pixel 占位 2-0 → 无需位移直接取 pixelself.has_global_color (flags 0b10000000)self.color_resolution (flags 0b01110000)self.sort_flag (flags 0b00001000) ! 0self.global_color_table_size 2 ** ((flags 0b00000111) 1)self.bg_color_index self.buffer[5]self.pixel_aspect_ratio self.buffer[6]if self.has_global_color:self.state 全局颜色表self.color_block_size self.global_color_table_size * 3self.buffer.clear()else:self.state 区块检测self.buffer.clear()elif self.state 全局颜色表:self.buffer.append(byte)if len(self.buffer) self.color_block_size:# 解析全局颜色表self.global_color [(self.buffer[i], self.buffer[i 1], self.buffer[i 2]) for i inrange(0, len(self.buffer), 3)]self.state 区块检测self.buffer.clear()elif self.state 结束符检测:self.state_child 开始 # 重置子状态if byte 0x00:self.state 区块检测else:raise ValueError(f无效的结束符: {bytes(byte)})elif self.state 区块检测:self.buffer.append(byte)if byte 0x3B: # 检测结束return Trueif self.state_child 开始:if len(self.buffer) 1:if self.buffer[0] 0x21:self.state_child 拓展块self.buffer.clear()elif self.buffer[0] 0x2C:self.state 图像标识符self.state_child 开始 # 重置子状态self.buffer.clear()else:raise ValueError(f无效的区块: {bytes(self.buffer)})elif self.state_child 拓展块:if self.buffer[0] 0xFF:self.state 应用程序扩展elif self.buffer[0] 0xF9:self.state 图形控制扩展self.state_child 开始 # 重置子状态self.buffer.clear()else:raise ValueError(f无效的区块: {bytes(self.buffer)})elif self.state 应用程序扩展:self.buffer.append(byte)if self.state_child 开始:if len(self.buffer) 1:self.application_size struct.unpack(B, self.buffer)[0]self.state_child 解析self.buffer.clear()elif self.state_child 解析:if len(self.buffer) self.application_size:self.application_text self.buffer[0:self.application_size].decode(ascii, errorsreplace)self.state_child 子块长度self.buffer.clear()elif self.state_child 子块长度:if len(self.buffer) 1:self.application_child_size struct.unpack(B, self.buffer)[0]self.state_child 子块解析self.buffer.clear()elif self.state_child 子块解析:if len(self.buffer) self.application_child_size:self.loop_type self.buffer[0]self.loop_parameter self.buffer[1:2]self.state 结束符检测self.buffer.clear()elif self.state 图形控制扩展:self.buffer.append(byte)if self.state_child 开始:if len(self.buffer) 1:self.graphic_control_size struct.unpack(B, self.buffer)[0]self.state_child 解析self.buffer.clear()elif self.state_child 解析:if len(self.buffer) self.graphic_control_size:sign self.buffer[0]# 解析标志位self.graphic_control_sign_transparent (sign 0b00000001)self.graphic_control_sign_dispose (sign 0b00000010)self.graphic_control_sign_input (sign 0b00011100)self.graphic_control_sign_customize (sign 0b11100000)self.graphic_control_delay struct.unpack(H, self.buffer[1:3])[0] * 0.01self.graphic_control_sign_transparent_index self.buffer[3]self.state 结束符检测self.buffer.clear()elif self.state 图像标识符:self.buffer.append(byte)if self.state_child 开始:if len(self.buffer) 9:self.image_offset_x struct.unpack(H, self.buffer[0:2])[0]self.image_offset_y struct.unpack(H, self.buffer[2:4])[0]self.image_width struct.unpack(H, self.buffer[4:6])[0]self.image_length struct.unpack(H, self.buffer[6:8])[0]sign self.buffer[8]- 第 0-2 位局部颜色表大小0 无局部颜色表- 第 3-4 位保留位0- 第 5 位排序标志0 未排序- 第 6 位交织标志0 非交织- 第 7 位局部颜色表标志0 无局部颜色表self.local_color_sign_number (sign 0b00000111)self.local_color_sign_retain (sign 0b00011000)self.image_local_color_sign_sort (sign 0b00100000)self.local_color_sign_interwoven (sign 0b01000000)self.local_color_sign_has_color_table (sign 0b10000000)# 检测是否存在局部颜色表格if self.local_color_sign_has_color_table 128:self.local_color_size 2 ** (self.local_color_sign_number 1) * 3self.state_child 获取局部颜色表self.buffer.clear()else:self.state_child 解析图像self.buffer.clear()elif self.state_child 获取局部颜色表:if len(self.buffer) self.local_color_size:# 获取局部颜色表放入局部颜色中self.local_color_one [(self.buffer[i], self.buffer[i 1], self.buffer[i 2]) for i inrange(0, len(self.buffer), 3)]self.local_color_all.append(self.local_color_one)self.state_child 解析图像self.buffer.clear()elif self.state_child 解析图像:if len(self.buffer) 2:self.image_compressed_bit self.buffer[0]self.image_block_size self.buffer[1]self.state_child 获取数据self.buffer.clear()elif self.state_child 获取数据:if len(self.buffer) self.image_block_size:self.image_bytes_data bytes(self.buffer) # 转换字节而非对象self.state_child 检测获取结束self.buffer.clear()elif self.state_child 检测获取结束:if self.buffer[0] 0x00:image_data self.lzw_decode(self.image_bytes_data)if self.local_color_one: # 如果局部存在 则按照局部生成 如果局部不存在则按照全局生成self.image_data.append([self.local_color_one[image_data[i]] for i in range(len(image_data))])else:self.image_data.append([self.global_color[image_data[i]] for i in range(len(image_data))])self.state 区块检测self.state_child 开始# 重置数据self.image_bytes_data bself.local_color_one.clear()self.buffer.clear()else:self.image_block_size self.buffer[0]self.state_child 获取数据self.buffer.clear()# 解码def lzw_decode(self, compressed):# 初始化字典dictionary {i: bytes([i]) for i in range(256)}next_code 258result bytearray()# 处理压缩数据buffer 0bits_in_buffer 0code_size 9prev_code Nonefor byte in compressed:buffer | byte bits_in_bufferbits_in_buffer 8while bits_in_buffer code_size:code buffer ((1 code_size) - 1)buffer code_sizebits_in_buffer - code_sizeif code 256: # 清除码dictionary {i: bytes([i]) for i in range(256)}next_code 258code_size 9prev_code Nonecontinueelif code 257: # 结束码return bytes(result)if prev_code is None:result.extend(dictionary[code])prev_code codecontinueif code in dictionary:entry dictionary[code]result.extend(entry)dictionary[next_code] dictionary[prev_code] entry[:1]else:entry dictionary[prev_code] dictionary[prev_code][:1]result.extend(entry)dictionary[next_code] entrynext_code 1prev_code codeif next_code (1 code_size) and code_size 12:code_size 1return bytes(result)passdecoder GIFDecode()
for byte in data:decoder.feed(byte)print(decoder.version)
print(decoder.image_data)
print(decoder)
