text: // Copyright 2014 PDFium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
  
  #ifndef CORE_FXCODEC_GIF_CFX_GIF_H_
  #define CORE_FXCODEC_GIF_CFX_GIF_H_
  
  #include <memory>
  #include <vector>
  
  #include "core/fxcrt/fx_memory_wrappers.h"
  
  class CFX_GifContext;
  
  extern const char kGifSignature87[];
  extern const char kGifSignature89[];
  
  #define GIF_SIG_EXTENSION 0x21
  #define GIF_SIG_IMAGE 0x2C
  #define GIF_SIG_TRAILER 0x3B
  #define GIF_BLOCK_GCE 0xF9
  #define GIF_BLOCK_PTE 0x01
  #define GIF_BLOCK_CE 0xFE
  #define GIF_BLOCK_TERMINAL 0x00
  #define GIF_MAX_LZW_EXP 12
  #define GIF_MAX_LZW_CODE 4096
  #define GIF_D_STATUS_SIG 0x01
  #define GIF_D_STATUS_TAIL 0x02
  #define GIF_D_STATUS_EXT 0x03
  #define GIF_D_STATUS_EXT_CE 0x05
  #define GIF_D_STATUS_EXT_GCE 0x06
  #define GIF_D_STATUS_EXT_PTE 0x07
  #define GIF_D_STATUS_EXT_UNE 0x08
  #define GIF_D_STATUS_IMG_INFO 0x09
  #define GIF_D_STATUS_IMG_DATA 0x0A
  
  #pragma pack(1)
  struct CFX_GifGlobalFlags {
    uint8_t pal_bits : 3;
    uint8_t sort_flag : 1;
    uint8_t color_resolution : 3;
    uint8_t global_pal : 1;
  };
  
  struct CFX_GifLocalFlags {
    uint8_t pal_bits : 3;
    uint8_t reserved : 2;
    uint8_t sort_flag : 1;
    uint8_t interlace : 1;
    uint8_t local_pal : 1;
  };
  
  struct CFX_GifHeader {
    char signature[6];
  };
  
  struct CFX_GifLocalScreenDescriptor {
    uint16_t width;
    uint16_t height;
    CFX_GifGlobalFlags global_flags;
    uint8_t bc_index;
    uint8_t pixel_aspect;
  };
  
  struct CFX_GifImageInfo {
    uint16_t left;
    uint16_t top;
    uint16_t width;
    uint16_t height;
    CFX_GifLocalFlags local_flags;
  };
  
  struct CFX_GifControlExtensionFlags {
    uint8_t transparency : 1;
    uint8_t user_input : 1;
    uint8_t disposal_method : 3;
    uint8_t reserved : 3;
  };
  
  struct CFX_GifGraphicControlExtension {
    uint8_t block_size;
    CFX_GifControlExtensionFlags gce_flags;
    uint16_t delay_time;
    uint8_t trans_index;
  };
  
  struct CFX_GifPlainTextExtension {
    uint8_t block_size;
    uint16_t grid_left;
    uint16_t grid_top;
    uint16_t grid_width;
    uint16_t grid_height;
    uint8_t char_width;
    uint8_t char_height;
    uint8_t fc_index;
    uint8_t bc_index;
  };
  
  struct GifApplicationExtension {
    uint8_t block_size;
    uint8_t app_identify[8];
    uint8_t app_authentication[3];
  };
  
  struct CFX_GifPalette {
    uint8_t r;
    uint8_t g;
    uint8_t b;
  };
  #pragma pack()
  
  enum class CFX_GifDecodeStatus {
    Error,
    Success,
    Unfinished,
    InsufficientDestSize,  // Only used internally by CGifLZWDecoder::Decode()
  };
  
  struct CFX_GifImage {
    CFX_GifImage();
    ~CFX_GifImage();
  
    std::unique_ptr<CFX_GifGraphicControlExtension> image_GCE;
    std::vector<CFX_GifPalette> local_palettes;
    std::vector<uint8_t, FxAllocAllocator<uint8_t>> row_buffer;
    CFX_GifImageInfo image_info;
    uint8_t local_palette_exp;
    uint8_t code_exp;
    uint32_t data_pos;
    int32_t row_num;
  };
  
  #endif  // CORE_FXCODEC_GIF_CFX_GIF_H_
  