GIF2.h - mozsearch

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/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_image_decoders_GIF2_H

#define mozilla_image_decoders_GIF2_H

#define MAX_LZW_BITS 12

#define MAX_BITS 4097  // 2^MAX_LZW_BITS+1

#define MAX_COLORS 256

#define MIN_HOLD_SIZE 256

enum { GIF_TRAILER = 0x3B };               // ';'

enum { GIF_IMAGE_SEPARATOR = 0x2C };       // ','

enum { GIF_EXTENSION_INTRODUCER = 0x21 };  // '!'

enum { GIF_GRAPHIC_CONTROL_LABEL = 0xF9 };

enum { GIF_APPLICATION_EXTENSION_LABEL = 0xFF };

// A GIF decoder's state

typedef struct gif_struct {

  // LZW decoder state machine

  uint8_t* stackp;  // Current stack pointer

  int datasize;

  int codesize;

  int codemask;

  int avail;  // Index of next available slot in dictionary

  int oldcode;

  uint8_t firstchar;

  int bits;       // Number of unread bits in "datum"

  int32_t datum;  // 32-bit input buffer

  // Output state machine

  int64_t pixels_remaining;  // Pixels remaining to be output.

  // Parameters for image frame currently being decoded

  int tpixel;                // Index of transparent pixel

  int32_t disposal_method;   // Restore to background, leave in place, etc.

  uint32_t* local_colormap;  // Per-image colormap

  uint32_t local_colormap_buffer_size;  // Size of the buffer containing the

                                        // local colormap.

  int local_colormap_size;              // Size of local colormap array.

  uint32_t delay_time;                  // Display time, in milliseconds,

                                        // for this image in a multi-image GIF

  // Global (multi-image) state

  int version;           // Either 89 for GIF89 or 87 for GIF87

  int32_t screen_width;  // Logical screen width & height

  int32_t screen_height;

  uint8_t global_colormap_depth;   // Depth of global colormap array

  uint16_t global_colormap_count;  // Number of colors in global colormap

  int images_decoded;              // Counts images for multi-part GIFs

  int loop_count;  // Netscape specific extension block to control

                   // the number of animation loops a GIF

                   // renders.

  bool is_transparent;  // TRUE, if tpixel is valid

  uint16_t prefix[MAX_BITS];             // LZW decoding tables

  uint32_t global_colormap[MAX_COLORS];  // Default colormap if local not

                                         //   supplied

  uint8_t suffix[MAX_BITS];              // LZW decoding tables

  uint8_t stack[MAX_BITS];               // Base of LZW decoder stack

} gif_struct;

#endif  // mozilla_image_decoders_GIF2_H