GIF2.h (2773B)
1 /* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ 2 /* This Source Code Form is subject to the terms of the Mozilla Public 3 * License, v. 2.0. If a copy of the MPL was not distributed with this 4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ 5 6 #ifndef mozilla_image_decoders_GIF2_H 7 #define mozilla_image_decoders_GIF2_H 8 9 #define MAX_LZW_BITS 12 10 #define MAX_BITS 4097 // 2^MAX_LZW_BITS+1 11 #define MAX_COLORS 256 12 #define MIN_HOLD_SIZE 256 13 14 enum { GIF_TRAILER = 0x3B }; // ';' 15 enum { GIF_IMAGE_SEPARATOR = 0x2C }; // ',' 16 enum { GIF_EXTENSION_INTRODUCER = 0x21 }; // '!' 17 enum { GIF_GRAPHIC_CONTROL_LABEL = 0xF9 }; 18 enum { GIF_APPLICATION_EXTENSION_LABEL = 0xFF }; 19 20 // A GIF decoder's state 21 typedef struct gif_struct { 22 // LZW decoder state machine 23 uint8_t* stackp; // Current stack pointer 24 int datasize; 25 int codesize; 26 int codemask; 27 int avail; // Index of next available slot in dictionary 28 int oldcode; 29 uint8_t firstchar; 30 int bits; // Number of unread bits in "datum" 31 int32_t datum; // 32-bit input buffer 32 33 // Output state machine 34 int64_t pixels_remaining; // Pixels remaining to be output. 35 36 // Parameters for image frame currently being decoded 37 int tpixel; // Index of transparent pixel 38 int32_t disposal_method; // Restore to background, leave in place, etc. 39 uint32_t* local_colormap; // Per-image colormap 40 uint32_t local_colormap_buffer_size; // Size of the buffer containing the 41 // local colormap. 42 int local_colormap_size; // Size of local colormap array. 43 uint32_t delay_time; // Display time, in milliseconds, 44 // for this image in a multi-image GIF 45 46 // Global (multi-image) state 47 int version; // Either 89 for GIF89 or 87 for GIF87 48 int32_t screen_width; // Logical screen width & height 49 int32_t screen_height; 50 uint8_t global_colormap_depth; // Depth of global colormap array 51 uint16_t global_colormap_count; // Number of colors in global colormap 52 int images_decoded; // Counts images for multi-part GIFs 53 int loop_count; // Netscape specific extension block to control 54 // the number of animation loops a GIF 55 // renders. 56 57 bool is_transparent; // TRUE, if tpixel is valid 58 59 uint16_t prefix[MAX_BITS]; // LZW decoding tables 60 uint32_t global_colormap[MAX_COLORS]; // Default colormap if local not 61 // supplied 62 uint8_t suffix[MAX_BITS]; // LZW decoding tables 63 uint8_t stack[MAX_BITS]; // Base of LZW decoder stack 64 65 } gif_struct; 66 67 #endif // mozilla_image_decoders_GIF2_H