image/decoders/GIF2.h@6474c204b198 (annotated)
image/decoders/GIF2.h
Wed, 31 Dec 2014 06:09:35 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:09:35 +0100
- changeset 0
- 6474c204b198
- permissions
- -rw-r--r--
Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.
| michael@0 | 1 | /* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ |
| michael@0 | 2 | /* This Source Code Form is subject to the terms of the Mozilla Public |
| michael@0 | 3 | * License, v. 2.0. If a copy of the MPL was not distributed with this |
| michael@0 | 4 | * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| michael@0 | 5 | #ifndef _GIF_H_ |
| michael@0 | 6 | #define _GIF_H_ |
| michael@0 | 7 | |
| michael@0 | 8 | #define MAX_LZW_BITS 12 |
| michael@0 | 9 | #define MAX_BITS 4097 /* 2^MAX_LZW_BITS+1 */ |
| michael@0 | 10 | #define MAX_COLORS 256 |
| michael@0 | 11 | #define MIN_HOLD_SIZE 256 |
| michael@0 | 12 | |
| michael@0 | 13 | enum { GIF_TRAILER = 0x3B }; //';' |
| michael@0 | 14 | enum { GIF_IMAGE_SEPARATOR = 0x2C }; //',' |
| michael@0 | 15 | enum { GIF_EXTENSION_INTRODUCER = 0x21 }; //'!' |
| michael@0 | 16 | enum { GIF_GRAPHIC_CONTROL_LABEL = 0xF9 }; |
| michael@0 | 17 | enum { GIF_COMMENT_LABEL = 0xFE }; |
| michael@0 | 18 | enum { GIF_PLAIN_TEXT_LABEL = 0x01 }; |
| michael@0 | 19 | enum { GIF_APPLICATION_EXTENSION_LABEL = 0xFF }; |
| michael@0 | 20 | |
| michael@0 | 21 | /* gif2.h |
| michael@0 | 22 | The interface for the GIF87/89a decoder. |
| michael@0 | 23 | */ |
| michael@0 | 24 | // List of possible parsing states |
| michael@0 | 25 | typedef enum { |
| michael@0 | 26 | gif_type, |
| michael@0 | 27 | gif_global_header, |
| michael@0 | 28 | gif_global_colormap, |
| michael@0 | 29 | gif_image_start, |
| michael@0 | 30 | gif_image_header, |
| michael@0 | 31 | gif_image_header_continue, |
| michael@0 | 32 | gif_image_colormap, |
| michael@0 | 33 | gif_image_body, |
| michael@0 | 34 | gif_lzw_start, |
| michael@0 | 35 | gif_lzw, |
| michael@0 | 36 | gif_sub_block, |
| michael@0 | 37 | gif_extension, |
| michael@0 | 38 | gif_control_extension, |
| michael@0 | 39 | gif_consume_block, |
| michael@0 | 40 | gif_skip_block, |
| michael@0 | 41 | gif_done, |
| michael@0 | 42 | gif_error, |
| michael@0 | 43 | gif_comment_extension, |
| michael@0 | 44 | gif_application_extension, |
| michael@0 | 45 | gif_netscape_extension_block, |
| michael@0 | 46 | gif_consume_netscape_extension, |
| michael@0 | 47 | gif_consume_comment |
| michael@0 | 48 | } gstate; |
| michael@0 | 49 | |
| michael@0 | 50 | /* A GIF decoder's state */ |
| michael@0 | 51 | typedef struct gif_struct { |
| michael@0 | 52 | /* Parsing state machine */ |
| michael@0 | 53 | gstate state; /* Curent decoder master state */ |
| michael@0 | 54 | uint32_t bytes_to_consume; /* Number of bytes to accumulate */ |
| michael@0 | 55 | uint32_t bytes_in_hold; /* bytes accumulated so far*/ |
| michael@0 | 56 | |
| michael@0 | 57 | /* LZW decoder state machine */ |
| michael@0 | 58 | uint8_t *stackp; /* Current stack pointer */ |
| michael@0 | 59 | int datasize; |
| michael@0 | 60 | int codesize; |
| michael@0 | 61 | int codemask; |
| michael@0 | 62 | int avail; /* Index of next available slot in dictionary */ |
| michael@0 | 63 | int oldcode; |
| michael@0 | 64 | uint8_t firstchar; |
| michael@0 | 65 | int count; /* Remaining # bytes in sub-block */ |
| michael@0 | 66 | int bits; /* Number of unread bits in "datum" */ |
| michael@0 | 67 | int32_t datum; /* 32-bit input buffer */ |
| michael@0 | 68 | |
| michael@0 | 69 | /* Output state machine */ |
| michael@0 | 70 | int ipass; /* Interlace pass; Ranges 1-4 if interlaced. */ |
| michael@0 | 71 | unsigned rows_remaining; /* Rows remaining to be output */ |
| michael@0 | 72 | unsigned irow; /* Current output row, starting at zero */ |
| michael@0 | 73 | uint8_t *rowp; /* Current output pointer */ |
| michael@0 | 74 | |
| michael@0 | 75 | /* Parameters for image frame currently being decoded*/ |
| michael@0 | 76 | unsigned x_offset, y_offset; /* With respect to "screen" origin */ |
| michael@0 | 77 | unsigned height, width; |
| michael@0 | 78 | int tpixel; /* Index of transparent pixel */ |
| michael@0 | 79 | int32_t disposal_method; /* Restore to background, leave in place, etc.*/ |
| michael@0 | 80 | uint32_t *local_colormap; /* Per-image colormap */ |
| michael@0 | 81 | int local_colormap_size; /* Size of local colormap array. */ |
| michael@0 | 82 | uint32_t delay_time; /* Display time, in milliseconds, |
| michael@0 | 83 | for this image in a multi-image GIF */ |
| michael@0 | 84 | |
| michael@0 | 85 | /* Global (multi-image) state */ |
| michael@0 | 86 | int version; /* Either 89 for GIF89 or 87 for GIF87 */ |
| michael@0 | 87 | unsigned screen_width; /* Logical screen width & height */ |
| michael@0 | 88 | unsigned screen_height; |
| michael@0 | 89 | uint32_t global_colormap_depth; /* Depth of global colormap array. */ |
| michael@0 | 90 | int images_decoded; /* Counts images for multi-part GIFs */ |
| michael@0 | 91 | int loop_count; /* Netscape specific extension block to control |
| michael@0 | 92 | the number of animation loops a GIF renders. */ |
| michael@0 | 93 | |
| michael@0 | 94 | bool progressive_display; /* If TRUE, do Haeberli interlace hack */ |
| michael@0 | 95 | bool interlaced; /* TRUE, if scanlines arrive interlaced order */ |
| michael@0 | 96 | bool is_transparent; /* TRUE, if tpixel is valid */ |
| michael@0 | 97 | |
| michael@0 | 98 | uint16_t prefix[MAX_BITS]; /* LZW decoding tables */ |
| michael@0 | 99 | uint8_t* hold; /* Accumulation buffer */ |
| michael@0 | 100 | uint32_t global_colormap[MAX_COLORS]; /* Default colormap if local not supplied */ |
| michael@0 | 101 | uint8_t suffix[MAX_BITS]; /* LZW decoding tables */ |
| michael@0 | 102 | uint8_t stack[MAX_BITS]; /* Base of LZW decoder stack */ |
| michael@0 | 103 | |
| michael@0 | 104 | } gif_struct; |
| michael@0 | 105 | |
| michael@0 | 106 | #endif |
| michael@0 | 107 |
