image/decoders/GIF2.h@6474c204b198
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.
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 #ifndef _GIF_H_
6 #define _GIF_H_
8 #define MAX_LZW_BITS 12
9 #define MAX_BITS 4097 /* 2^MAX_LZW_BITS+1 */
10 #define MAX_COLORS 256
11 #define MIN_HOLD_SIZE 256
13 enum { GIF_TRAILER = 0x3B }; //';'
14 enum { GIF_IMAGE_SEPARATOR = 0x2C }; //','
15 enum { GIF_EXTENSION_INTRODUCER = 0x21 }; //'!'
16 enum { GIF_GRAPHIC_CONTROL_LABEL = 0xF9 };
17 enum { GIF_COMMENT_LABEL = 0xFE };
18 enum { GIF_PLAIN_TEXT_LABEL = 0x01 };
19 enum { GIF_APPLICATION_EXTENSION_LABEL = 0xFF };
21 /* gif2.h
22 The interface for the GIF87/89a decoder.
23 */
24 // List of possible parsing states
25 typedef enum {
26 gif_type,
27 gif_global_header,
28 gif_global_colormap,
29 gif_image_start,
30 gif_image_header,
31 gif_image_header_continue,
32 gif_image_colormap,
33 gif_image_body,
34 gif_lzw_start,
35 gif_lzw,
36 gif_sub_block,
37 gif_extension,
38 gif_control_extension,
39 gif_consume_block,
40 gif_skip_block,
41 gif_done,
42 gif_error,
43 gif_comment_extension,
44 gif_application_extension,
45 gif_netscape_extension_block,
46 gif_consume_netscape_extension,
47 gif_consume_comment
48 } gstate;
50 /* A GIF decoder's state */
51 typedef struct gif_struct {
52 /* Parsing state machine */
53 gstate state; /* Curent decoder master state */
54 uint32_t bytes_to_consume; /* Number of bytes to accumulate */
55 uint32_t bytes_in_hold; /* bytes accumulated so far*/
57 /* LZW decoder state machine */
58 uint8_t *stackp; /* Current stack pointer */
59 int datasize;
60 int codesize;
61 int codemask;
62 int avail; /* Index of next available slot in dictionary */
63 int oldcode;
64 uint8_t firstchar;
65 int count; /* Remaining # bytes in sub-block */
66 int bits; /* Number of unread bits in "datum" */
67 int32_t datum; /* 32-bit input buffer */
69 /* Output state machine */
70 int ipass; /* Interlace pass; Ranges 1-4 if interlaced. */
71 unsigned rows_remaining; /* Rows remaining to be output */
72 unsigned irow; /* Current output row, starting at zero */
73 uint8_t *rowp; /* Current output pointer */
75 /* Parameters for image frame currently being decoded*/
76 unsigned x_offset, y_offset; /* With respect to "screen" origin */
77 unsigned height, width;
78 int tpixel; /* Index of transparent pixel */
79 int32_t disposal_method; /* Restore to background, leave in place, etc.*/
80 uint32_t *local_colormap; /* Per-image colormap */
81 int local_colormap_size; /* Size of local colormap array. */
82 uint32_t delay_time; /* Display time, in milliseconds,
83 for this image in a multi-image GIF */
85 /* Global (multi-image) state */
86 int version; /* Either 89 for GIF89 or 87 for GIF87 */
87 unsigned screen_width; /* Logical screen width & height */
88 unsigned screen_height;
89 uint32_t global_colormap_depth; /* Depth of global colormap array. */
90 int images_decoded; /* Counts images for multi-part GIFs */
91 int loop_count; /* Netscape specific extension block to control
92 the number of animation loops a GIF renders. */
94 bool progressive_display; /* If TRUE, do Haeberli interlace hack */
95 bool interlaced; /* TRUE, if scanlines arrive interlaced order */
96 bool is_transparent; /* TRUE, if tpixel is valid */
98 uint16_t prefix[MAX_BITS]; /* LZW decoding tables */
99 uint8_t* hold; /* Accumulation buffer */
100 uint32_t global_colormap[MAX_COLORS]; /* Default colormap if local not supplied */
101 uint8_t suffix[MAX_BITS]; /* LZW decoding tables */
102 uint8_t stack[MAX_BITS]; /* Base of LZW decoder stack */
104 } gif_struct;
106 #endif
