1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/image/decoders/GIF2.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,107 @@
1.4 +/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +#ifndef _GIF_H_
1.9 +#define _GIF_H_
1.10 +
1.11 +#define MAX_LZW_BITS 12
1.12 +#define MAX_BITS 4097 /* 2^MAX_LZW_BITS+1 */
1.13 +#define MAX_COLORS 256
1.14 +#define MIN_HOLD_SIZE 256
1.15 +
1.16 +enum { GIF_TRAILER = 0x3B }; //';'
1.17 +enum { GIF_IMAGE_SEPARATOR = 0x2C }; //','
1.18 +enum { GIF_EXTENSION_INTRODUCER = 0x21 }; //'!'
1.19 +enum { GIF_GRAPHIC_CONTROL_LABEL = 0xF9 };
1.20 +enum { GIF_COMMENT_LABEL = 0xFE };
1.21 +enum { GIF_PLAIN_TEXT_LABEL = 0x01 };
1.22 +enum { GIF_APPLICATION_EXTENSION_LABEL = 0xFF };
1.23 +
1.24 +/* gif2.h
1.25 + The interface for the GIF87/89a decoder.
1.26 +*/
1.27 +// List of possible parsing states
1.28 +typedef enum {
1.29 + gif_type,
1.30 + gif_global_header,
1.31 + gif_global_colormap,
1.32 + gif_image_start,
1.33 + gif_image_header,
1.34 + gif_image_header_continue,
1.35 + gif_image_colormap,
1.36 + gif_image_body,
1.37 + gif_lzw_start,
1.38 + gif_lzw,
1.39 + gif_sub_block,
1.40 + gif_extension,
1.41 + gif_control_extension,
1.42 + gif_consume_block,
1.43 + gif_skip_block,
1.44 + gif_done,
1.45 + gif_error,
1.46 + gif_comment_extension,
1.47 + gif_application_extension,
1.48 + gif_netscape_extension_block,
1.49 + gif_consume_netscape_extension,
1.50 + gif_consume_comment
1.51 +} gstate;
1.52 +
1.53 +/* A GIF decoder's state */
1.54 +typedef struct gif_struct {
1.55 + /* Parsing state machine */
1.56 + gstate state; /* Curent decoder master state */
1.57 + uint32_t bytes_to_consume; /* Number of bytes to accumulate */
1.58 + uint32_t bytes_in_hold; /* bytes accumulated so far*/
1.59 +
1.60 + /* LZW decoder state machine */
1.61 + uint8_t *stackp; /* Current stack pointer */
1.62 + int datasize;
1.63 + int codesize;
1.64 + int codemask;
1.65 + int avail; /* Index of next available slot in dictionary */
1.66 + int oldcode;
1.67 + uint8_t firstchar;
1.68 + int count; /* Remaining # bytes in sub-block */
1.69 + int bits; /* Number of unread bits in "datum" */
1.70 + int32_t datum; /* 32-bit input buffer */
1.71 +
1.72 + /* Output state machine */
1.73 + int ipass; /* Interlace pass; Ranges 1-4 if interlaced. */
1.74 + unsigned rows_remaining; /* Rows remaining to be output */
1.75 + unsigned irow; /* Current output row, starting at zero */
1.76 + uint8_t *rowp; /* Current output pointer */
1.77 +
1.78 + /* Parameters for image frame currently being decoded*/
1.79 + unsigned x_offset, y_offset; /* With respect to "screen" origin */
1.80 + unsigned height, width;
1.81 + int tpixel; /* Index of transparent pixel */
1.82 + int32_t disposal_method; /* Restore to background, leave in place, etc.*/
1.83 + uint32_t *local_colormap; /* Per-image colormap */
1.84 + int local_colormap_size; /* Size of local colormap array. */
1.85 + uint32_t delay_time; /* Display time, in milliseconds,
1.86 + for this image in a multi-image GIF */
1.87 +
1.88 + /* Global (multi-image) state */
1.89 + int version; /* Either 89 for GIF89 or 87 for GIF87 */
1.90 + unsigned screen_width; /* Logical screen width & height */
1.91 + unsigned screen_height;
1.92 + uint32_t global_colormap_depth; /* Depth of global colormap array. */
1.93 + int images_decoded; /* Counts images for multi-part GIFs */
1.94 + int loop_count; /* Netscape specific extension block to control
1.95 + the number of animation loops a GIF renders. */
1.96 +
1.97 + bool progressive_display; /* If TRUE, do Haeberli interlace hack */
1.98 + bool interlaced; /* TRUE, if scanlines arrive interlaced order */
1.99 + bool is_transparent; /* TRUE, if tpixel is valid */
1.100 +
1.101 + uint16_t prefix[MAX_BITS]; /* LZW decoding tables */
1.102 + uint8_t* hold; /* Accumulation buffer */
1.103 + uint32_t global_colormap[MAX_COLORS]; /* Default colormap if local not supplied */
1.104 + uint8_t suffix[MAX_BITS]; /* LZW decoding tables */
1.105 + uint8_t stack[MAX_BITS]; /* Base of LZW decoder stack */
1.106 +
1.107 +} gif_struct;
1.108 +
1.109 +#endif
1.110 +
