109 lines
4.6 KiB
C
109 lines
4.6 KiB
C
/*
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* Copyright 2004 Richard Wilson <richard.wilson@netsurf-browser.org>
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* Copyright 2008 Sean Fox <dyntryx@gmail.com>
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*
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* This file is part of NetSurf's libnsgif, http://www.netsurf-browser.org/
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* Licenced under the MIT License,
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* http://www.opensource.org/licenses/mit-license.php
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*/
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/** \file
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* Progressive animated GIF file decoding (interface).
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*/
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#ifndef _LIBNSGIF_H_
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#define _LIBNSGIF_H_
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#include <stdbool.h>
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#include <inttypes.h>
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/* Error return values
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*/
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typedef enum {
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GIF_WORKING = 1,
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GIF_OK = 0,
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GIF_INSUFFICIENT_FRAME_DATA = -1,
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GIF_FRAME_DATA_ERROR = -2,
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GIF_INSUFFICIENT_DATA = -3,
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GIF_DATA_ERROR = -4,
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GIF_INSUFFICIENT_MEMORY = -5,
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GIF_FRAME_NO_DISPLAY = -6,
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GIF_END_OF_FRAME = -7
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} gif_result;
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/* The GIF frame data
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*/
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typedef struct gif_frame {
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bool display; /**< whether the frame should be displayed/animated */
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unsigned int frame_delay; /**< delay (in cs) before animating the frame */
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/** Internal members are listed below
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*/
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unsigned int frame_pointer; /**< offset (in bytes) to the GIF frame data */
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bool virgin; /**< whether the frame has previously been used */
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bool opaque; /**< whether the frame is totally opaque */
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bool redraw_required; /**< whether a forcable screen redraw is required */
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unsigned char disposal_method; /**< how the previous frame should be disposed; affects plotting */
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bool transparency; /**< whether we acknoledge transparency */
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unsigned char transparency_index; /**< the index designating a transparent pixel */
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unsigned int redraw_x; /**< x co-ordinate of redraw rectangle */
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unsigned int redraw_y; /**< y co-ordinate of redraw rectangle */
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unsigned int redraw_width; /**< width of redraw rectangle */
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unsigned int redraw_height; /**< height of redraw rectangle */
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} gif_frame;
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/* API for Bitmap callbacks
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*/
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typedef void* (*gif_bitmap_cb_create)(int width, int height);
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typedef void (*gif_bitmap_cb_destroy)(void *bitmap);
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typedef unsigned char* (*gif_bitmap_cb_get_buffer)(void *bitmap);
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typedef void (*gif_bitmap_cb_set_opaque)(void *bitmap, bool opaque);
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typedef bool (*gif_bitmap_cb_test_opaque)(void *bitmap);
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typedef void (*gif_bitmap_cb_modified)(void *bitmap);
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/* The Bitmap callbacks function table
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*/
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typedef struct gif_bitmap_callback_vt {
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gif_bitmap_cb_create bitmap_create; /**< Create a bitmap. */
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gif_bitmap_cb_destroy bitmap_destroy; /**< Free a bitmap. */
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gif_bitmap_cb_get_buffer bitmap_get_buffer; /**< Return a pointer to the pixel data in a bitmap. */
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/** Members below are optional
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*/
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gif_bitmap_cb_set_opaque bitmap_set_opaque; /**< Sets whether a bitmap should be plotted opaque. */
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gif_bitmap_cb_test_opaque bitmap_test_opaque; /**< Tests whether a bitmap has an opaque alpha channel. */
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gif_bitmap_cb_modified bitmap_modified; /**< The bitmap image has changed, so flush any persistant cache. */
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} gif_bitmap_callback_vt;
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/* The GIF animation data
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*/
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typedef struct gif_animation {
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gif_bitmap_callback_vt bitmap_callbacks; /**< callbacks for bitmap functions */
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unsigned char *gif_data; /**< pointer to GIF data */
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unsigned int width; /**< width of GIF (may increase during decoding) */
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unsigned int height; /**< heigth of GIF (may increase during decoding) */
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unsigned int frame_count; /**< number of frames decoded */
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unsigned int frame_count_partial; /**< number of frames partially decoded */
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gif_frame *frames; /**< decoded frames */
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int decoded_frame; /**< current frame decoded to bitmap */
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void *frame_image; /**< currently decoded image; stored as bitmap from bitmap_create callback */
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int loop_count; /**< number of times to loop animation */
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gif_result current_error; /**< current error type, or 0 for none*/
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/** Internal members are listed below
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*/
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unsigned int buffer_position; /**< current index into GIF data */
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unsigned int buffer_size; /**< total number of bytes of GIF data available */
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unsigned int frame_holders; /**< current number of frame holders */
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unsigned int background_index; /**< index in the colour table for the background colour */
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unsigned int aspect_ratio; /**< image aspect ratio (ignored) */
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unsigned int colour_table_size; /**< size of colour table (in entries) */
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bool global_colours; /**< whether the GIF has a global colour table */
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unsigned int *global_colour_table; /**< global colour table */
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unsigned int *local_colour_table; /**< local colour table */
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} gif_animation;
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void gif_create(gif_animation *gif, gif_bitmap_callback_vt *bitmap_callbacks);
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gif_result gif_initialise(gif_animation *gif, size_t size, unsigned char *data);
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gif_result gif_decode_frame(gif_animation *gif, unsigned int frame);
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void gif_finalise(gif_animation *gif);
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#endif
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