/usr/include/libnsgif.h is in libnsgif0-dev 0.0.1-1.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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* Copyright 2004 Richard Wilson <richard.wilson@netsurf-browser.org>
* Copyright 2008 Sean Fox <dyntryx@gmail.com>
*
* This file is part of NetSurf's libnsgif, http://www.netsurf-browser.org/
* Licenced under the MIT License,
* http://www.opensource.org/licenses/mit-license.php
*/
/** \file
* Progressive animated GIF file decoding (interface).
*/
#ifndef _LIBNSGIF_H_
#define _LIBNSGIF_H_
#include <stdbool.h>
/* Error return values
*/
typedef enum {
GIF_WORKING = 1,
GIF_OK = 0,
GIF_INSUFFICIENT_FRAME_DATA = -1,
GIF_FRAME_DATA_ERROR = -2,
GIF_INSUFFICIENT_DATA = -3,
GIF_DATA_ERROR = -4,
GIF_INSUFFICIENT_MEMORY = -5,
GIF_FRAME_NO_DISPLAY = -6,
GIF_END_OF_FRAME = -7
} gif_result;
/* The GIF frame data
*/
typedef struct gif_frame {
bool display; /**< whether the frame should be displayed/animated */
unsigned int frame_delay; /**< delay (in cs) before animating the frame */
/** Internal members are listed below
*/
unsigned int frame_pointer; /**< offset (in bytes) to the GIF frame data */
bool virgin; /**< whether the frame has previously been used */
bool opaque; /**< whether the frame is totally opaque */
bool redraw_required; /**< whether a forcable screen redraw is required */
unsigned char disposal_method; /**< how the previous frame should be disposed; affects plotting */
bool transparency; /**< whether we acknoledge transparency */
unsigned char transparency_index; /**< the index designating a transparent pixel */
unsigned int redraw_x; /**< x co-ordinate of redraw rectangle */
unsigned int redraw_y; /**< y co-ordinate of redraw rectangle */
unsigned int redraw_width; /**< width of redraw rectangle */
unsigned int redraw_height; /**< height of redraw rectangle */
} gif_frame;
/* API for Bitmap callbacks
*/
typedef void* (*gif_bitmap_cb_create)(int width, int height);
typedef void (*gif_bitmap_cb_destroy)(void *bitmap);
typedef unsigned char* (*gif_bitmap_cb_get_buffer)(void *bitmap);
typedef void (*gif_bitmap_cb_set_opaque)(void *bitmap, bool opaque);
typedef bool (*gif_bitmap_cb_test_opaque)(void *bitmap);
typedef void (*gif_bitmap_cb_modified)(void *bitmap);
/* The Bitmap callbacks function table
*/
typedef struct gif_bitmap_callback_vt {
gif_bitmap_cb_create bitmap_create; /**< Create a bitmap. */
gif_bitmap_cb_destroy bitmap_destroy; /**< Free a bitmap. */
gif_bitmap_cb_get_buffer bitmap_get_buffer; /**< Return a pointer to the pixel data in a bitmap. */
/** Members below are optional
*/
gif_bitmap_cb_set_opaque bitmap_set_opaque; /**< Sets whether a bitmap should be plotted opaque. */
gif_bitmap_cb_test_opaque bitmap_test_opaque; /**< Tests whether a bitmap has an opaque alpha channel. */
gif_bitmap_cb_modified bitmap_modified; /**< The bitmap image has changed, so flush any persistant cache. */
} gif_bitmap_callback_vt;
/* The GIF animation data
*/
typedef struct gif_animation {
gif_bitmap_callback_vt bitmap_callbacks; /**< callbacks for bitmap functions */
unsigned char *gif_data; /**< pointer to GIF data */
unsigned int width; /**< width of GIF (may increase during decoding) */
unsigned int height; /**< heigth of GIF (may increase during decoding) */
unsigned int frame_count; /**< number of frames decoded */
unsigned int frame_count_partial; /**< number of frames partially decoded */
gif_frame *frames; /**< decoded frames */
int decoded_frame; /**< current frame decoded to bitmap */
void *frame_image; /**< currently decoded image; stored as bitmap from bitmap_create callback */
int loop_count; /**< number of times to loop animation */
gif_result current_error; /**< current error type, or 0 for none*/
/** Internal members are listed below
*/
unsigned int buffer_position; /**< current index into GIF data */
unsigned int buffer_size; /**< total number of bytes of GIF data available */
unsigned int frame_holders; /**< current number of frame holders */
unsigned int background_index; /**< index in the colour table for the background colour */
unsigned int aspect_ratio; /**< image aspect ratio (ignored) */
unsigned int colour_table_size; /**< size of colour table (in entries) */
bool global_colours; /**< whether the GIF has a global colour table */
unsigned int *global_colour_table; /**< global colour table */
unsigned int *local_colour_table; /**< local colour table */
} gif_animation;
void gif_create(gif_animation *gif, gif_bitmap_callback_vt *bitmap_callbacks);
gif_result gif_initialise(gif_animation *gif, size_t size, unsigned char *data);
gif_result gif_decode_frame(gif_animation *gif, unsigned int frame);
void gif_finalise(gif_animation *gif);
#endif
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