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author | John Mark Bell <jmb@netsurf-browser.org> | 2009-03-29 01:38:08 +0000 |
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committer | John Mark Bell <jmb@netsurf-browser.org> | 2009-03-29 01:38:08 +0000 |
commit | 0e9f500cdd1193c6c32c7fc460453f830fdeff1a (patch) | |
tree | 2eccdb5ec1811f39018c08db4c3f8a8e533c63f2 /libnsgif.c | |
parent | 68a1ebce3438ee4fc2a2ba5b0236f56d9eec244f (diff) | |
download | libnsgif-0e9f500cdd1193c6c32c7fc460453f830fdeff1a.tar.gz libnsgif-0e9f500cdd1193c6c32c7fc460453f830fdeff1a.tar.bz2 |
First cut at a port to the core buildsystem
svn path=/trunk/libnsgif/; revision=6983
Diffstat (limited to 'libnsgif.c')
-rw-r--r-- | libnsgif.c | 1260 |
1 files changed, 0 insertions, 1260 deletions
diff --git a/libnsgif.c b/libnsgif.c deleted file mode 100644 index 1eb46c5..0000000 --- a/libnsgif.c +++ /dev/null @@ -1,1260 +0,0 @@ -/* - * 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 - */ - -#include <stdbool.h> -#include <stdio.h> -#include <string.h> -#include <stdlib.h> -#include <assert.h> -#include "libnsgif.h" -#include "utils/log.h" - -/* READING GIF FILES - ================= - - The functions provided by this file allow for efficient progressive GIF - decoding. Whilst the initialisation does not ensure that there is - sufficient image data to complete the entire frame, it does ensure that - the information provided is valid. Any subsequent attempts to decode an - initialised GIF are guaranteed to succeed, and any bytes of the image - not present are assumed to be totally transparent. - - To begin decoding a GIF, the 'gif' structure must be initialised with - the 'gif_data' and 'buffer_size' set to their initial values. The - 'buffer_position' should initially be 0, and will be internally updated - as the decoding commences. The caller should then repeatedly call - gif_initialise() with the structure until the function returns 1, or - no more data is avaliable. - - Once the initialisation has begun, the decoder completes the variables - 'frame_count' and 'frame_count_partial'. The former being the total - number of frames that have been successfully initialised, and the - latter being the number of frames that a partial amount of data is - available for. This assists the caller in managing the animation whilst - decoding is continuing. - - To decode a frame, the caller must use gif_decode_frame() which updates - the current 'frame_image' to reflect the desired frame. The required - 'disposal_method' is also updated to reflect how the frame should be - plotted. The caller must not assume that the current 'frame_image' will - be valid between calls if initialisation is still occuring, and should - either always request that the frame is decoded (no processing will - occur if the 'decoded_frame' has not been invalidated by initialisation) - or perform the check itself. - - It should be noted that gif_finalise() should always be called, even if - no frames were initialised. Additionally, it is the responsibility of - the caller to free 'gif_data'. - - [rjw] - Fri 2nd April 2004 -*/ - -/* TO-DO LIST - ================= - - + Plain text and comment extensions could be implemented if there is any - interest in doing so. -*/ - - - - -/* Maximum colour table size -*/ -#define GIF_MAX_COLOURS 256 - -/* Internal flag that the colour table needs to be processed -*/ -#define GIF_PROCESS_COLOURS 0xaa000000 - -/* Internal flag that a frame is invalid/unprocessed -*/ -#define GIF_INVALID_FRAME -1 - -/* Maximum LZW bits available -*/ -#define GIF_MAX_LZW 12 - -/* Transparent colour -*/ -#define GIF_TRANSPARENT_COLOUR 0x00 - -/* GIF Flags -*/ -#define GIF_FRAME_COMBINE 1 -#define GIF_FRAME_CLEAR 2 -#define GIF_FRAME_RESTORE 3 -#define GIF_FRAME_QUIRKS_RESTORE 4 -#define GIF_IMAGE_SEPARATOR 0x2c -#define GIF_INTERLACE_MASK 0x40 -#define GIF_COLOUR_TABLE_MASK 0x80 -#define GIF_COLOUR_TABLE_SIZE_MASK 0x07 -#define GIF_EXTENSION_INTRODUCER 0x21 -#define GIF_EXTENSION_GRAPHIC_CONTROL 0xf9 -#define GIF_DISPOSAL_MASK 0x1c -#define GIF_TRANSPARENCY_MASK 0x01 -#define GIF_EXTENSION_COMMENT 0xfe -#define GIF_EXTENSION_PLAIN_TEXT 0x01 -#define GIF_EXTENSION_APPLICATION 0xff -#define GIF_BLOCK_TERMINATOR 0x00 -#define GIF_TRAILER 0x3b - -/* Internal GIF routines -*/ -static gif_result gif_initialise_sprite(gif_animation *gif, unsigned int width, unsigned int height); -static gif_result gif_initialise_frame(gif_animation *gif); -static gif_result gif_initialise_frame_extensions(gif_animation *gif, const int frame); -static gif_result gif_skip_frame_extensions(gif_animation *gif); -static unsigned int gif_interlaced_line(int height, int y); - - - -/* Internal LZW routines -*/ -static void gif_init_LZW(gif_animation *gif); -static bool gif_next_LZW(gif_animation *gif); -static int gif_next_code(gif_animation *gif, int code_size); - -/* General LZW values. They are shared for all GIFs being decoded, and - thus we can't handle progressive decoding efficiently without having - the data for each image which would use an extra 10Kb or so per GIF. -*/ -static unsigned char buf[4]; -static unsigned char *direct; -static int maskTbl[16] = {0x0000, 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, - 0x00ff, 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff}; -static int table[2][(1 << GIF_MAX_LZW)]; -static unsigned char stack[(1 << GIF_MAX_LZW) * 2]; -static unsigned char *stack_pointer; -static int code_size, set_code_size; -static int max_code, max_code_size; -static int clear_code, end_code; -static int curbit, lastbit, last_byte; -static int firstcode, oldcode; -static bool zero_data_block = false; -static bool get_done; - -/* Whether to clear the decoded image rather than plot -*/ -static bool clear_image = false; - - - -/** Initialises necessary gif_animation members. -*/ -void gif_create(gif_animation *gif, gif_bitmap_callback_vt *bitmap_callbacks) { - memset(gif, 0, sizeof(gif_animation)); - gif->bitmap_callbacks = *bitmap_callbacks; - gif->decoded_frame = GIF_INVALID_FRAME; -} - - -/** Initialises any workspace held by the animation and attempts to decode - any information that hasn't already been decoded. - If an error occurs, all previously decoded frames are retained. - - @return GIF_FRAME_DATA_ERROR for GIF frame data error - GIF_INSUFFICIENT_FRAME_DATA for insufficient data to process - any more frames - GIF_INSUFFICIENT_MEMORY for memory error - GIF_DATA_ERROR for GIF error - GIF_INSUFFICIENT_DATA for insufficient data to do anything - GIF_OK for successful decoding - GIF_WORKING for successful decoding if more frames are expected -*/ -gif_result gif_initialise(gif_animation *gif, size_t size, unsigned char *data) { - unsigned char *gif_data; - unsigned int index; - gif_result return_value; - - /* The GIF format is thoroughly documented; a full description - * can be found at http://www.w3.org/Graphics/GIF/spec-gif89a.txt - */ - - /* Initialize values - */ - gif->buffer_size = size; - gif->gif_data = data; - - /* Check for sufficient data to be a GIF (6-byte header + 7-byte logical screen descriptor) - */ - if (gif->buffer_size < 13) return GIF_INSUFFICIENT_DATA; - - /* Get our current processing position - */ - gif_data = gif->gif_data + gif->buffer_position; - - /* See if we should initialise the GIF - */ - if (gif->buffer_position == 0) { - - /* We want everything to be NULL before we start so we've no chance - of freeing bad pointers (paranoia) - */ - gif->frame_image = NULL; - gif->frames = NULL; - gif->local_colour_table = NULL; - gif->global_colour_table = NULL; - - /* The caller may have been lazy and not reset any values - */ - gif->frame_count = 0; - gif->frame_count_partial = 0; - gif->decoded_frame = GIF_INVALID_FRAME; - - /* 6-byte GIF file header is: - * - * +0 3CHARS Signature ('GIF') - * +3 3CHARS Version ('87a' or '89a') - */ - if (strncmp((const char *) gif_data, "GIF", 3) != 0) - return GIF_DATA_ERROR; - gif_data += 3; - - /* Ensure GIF reports version 87a or 89a - */ -/* if ((strncmp(gif_data, "87a", 3) != 0) && - (strncmp(gif_data, "89a", 3) != 0)) - LOG(("Unknown GIF format - proceeding anyway")); -*/ gif_data += 3; - - /* 7-byte Logical Screen Descriptor is: - * - * +0 SHORT Logical Screen Width - * +2 SHORT Logical Screen Height - * +4 CHAR __Packed Fields__ - * 1BIT Global Colour Table Flag - * 3BITS Colour Resolution - * 1BIT Sort Flag - * 3BITS Size of Global Colour Table - * +5 CHAR Background Colour Index - * +6 CHAR Pixel Aspect Ratio - */ - gif->width = gif_data[0] | (gif_data[1] << 8); - gif->height = gif_data[2] | (gif_data[3] << 8); - gif->global_colours = (gif_data[4] & GIF_COLOUR_TABLE_MASK); - gif->colour_table_size = (2 << (gif_data[4] & GIF_COLOUR_TABLE_SIZE_MASK)); - gif->background_index = gif_data[5]; - gif->aspect_ratio = gif_data[6]; - gif->loop_count = 1; - gif_data += 7; - - /* Some broken GIFs report the size as the screen size they were created in. As - such, we detect for the common cases and set the sizes as 0 if they are found - which results in the GIF being the maximum size of the frames. - */ - if (((gif->width == 640) && (gif->height == 480)) || - ((gif->width == 640) && (gif->height == 512)) || - ((gif->width == 800) && (gif->height == 600)) || - ((gif->width == 1024) && (gif->height == 768)) || - ((gif->width == 1280) && (gif->height == 1024)) || - ((gif->width == 1600) && (gif->height == 1200)) || - ((gif->width == 0) || (gif->height == 0)) || - ((gif->width > 2048) || (gif->height > 2048))) { - gif->width = 1; - gif->height = 1; - } - - /* Allocate some data irrespective of whether we've got any colour tables. We - always get the maximum size in case a GIF is lying to us. It's far better - to give the wrong colours than to trample over some memory somewhere. - */ - gif->global_colour_table = (unsigned int *)calloc(GIF_MAX_COLOURS, sizeof(int)); - gif->local_colour_table = (unsigned int *)calloc(GIF_MAX_COLOURS, sizeof(int)); - if ((gif->global_colour_table == NULL) || (gif->local_colour_table == NULL)) { - gif_finalise(gif); - return GIF_INSUFFICIENT_MEMORY; - } - - /* Set the first colour to a value that will never occur in reality so we - know if we've processed it - */ - gif->global_colour_table[0] = GIF_PROCESS_COLOURS; - - /* Check if the GIF has no frame data (13-byte header + 1-byte termination block) - * Although generally useless, the GIF specification does not expressly prohibit this - */ - if (gif->buffer_size == 14) { - if (gif_data[0] == GIF_TRAILER) - return GIF_OK; - else - return GIF_INSUFFICIENT_DATA; - } - - /* Initialise enough workspace for 4 frames initially - */ - if ((gif->frames = (gif_frame *)malloc(sizeof(gif_frame))) == NULL) { - gif_finalise(gif); - return GIF_INSUFFICIENT_MEMORY; - } - gif->frame_holders = 1; - - /* Initialise the sprite header - */ - assert(gif->bitmap_callbacks.bitmap_create); - if ((gif->frame_image = gif->bitmap_callbacks.bitmap_create(gif->width, gif->height)) == NULL) { - gif_finalise(gif); - return GIF_INSUFFICIENT_MEMORY; - } - - /* Remember we've done this now - */ - gif->buffer_position = gif_data - gif->gif_data; - } - - /* Do the colour map if we haven't already. As the top byte is always 0xff or 0x00 - depending on the transparency we know if it's been filled in. - */ - if (gif->global_colour_table[0] == GIF_PROCESS_COLOURS) { - /* Check for a global colour map signified by bit 7 - */ - if (gif->global_colours) { - if (gif->buffer_size < (gif->colour_table_size * 3 + 12)) { - return GIF_INSUFFICIENT_DATA; - } - for (index = 0; index < gif->colour_table_size; index++) { - char colour[] = {0, 0, 0, (char)0xff}; - colour[0] = gif_data[0]; - colour[1] = gif_data[1]; - colour[2] = gif_data[2]; - gif->global_colour_table[index] = *((int *) colour); - gif_data += 3; - } - gif->buffer_position = (gif_data - gif->gif_data); - } else { - /* Create a default colour table with the first two colours as black and white - */ - gif->global_colour_table[0] = 0xff000000; - gif->global_colour_table[1] = 0xffffffff; - } - } - - /* Repeatedly try to initialise frames - */ - while ((return_value = gif_initialise_frame(gif)) == GIF_WORKING); - - /* If there was a memory error tell the caller - */ - if ((return_value == GIF_INSUFFICIENT_MEMORY) || - (return_value == GIF_DATA_ERROR)) - return return_value; - - /* If we didn't have some frames then a GIF_INSUFFICIENT_DATA becomes a - GIF_INSUFFICIENT_FRAME_DATA - */ - if ((return_value == GIF_INSUFFICIENT_DATA) && (gif->frame_count_partial > 0)) - return GIF_INSUFFICIENT_FRAME_DATA; - - /* Return how many we got - */ - return return_value; -} - - -/** Updates the sprite memory size - - @return GIF_INSUFFICIENT_MEMORY for a memory error - GIF_OK for success -*/ -static gif_result gif_initialise_sprite(gif_animation *gif, unsigned int width, unsigned int height) { - unsigned int max_width; - unsigned int max_height; - struct bitmap *buffer; - - /* Check if we've changed - */ - if ((width <= gif->width) && (height <= gif->height)) - return GIF_OK; - - /* Get our maximum values - */ - max_width = (width > gif->width) ? width : gif->width; - max_height = (height > gif->height) ? height : gif->height; - - /* Allocate some more memory - */ - assert(gif->bitmap_callbacks.bitmap_create); - if ((buffer = gif->bitmap_callbacks.bitmap_create(max_width, max_height)) == NULL) - return GIF_INSUFFICIENT_MEMORY; - assert(gif->bitmap_callbacks.bitmap_destroy); - gif->bitmap_callbacks.bitmap_destroy(gif->frame_image); - gif->frame_image = buffer; - gif->width = max_width; - gif->height = max_height; - - /* Invalidate our currently decoded image - */ - gif->decoded_frame = GIF_INVALID_FRAME; - return GIF_OK; -} - - -/** Attempts to initialise the next frame - - @return GIF_INSUFFICIENT_DATA for insufficient data to do anything - GIF_FRAME_DATA_ERROR for GIF frame data error - GIF_INSUFFICIENT_MEMORY for insufficient memory to process - GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the frame - GIF_DATA_ERROR for GIF error (invalid frame header) - GIF_OK for successful decoding - GIF_WORKING for successful decoding if more frames are expected -*/ -static gif_result gif_initialise_frame(gif_animation *gif) { - int frame; - gif_frame *temp_buf; - - unsigned char *gif_data, *gif_end; - int gif_bytes; - unsigned int flags = 0; - unsigned int width, height, offset_x, offset_y; - unsigned int block_size, colour_table_size; - bool first_image = true; - gif_result return_value; - - /* Get the frame to decode and our data position - */ - frame = gif->frame_count; - - /* Get our buffer position etc. - */ - gif_data = (unsigned char *)(gif->gif_data + gif->buffer_position); - gif_end = (unsigned char *)(gif->gif_data + gif->buffer_size); - gif_bytes = (gif_end - gif_data); - - /* Check if we've finished - */ - if ((gif_bytes > 0) && (gif_data[0] == GIF_TRAILER)) return GIF_OK; - - /* Check if we have enough data - * The shortest block of data is a 4-byte comment extension + 1-byte block terminator + 1-byte gif trailer - */ - if (gif_bytes < 6) return GIF_INSUFFICIENT_DATA; - - /* We could theoretically get some junk data that gives us millions of frames, so - we ensure that we don't have a silly number - */ - if (frame > 4096) return GIF_FRAME_DATA_ERROR; - - /* Get some memory to store our pointers in etc. - */ - if ((int)gif->frame_holders <= frame) { - /* Allocate more memory - */ - if ((temp_buf = (gif_frame *)realloc(gif->frames, - (frame + 1) * sizeof(gif_frame))) == NULL) - return GIF_INSUFFICIENT_MEMORY; - gif->frames = temp_buf; - gif->frame_holders = frame + 1; - } - - /* Store our frame pointer. We would do it when allocating except we - start off with one frame allocated so we can always use realloc. - */ - gif->frames[frame].frame_pointer = gif->buffer_position; - gif->frames[frame].display = false; - gif->frames[frame].virgin = true; - gif->frames[frame].disposal_method = 0; - gif->frames[frame].transparency = false; - gif->frames[frame].frame_delay = 100; - gif->frames[frame].redraw_required = false; - - /* Invalidate any previous decoding we have of this frame - */ - if (gif->decoded_frame == frame) - gif->decoded_frame = GIF_INVALID_FRAME; - - /* We pretend to initialise the frames, but really we just skip over all - the data contained within. This is all basically a cut down version of - gif_decode_frame that doesn't have any of the LZW bits in it. - */ - - /* Initialise any extensions - */ - gif->buffer_position = gif_data - gif->gif_data; - if ((return_value = gif_initialise_frame_extensions(gif, frame)) != GIF_OK) - return return_value; - gif_data = (gif->gif_data + gif->buffer_position); - gif_bytes = (gif_end - gif_data); - - /* Check if we've finished - */ - if ((gif_bytes = (gif_end - gif_data)) < 1) - return GIF_INSUFFICIENT_FRAME_DATA; - else if (gif_data[0] == GIF_TRAILER) { - gif->buffer_position = (gif_data - gif->gif_data); - gif->frame_count = frame + 1; - return GIF_OK; - } - - /* If we're not done, there should be an image descriptor - */ - if (gif_data[0] != GIF_IMAGE_SEPARATOR) return GIF_FRAME_DATA_ERROR; - - /* Do some simple boundary checking - */ - offset_x = gif_data[1] | (gif_data[2] << 8); - offset_y = gif_data[3] | (gif_data[4] << 8); - width = gif_data[5] | (gif_data[6] << 8); - height = gif_data[7] | (gif_data[8] << 8); - - /* Set up the redraw characteristics. We have to check for extending the area - due to multi-image frames. - */ - if (!first_image) { - if (gif->frames[frame].redraw_x > offset_x) { - gif->frames[frame].redraw_width += (gif->frames[frame].redraw_x - offset_x); - gif->frames[frame].redraw_x = offset_x; - } - if (gif->frames[frame].redraw_y > offset_y) { - gif->frames[frame].redraw_height += (gif->frames[frame].redraw_y - offset_y); - gif->frames[frame].redraw_y = offset_y; - } - if ((offset_x + width) > (gif->frames[frame].redraw_x + gif->frames[frame].redraw_width)) - gif->frames[frame].redraw_width = (offset_x + width) - gif->frames[frame].redraw_x; - if ((offset_y + height) > (gif->frames[frame].redraw_y + gif->frames[frame].redraw_height)) - gif->frames[frame].redraw_height = (offset_y + height) - gif->frames[frame].redraw_y; - } else { - first_image = false; - gif->frames[frame].redraw_x = offset_x; - gif->frames[frame].redraw_y = offset_y; - gif->frames[frame].redraw_width = width; - gif->frames[frame].redraw_height = height; - } - - /* if we are clearing the background then we need to redraw enough to cover the previous - frame too - */ - gif->frames[frame].redraw_required = ((gif->frames[frame].disposal_method == GIF_FRAME_CLEAR) || - (gif->frames[frame].disposal_method == GIF_FRAME_RESTORE)); - - /* Boundary checking - shouldn't ever happen except with junk data - */ - if (gif_initialise_sprite(gif, (offset_x + width), (offset_y + height))) - return GIF_INSUFFICIENT_MEMORY; - - /* Decode the flags - */ - flags = gif_data[9]; - colour_table_size = 2 << (flags & GIF_COLOUR_TABLE_SIZE_MASK); - - /* Move our data onwards and remember we've got a bit of this frame - */ - gif_data += 10; - gif_bytes = (gif_end - gif_data); - gif->frame_count_partial = frame + 1; - - /* Skip the local colour table - */ - if (flags & GIF_COLOUR_TABLE_MASK) { - gif_data += 3 * colour_table_size; - if ((gif_bytes = (gif_end - gif_data)) < 0) - return GIF_INSUFFICIENT_FRAME_DATA; - } - - /* Ensure we have a correct code size - */ - if (gif_data[0] > GIF_MAX_LZW) - return GIF_DATA_ERROR; - - /* Move our pointer to the actual image data - */ - gif_data++; - if (--gif_bytes < 0) - return GIF_INSUFFICIENT_FRAME_DATA; - - /* Repeatedly skip blocks until we get a zero block or run out of data - * These blocks of image data are processed later by gif_decode_frame() - */ - block_size = 0; - while (block_size != 1) { - block_size = gif_data[0] + 1; - /* Check if the frame data runs off the end of the file - */ - if ((int)(gif_bytes - block_size) < 0) { - /* Try to recover by signaling the end of the gif. - * Once we get garbage data, there is no logical - * way to determine where the next frame is. - * It's probably better to partially load the gif - * than not at all. - */ - if (gif_bytes >= 2) { - gif_data[0] = 0; - gif_data[1] = GIF_TRAILER; - gif_bytes = 1; - ++gif_data; - break; - } else - return GIF_INSUFFICIENT_FRAME_DATA; - } else { - gif_bytes -= block_size; - gif_data += block_size; - } - } - - /* Add the frame and set the display flag - */ - gif->buffer_position = gif_data - gif->gif_data; - gif->frame_count = frame + 1; - gif->frames[frame].display = true; - - /* Check if we've finished - */ - if (gif_bytes < 1) - return GIF_INSUFFICIENT_FRAME_DATA; - else - if (gif_data[0] == GIF_TRAILER) return GIF_OK; - return GIF_WORKING; -} - -/** Attempts to initialise the frame's extensions - - @return GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the frame - GIF_OK for successful initialisation -*/ -static gif_result gif_initialise_frame_extensions(gif_animation *gif, const int frame) { - unsigned char *gif_data, *gif_end; - int gif_bytes; - unsigned int block_size; - - /* Get our buffer position etc. - */ - gif_data = (unsigned char *)(gif->gif_data + gif->buffer_position); - gif_end = (unsigned char *)(gif->gif_data + gif->buffer_size); - - /* Initialise the extensions - */ - while (gif_data[0] == GIF_EXTENSION_INTRODUCER) { - ++gif_data; - gif_bytes = (gif_end - gif_data); - - /* Switch on extension label - */ - switch(gif_data[0]) { - /* 6-byte Graphic Control Extension is: - * - * +0 CHAR Graphic Control Label - * +1 CHAR Block Size - * +2 CHAR __Packed Fields__ - * 3BITS Reserved - * 3BITS Disposal Method - * 1BIT User Input Flag - * 1BIT Transparent Color Flag - * +3 SHORT Delay Time - * +5 CHAR Transparent Color Index - */ - case GIF_EXTENSION_GRAPHIC_CONTROL: - if (gif_bytes < 6) return GIF_INSUFFICIENT_FRAME_DATA; - gif->frames[frame].frame_delay = gif_data[3] | (gif_data[4] << 8); - if (gif_data[2] & GIF_TRANSPARENCY_MASK) { - gif->frames[frame].transparency = true; - gif->frames[frame].transparency_index = gif_data[5]; - } - gif->frames[frame].disposal_method = ((gif_data[2] & GIF_DISPOSAL_MASK) >> 2); - /* I have encountered documentation and GIFs in the wild that use - * 0x04 to restore the previous frame, rather than the officially - * documented 0x03. I believe some (older?) software may even actually - * export this way. We handle this as a type of "quirks" mode. - */ - if (gif->frames[frame].disposal_method == GIF_FRAME_QUIRKS_RESTORE) - gif->frames[frame].disposal_method = GIF_FRAME_RESTORE; - gif_data += (2 + gif_data[1]); - break; - - /* 14-byte+ Application Extension is: - * - * +0 CHAR Application Extension Label - * +1 CHAR Block Size - * +2 8CHARS Application Identifier - * +10 3CHARS Appl. Authentication Code - * +13 1-256 Application Data (Data sub-blocks) - */ - case GIF_EXTENSION_APPLICATION: - if (gif_bytes < 17) return GIF_INSUFFICIENT_FRAME_DATA; - if ((gif_data[1] == 0x0b) && - (strncmp((const char *) gif_data + 2, - "NETSCAPE2.0", 11) == 0) && - (gif_data[13] == 0x03) && - (gif_data[14] == 0x01)) { - gif->loop_count = gif_data[15] | (gif_data[16] << 8); - } - gif_data += (2 + gif_data[1]); - break; - - /* Move the pointer to the first data sub-block - * Skip 1 byte for the extension label - */ - case GIF_EXTENSION_COMMENT: - ++gif_data; - break; - - /* Move the pointer to the first data sub-block - * Skip 2 bytes for the extension label and size fields - * Skip the extension size itself - */ - default: - gif_data += (2 + gif_data[1]); - } - - /* Repeatedly skip blocks until we get a zero block or run out of data - * This data is ignored by this gif decoder - */ - gif_bytes = (gif_end - gif_data); - block_size = 0; - while (gif_data[0] != GIF_BLOCK_TERMINATOR) { - block_size = gif_data[0] + 1; - if ((gif_bytes -= block_size) < 0) - return GIF_INSUFFICIENT_FRAME_DATA; - gif_data += block_size; - } - ++gif_data; - } - - /* Set buffer position and return - */ - gif->buffer_position = (gif_data - gif->gif_data); - return GIF_OK; -} - - -/** Decodes a GIF frame. - - @return GIF_FRAME_DATA_ERROR for GIF frame data error - GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the frame - GIF_DATA_ERROR for GIF error (invalid frame header) - GIF_INSUFFICIENT_DATA for insufficient data to do anything - GIF_INSUFFICIENT_MEMORY for insufficient memory to process - GIF_OK for successful decoding - If a frame does not contain any image data, GIF_OK is returned and - gif->current_error is set to GIF_FRAME_NO_DISPLAY -*/ -gif_result gif_decode_frame(gif_animation *gif, unsigned int frame) { - unsigned int index = 0; - unsigned char *gif_data, *gif_end; - int gif_bytes; - unsigned int width, height, offset_x, offset_y; - unsigned int flags, colour_table_size, interlace; - unsigned int *colour_table; - unsigned int *frame_data = 0; // Set to 0 for no warnings - unsigned int *frame_scanline; - unsigned int save_buffer_position; - unsigned int return_value = 0; - unsigned int x, y, decode_y, burst_bytes; - int last_undisposed_frame = (frame - 1); - register unsigned char colour; - - /* Ensure this frame is supposed to be decoded - */ - if (gif->frames[frame].display == false) { - gif->current_error = GIF_FRAME_NO_DISPLAY; - return GIF_OK; - } - - /* Ensure we have a frame to decode - */ - if (frame > gif->frame_count_partial) - return GIF_INSUFFICIENT_DATA; - if ((!clear_image) && ((int)frame == gif->decoded_frame)) - return GIF_OK; - - /* Get the start of our frame data and the end of the GIF data - */ - gif_data = gif->gif_data + gif->frames[frame].frame_pointer; - gif_end = gif->gif_data + gif->buffer_size; - gif_bytes = (gif_end - gif_data); - - /* Check if we have enough data - * The shortest block of data is a 10-byte image descriptor + 1-byte gif trailer - */ - if (gif_bytes < 12) return GIF_INSUFFICIENT_FRAME_DATA; - - /* Save the buffer position - */ - save_buffer_position = gif->buffer_position; - gif->buffer_position = gif_data - gif->gif_data; - - /* Skip any extensions because we all ready processed them - */ - if ((return_value = gif_skip_frame_extensions(gif)) != GIF_OK) - goto gif_decode_frame_exit; - gif_data = (gif->gif_data + gif->buffer_position); - gif_bytes = (gif_end - gif_data); - - /* Ensure we have enough data for the 10-byte image descriptor + 1-byte gif trailer - */ - if (gif_bytes < 12) { - return_value = GIF_INSUFFICIENT_FRAME_DATA; - goto gif_decode_frame_exit; - } - - /* 10-byte Image Descriptor is: - * - * +0 CHAR Image Separator (0x2c) - * +1 SHORT Image Left Position - * +3 SHORT Image Top Position - * +5 SHORT Width - * +7 SHORT Height - * +9 CHAR __Packed Fields__ - * 1BIT Local Colour Table Flag - * 1BIT Interlace Flag - * 1BIT Sort Flag - * 2BITS Reserved - * 3BITS Size of Local Colour Table - */ - if (gif_data[0] != GIF_IMAGE_SEPARATOR) { - return_value = GIF_DATA_ERROR; - goto gif_decode_frame_exit; - } - offset_x = gif_data[1] | (gif_data[2] << 8); - offset_y = gif_data[3] | (gif_data[4] << 8); - width = gif_data[5] | (gif_data[6] << 8); - height = gif_data[7] | (gif_data[8] << 8); - - /* Boundary checking - shouldn't ever happen except unless the data has been - modified since initialisation. - */ - if ((offset_x + width > gif->width) || (offset_y + height > gif->height)) { - return_value = GIF_DATA_ERROR; - goto gif_decode_frame_exit; - } - - /* Decode the flags - */ - flags = gif_data[9]; - colour_table_size = 2 << (flags & GIF_COLOUR_TABLE_SIZE_MASK); - interlace = flags & GIF_INTERLACE_MASK; - - /* Move our pointer to the colour table or image data (if no colour table is given) - */ - gif_data += 10; - gif_bytes = (gif_end - gif_data); - - /* Set up the colour table - */ - if (flags & GIF_COLOUR_TABLE_MASK) { - if (gif_bytes < (int)(3 * colour_table_size)) { - return_value = GIF_INSUFFICIENT_FRAME_DATA; - goto gif_decode_frame_exit; - } - colour_table = gif->local_colour_table; - if (!clear_image) { - for (index = 0; index < colour_table_size; index++) { - char colour[] = {0, 0, 0, (char)0xff}; - colour[0] = gif_data[0]; - colour[1] = gif_data[1]; - colour[2] = gif_data[2]; - colour_table[index] = *((int *) colour); - gif_data += 3; - } - } else { - gif_data += 3 * colour_table_size; - } - gif_bytes = (gif_end - gif_data); - } else { - colour_table = gif->global_colour_table; - } - - /* Check if we've finished - */ - if (gif_bytes < 1) { - return_value = GIF_INSUFFICIENT_FRAME_DATA; - goto gif_decode_frame_exit; - } else if (gif_data[0] == GIF_TRAILER) { - return_value = GIF_OK; - goto gif_decode_frame_exit; - } - - /* Get the frame data - */ - assert(gif->bitmap_callbacks.bitmap_get_buffer); - frame_data = (unsigned int *)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image); - if (!frame_data) - return GIF_INSUFFICIENT_MEMORY; - - /* If we are clearing the image we just clear, if not decode - */ - if (!clear_image) { - /* Ensure we have enough data for a 1-byte LZW code size + 1-byte gif trailer - */ - if (gif_bytes < 2) { - return_value = GIF_INSUFFICIENT_FRAME_DATA; - goto gif_decode_frame_exit; - /* If we only have a 1-byte LZW code size + 1-byte gif trailer, we're finished - */ - } else if ((gif_bytes == 2) && (gif_data[1] == GIF_TRAILER)) { - return_value = GIF_OK; - goto gif_decode_frame_exit; - } - - /* If the previous frame's disposal method requires we restore the background - * colour or this is the first frame, clear the frame data - */ - if ((frame == 0) || (gif->decoded_frame == GIF_INVALID_FRAME)) { - memset((char*)frame_data, GIF_TRANSPARENT_COLOUR, gif->width * gif->height * sizeof(int)); - gif->decoded_frame = frame; - /* The line below would fill the image with its background color, but because GIFs support - * transparency we likely wouldn't want to do that. */ - /* memset((char*)frame_data, colour_table[gif->background_index], gif->width * gif->height * sizeof(int)); */ - } else if ((frame != 0) && (gif->frames[frame - 1].disposal_method == GIF_FRAME_CLEAR)) { - clear_image = true; - if ((return_value = gif_decode_frame(gif, (frame - 1))) != GIF_OK) - goto gif_decode_frame_exit; - clear_image = false; - /* If the previous frame's disposal method requires we restore the previous - * image, find the last image set to "do not dispose" and get that frame data - */ - } else if ((frame != 0) && (gif->frames[frame - 1].disposal_method == GIF_FRAME_RESTORE)) { - while ((last_undisposed_frame != -1) && (gif->frames[--last_undisposed_frame].disposal_method == GIF_FRAME_RESTORE)); - /* If we don't find one, clear the frame data - */ - if (last_undisposed_frame == -1) { - /* see notes above on transparency vs. background color */ - memset((char*)frame_data, GIF_TRANSPARENT_COLOUR, gif->width * gif->height * sizeof(int)); - } else { - if ((return_value = gif_decode_frame(gif, last_undisposed_frame)) != GIF_OK) - goto gif_decode_frame_exit; - /* Get this frame's data - */ - assert(gif->bitmap_callbacks.bitmap_get_buffer); - frame_data = (unsigned int *)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image); - if (!frame_data) - return GIF_INSUFFICIENT_MEMORY; - } - } - gif->decoded_frame = frame; - - /* Initialise the LZW decoding - */ - set_code_size = gif_data[0]; - gif->buffer_position = (gif_data - gif->gif_data) + 1; - - /* Set our code variables - */ - code_size = set_code_size + 1; - clear_code = (1 << set_code_size); - end_code = clear_code + 1; - max_code_size = clear_code << 1; - max_code = clear_code + 2; - curbit = lastbit = 0; - last_byte = 2; - get_done = false; - direct = buf; - gif_init_LZW(gif); - - /* Decompress the data - */ - for (y = 0; y < height; y++) { - if (interlace) - decode_y = gif_interlaced_line(height, y) + offset_y; - else - decode_y = y + offset_y; - frame_scanline = frame_data + offset_x + (decode_y * gif->width); - - /* Rather than decoding pixel by pixel, we try to burst out streams - of data to remove the need for end-of data checks every pixel. - */ - x = width; - while (x > 0) { - burst_bytes = (stack_pointer - stack); - if (burst_bytes > 0) { - if (burst_bytes > x) - burst_bytes = x; - x -= burst_bytes; - while (burst_bytes-- > 0) { - colour = *--stack_pointer; - if (((gif->frames[frame].transparency) && - (colour != gif->frames[frame].transparency_index)) || - (!gif->frames[frame].transparency)) - *frame_scanline = colour_table[colour]; - frame_scanline++; - } - } else { - if (!gif_next_LZW(gif)) { - /* Unexpected end of frame, try to recover - */ - if (gif->current_error == GIF_END_OF_FRAME) - return_value = GIF_OK; - else - return_value = gif->current_error; - goto gif_decode_frame_exit; - } - } - } - } - } else { - /* Clear our frame - */ - if (gif->frames[frame].disposal_method == GIF_FRAME_CLEAR) { - for (y = 0; y < height; y++) { - frame_scanline = frame_data + offset_x + ((offset_y + y) * gif->width); - if (gif->frames[frame].transparency) - memset(frame_scanline, GIF_TRANSPARENT_COLOUR, width * 4); - else - memset(frame_scanline, colour_table[gif->background_index], width * 4); - } - } - } -gif_decode_frame_exit: - - /* Check if we should test for optimisation - */ - if (gif->frames[frame].virgin) { - if (gif->bitmap_callbacks.bitmap_test_opaque) - gif->frames[frame].opaque = gif->bitmap_callbacks.bitmap_test_opaque(gif->frame_image); - else - gif->frames[frame].opaque = false; - gif->frames[frame].virgin = false; - } - if (gif->bitmap_callbacks.bitmap_set_opaque) - gif->bitmap_callbacks.bitmap_set_opaque(gif->frame_image, gif->frames[frame].opaque); - if (gif->bitmap_callbacks.bitmap_modified) - gif->bitmap_callbacks.bitmap_modified(gif->frame_image); - - /* Restore the buffer position - */ - gif->buffer_position = save_buffer_position; - - /* Success! - */ - return return_value; - -} - -/** Skips the frame's extensions (which have been previously initialised) - - @return GIF_INSUFFICIENT_FRAME_DATA for insufficient data to complete the frame - GIF_OK for successful decoding -*/ -static gif_result gif_skip_frame_extensions(gif_animation *gif) { - unsigned char *gif_data, *gif_end; - int gif_bytes; - unsigned int block_size; - - /* Get our buffer position etc. - */ - gif_data = (unsigned char *)(gif->gif_data + gif->buffer_position); - gif_end = (unsigned char *)(gif->gif_data + gif->buffer_size); - gif_bytes = (gif_end - gif_data); - - /* Skip the extensions - */ - while (gif_data[0] == GIF_EXTENSION_INTRODUCER) { - ++gif_data; - - /* Switch on extension label - */ - switch(gif_data[0]) { - /* Move the pointer to the first data sub-block - * 1 byte for the extension label - */ - case GIF_EXTENSION_COMMENT: - ++gif_data; - break; - - /* Move the pointer to the first data sub-block - * 2 bytes for the extension label and size fields - * Skip the extension size itself - */ - default: - gif_data += (2 + gif_data[1]); - } - - /* Repeatedly skip blocks until we get a zero block or run out of data - * This data is ignored by this gif decoder - */ - gif_bytes = (gif_end - gif_data); - block_size = 0; - while (gif_data[0] != GIF_BLOCK_TERMINATOR) { - block_size = gif_data[0] + 1; - if ((gif_bytes -= block_size) < 0) - return GIF_INSUFFICIENT_FRAME_DATA; - gif_data += block_size; - } - ++gif_data; - } - - /* Set buffer position and return - */ - gif->buffer_position = (gif_data - gif->gif_data); - return GIF_OK; -} - -static unsigned int gif_interlaced_line(int height, int y) { - if ((y << 3) < height) return (y << 3); - y -= ((height + 7) >> 3); - if ((y << 3) < (height - 4)) return (y << 3) + 4; - y -= ((height + 3) >> 3); - if ((y << 2) < (height - 2)) return (y << 2) + 2; - y -= ((height + 1) >> 2); - return (y << 1) + 1; -} - -/* Releases any workspace held by the animation -*/ -void gif_finalise(gif_animation *gif) { - /* Release all our memory blocks - */ - if (gif->frame_image) { - assert(gif->bitmap_callbacks.bitmap_destroy); - gif->bitmap_callbacks.bitmap_destroy(gif->frame_image); - } - gif->frame_image = NULL; - free(gif->frames); - gif->frames = NULL; - free(gif->local_colour_table); - gif->local_colour_table = NULL; - free(gif->global_colour_table); - gif->global_colour_table = NULL; -} - -/** - * Initialise LZW decoding - */ -void gif_init_LZW(gif_animation *gif) { - int i; - - gif->current_error = 0; - if (clear_code >= (1 << GIF_MAX_LZW)) { - stack_pointer = stack; - gif->current_error = GIF_FRAME_DATA_ERROR; - return; - } - - /* initialise our table */ - memset(table, 0x00, (1 << GIF_MAX_LZW) * 8); - for (i = 0; i < clear_code; ++i) - table[1][i] = i; - - /* update our LZW parameters */ - code_size = set_code_size + 1; - max_code_size = clear_code << 1; - max_code = clear_code + 2; - stack_pointer = stack; - do { - firstcode = oldcode = gif_next_code(gif, code_size); - } while (firstcode == clear_code); - *stack_pointer++ =firstcode; -} - - -static bool gif_next_LZW(gif_animation *gif) { - int code, incode; - int block_size; - int new_code; - - code = gif_next_code(gif, code_size); - if (code < 0) { - gif->current_error = code; - return false; - } else if (code == clear_code) { - gif_init_LZW(gif); - return true; - } else if (code == end_code) { - /* skip to the end of our data so multi-image GIFs work */ - if (zero_data_block) { - gif->current_error = GIF_FRAME_DATA_ERROR; - return false; - } - block_size = 0; - while (block_size != 1) { - block_size = gif->gif_data[gif->buffer_position] + 1; - gif->buffer_position += block_size; - } - gif->current_error = GIF_FRAME_DATA_ERROR; - return false; - } - - incode = code; - if (code >= max_code) { - *stack_pointer++ = firstcode; - code = oldcode; - } - - /* The following loop is the most important in the GIF decoding cycle as every - * single pixel passes through it. - * - * Note: our stack is always big enough to hold a complete decompressed chunk. */ - while (code >= clear_code) { - *stack_pointer++ = table[1][code]; - new_code = table[0][code]; - if (new_code < clear_code) { - code = new_code; - break; - } - *stack_pointer++ = table[1][new_code]; - code = table[0][new_code]; - if (code == new_code) { - gif->current_error = GIF_FRAME_DATA_ERROR; - return false; - } - } - - *stack_pointer++ = firstcode = table[1][code]; - - if ((code = max_code) < (1 << GIF_MAX_LZW)) { - table[0][code] = oldcode; - table[1][code] = firstcode; - ++max_code; - if ((max_code >= max_code_size) && (max_code_size < (1 << GIF_MAX_LZW))) { - max_code_size = max_code_size << 1; - ++code_size; - } - } - oldcode = incode; - return true; -} - -static int gif_next_code(gif_animation *gif, int code_size) { - int i, j, end, count, ret; - unsigned char *b; - - end = curbit + code_size; - if (end >= lastbit) { - if (get_done) - return GIF_END_OF_FRAME; - buf[0] = direct[last_byte - 2]; - buf[1] = direct[last_byte - 1]; - - /* get the next block */ - direct = gif->gif_data + gif->buffer_position; - zero_data_block = ((count = direct[0]) == 0); - if ((gif->buffer_position + count) >= gif->buffer_size) - return GIF_INSUFFICIENT_FRAME_DATA; - if (count == 0) - get_done = true; - else { - direct -= 1; - buf[2] = direct[2]; - buf[3] = direct[3]; - } - gif->buffer_position += count + 1; - - /* update our variables */ - last_byte = 2 + count; - curbit = (curbit - lastbit) + 16; - lastbit = (2 + count) << 3; - end = curbit + code_size; - } - - i = curbit >> 3; - if (i < 2) - b = buf; - else - b = direct; - - ret = b[i]; - j = (end >> 3) - 1; - if (i <= j) { - ret |= (b[i + 1] << 8); - if (i < j) - ret |= (b[i + 2] << 16); - } - ret = (ret >> (curbit % 8)) & maskTbl[code_size]; - curbit += code_size; - return ret; -} |