diff options
Diffstat (limited to 'image/gifread.c')
| -rw-r--r-- | image/gifread.c | 1004 |
1 files changed, 0 insertions, 1004 deletions
diff --git a/image/gifread.c b/image/gifread.c deleted file mode 100644 index 30fd19e0f..000000000 --- a/image/gifread.c +++ /dev/null @@ -1,1004 +0,0 @@ -/* - * Copyright 2004 Richard Wilson <not_ginger_matt@users.sourceforge.net> - * - * This file is part of NetSurf, http://www.netsurf-browser.org/ - * - * NetSurf is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; version 2 of the License. - * - * NetSurf is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program. If not, see <http://www.gnu.org/licenses/>. - */ - -#include <stdbool.h> -#include <stdio.h> -#include <string.h> -#include <stdlib.h> -#include "gifread.h" -#include "image/bitmap.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 - 'background_action' 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. - - [rjw] - Fri 2nd April 2004 -*/ - - - -/* Internal GIF routines -*/ -static int gif_initialise_sprite(struct gif_animation *gif, unsigned int width, unsigned int height); -static int gif_initialise_frame(struct gif_animation *gif); -static unsigned int gif_interlaced_line(int height, int y); - - - -/* Internal LZW routines -*/ -static void gif_init_LZW(struct gif_animation *gif); -static bool gif_next_LZW(struct gif_animation *gif); -static int gif_next_code(struct 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 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 - 0 for successful decoding - 1 for successful decoding (all frames completely read) -*/ -int gif_initialise(struct gif_animation *gif) { - unsigned char *gif_data; - unsigned int index; - int return_value; - - /* Check for sufficient data to be a GIF - */ - 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 = -1; - - /* Check we are a GIF - */ - if (strncmp((const char *) gif_data, "GIF", 3) != 0) - return GIF_DATA_ERROR; - gif_data += 3; - - /* Check we are a GIF type 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; - - /* Get our GIF data. - */ - gif->width = gif_data[0] | (gif_data[1] << 8); - gif->height = gif_data[2] | (gif_data[3] << 8); - gif->global_colours = (gif_data[4] & 0x80); - gif->colour_table_size = (2 << (gif_data[4] & 0x07)); - gif->background_colour = gif_data[5]; - gif->aspect_ratio = gif_data[6]; - gif->dirty_frame = -1; - 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] = 0xaa000000; - - /* Initialise enough workspace for 4 frame 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 - */ - if ((gif->frame_image = bitmap_create(gif->width, gif->height, BITMAP_NEW)) == 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] == 0xaa000000) { - /* 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[] = {gif_data[0], gif_data[1], gif_data[2], 0xff}; - 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 decode frames - */ - while ((return_value = gif_initialise_frame(gif)) == 0); - - /* 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 -3 for a memory error - 0 for success -*/ -static int gif_initialise_sprite(struct 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 0; - - /* Get our maximum values - */ - max_width = (width > gif->width) ? width : gif->width; - max_height = (height > gif->height) ? height : gif->height; - - /* Allocate some more memory - */ - if ((buffer = bitmap_create(max_width, max_height, BITMAP_NEW)) == NULL) - return GIF_INSUFFICIENT_MEMORY; - 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 = -1; - return 0; -} - - -/* Attempts to initialise the next frame - - @return -4 for insufficient data to process the entire frame - -3 for a memory error - -2 for a data error - -1 for insufficient data to process anything - 0 for success - 1 for success (GIF terminator found) -*/ -int gif_initialise_frame(struct gif_animation *gif) { - int frame; - gif_frame *temp_buf; - - unsigned char *gif_data, *gif_end; - int gif_bytes; - unsigned int flags = 0; - unsigned int background_action; - unsigned int width, height, offset_x, offset_y; - unsigned int extension_size, colour_table_size; - unsigned int block_size; - bool more_images = true; - bool first_image = true; - - /* 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 we have enough data for at least the header, or if we've finished - */ - if ((gif_bytes > 0) && (gif_data[0] == 0x3b)) return 1; - if (gif_bytes < 11) return -1; - - /* 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_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].virgin = true; - 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 = -1; - - /* 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. - */ - while (more_images) { - - /* Ensure we have some data - */ - if ((gif_end - gif_data) < 10) - return GIF_INSUFFICIENT_FRAME_DATA; - - /* Decode the extensions - */ - background_action = 0; - while (gif_data[0] == 0x21) { - /* Get the extension size - */ - extension_size = gif_data[2]; - - /* Check we've enough data for the extension then header - */ - if ((gif_end - gif_data) < (int)(extension_size + 13)) - return GIF_INSUFFICIENT_FRAME_DATA; - - /* Graphic control extension - store the frame delay. - */ - if (gif_data[1] == 0xf9) { - gif->frames[frame].frame_delay = gif_data[4] | (gif_data[5] << 8); - background_action = ((gif_data[3] & 0x1c) >> 2); - more_images = false; - - /* Application extension - handle NETSCAPE2.0 looping - */ - } else if ((gif_data[1] == 0xff) && - (gif_data[2] == 0x0b) && - (strncmp((const char *) gif_data + 3, - "NETSCAPE2.0", 11) == 0) && - (gif_data[14] == 0x03) && - (gif_data[15] == 0x01)) { - gif->loop_count = gif_data[16] | (gif_data[17] << 8); - } - - /* Move to the first sub-block - */ - gif_data += 2; - - /* Skip all the sub-blocks - */ - while (gif_data[0] != 0x00) { - gif_data += gif_data[0] + 1; - if ((gif_end - gif_data) < 10) return GIF_INSUFFICIENT_FRAME_DATA; - } - gif_data++; - } - - /* We must have at least one image descriptor - */ - if (gif_data[0] != 0x2c) 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 = ((background_action == 2) || (background_action == 3)); - - /* 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 & 0x07); - - /* 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 & 0x80) { - 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 data onwards - */ - 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 - */ - block_size = 0; - while (block_size != 1) { - /* Skip the block data - */ - block_size = gif_data[0] + 1; - if ((gif_bytes -= block_size) < 0) - return GIF_INSUFFICIENT_FRAME_DATA; - gif_data += block_size; - } - - /* Check for end of data - */ - more_images &= !((gif_bytes < 1) || (gif_data[0] == 0x3b)); - } - - /* Check if we've finished - */ - if (gif_bytes < 1) - return GIF_INSUFFICIENT_FRAME_DATA; - else { - gif->buffer_position = gif_data - gif->gif_data; - gif->frame_count = frame + 1; - if (gif_data[0] == 0x3b) return 1; - } - return 0; -} - - -/** 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 - 0 for successful decoding -*/ -int gif_decode_frame(struct gif_animation *gif, unsigned int frame) { - unsigned int index = 0; - unsigned char *gif_data; - unsigned char *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 extension_size; - unsigned int background_action; - int transparency_index = -1; - unsigned int save_buffer_position; - unsigned int return_value = 0; - unsigned int x, y, decode_y, burst_bytes; - unsigned int block_size; - register int colour; - bool more_images = true; - - /* 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 0; - - /* If the previous frame was dirty, remove it - */ - if (!clear_image) { - if (frame == 0) - gif->dirty_frame = -1; - if (gif->decoded_frame == gif->dirty_frame) { - clear_image = true; - if (frame != 0) - gif_decode_frame(gif, gif->dirty_frame); - clear_image = false; - } - gif->dirty_frame = -1; - } - - /* 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 we have enough data for the header - */ - if (gif_bytes < 9) - return GIF_INSUFFICIENT_DATA; - - /* Clear the previous frame totally. We can't just pretend we've got a smaller - sprite and clear what we need as some frames have multiple images which would - produce errors. - */ - frame_data = (unsigned int *)bitmap_get_buffer(gif->frame_image); - if (!frame_data) - return GIF_INSUFFICIENT_MEMORY; - if (!clear_image) { - if ((frame == 0) || (gif->decoded_frame == -1)) - memset((char*)frame_data, 0x00, gif->width * gif->height * sizeof(int)); - gif->decoded_frame = frame; - } - - /* Save the buffer position - */ - save_buffer_position = gif->buffer_position; - gif->buffer_position = gif_data - gif->gif_data; - - /* We've got to do this more than one time if we've got multiple images - */ - while (more_images) { - background_action = 0; - - /* Ensure we have some data - */ - gif_data = gif->gif_data + gif->buffer_position; - if ((gif_end - gif_data) < 10) { - return_value = GIF_INSUFFICIENT_FRAME_DATA; - break; - } - - /* Decode the extensions - */ - while (gif_data[0] == 0x21) { - - /* Get the extension size - */ - extension_size = gif_data[2]; - - /* Check we've enough data for the extension then header - */ - if ((gif_end - gif_data) < (int)(extension_size + 13)) { - return_value = GIF_INSUFFICIENT_FRAME_DATA; - break; - } - - /* Graphic control extension - store the frame delay. - */ - if (gif_data[1] == 0xf9) { - flags = gif_data[3]; - if (flags & 0x01) transparency_index = gif_data[6]; - background_action = ((flags & 0x1c) >> 2); - more_images = false; - } - /* Move to the first sub-block - */ - gif_data += 2; - - /* Skip all the sub-blocks - */ - while (gif_data[0] != 0x00) { - gif_data += gif_data[0] + 1; - if ((gif_end - gif_data) < 10) { - return_value = GIF_INSUFFICIENT_FRAME_DATA; - break; - } - } - gif_data++; - } - - /* Decode the header - */ - if (gif_data[0] != 0x2c) { - return_value = GIF_DATA_ERROR; - break; - } - 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; - break; - } - - /* Decode the flags - */ - flags = gif_data[9]; - colour_table_size = 2 << (flags & 0x07); - interlace = flags & 0x40; - - /* Move through our data - */ - gif_data += 10; - gif_bytes = (int)(gif_end - gif_data); - - /* Set up the colour table - */ - if (flags & 0x80) { - if (gif_bytes < (int)(3 * colour_table_size)) { - return_value = GIF_INSUFFICIENT_FRAME_DATA; - break; - } - colour_table = gif->local_colour_table; - if (!clear_image) { - for (index = 0; index < colour_table_size; index++) { - char colour[] = {gif_data[0], gif_data[1], - gif_data[2], 0xff}; - colour_table[index] = *((int *) colour); - gif_data += 3; - } - } else { - gif_data += 3 * colour_table_size; - } - gif_bytes = (int)(gif_end - gif_data); - } else { - colour_table = gif->global_colour_table; - } - - /* If we are clearing the image we just clear, if not decode - */ - if (!clear_image) { - /* Set our dirty status - */ - if ((background_action == 2) || (background_action == 3)) - gif->dirty_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) { - if ((colour = *--stack_pointer) != transparency_index) - *frame_scanline = colour_table[colour]; - frame_scanline++; - } - } else { - if (!gif_next_LZW(gif)) { - return_value = gif->current_error; - goto gif_decode_frame_exit; - } - } - } - } - } else { - /* Clear our frame - */ - if ((background_action == 2) || (background_action == 3)) { - for (y = 0; y < height; y++) { - frame_scanline = frame_data + offset_x + ((offset_y + y) * gif->width); - memset(frame_scanline, 0x00, width * 4); - } - } - - /* Repeatedly skip blocks until we get a zero block or run out of data - */ - gif_bytes = gif->buffer_size - gif->buffer_position; - gif_data = gif->gif_data + gif->buffer_size; - block_size = 0; - while (block_size != 1) { - /* Skip the block data - */ - block_size = gif_data[0] + 1; - if ((gif_bytes -= block_size) < 0) { - return_value = GIF_INSUFFICIENT_FRAME_DATA; - goto gif_decode_frame_exit; - } - gif_data += block_size; - } - } -gif_decode_frame_exit: - - /* Check for end of data - */ - gif_bytes = gif->buffer_size - gif->buffer_position; - more_images &= !((gif_bytes < 1) || (gif_data[0] == 0x3b)); - gif->buffer_position++; - } - - /* Check if we should test for optimisation - */ - if (gif->frames[frame].virgin) { - gif->frames[frame].opaque = bitmap_test_opaque(gif->frame_image); - gif->frames[frame].virgin = false; - } - bitmap_set_opaque(gif->frame_image, gif->frames[frame].opaque); - bitmap_modified(gif->frame_image); - - /* Restore the buffer position - */ - gif->buffer_position = save_buffer_position; - - /* Success! - */ - return return_value; - -} - -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(struct gif_animation *gif) { - /* Release all our memory blocks - */ - if (gif->frame_image) - 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(struct 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(struct 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(struct 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_INSUFFICIENT_FRAME_DATA; - 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; -} |