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Diffstat (limited to 'riscos/gifread.c')
| -rw-r--r-- | riscos/gifread.c | 1038 |
1 files changed, 0 insertions, 1038 deletions
diff --git a/riscos/gifread.c b/riscos/gifread.c deleted file mode 100644 index 64038ea6e..000000000 --- a/riscos/gifread.c +++ /dev/null @@ -1,1038 +0,0 @@ -/* - * This file is part of NetSurf, http://netsurf.sourceforge.net/ - * Licensed under the GNU General Public License, - * http://www.opensource.org/licenses/gpl-license - * Copyright 2004 Richard Wilson <not_ginger_matt@sourceforge.net> - */ - - -#include <stdio.h> -#include <string.h> -#include <stdlib.h> -#include "gifread.h" -#include "netsurf/utils/log.h" -#include "oslib/osspriteop.h" -#include "oslib/osfile.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 int gif_next_LZW(struct gif_animation *gif); -static int gif_next_code(struct gif_animation *gif, int code_size); -#define gif_read_LZW(gif) ((stack_pointer > stack) ? *--stack_pointer : gif_next_LZW(gif)) - -/* 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[280]; -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 int stack[(1 << GIF_MAX_LZW) * 2]; -static int *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, get_done, last_byte; -static int return_clear; -static int zero_data_block = FALSE; - -/* Whether to clear the decoded image rather than plot -*/ -static int 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; - unsigned int frame; - osspriteop_header *header; - - /* 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 = 0xffffffff; - - /* Check we are a GIF - */ - if (strncmp(gif_data, "GIF", 3) != 0) { -// LOG(("Invalid GIF header - should be 'GIF'")); - 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->width == 480)) || - ((gif->width == 640) && (gif->width == 512)) || - ((gif->width == 800) && (gif->width == 600)) || - ((gif->width == 1280) && (gif->width == 1024))) { - gif->width = 0; - gif->height = 0; - } - - /* 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 = (osspriteop_area *)malloc(sizeof(osspriteop_area) + - sizeof(osspriteop_header) + (gif->width * gif->height * 4))) == NULL) { - gif_finalise(gif); - return GIF_INSUFFICIENT_MEMORY; - } - gif->frame_image->size = sizeof(osspriteop_area) + sizeof(osspriteop_header) + - (gif->width * gif->height * 4); - gif->frame_image->sprite_count = 1; - gif->frame_image->first = 16; - gif->frame_image->used = gif->frame_image->size; - header = (osspriteop_header*)((char*)gif->frame_image + - gif->frame_image->first); - header->size = sizeof(osspriteop_header) + (gif->width * gif->height * 4); - memset(header->name, 0x00, 12); - strcpy(header->name, "gif"); - header->left_bit = 0; - header->right_bit = 31; - header->width = gif->width - 1; - header->height = gif->height - 1; - header->image = sizeof(osspriteop_header); - header->mask = sizeof(osspriteop_header); - header->mode = (os_mode) 0x301680b5; - - /* 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; - } -// LOG(("Found global colour table with %i entries", gif->colour_table_size)); - for (index = 0; index < gif->colour_table_size; index++) { - gif->global_colour_table[index] = gif_data[0] | (gif_data[1] << 8) | - (gif_data[2] << 16) | 0xff000000; - gif_data += 3; - } - gif->buffer_position = (gif_data - gif->gif_data); - } else { -// LOG(("No global colour table")); - /* 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); - - /* Update the redraw areas now we know the full data set - */ - if (gif->frame_count_partial > 0) { - /* Set the redraw for the first frame to the maximum frame size - */ - gif->frames[0].redraw_x = 0; - gif->frames[0].redraw_y = 0; - gif->frames[0].redraw_width = gif->width; - gif->frames[0].redraw_height = gif->height; - - /* We now work backwards to update the redraw characteristics of frames - with clear codes to stop a snowball effect of the redraw areas. It doesn't - really make much difference for most images, and will not work as well - (ie will not optimise as well as for a single-pass call, but still works) - for multiple calls to this routine when decoding progressively. - */ - for (frame = gif->frame_count_partial - 1; frame > 0; frame--) { - if (gif->frames[frame].redraw_required) { - if (gif->frames[frame].redraw_x > gif->frames[frame - 1].redraw_x) { - gif->frames[frame].redraw_width += - (gif->frames[frame].redraw_x - gif->frames[frame - 1].redraw_x); - gif->frames[frame].redraw_x = gif->frames[frame - 1].redraw_x; - } - if (gif->frames[frame].redraw_y > gif->frames[frame - 1].redraw_y) { - gif->frames[frame].redraw_height += - (gif->frames[frame].redraw_y - gif->frames[frame - 1].redraw_y); - gif->frames[frame].redraw_y = gif->frames[frame - 1].redraw_y; - } - if ((gif->frames[frame - 1].redraw_x + gif->frames[frame - 1].redraw_width) > - (gif->frames[frame].redraw_x + gif->frames[frame].redraw_width)) { - gif->frames[frame].redraw_width = - (gif->frames[frame - 1].redraw_x + gif->frames[frame - 1].redraw_width) - - gif->frames[frame].redraw_x; - } - if ((gif->frames[frame - 1].redraw_y + gif->frames[frame - 1].redraw_height) > - (gif->frames[frame].redraw_y + gif->frames[frame].redraw_height)) { - gif->frames[frame].redraw_height = - (gif->frames[frame - 1].redraw_y + gif->frames[frame - 1].redraw_height) - - gif->frames[frame].redraw_y; - } - } - } - - } - - /* 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_value = 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) { - struct osspriteop_area *buffer; - struct osspriteop_header *header; - unsigned int max_width; - unsigned int max_height; - unsigned int frame_bytes; - - /* 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; - frame_bytes = max_width * max_height * 4 + - sizeof(osspriteop_header) + sizeof(osspriteop_area); - - /* Allocate some more memory - */ - if ((buffer = (osspriteop_area *)realloc(gif->frame_image, frame_bytes)) == NULL) { - return GIF_INSUFFICIENT_MEMORY; - } - gif->frame_image = buffer; - - /* Update the sizes - */ - gif->width = max_width; - gif->height = max_height; - - /* Update our sprite image - */ - buffer->size = frame_bytes; - buffer->used = frame_bytes; - header = (osspriteop_header*)((char*)gif->frame_image + - gif->frame_image->first); - header->size = frame_bytes - sizeof(osspriteop_area); - header->width = max_width - 1; - header->height = max_height - 1; - - /* Invalidate our currently decoded image - */ - gif->decoded_frame = 0xffffffff; - 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) { - unsigned 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; - unsigned int more_images; - unsigned int first_image; - - /* 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 (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; - - /* Remember we allocated it - */ - 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].frame_delay = 100; // Paranoia - gif->frames[frame].redraw_required = 0; // Paranoia - - /* Invalidate any previous decoding we have of this frame - */ - if (gif->decoded_frame == frame) gif->decoded_frame = 0xffffffff; - - /* 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. - */ - more_images = 1; - first_image = 1; - while (more_images != 0) { - - /* 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 = ((gif->frames[frame].frame_delay) == 0); - - /* Application extension - handle NETSCAPE2.0 looping - */ - } else if ((gif_data[1] == 0xff) && - (gif_data[2] == 0x0b) && - (strncmp(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 == 0) { - 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 = 0; - 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 - */ - if ((background_action == 2) || (background_action == 3)) { - gif->frames[frame].redraw_required = 1; - } - - /* 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 - */ - if ((gif_bytes < 1) || (gif_data[0] == 0x3b)) more_images = 0; - } - - /* 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; - unsigned int more_images; - - /* Ensure we have a frame to decode - */ - if (frame > gif->frame_count_partial) return GIF_INSUFFICIENT_DATA; - if ((!clear_image) && (frame == gif->decoded_frame)) return 0; - - /* If the previous frame was dirty, remove it - */ - if (!clear_image) { - 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*)((char *)gif->frame_image + gif->frame_image->first + sizeof(osspriteop_header)); - if (!clear_image) { - if ((frame == 0) || (gif->decoded_frame == 0xffffffff)) { - 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 - */ - more_images = 1; - while (more_images != 0) { - background_action = 0; - - /* Ensure we have some data - */ - gif_data = gif->gif_data + gif->buffer_position; - if ((gif_end - gif_data) < 10) return GIF_INSUFFICIENT_FRAME_DATA; - - /* 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 GIF_INSUFFICIENT_FRAME_DATA; - - /* 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 = ((gif_data[4] | (gif_data[5] << 8)) == 0); - } - /* 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++; - } - - /* Decode the header - */ - if (gif_data[0] != 0x2c) return GIF_DATA_ERROR; - 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 GIF_DATA_ERROR; - } - - /* 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 GIF_INSUFFICIENT_FRAME_DATA; - colour_table = gif->local_colour_table; - if (!clear_image) { - for (index = 0; index < colour_table_size; index++) { - colour_table[index] = gif_data[0] | (gif_data[1] << 8) | - (gif_data[2] << 16) | 0xff000000; - 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 = 0; - return_clear = 1; - stack_pointer = stack; - - /* 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) { - /* Do the first pixel to get the stack of some sort - */ - if ((colour = gif_read_LZW(gif)) >= 0) { - if (colour != transparency_index) { - *frame_scanline = colour_table[colour]; - } - frame_scanline++; - } else { - return_value = GIF_INSUFFICIENT_FRAME_DATA; - goto gif_decode_frame_exit; - } - - /* Try to burst some bytes out - */ - burst_bytes = (stack_pointer - stack); - 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 { - /* 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; - if ((gif_bytes < 1) || (gif_data[0] == 0x3b)) more_images = 0; - gif->buffer_position++; - } - - /* 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 - */ - free(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; -} - - -static int gif_next_LZW(struct gif_animation *gif) { - static int firstcode, oldcode; - int code, incode; - unsigned int i, block_size; - - while ((code = gif_next_code(gif, code_size)) >= 0) { - if (code == clear_code) { - /* Check we have a valid clear code - */ - if (clear_code >= (1 << GIF_MAX_LZW)) return -2; - - /* Initialise our table - */ - memset(table, 0x00, (1 << GIF_MAX_LZW) * 8); - for (i = 0; i < (unsigned int)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); - return firstcode; - } - - if (code == end_code) { - /* Skip to the end of our data so multi-image GIFs work - */ - if (zero_data_block) return -2; - block_size = 0; - while (block_size != 1) { - block_size = gif->gif_data[gif->buffer_position] + 1; - gif->buffer_position += block_size; - } - return -2; - } - - /* Fill the stack with some data - */ - incode = code; - - if (code >= max_code) { - *stack_pointer++ = firstcode; - code = oldcode; - } - - while (code >= clear_code) { - *stack_pointer++ = table[1][code]; - if (code == table[0][code]) return(code); - if (((char *)stack_pointer - (char *)stack) >= (int)sizeof(stack)) return(code); - code = table[0][code]; - } - - *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; - - if (stack_pointer > stack) return *--stack_pointer; - } - return code; -} - - -static int gif_next_code(struct gif_animation *gif, int code_size) { - int i, j, end, count; - long ret; - unsigned char *gif_data; - - if (return_clear) { - return_clear = 0; - return clear_code; - } - - end = curbit + code_size; - if (end >= lastbit) { - if (get_done) return -1; - buf[0] = buf[last_byte - 2]; - buf[1] = buf[last_byte - 1]; - - /* Get the next block - */ - gif_data = gif->gif_data + gif->buffer_position; - zero_data_block = ((count = gif_data[0]) == 0); - if ((gif->buffer_position + count) >= gif->buffer_size) return -1; - if (count == 0) { - get_done = 1; - } else { - memcpy(&buf[2], gif_data + 1, count); - } - gif->buffer_position += count + 1; - - /* Update our variables - */ - last_byte = 2 + count; - curbit = (curbit - lastbit) + 16; - lastbit = (2 + count) << 3; - end = curbit + code_size; - } - - j = end >> 3; - i = curbit >> 3; - if (i == j) { - ret = (long)buf[i]; - } else if (i + 1 == j) { - ret = (long)buf[i] | ((long)buf[i+1] << 8); - } else { - ret = (long)buf[i] | ((long)buf[i+1] << 8) | ((long)buf[i+2] << 16); - } - - ret = (ret >> (curbit % 8)) & maskTbl[code_size]; - curbit += code_size; - return (int)ret; -} |