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Diffstat (limited to 'src/libnsgif.c')
| -rw-r--r-- | src/libnsgif.c | 1228 |
1 files changed, 0 insertions, 1228 deletions
diff --git a/src/libnsgif.c b/src/libnsgif.c deleted file mode 100644 index 95bbbfb..0000000 --- a/src/libnsgif.c +++ /dev/null @@ -1,1228 +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 <stdint.h> -#include <stdio.h> -#include <string.h> -#include <stdlib.h> -#include <assert.h> -#include "libnsgif.h" -#include "utils/log.h" - -#include "lzw.h" - -/** - * - * \file - * \brief GIF image decoder - * - * The GIF format is thoroughly documented; a full description can be found at - * http://www.w3.org/Graphics/GIF/spec-gif89a.txt - * - * \todo Plain text and comment extensions should be implemented. - */ - - -/** 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 - -/** 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 - -/** standard GIF header size */ -#define GIF_STANDARD_HEADER_SIZE 13 - - -/** - * Updates the sprite memory size - * - * \param gif The animation context - * \param width The width of the sprite - * \param height The height of the sprite - * \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); - buffer = gif->bitmap_callbacks.bitmap_create(max_width, max_height); - if (buffer == 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 frame's extensions - * - * \param gif The animation context - * \param frame The frame number - * @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 < gif_end && gif_data[0] == GIF_EXTENSION_INTRODUCER) { - ++gif_data; - if ((gif_bytes = (gif_end - gif_data)) < 1) { - return GIF_INSUFFICIENT_FRAME_DATA; - } - - /* Switch on extension label */ - switch (gif_data[0]) { - case GIF_EXTENSION_GRAPHIC_CONTROL: - /* 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 - */ - 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; - - case GIF_EXTENSION_APPLICATION: - /* 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) - */ - 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; - - case GIF_EXTENSION_COMMENT: - /* Move the pointer to the first data sub-block Skip 1 - * byte for the extension label - */ - ++gif_data; - break; - - default: - /* Move the pointer to the first data sub-block Skip 2 - * bytes for the extension label and size fields Skip - * the extension size itself - */ - if (gif_bytes < 2) { - return GIF_INSUFFICIENT_FRAME_DATA; - } - 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 < gif_end && 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; -} - - -/** - * Attempts to initialise the next frame - * - * \param gif The animation context - * \return error code - * - 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 there is enough data remaining. 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 */ - temp_buf = (gif_frame *)realloc(gif->frames, (frame + 1) * sizeof(gif_frame)); - if (temp_buf == 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; - return_value = gif_initialise_frame_extensions(gif, frame); - if (return_value != 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; - } - - 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 */ - if (gif_bytes < 10) { - return GIF_INSUFFICIENT_FRAME_DATA; - } - 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_bytes < 1) { - return GIF_INSUFFICIENT_FRAME_DATA; - } - if (gif_data[0] > LZW_CODE_MAX) { - return GIF_DATA_ERROR; - } - - /* Move our pointer to the actual image data */ - gif_data++; - --gif_bytes; - - /* 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) { - if (gif_bytes < 1) return GIF_INSUFFICIENT_FRAME_DATA; - 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; -} - - - - -/** - * Skips the frame's extensions (which have been previously initialised) - * - * \param gif The animation context - * \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 < gif_end && gif_data[0] == GIF_EXTENSION_INTRODUCER) { - ++gif_data; - if (gif_data >= gif_end) { - return GIF_INSUFFICIENT_FRAME_DATA; - } - - /* Switch on extension label */ - switch(gif_data[0]) { - case GIF_EXTENSION_COMMENT: - /* Move the pointer to the first data sub-block - * 1 byte for the extension label - */ - ++gif_data; - break; - - default: - /* Move the pointer to the first data sub-block 2 bytes - * for the extension label and size fields Skip the - * extension size itself - */ - if (gif_data + 1 >= gif_end) { - return GIF_INSUFFICIENT_FRAME_DATA; - } - 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 < gif_end && 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; -} - - -static gif_result gif_error_from_lzw(lzw_result l_res) -{ - static const gif_result g_res[] = { - [LZW_OK] = GIF_OK, - [LZW_OK_EOD] = GIF_END_OF_FRAME, - [LZW_NO_MEM] = GIF_INSUFFICIENT_MEMORY, - [LZW_NO_DATA] = GIF_INSUFFICIENT_FRAME_DATA, - [LZW_EOI_CODE] = GIF_FRAME_DATA_ERROR, - [LZW_BAD_ICODE] = GIF_FRAME_DATA_ERROR, - [LZW_BAD_CODE] = GIF_FRAME_DATA_ERROR, - }; - return g_res[l_res]; -} - -static void gif__record_previous_frame(gif_animation *gif) -{ - bool need_alloc = gif->prev_frame == NULL; - const uint32_t *frame_data; - uint32_t *prev_frame; - - if (gif->decoded_frame == GIF_INVALID_FRAME || - gif->decoded_frame == gif->prev_index) { - /* No frame to copy, or already have this frame recorded. */ - return; - } - - assert(gif->bitmap_callbacks.bitmap_get_buffer); - frame_data = (void *)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image); - if (!frame_data) { - return; - } - - if (gif->prev_frame != NULL && - gif->width * gif->height < gif->prev_width * gif->prev_height) { - need_alloc = true; - } - - if (need_alloc) { - prev_frame = realloc(gif->prev_frame, - gif->width * gif->height * 4); - if (prev_frame == NULL) { - return; - } - } else { - prev_frame = gif->prev_frame; - } - - memcpy(prev_frame, frame_data, gif->width * gif->height * 4); - - gif->prev_frame = prev_frame; - gif->prev_width = gif->width; - gif->prev_height = gif->height; - gif->prev_index = gif->decoded_frame; -} - -static gif_result gif__recover_previous_frame(const gif_animation *gif) -{ - const uint32_t *prev_frame = gif->prev_frame; - unsigned height = gif->height < gif->prev_height ? gif->height : gif->prev_height; - unsigned width = gif->width < gif->prev_width ? gif->width : gif->prev_width; - uint32_t *frame_data; - - if (prev_frame == NULL) { - return GIF_FRAME_DATA_ERROR; - } - - assert(gif->bitmap_callbacks.bitmap_get_buffer); - frame_data = (void *)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image); - if (!frame_data) { - return GIF_INSUFFICIENT_MEMORY; - } - - for (unsigned y = 0; y < height; y++) { - memcpy(frame_data, prev_frame, width * 4); - - frame_data += gif->width; - prev_frame += gif->prev_width; - } - - return GIF_OK; -} - -/** - * decode a gif frame - * - * \param gif gif animation context. - * \param frame The frame number to decode. - * \param clear_image flag for image data being cleared instead of plotted. - */ -static gif_result -gif_internal_decode_frame(gif_animation *gif, - unsigned int frame, - bool clear_image) -{ - gif_result err; - 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; - register unsigned char colour; - - /* Ensure this frame is supposed to be decoded */ - if (gif->frames[frame].display == false) { - return GIF_OK; - } - - /* Ensure the frame is in range to decode */ - if (frame > gif->frame_count_partial) { - return GIF_INSUFFICIENT_DATA; - } - - /* done if frame is already decoded */ - if ((!clear_image) && - ((int)frame == gif->decoded_frame)) { - return GIF_OK; - } - - if (gif->frames[frame].disposal_method == GIF_FRAME_RESTORE) { - /* Store the previous frame for later restoration */ - gif__record_previous_frame(gif); - } - - /* 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); - - /* - * Ensure there is a minimal amount of data to proceed. 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 they have allready been processed */ - 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; - - /* Advance data pointer to next block either colour table or image - * data. - */ - 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++) { - /* Gif colour map contents are r,g,b. - * - * We want to pack them bytewise into the - * colour table, such that the red component - * is in byte 0 and the alpha component is in - * byte 3. - */ - unsigned char *entry = - (unsigned char *) &colour_table[index]; - - entry[0] = gif_data[0]; /* r */ - entry[1] = gif_data[1]; /* g */ - entry[2] = gif_data[2]; /* b */ - entry[3] = 0xff; /* a */ - - gif_data += 3; - } - } else { - gif_data += 3 * colour_table_size; - } - gif_bytes = (gif_end - gif_data); - } else { - colour_table = gif->global_colour_table; - } - - /* Ensure sufficient data remains */ - if (gif_bytes < 1) { - return_value = GIF_INSUFFICIENT_FRAME_DATA; - goto gif_decode_frame_exit; - } - - /* check for an end marker */ - 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 = (void *)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) { - lzw_result res; - const uint8_t *stack_base; - const uint8_t *stack_pos; - - /* 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 - */ - 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)) { - return_value = gif_internal_decode_frame(gif, - (frame - 1), - true); - if (return_value != GIF_OK) { - goto gif_decode_frame_exit; - } - - } else if ((frame != 0) && - (gif->frames[frame - 1].disposal_method == GIF_FRAME_RESTORE)) { - /* - * If the previous frame's disposal method requires we - * restore the previous image, restore our saved image. - */ - err = gif__recover_previous_frame(gif); - if (err != GIF_OK) { - /* see notes above on transparency - * vs. background color - */ - memset((char*)frame_data, - GIF_TRANSPARENT_COLOUR, - gif->width * gif->height * sizeof(int)); - } - } - gif->decoded_frame = frame; - gif->buffer_position = (gif_data - gif->gif_data) + 1; - - /* Initialise the LZW decoding */ - res = lzw_decode_init(gif->lzw_ctx, gif->gif_data, - gif->buffer_size, gif->buffer_position, - gif_data[0], &stack_base, &stack_pos); - if (res != LZW_OK) { - return gif_error_from_lzw(res); - } - - /* 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_pos - stack_base); - if (burst_bytes > 0) { - if (burst_bytes > x) { - burst_bytes = x; - } - x -= burst_bytes; - while (burst_bytes-- > 0) { - colour = *--stack_pos; - if (((gif->frames[frame].transparency) && - (colour != gif->frames[frame].transparency_index)) || - (!gif->frames[frame].transparency)) { - *frame_scanline = colour_table[colour]; - } - frame_scanline++; - } - } else { - res = lzw_decode(gif->lzw_ctx, &stack_pos); - if (res != LZW_OK) { - /* Unexpected end of frame, try to recover */ - if (res == LZW_OK_EOD) { - return_value = GIF_OK; - } else { - return_value = gif_error_from_lzw(res); - } - 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; - - return return_value; -} - - -/* exported function documented in libnsgif.h */ -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; - gif->prev_index = GIF_INVALID_FRAME; -} - - -/* exported function documented in libnsgif.h */ -gif_result gif_initialise(gif_animation *gif, size_t size, unsigned char *data) -{ - unsigned char *gif_data; - unsigned int index; - gif_result return_value; - - /* Initialize values */ - gif->buffer_size = size; - gif->gif_data = data; - - if (gif->lzw_ctx == NULL) { - lzw_result res = lzw_context_create( - (struct lzw_ctx **)&gif->lzw_ctx); - if (res != LZW_OK) { - return gif_error_from_lzw(res); - } - } - - /* Check for sufficient data to be a GIF (6-byte header + 7-byte - * logical screen descriptor) - */ - if (gif->buffer_size < GIF_STANDARD_HEADER_SIZE) { - 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 = calloc(GIF_MAX_COLOURS, sizeof(unsigned int)); - gif->local_colour_table = calloc(GIF_MAX_COLOURS, sizeof(unsigned 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 == (GIF_STANDARD_HEADER_SIZE + 1)) { - if (gif_data[0] == GIF_TRAILER) { - return GIF_OK; - } else { - return GIF_INSUFFICIENT_DATA; - } - } - - /* Initialise enough workspace for a frame */ - if ((gif->frames = (gif_frame *)malloc(sizeof(gif_frame))) == NULL) { - gif_finalise(gif); - return GIF_INSUFFICIENT_MEMORY; - } - gif->frame_holders = 1; - - /* Initialise the bitmap header */ - assert(gif->bitmap_callbacks.bitmap_create); - gif->frame_image = gif->bitmap_callbacks.bitmap_create(gif->width, gif->height); - if (gif->frame_image == 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 + GIF_STANDARD_HEADER_SIZE)) { - return GIF_INSUFFICIENT_DATA; - } - for (index = 0; index < gif->colour_table_size; index++) { - /* Gif colour map contents are r,g,b. - * - * We want to pack them bytewise into the - * colour table, such that the red component - * is in byte 0 and the alpha component is in - * byte 3. - */ - unsigned char *entry = (unsigned char *) &gif-> - global_colour_table[index]; - - entry[0] = gif_data[0]; /* r */ - entry[1] = gif_data[1]; /* g */ - entry[2] = gif_data[2]; /* b */ - entry[3] = 0xff; /* a */ - - 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 - */ - unsigned int *entry = gif->global_colour_table; - - entry[0] = 0x00000000; - /* Force Alpha channel to opaque */ - ((unsigned char *) entry)[3] = 0xff; - - entry[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; -} - - -/* exported function documented in libnsgif.h */ -gif_result gif_decode_frame(gif_animation *gif, unsigned int frame) -{ - return gif_internal_decode_frame(gif, frame, false); -} - - -/* exported function documented in libnsgif.h */ -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; - - free(gif->prev_frame); - gif->prev_frame = NULL; - - lzw_context_destroy(gif->lzw_ctx); - gif->lzw_ctx = NULL; -} |