diff options
Diffstat (limited to 'src/libnsgif.c')
| -rw-r--r-- | src/libnsgif.c | 19 |
1 files changed, 9 insertions, 10 deletions
diff --git a/src/libnsgif.c b/src/libnsgif.c index ed394a2..3b070b3 100644 --- a/src/libnsgif.c +++ b/src/libnsgif.c @@ -637,17 +637,19 @@ gif__decode(gif_animation *gif, { const uint8_t *stack_base; const uint8_t *stack_pos; + uint32_t written = 0; gif_result ret = GIF_OK; lzw_result res; /* Initialise the LZW decoding */ res = lzw_decode_init(gif->lzw_ctx, gif->gif_data, gif->buffer_size, gif->buffer_position, - minimum_code_size, &stack_base, &stack_pos); + minimum_code_size, &stack_base); if (res != LZW_OK) { return gif_error_from_lzw(res); } + stack_pos = stack_base; for (unsigned int y = 0; y < height; y++) { unsigned int x; unsigned int decode_y; @@ -660,21 +662,18 @@ gif__decode(gif_animation *gif, } 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) { - unsigned int burst_bytes = (stack_pos - stack_base); - if (burst_bytes > 0) { + if (written > 0) { + unsigned burst_bytes = written; if (burst_bytes > x) { burst_bytes = x; } x -= burst_bytes; + written -= burst_bytes; while (burst_bytes-- > 0) { register unsigned char colour; - colour = *--stack_pos; + colour = *stack_pos++; if (((gif->frames[frame].transparency) && (colour != gif->frames[frame].transparency_index)) || (!gif->frames[frame].transparency)) { @@ -683,7 +682,7 @@ gif__decode(gif_animation *gif, frame_scanline++; } } else { - res = lzw_decode(gif->lzw_ctx, &stack_pos); + res = lzw_decode(gif->lzw_ctx, &written); if (res != LZW_OK) { /* Unexpected end of frame, try to recover */ if (res == LZW_OK_EOD) { @@ -693,10 +692,10 @@ gif__decode(gif_animation *gif, } break; } + stack_pos = stack_base; } } } - return ret; } |