From 87a3143fb4ca2111d77b27edda2b91ae493cc9a5 Mon Sep 17 00:00:00 2001 From: Chris Forseth <christopher.forseth@gmail.com> Date: Mon, 27 Nov 2017 22:41:51 -0600 Subject: [PATCH 1/4] GIF Loading - multiple frames; - Allow loading a gif as multiple frames into a single buffer. Each frame is a full image seperated by a (w * h * comp) stride. - Optionally, can pass in a pointer to a int, which will be filled with an array layers long contain ms for each frame. - Fix gif's not loading the initial transparent background - I believe also fix disposal rules for subsequent frames (though being somewhat inefficient with memory to do so) - Add a flip_vertical that takes into account slices as well. Compiled using VS2017, but nothing else as I'm not really setup for it. Apologies. --- stb_image.h | 290 ++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 214 insertions(+), 76 deletions(-) diff --git a/stb_image.h b/stb_image.h index a056138..aa25fb2 100644 --- a/stb_image.h +++ b/stb_image.h @@ -353,6 +353,10 @@ typedef struct STBIDEF stbi_uc *stbi_load_from_memory (stbi_uc const *buffer, int len , int *x, int *y, int *channels_in_file, int desired_channels); STBIDEF stbi_uc *stbi_load_from_callbacks(stbi_io_callbacks const *clbk , void *user, int *x, int *y, int *channels_in_file, int desired_channels); +#ifndef STBI_NO_GIF +STBIDEF stbi_uc *stbi_load_gif_from_memory(stbi_uc const *buffer, int len, int **delays, int *x, int *y, int *z, int *comp, int req_comp); +#endif + #ifndef STBI_NO_STDIO STBIDEF stbi_uc *stbi_load (char const *filename, int *x, int *y, int *channels_in_file, int desired_channels); @@ -819,6 +823,7 @@ static int stbi__pic_info(stbi__context *s, int *x, int *y, int *comp); #ifndef STBI_NO_GIF static int stbi__gif_test(stbi__context *s); static void *stbi__gif_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri); +static void *stbi__load_gif_main(stbi__context *s, int **delays, int *x, int *y, int *z, int *comp, int req_comp); static int stbi__gif_info(stbi__context *s, int *x, int *y, int *comp); #endif @@ -1054,6 +1059,18 @@ static void stbi__vertical_flip(void *image, int w, int h, int bytes_per_pixel) } } +static void stbi__vertical_flip_slices(void *image, int w, int h, int z, int bytes_per_pixel) +{ + int slice; + int slice_size = w * h * bytes_per_pixel; + + stbi_uc *bytes = (stbi_uc *)image; + for (slice = 0; slice < z; ++slice) { + stbi__vertical_flip(bytes, w, h, bytes_per_pixel); + bytes += slice_size; + } +} + static unsigned char *stbi__load_and_postprocess_8bit(stbi__context *s, int *x, int *y, int *comp, int req_comp) { stbi__result_info ri; @@ -1205,6 +1222,21 @@ STBIDEF stbi_uc *stbi_load_from_callbacks(stbi_io_callbacks const *clbk, void *u return stbi__load_and_postprocess_8bit(&s,x,y,comp,req_comp); } +#ifndef STBI_NO_GIF +STBIDEF stbi_uc *stbi_load_gif_from_memory(stbi_uc const *buffer, int len, int **delays, int *x, int *y, int *z, int *comp, int req_comp) +{ + stbi__context s; + stbi__start_mem(&s,buffer,len); + + unsigned char *result = (unsigned char*) stbi__load_gif_main(&s, delays, x, y, z, comp, req_comp); + if (stbi__vertically_flip_on_load) { + stbi__vertical_flip_slices( result, *x, *y, *z, *comp ); + } + + return result; +} +#endif + #ifndef STBI_NO_LINEAR static float *stbi__loadf_main(stbi__context *s, int *x, int *y, int *comp, int req_comp) { @@ -6038,11 +6070,13 @@ typedef struct typedef struct { int w,h; - stbi_uc *out, *old_out; // output buffer (always 4 components) - int flags, bgindex, ratio, transparent, eflags, delay; + stbi_uc *out; // output buffer (always 4 components) + stbi_uc *background; // The current "background" as far as a gif is concerned + stbi_uc *history; + int flags, bgindex, ratio, transparent, eflags; stbi_uc pal[256][4]; stbi_uc lpal[256][4]; - stbi__gif_lzw codes[4096]; + stbi__gif_lzw codes[8192]; stbi_uc *color_table; int parse, step; int lflags; @@ -6050,6 +6084,7 @@ typedef struct int max_x, max_y; int cur_x, cur_y; int line_size; + int delay; } stbi__gif; static int stbi__gif_test_raw(stbi__context *s) @@ -6125,6 +6160,7 @@ static int stbi__gif_info_raw(stbi__context *s, int *x, int *y, int *comp) static void stbi__out_gif_code(stbi__gif *g, stbi__uint16 code) { stbi_uc *p, *c; + int idx; // recurse to decode the prefixes, since the linked-list is backwards, // and working backwards through an interleaved image would be nasty @@ -6133,10 +6169,12 @@ static void stbi__out_gif_code(stbi__gif *g, stbi__uint16 code) if (g->cur_y >= g->max_y) return; - p = &g->out[g->cur_x + g->cur_y]; - c = &g->color_table[g->codes[code].suffix * 4]; + idx = g->cur_x + g->cur_y; + p = &g->out[idx]; + g->history[idx / 4] = 1; - if (c[3] >= 128) { + c = &g->color_table[g->codes[code].suffix * 4]; + if (c[3] > 128) { // don't render transparent pixels; p[0] = c[2]; p[1] = c[1]; p[2] = c[0]; @@ -6210,11 +6248,16 @@ static stbi_uc *stbi__process_gif_raster(stbi__context *s, stbi__gif *g) stbi__skip(s,len); return g->out; } else if (code <= avail) { - if (first) return stbi__errpuc("no clear code", "Corrupt GIF"); + if (first) { + return stbi__errpuc("no clear code", "Corrupt GIF"); + } if (oldcode >= 0) { p = &g->codes[avail++]; - if (avail > 4096) return stbi__errpuc("too many codes", "Corrupt GIF"); + if (avail > 8192) { + return stbi__errpuc("too many codes", "Corrupt GIF"); + } + p->prefix = (stbi__int16) oldcode; p->first = g->codes[oldcode].first; p->suffix = (code == avail) ? p->first : g->codes[code].first; @@ -6236,62 +6279,72 @@ static stbi_uc *stbi__process_gif_raster(stbi__context *s, stbi__gif *g) } } -static void stbi__fill_gif_background(stbi__gif *g, int x0, int y0, int x1, int y1) -{ - int x, y; - stbi_uc *c = g->pal[g->bgindex]; - for (y = y0; y < y1; y += 4 * g->w) { - for (x = x0; x < x1; x += 4) { - stbi_uc *p = &g->out[y + x]; - p[0] = c[2]; - p[1] = c[1]; - p[2] = c[0]; - p[3] = 0; - } - } -} - // this function is designed to support animated gifs, although stb_image doesn't support it -static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, int req_comp) +// two back is the image from two frames ago, used for a very specific disposal format +static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, int req_comp, stbi_uc *two_back) { - int i; - stbi_uc *prev_out = 0; + int dispose; + int first_frame; + int pi; + int pcount; - if (g->out == 0 && !stbi__gif_header(s, g, comp,0)) - return 0; // stbi__g_failure_reason set by stbi__gif_header + // on first frame, any non-written pixels get the background colour (non-transparent) + first_frame = 0; + if (g->out == 0) { + if (!stbi__gif_header(s, g, comp,0)) return 0; // stbi__g_failure_reason set by stbi__gif_header + g->out = (stbi_uc *) stbi__malloc(4 * g->w * g->h); + g->background = (stbi_uc *) stbi__malloc(4 * g->w * g->h); + g->history = (stbi_uc *) stbi__malloc(g->w * g->h); + if (g->out == 0) return stbi__errpuc("outofmem", "Out of memory"); - if (!stbi__mad3sizes_valid(g->w, g->h, 4, 0)) - return stbi__errpuc("too large", "GIF too large"); + // image is treated as "tranparent" at the start - ie, nothing overwrites the current background; + // background colour is only used for pixels that are not rendered first frame, after that "background" + // color refers to teh color that was there the previous frame. + memset( g->out, 0x00, 4 * g->w * g->h ); + memset( g->background, 0x00, 4 * g->w * g->h ); // state of the background (starts transparent) + memset( g->history, 0x00, g->w * g->h ); // pixels that were affected previous frame + first_frame = 1; + } else { + // second frame - how do we dispoase of the previous one? + dispose = (g->eflags & 0x1C) >> 2; + pcount = g->w * g->h; - prev_out = g->out; - g->out = (stbi_uc *) stbi__malloc_mad3(4, g->w, g->h, 0); - if (g->out == 0) return stbi__errpuc("outofmem", "Out of memory"); + if ((dispose == 4) && (two_back == 0)) { + dispose = 2; // if I don't have an image to revert back to, default to the old background + } - switch ((g->eflags & 0x1C) >> 2) { - case 0: // unspecified (also always used on 1st frame) - stbi__fill_gif_background(g, 0, 0, 4 * g->w, 4 * g->w * g->h); - break; - case 1: // do not dispose - if (prev_out) memcpy(g->out, prev_out, 4 * g->w * g->h); - g->old_out = prev_out; - break; - case 2: // dispose to background - if (prev_out) memcpy(g->out, prev_out, 4 * g->w * g->h); - stbi__fill_gif_background(g, g->start_x, g->start_y, g->max_x, g->max_y); - break; - case 3: // dispose to previous - if (g->old_out) { - for (i = g->start_y; i < g->max_y; i += 4 * g->w) - memcpy(&g->out[i + g->start_x], &g->old_out[i + g->start_x], g->max_x - g->start_x); + if (dispose == 4) { // use previous graphic + for (pi = 0; pi < pcount; ++pi) { + if (g->history[pi]) { + memcpy( &g->out[pi * 4], &two_back[pi * 4], 4 ); + } } - break; + } else if (dispose == 2) { + // restore what was changed last frame to background before that frame; + for (pi = 0; pi < pcount; ++pi) { + if (g->history[pi]) { + memcpy( &g->out[pi * 4], &g->background[pi * 4], 4 ); + } + } + } else { + // This is a non-disposal case eithe way, so just + // leave the pixels as is, and they will become the new background + // 1: do not dispose? Same as 4? + // 0: not specified. + } + + // background is what out is after the undoing of the previou frame; + memcpy( g->background, g->out, 4 * g->w * g->h ); } + // clear my history; + memset( g->history, 0x00, g->w * g->h ); // pixels that were affected previous frame + for (;;) { - switch (stbi__get8(s)) { + int tag = stbi__get8(s); + switch (tag) { case 0x2C: /* Image Descriptor */ { - int prev_trans = -1; stbi__int32 x, y, w, h; stbi_uc *o; @@ -6324,19 +6377,24 @@ static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, i stbi__gif_parse_colortable(s,g->lpal, 2 << (g->lflags & 7), g->eflags & 0x01 ? g->transparent : -1); g->color_table = (stbi_uc *) g->lpal; } else if (g->flags & 0x80) { - if (g->transparent >= 0 && (g->eflags & 0x01)) { - prev_trans = g->pal[g->transparent][3]; - g->pal[g->transparent][3] = 0; - } g->color_table = (stbi_uc *) g->pal; } else - return stbi__errpuc("missing color table", "Corrupt GIF"); - + return stbi__errpuc("missing color table", "Corrupt GIF"); + o = stbi__process_gif_raster(s, g); if (o == NULL) return NULL; - if (prev_trans != -1) - g->pal[g->transparent][3] = (stbi_uc) prev_trans; + // if this was the first frame, + pcount = g->w * g->h; + if (first_frame && (g->bgindex >= 0)) { + // if first frame, any pixel not drawn to gets the background color + for (pi = 0; pi < pcount; ++pi) { + if (g->history[pi] == 0) { + g->pal[g->bgindex][3] = 255; // just in case it was made transparent, undo that; It will be reset next frame if need be; + memcpy( &g->out[pi * 4], &g->pal[g->bgindex], 4 ); + } + } + } return o; } @@ -6344,19 +6402,35 @@ static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, i case 0x21: // Comment Extension. { int len; - if (stbi__get8(s) == 0xF9) { // Graphic Control Extension. + int ext = stbi__get8(s); + if (ext == 0xF9) { // Graphic Control Extension. len = stbi__get8(s); if (len == 4) { g->eflags = stbi__get8(s); - g->delay = stbi__get16le(s); - g->transparent = stbi__get8(s); + g->delay = 10 * stbi__get16le(s); // delay - 1/100th of a second, saving as 1/1000ths. + + // unset old transparent + if (g->transparent >= 0) { + g->pal[g->transparent][3] = 255; + } + if (g->eflags & 0x01) { + g->transparent = stbi__get8(s); + if (g->transparent >= 0) { + g->pal[g->transparent][3] = 0; + } + } else { + // don't need transparent + stbi__skip(s, 1); + g->transparent = -1; + } } else { stbi__skip(s, len); break; } - } - while ((len = stbi__get8(s)) != 0) + } + while ((len = stbi__get8(s)) != 0) { stbi__skip(s, len); + } break; } @@ -6367,28 +6441,92 @@ static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, i return stbi__errpuc("unknown code", "Corrupt GIF"); } } +} - STBI_NOTUSED(req_comp); +static void *stbi__load_gif_main(stbi__context *s, int **delays, int *x, int *y, int *z, int *comp, int req_comp) +{ + if (stbi__gif_test(s)) { + int layers = 0; + stbi_uc *u = 0; + stbi_uc *out = 0; + stbi_uc *two_back = 0; + stbi__gif g; + int stride; + memset(&g, 0, sizeof(g)); + if (delays) { + *delays = 0; + } + + do { + u = stbi__gif_load_next(s, &g, comp, req_comp, two_back); + if (u == (stbi_uc *) s) u = 0; // end of animated gif marker + + if (u) { + *x = g.w; + *y = g.h; + ++layers; + stride = g.w * g.h * 4; + + if (out) { + out = (stbi_uc*) STBI_REALLOC( out, layers * stride ); + if (delays) { + *delays = (int*) STBI_REALLOC( *delays, sizeof(int) * layers ); + } + } else { + out = (stbi_uc*)stbi__malloc( layers * stride ); + if (delays) { + *delays = (int*) stbi__malloc( layers * sizeof(int) ); + } + } + memcpy( out + ((layers - 1) * stride), u, stride ); + if (layers >= 2) { + two_back = out - 2 * stride; + } + + if (delays) { + (*delays)[layers - 1U] = g.delay; + } + } + } while (u != nullptr); + + // free temp buffer; + STBI_FREE(g.out); + STBI_FREE(g.history); + STBI_FREE(g.background); + + // do the final conversion after loading everything; + if (req_comp && req_comp != 4) + out = stbi__convert_format(out, 4, req_comp, layers * g.w, g.h); + + *z = layers; + return out; + } else { + return stbi__errpuc("not GIF", "Image was not as a gif type."); + } } static void *stbi__gif_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri) { stbi_uc *u = 0; - stbi__gif* g = (stbi__gif*) stbi__malloc(sizeof(stbi__gif)); - memset(g, 0, sizeof(*g)); - STBI_NOTUSED(ri); + stbi__gif g; + memset(&g, 0, sizeof(g)); - u = stbi__gif_load_next(s, g, comp, req_comp); + u = stbi__gif_load_next(s, &g, comp, req_comp, 0); if (u == (stbi_uc *) s) u = 0; // end of animated gif marker if (u) { - *x = g->w; - *y = g->h; + *x = g.w; + *y = g.h; + + // moved conversion to after successful load so that the same + // can be done for multiple frames. if (req_comp && req_comp != 4) - u = stbi__convert_format(u, 4, req_comp, g->w, g->h); + u = stbi__convert_format(u, 4, req_comp, g.w, g.h); } - else if (g->out) - STBI_FREE(g->out); - STBI_FREE(g); + + // free buffers needed for multiple frame loading; + STBI_FREE(g.history); + STBI_FREE(g.background); + return u; } From 28c28b0bd23534f405938e29505fb47780fadd3d Mon Sep 17 00:00:00 2001 From: Chris Forseth <christopher.forseth@gmail.com> Date: Mon, 27 Nov 2017 23:06:53 -0600 Subject: [PATCH 2/4] Per the contributor doc - added my name. Noticed urraka also did some work here, so hopefully didn't step on any toes. - Fix an issue where the spec of the gif for restore to previous uses code 3, not 4. - To get results that worked - made an assumption that "clear to background" meant "revert back to what was there before I drew", where mode 1 would revert back to the previous frame [slightly different]. If I clear to background color instead, I ended up with large opaque squares in gifs that changes their transparent colour each frame. - Background color is supposed to be used only for pixels not rendered by the image, so took that to mean it only really affected the previous frame, or potentially any frame that used full disposal. Since background color is allowed to be unspecified this is what lead me to believe I shouldn't use it for disposal. - Oh, also upped the codes table to 8192 as 4096 ended up being too small for a few of my test cases. Full disclaimer - I only read through the GIF format for this contribution, so competly could be misinterpreting the spec - but this gave me reuslts that matched Chrome. --- stb_image.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/stb_image.h b/stb_image.h index aa25fb2..167904f 100644 --- a/stb_image.h +++ b/stb_image.h @@ -74,7 +74,7 @@ RECENT REVISION HISTORY: Thatcher Ulrich (psd) Nicolas Guillemot (vertical flip) Ken Miller (pgm, ppm) Richard Mitton (16-bit PSD) github:urraka (animated gif) Junggon Kim (PNM comments) - Daniel Gibson (16-bit TGA) + github:tocchan (animated gif) Daniel Gibson (16-bit TGA) socks-the-fox (16-bit PNG) Jeremy Sawicki (handle all ImageNet JPGs) Optimizations & bugfixes @@ -6313,7 +6313,7 @@ static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, i dispose = 2; // if I don't have an image to revert back to, default to the old background } - if (dispose == 4) { // use previous graphic + if (dispose == 3) { // use previous graphic for (pi = 0; pi < pcount; ++pi) { if (g->history[pi]) { memcpy( &g->out[pi * 4], &two_back[pi * 4], 4 ); @@ -6329,7 +6329,7 @@ static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, i } else { // This is a non-disposal case eithe way, so just // leave the pixels as is, and they will become the new background - // 1: do not dispose? Same as 4? + // 1: do not dispose // 0: not specified. } From 03b4bbc5d2d51831baf6359c9527a1733de74cdd Mon Sep 17 00:00:00 2001 From: Chris Forseth <christopher.forseth@gmail.com> Date: Mon, 27 Nov 2017 23:32:44 -0600 Subject: [PATCH 3/4] Fix a disposal flag mistype. Only clear to background color if index is non-zero. Fixed a the disposal test gif I was using - now renders properly (gif has no transparent set, but all renderers still considered it transparent. Spec says 0 should be ignored if 0, but was confusing by saying it only in the context of the pal not existing.. but seems to be the case always. --- stb_image.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/stb_image.h b/stb_image.h index 167904f..4c297cc 100644 --- a/stb_image.h +++ b/stb_image.h @@ -6309,7 +6309,7 @@ static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, i dispose = (g->eflags & 0x1C) >> 2; pcount = g->w * g->h; - if ((dispose == 4) && (two_back == 0)) { + if ((dispose == 3) && (two_back == 0)) { dispose = 2; // if I don't have an image to revert back to, default to the old background } @@ -6386,7 +6386,7 @@ static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, i // if this was the first frame, pcount = g->w * g->h; - if (first_frame && (g->bgindex >= 0)) { + if (first_frame && (g->bgindex > 0)) { // if first frame, any pixel not drawn to gets the background color for (pi = 0; pi < pcount; ++pi) { if (g->history[pi] == 0) { From de75509b1c35f6d8a03c341364600922391d6b94 Mon Sep 17 00:00:00 2001 From: Chris Forseth <christopher.forseth@gmail.com> Date: Mon, 27 Nov 2017 23:42:13 -0600 Subject: [PATCH 4/4] Remove a nullptr --- stb_image.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/stb_image.h b/stb_image.h index 4c297cc..4d6b959 100644 --- a/stb_image.h +++ b/stb_image.h @@ -6487,7 +6487,7 @@ static void *stbi__load_gif_main(stbi__context *s, int **delays, int *x, int *y, (*delays)[layers - 1U] = g.delay; } } - } while (u != nullptr); + } while (u != 0); // free temp buffer; STBI_FREE(g.out);