// Copyright 2012 Google Inc. All Rights Reserved.

//

// Use of this source code is governed by a BSD-style license

// that can be found in the COPYING file in the root of the source

// tree. An additional intellectual property rights grant can be found

// in the file PATENTS. All contributing project authors may

// be found in the AUTHORS file in the root of the source tree.

// -----------------------------------------------------------------------------

//

// GIF decode.

#include "./gifdec.h"

#include <stdio.h>

#ifdef WEBP_HAVE_GIF

#include <assert.h>

#include <stdlib.h>

#include <string.h>

#include "webp/encode.h"

#include "webp/mux_types.h"

#define GIF_TRANSPARENT_COLOR 0x00000000u

#define GIF_WHITE_COLOR 0xffffffffu

#define GIF_TRANSPARENT_MASK 0x01

#define GIF_DISPOSE_MASK 0x07

#define GIF_DISPOSE_SHIFT 2

// from utils/utils.h

#ifdef __cplusplus

extern "C" {

#endif

extern void WebPCopyPlane(const uint8_t* src, int src_stride,

uint8_t* dst, int dst_stride,

int width, int height);

extern void WebPCopyPixels(const WebPPicture* const src,

WebPPicture* const dst);

#ifdef __cplusplus

}

#endif

void GIFGetBackgroundColor(const ColorMapObject* const color_map,

int bgcolor_index, int transparent_index,

uint32_t* const bgcolor) {

if (transparent_index != GIF_INDEX_INVALID &&

bgcolor_index == transparent_index) {

*bgcolor = GIF_TRANSPARENT_COLOR; // Special case.

} else if (color_map == NULL || color_map->Colors == NULL

|| bgcolor_index >= color_map->ColorCount) {

*bgcolor = GIF_WHITE_COLOR;

fprintf(stderr,

"GIF decode warning: invalid background color index. Assuming "

"white background.\n");

} else {

const GifColorType color = color_map->Colors[bgcolor_index];

*bgcolor = (0xffu << 24)

| (color.Red << 16)

| (color.Green << 8)

| (color.Blue << 0);

}

}

int GIFReadGraphicsExtension(const GifByteType* const buf, int* const duration,

GIFDisposeMethod* const dispose,

int* const transparent_index) {

const int flags = buf[1];

const int dispose_raw = (flags >> GIF_DISPOSE_SHIFT) & GIF_DISPOSE_MASK;

const int duration_raw = buf[2] | (buf[3] << 8); // In 10 ms units.

if (buf[0] != 4) return 0;

*duration = duration_raw * 10; // Duration is in 1 ms units.

switch (dispose_raw) {

case 3:

*dispose = GIF_DISPOSE_RESTORE_PREVIOUS;

break;

case 2:

*dispose = GIF_DISPOSE_BACKGROUND;

break;

case 1:

case 0:

default:

*dispose = GIF_DISPOSE_NONE;

break;

}

*transparent_index =

(flags & GIF_TRANSPARENT_MASK) ? buf[4] : GIF_INDEX_INVALID;

return 1;

}

static int Remap(const GifFileType* const gif, const uint8_t* const src,

int len, int transparent_index, uint32_t* dst) {

int i;

const GifColorType* colors;

const ColorMapObject* const cmap =

gif->Image.ColorMap ? gif->Image.ColorMap : gif->SColorMap;

if (cmap == NULL) return 1;

if (cmap->Colors == NULL || cmap->ColorCount <= 0) return 0;

colors = cmap->Colors;

for (i = 0; i < len; ++i) {

if (src[i] == transparent_index) {

dst[i] = GIF_TRANSPARENT_COLOR;

} else if (src[i] < cmap->ColorCount) {

const GifColorType c = colors[src[i]];

dst[i] = c.Blue | (c.Green << 8) | (c.Red << 16) | (0xffu << 24);

} else {

return 0;

}

}

return 1;

}

int GIFReadFrame(GifFileType* const gif, int transparent_index,

GIFFrameRect* const gif_rect, WebPPicture* const picture) {

WebPPicture sub_image;

const GifImageDesc* const image_desc = &gif->Image;

uint32_t* dst = NULL;

uint8_t* tmp = NULL;

const GIFFrameRect rect = {

image_desc->Left, image_desc->Top, image_desc->Width, image_desc->Height

};

const uint64_t memory_needed = 4 * rect.width * (uint64_t)rect.height;

int ok = 0;

*gif_rect = rect;

if (memory_needed != (size_t)memory_needed || memory_needed > (4ULL << 32)) {

fprintf(stderr, "Image is too large (%d x %d).", rect.width, rect.height);

return 0;

}

// Use a view for the sub-picture:

if (!WebPPictureView(picture, rect.x_offset, rect.y_offset,

rect.width, rect.height, &sub_image)) {

fprintf(stderr, "Sub-image %dx%d at position %d,%d is invalid!\n",

rect.width, rect.height, rect.x_offset, rect.y_offset);

return 0;

}

dst = sub_image.argb;

tmp = (uint8_t*)malloc(rect.width * sizeof(*tmp));

if (tmp == NULL) goto End;

if (image_desc->Interlace) { // Interlaced image.

// We need 4 passes, with the following offsets and jumps.

const int interlace_offsets[] = { 0, 4, 2, 1 };

const int interlace_jumps[] = { 8, 8, 4, 2 };

int pass;

for (pass = 0; pass < 4; ++pass) {

const size_t stride = (size_t)sub_image.argb_stride;

int y = interlace_offsets[pass];

uint32_t* row = dst + y * stride;

const size_t jump = interlace_jumps[pass] * stride;

for (; y < rect.height; y += interlace_jumps[pass], row += jump) {

if (DGifGetLine(gif, tmp, rect.width) == GIF_ERROR) goto End;

if (!Remap(gif, tmp, rect.width, transparent_index, row)) goto End;

}

}

} else { // Non-interlaced image.

int y;

uint32_t* ptr = dst;

for (y = 0; y < rect.height; ++y, ptr += sub_image.argb_stride) {

if (DGifGetLine(gif, tmp, rect.width) == GIF_ERROR) goto End;

if (!Remap(gif, tmp, rect.width, transparent_index, ptr)) goto End;

}

}

ok = 1;

End:

if (!ok) picture->error_code = sub_image.error_code;

WebPPictureFree(&sub_image);

free(tmp);

return ok;

}

int GIFReadLoopCount(GifFileType* const gif, GifByteType** const buf,

int* const loop_count) {

assert(!memcmp(*buf + 1, "NETSCAPE2.0", 11) ||

!memcmp(*buf + 1, "ANIMEXTS1.0", 11));

if (DGifGetExtensionNext(gif, buf) == GIF_ERROR) {

return 0;

}

if (*buf == NULL) {

return 0; // Loop count sub-block missing.

}

if ((*buf)[0] < 3 || (*buf)[1] != 1) {

return 0; // wrong size/marker

}

*loop_count = (*buf)[2] | ((*buf)[3] << 8);

return 1;

}

int GIFReadMetadata(GifFileType* const gif, GifByteType** const buf,

WebPData* const metadata) {

const int is_xmp = !memcmp(*buf + 1, "XMP DataXMP", 11);

const int is_icc = !memcmp(*buf + 1, "ICCRGBG1012", 11);

assert(is_xmp || is_icc);

(void)is_icc; // silence unused warning.

// Construct metadata from sub-blocks.

// Usual case (including ICC profile): In each sub-block, the

// first byte specifies its size in bytes (0 to 255) and the

// rest of the bytes contain the data.

// Special case for XMP data: In each sub-block, the first byte

// is also part of the XMP payload. XMP in GIF also has a 257

// byte padding data. See the XMP specification for details.

while (1) {

WebPData subblock;

const uint8_t* tmp;

if (DGifGetExtensionNext(gif, buf) == GIF_ERROR) {

return 0;

}

if (*buf == NULL) break; // Finished.

subblock.size = is_xmp ? (*buf)[0] + 1 : (*buf)[0];

assert(subblock.size > 0);

subblock.bytes = is_xmp ? *buf : *buf + 1;

// Note: We store returned value in 'tmp' first, to avoid

// leaking old memory in metadata->bytes on error.

tmp = (uint8_t*)realloc((void*)metadata->bytes,

metadata->size + subblock.size);

if (tmp == NULL) {

return 0;

}

memcpy((void*)(tmp + metadata->size),

subblock.bytes, subblock.size);

metadata->bytes = tmp;

metadata->size += subblock.size;

}

if (is_xmp) {

// XMP padding data is 0x01, 0xff, 0xfe ... 0x01, 0x00.

const size_t xmp_pading_size = 257;

if (metadata->size > xmp_pading_size) {

metadata->size -= xmp_pading_size;

}

}

return 1;

}

static void ClearRectangle(WebPPicture* const picture,

int left, int top, int width, int height) {

int i, j;

const size_t stride = picture->argb_stride;

uint32_t* dst = picture->argb + top * stride + left;

for (j = 0; j < height; ++j, dst += stride) {

for (i = 0; i < width; ++i) dst[i] = GIF_TRANSPARENT_COLOR;

}

}

void GIFClearPic(WebPPicture* const pic, const GIFFrameRect* const rect) {

if (rect != NULL) {

ClearRectangle(pic, rect->x_offset, rect->y_offset,

rect->width, rect->height);

} else {

ClearRectangle(pic, 0, 0, pic->width, pic->height);

}

}

void GIFCopyPixels(const WebPPicture* const src, WebPPicture* const dst) {

WebPCopyPixels(src, dst);

}

void GIFDisposeFrame(GIFDisposeMethod dispose, const GIFFrameRect* const rect,

const WebPPicture* const prev_canvas,

WebPPicture* const curr_canvas) {

assert(rect != NULL);

if (dispose == GIF_DISPOSE_BACKGROUND) {

GIFClearPic(curr_canvas, rect);

} else if (dispose == GIF_DISPOSE_RESTORE_PREVIOUS) {

const size_t src_stride = prev_canvas->argb_stride;

const uint32_t* const src = prev_canvas->argb + rect->x_offset

+ rect->y_offset * src_stride;

const size_t dst_stride = curr_canvas->argb_stride;

uint32_t* const dst = curr_canvas->argb + rect->x_offset

+ rect->y_offset * dst_stride;

assert(prev_canvas != NULL);

WebPCopyPlane((uint8_t*)src, (int)(4 * src_stride),

(uint8_t*)dst, (int)(4 * dst_stride),

4 * rect->width, rect->height);

}

}

void GIFBlendFrames(const WebPPicture* const src,

const GIFFrameRect* const rect, WebPPicture* const dst) {

int i, j;

const size_t src_stride = src->argb_stride;

const size_t dst_stride = dst->argb_stride;

assert(src->width == dst->width && src->height == dst->height);

for (j = rect->y_offset; j < rect->y_offset + rect->height; ++j) {

for (i = rect->x_offset; i < rect->x_offset + rect->width; ++i) {

const uint32_t src_pixel = src->argb[j * src_stride + i];

const int src_alpha = src_pixel >> 24;

if (src_alpha != 0) {

dst->argb[j * dst_stride + i] = src_pixel;

}

}

}

}

void GIFDisplayError(const GifFileType* const gif, int gif_error) {

// libgif 4.2.0 has retired PrintGifError() and added GifErrorString().

#if LOCAL_GIF_PREREQ(4,2)

#if LOCAL_GIF_PREREQ(5,0)

// Static string actually, hence the const char* cast.

const char* error_str = (const char*)GifErrorString(

(gif == NULL) ? gif_error : gif->Error);

#else

const char* error_str = (const char*)GifErrorString();

(void)gif;

#endif

if (error_str == NULL) error_str = "Unknown error";

fprintf(stderr, "GIFLib Error %d: %s\n", gif_error, error_str);

#else

(void)gif;

fprintf(stderr, "GIFLib Error %d: ", gif_error);

PrintGifError();

fprintf(stderr, "\n");

#endif

}

#else // !WEBP_HAVE_GIF

static void ErrorGIFNotAvailable() {

fprintf(stderr, "GIF support not compiled. Please install the libgif-dev "

"package before building.\n");

}

void GIFGetBackgroundColor(const struct ColorMapObject* const color_map,

int bgcolor_index, int transparent_index,

uint32_t* const bgcolor) {

(void)color_map;

(void)bgcolor_index;

(void)transparent_index;

(void)bgcolor;

ErrorGIFNotAvailable();

}

int GIFReadGraphicsExtension(const GifByteType* const data, int* const duration,

GIFDisposeMethod* const dispose,

int* const transparent_index) {

(void)data;

(void)duration;

(void)dispose;

(void)transparent_index;

ErrorGIFNotAvailable();

return 0;

}

int GIFReadFrame(struct GifFileType* const gif, int transparent_index,

GIFFrameRect* const gif_rect,

struct WebPPicture* const picture) {

(void)gif;

(void)transparent_index;

(void)gif_rect;

(void)picture;

ErrorGIFNotAvailable();

return 0;

}

int GIFReadLoopCount(struct GifFileType* const gif, GifByteType** const buf,

int* const loop_count) {

(void)gif;

(void)buf;

(void)loop_count;

ErrorGIFNotAvailable();

return 0;

}

int GIFReadMetadata(struct GifFileType* const gif, GifByteType** const buf,

struct WebPData* const metadata) {

(void)gif;

(void)buf;

(void)metadata;

ErrorGIFNotAvailable();

return 0;

}

void GIFDisposeFrame(GIFDisposeMethod dispose, const GIFFrameRect* const rect,

const struct WebPPicture* const prev_canvas,

struct WebPPicture* const curr_canvas) {

(void)dispose;

(void)rect;

(void)prev_canvas;

(void)curr_canvas;

ErrorGIFNotAvailable();

}

void GIFBlendFrames(const struct WebPPicture* const src,

const GIFFrameRect* const rect,

struct WebPPicture* const dst) {

(void)src;

(void)rect;

(void)dst;

ErrorGIFNotAvailable();

}

void GIFDisplayError(const struct GifFileType* const gif, int gif_error) {

(void)gif;

(void)gif_error;

ErrorGIFNotAvailable();

}

void GIFClearPic(struct WebPPicture* const pic,

const GIFFrameRect* const rect) {

(void)pic;

(void)rect;

ErrorGIFNotAvailable();

}

void GIFCopyPixels(const struct WebPPicture* const src,

struct WebPPicture* const dst) {

(void)src;

(void)dst;

ErrorGIFNotAvailable();

}

#endif // WEBP_HAVE_GIF

// -----------------------------------------------------------------------------