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libwebp/examples/gif2webp.c
Urvang Joshi 54b65108ad gif2webp: If aligning to even offsets, extra pixels should be transparent 
This is to ensure that the output WebP image is consistent with original
GIF when displayed against any background color.

Change-Id: I14218848153eb40358aa4ce331b2543d2fc2e86c
2013-06-24 15:18:35 -07:00

537 lines
18 KiB
C
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// 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.
// -----------------------------------------------------------------------------
//
// simple tool to convert animated GIFs to WebP
//
// Authors: Skal (pascal.massimino@gmail.com)
// Urvang (urvang@google.com)
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gif_lib.h>
#include "webp/encode.h"
#include "webp/mux.h"
#include "./example_util.h"
#define GIF_TRANSPARENT_MASK 0x01
#define GIF_DISPOSE_MASK 0x07
#define GIF_DISPOSE_SHIFT 2
#define TRANSPARENT_COLOR 0x00ffffff
#define WHITE_COLOR 0xffffffff
//------------------------------------------------------------------------------
static int transparent_index = -1; // No transparency by default.
static void ClearPicture(WebPPicture* const picture) {
int x, y;
for (y = 0; y < picture->height; ++y) {
uint32_t* const dst = picture->argb + y * picture->argb_stride;
for (x = 0; x < picture->width; ++x) dst[x] = TRANSPARENT_COLOR;
}
}
static void Remap(const uint8_t* const src, const GifFileType* const gif,
uint32_t* dst, int len) {
int i;
const GifColorType* colors;
const ColorMapObject* const cmap =
gif->Image.ColorMap ? gif->Image.ColorMap : gif->SColorMap;
if (cmap == NULL) return;
colors = cmap->Colors;
for (i = 0; i < len; ++i) {
const GifColorType c = colors[src[i]];
dst[i] = (src[i] == transparent_index) ? TRANSPARENT_COLOR
: c.Blue | (c.Green << 8) | (c.Red << 16) | (0xff << 24);
}
}
static int ReadSubImage(GifFileType* gif, WebPPicture* pic, WebPPicture* view) {
const GifImageDesc image_desc = gif->Image;
const int offset_x = image_desc.Left;
const int offset_y = image_desc.Top;
const int sub_w = image_desc.Width;
const int sub_h = image_desc.Height;
uint32_t* dst = NULL;
uint8_t* tmp = NULL;
int ok = 0;
// Use a view for the sub-picture:
if (!WebPPictureView(pic, offset_x, offset_y, sub_w, sub_h, view)) {
fprintf(stderr, "Sub-image %dx%d at position %d,%d is invalid!\n",
sub_w, sub_h, offset_x, offset_y);
goto End;
}
dst = view->argb;
tmp = (uint8_t*)malloc(sub_w * 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) {
int y;
for (y = interlace_offsets[pass]; y < sub_h; y += interlace_jumps[pass]) {
if (DGifGetLine(gif, tmp, sub_w) == GIF_ERROR) goto End;
Remap(tmp, gif, dst + y * view->argb_stride, sub_w);
}
}
} else { // Non-interlaced image.
int y;
for (y = 0; y < sub_h; ++y) {
if (DGifGetLine(gif, tmp, sub_w) == GIF_ERROR) goto End;
Remap(tmp, gif, dst + y * view->argb_stride, sub_w);
}
}
// re-align the view with even offset (and adjust dimensions if needed).
WebPPictureView(pic, offset_x & ~1, offset_y & ~1,
sub_w + (offset_x & 1), sub_h + (offset_y & 1), view);
ok = 1;
End:
free(tmp);
return ok;
}
static int GetBackgroundColor(const ColorMapObject* const color_map,
GifWord bgcolor_idx, uint32_t* const bgcolor) {
if (transparent_index != -1 && bgcolor_idx == transparent_index) {
*bgcolor = TRANSPARENT_COLOR; // Special case.
return 1;
} else if (color_map == NULL || color_map->Colors == NULL
|| bgcolor_idx >= color_map->ColorCount) {
return 0; // Invalid color map or index.
} else {
const GifColorType color = color_map->Colors[bgcolor_idx];
*bgcolor = (0xff << 24)
| (color.Red << 16)
| (color.Green << 8)
| (color.Blue << 0);
return 1;
}
}
static void DisplayGifError(const GifFileType* const gif, int gif_error) {
// GIFLIB_MAJOR is only defined in libgif >= 4.2.0.
// libgif 4.2.0 has retired PrintGifError() and added GifErrorString().
#if defined(GIFLIB_MAJOR) && defined(GIFLIB_MINOR) && \
((GIFLIB_MAJOR == 4 && GIFLIB_MINOR >= 2) || GIFLIB_MAJOR > 4)
#if GIFLIB_MAJOR >= 5
// 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
}
static const char* const kErrorMessages[] = {
"WEBP_MUX_NOT_FOUND", "WEBP_MUX_INVALID_ARGUMENT", "WEBP_MUX_BAD_DATA",
"WEBP_MUX_MEMORY_ERROR", "WEBP_MUX_NOT_ENOUGH_DATA"
};
static const char* ErrorString(WebPMuxError err) {
assert(err <= WEBP_MUX_NOT_FOUND && err >= WEBP_MUX_NOT_ENOUGH_DATA);
return kErrorMessages[-err];
}
//------------------------------------------------------------------------------
static void Help(void) {
printf("Usage:\n");
printf(" gif2webp [options] gif_file -o webp_file\n");
printf("options:\n");
printf(" -h / -help ............ this help\n");
printf(" -lossy ................. Encode image using lossy compression.\n");
printf(" -q <float> ............. quality factor (0:small..100:big)\n");
printf(" -m <int> ............... compression method (0=fast, 6=slowest)\n");
printf(" -f <int> ............... filter strength (0=off..100)\n");
printf("\n");
printf(" -version ............... print version number and exit.\n");
printf(" -v ..................... verbose.\n");
printf(" -quiet ................. don't print anything.\n");
printf("\n");
}
//------------------------------------------------------------------------------
int main(int argc, const char *argv[]) {
int verbose = 0;
int gif_error = GIF_ERROR;
WebPMuxError err = WEBP_MUX_OK;
int ok = 0;
const char *in_file = NULL, *out_file = NULL;
FILE* out = NULL;
GifFileType* gif = NULL;
WebPPicture picture;
WebPMuxFrameInfo frame;
WebPMuxAnimParams anim = { WHITE_COLOR, 0 };
int is_first_frame = 1;
int done;
int c;
int quiet = 0;
WebPConfig config;
WebPMux* mux = NULL;
WebPData webp_data = { NULL, 0 };
int stored_icc = 0; // Whether we have already stored an ICC profile.
int stored_xmp = 0;
memset(&frame, 0, sizeof(frame));
frame.id = WEBP_CHUNK_ANMF;
frame.dispose_method = WEBP_MUX_DISPOSE_BACKGROUND;
if (!WebPConfigInit(&config) || !WebPPictureInit(&picture)) {
fprintf(stderr, "Error! Version mismatch!\n");
return -1;
}
config.lossless = 1; // Use lossless compression by default.
if (argc == 1) {
Help();
return 0;
}
for (c = 1; c < argc; ++c) {
if (!strcmp(argv[c], "-h") || !strcmp(argv[c], "-help")) {
Help();
return 0;
} else if (!strcmp(argv[c], "-o") && c < argc - 1) {
out_file = argv[++c];
} else if (!strcmp(argv[c], "-lossy")) {
config.lossless = 0;
} else if (!strcmp(argv[c], "-q") && c < argc - 1) {
config.quality = (float)strtod(argv[++c], NULL);
} else if (!strcmp(argv[c], "-m") && c < argc - 1) {
config.method = strtol(argv[++c], NULL, 0);
} else if (!strcmp(argv[c], "-f") && c < argc - 1) {
config.filter_strength = strtol(argv[++c], NULL, 0);
} else if (!strcmp(argv[c], "-version")) {
const int enc_version = WebPGetEncoderVersion();
const int mux_version = WebPGetMuxVersion();
printf("WebP Encoder version: %d.%d.%d\nWebP Mux version: %d.%d.%d\n",
(enc_version >> 16) & 0xff, (enc_version >> 8) & 0xff,
enc_version & 0xff, (mux_version >> 16) & 0xff,
(mux_version >> 8) & 0xff, mux_version & 0xff);
return 0;
} else if (!strcmp(argv[c], "-quiet")) {
quiet = 1;
} else if (!strcmp(argv[c], "-v")) {
verbose = 1;
} else if (argv[c][0] == '-') {
fprintf(stderr, "Error! Unknown option '%s'\n", argv[c]);
Help();
return -1;
} else {
in_file = argv[c];
}
}
if (!WebPValidateConfig(&config)) {
fprintf(stderr, "Error! Invalid configuration.\n");
goto End;
}
if (in_file == NULL) {
fprintf(stderr, "No input file specified!\n");
Help();
goto End;
}
// Start the decoder object
#if defined(GIFLIB_MAJOR) && (GIFLIB_MAJOR >= 5)
// There was an API change in version 5.0.0.
gif = DGifOpenFileName(in_file, &gif_error);
#else
gif = DGifOpenFileName(in_file);
#endif
if (gif == NULL) goto End;
// Allocate picture buffer
picture.width = gif->SWidth;
picture.height = gif->SHeight;
picture.use_argb = 1;
if (!WebPPictureAlloc(&picture)) goto End;
mux = WebPMuxNew();
if (mux == NULL) {
fprintf(stderr, "ERROR: could not create a mux object.\n");
goto End;
}
// Loop over GIF images
done = 0;
do {
GifRecordType type;
if (DGifGetRecordType(gif, &type) == GIF_ERROR) goto End;
switch (type) {
case IMAGE_DESC_RECORD_TYPE: {
WebPPicture sub_image;
WebPMemoryWriter memory;
if (frame.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND) {
ClearPicture(&picture);
}
if (!DGifGetImageDesc(gif)) goto End;
if (!ReadSubImage(gif, &picture, &sub_image)) goto End;
if (!config.lossless) {
// We need to call BGRA variant because of the way we do Remap(). Note
// that 'sub_image' will no longer be a view and own some memory.
WebPPictureImportBGRA(
&sub_image, (uint8_t*)sub_image.argb,
sub_image.argb_stride * sizeof(*sub_image.argb));
sub_image.use_argb = 0;
} else {
sub_image.use_argb = 1;
}
sub_image.writer = WebPMemoryWrite;
sub_image.custom_ptr = &memory;
WebPMemoryWriterInit(&memory);
if (!WebPEncode(&config, &sub_image)) {
fprintf(stderr, "Error! Cannot encode picture as WebP\n");
fprintf(stderr, "Error code: %d\n", sub_image.error_code);
goto End;
}
// Now we have all the info about the frame, as a Graphic Control
// Extension Block always appears before the Image Descriptor Block.
// So add the frame to mux.
frame.x_offset = gif->Image.Left & ~1;
frame.y_offset = gif->Image.Top & ~1;
frame.bitstream.bytes = memory.mem;
frame.bitstream.size = memory.size;
err = WebPMuxPushFrame(mux, &frame, 1);
if (err != WEBP_MUX_OK) {
fprintf(stderr, "ERROR (%s): Could not add animation frame.\n",
ErrorString(err));
goto End;
}
if (verbose) {
printf("Added frame %dx%d (offset:%d,%d duration:%d) ",
sub_image.width, sub_image.height,
frame.x_offset, frame.y_offset,
frame.duration);
printf("dispose:%d transparent index:%d\n",
frame.dispose_method, transparent_index);
}
WebPDataClear(&frame.bitstream);
WebPPictureFree(&sub_image);
break;
}
case EXTENSION_RECORD_TYPE: {
int extension;
GifByteType *data = NULL;
if (DGifGetExtension(gif, &extension, &data) == GIF_ERROR) {
goto End;
}
switch (extension) {
case COMMENT_EXT_FUNC_CODE: {
break; // Do nothing for now.
}
case GRAPHICS_EXT_FUNC_CODE: {
const int flags = data[1];
const int dispose = (flags >> GIF_DISPOSE_SHIFT) & GIF_DISPOSE_MASK;
const int delay = data[2] | (data[3] << 8); // In 10 ms units.
if (data[0] != 4) goto End;
frame.duration = delay * 10; // Duration is in 1 ms units for WebP.
if (dispose == 3) {
fprintf(stderr, "WARNING: GIF_DISPOSE_RESTORE not supported.");
// failsafe. TODO(urvang): emulate the correct behaviour by
// recoding the whole frame.
frame.dispose_method = WEBP_MUX_DISPOSE_BACKGROUND;
} else {
frame.dispose_method =
(dispose == 2) ? WEBP_MUX_DISPOSE_BACKGROUND
: WEBP_MUX_DISPOSE_NONE;
}
transparent_index = (flags & GIF_TRANSPARENT_MASK) ? data[4] : -1;
if (is_first_frame) {
if (!GetBackgroundColor(gif->SColorMap, gif->SBackGroundColor,
&anim.bgcolor)) {
fprintf(stderr, "GIF decode warning: invalid background color "
"index. Assuming white background.\n");
}
ClearPicture(&picture);
is_first_frame = 0;
}
break;
}
case PLAINTEXT_EXT_FUNC_CODE: {
break;
}
case APPLICATION_EXT_FUNC_CODE: {
if (data[0] != 11) break; // Chunk is too short
if (!memcmp(data + 1, "NETSCAPE2.0", 11)) {
// Recognize and parse Netscape2.0 NAB extension for loop count.
if (DGifGetExtensionNext(gif, &data) == GIF_ERROR) goto End;
if (data == NULL) goto End; // Loop count sub-block missing.
if (data[0] != 3 && data[1] != 1) break; // wrong size/marker
anim.loop_count = data[2] | (data[3] << 8);
if (verbose) printf("Loop count: %d\n", anim.loop_count);
} else { // An extension containing metadata.
// We only store the first encountered chunk of each type.
const int is_xmp =
!stored_xmp && !memcmp(data + 1, "XMP DataXMP", 11);
const int is_icc =
!stored_icc && !memcmp(data + 1, "ICCRGBG1012", 11);
if (is_xmp || is_icc) {
const char* const fourccs[2] = { "XMP " , "ICCP" };
const char* const features[2] = { "XMP" , "ICC" };
WebPData metadata = { NULL, 0 };
// 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 prev_metadata = metadata;
WebPData subblock;
if (DGifGetExtensionNext(gif, &data) == GIF_ERROR) {
WebPDataClear(&metadata);
goto End;
}
if (data == NULL) break; // Finished.
subblock.size = is_xmp ? data[0] + 1 : data[0];
assert(subblock.size > 0);
subblock.bytes = is_xmp ? data : data + 1;
metadata.bytes =
(uint8_t*)realloc((void*)metadata.bytes,
prev_metadata.size + subblock.size);
if (metadata.bytes == NULL) {
WebPDataClear(&prev_metadata);
goto End;
}
metadata.size += subblock.size;
memcpy((void*)(metadata.bytes + prev_metadata.size),
subblock.bytes, 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;
}
}
// Add metadata chunk.
err = WebPMuxSetChunk(mux, fourccs[is_icc], &metadata, 1);
if (verbose) {
printf("%s size: %d\n", features[is_icc], (int)metadata.size);
}
WebPDataClear(&metadata);
if (err != WEBP_MUX_OK) {
fprintf(stderr, "ERROR (%s): Could not set %s chunk.\n",
ErrorString(err), features[is_icc]);
goto End;
}
if (is_icc) {
stored_icc = 1;
} else if (is_xmp) {
stored_xmp = 1;
}
}
}
break;
}
default: {
break; // skip
}
}
while (data != NULL) {
if (DGifGetExtensionNext(gif, &data) == GIF_ERROR) goto End;
}
break;
}
case TERMINATE_RECORD_TYPE: {
done = 1;
break;
}
default: {
if (verbose) {
fprintf(stderr, "Skipping over unknown record type %d\n", type);
}
break;
}
}
} while (!done);
// Finish muxing
err = WebPMuxSetAnimationParams(mux, &anim);
if (err != WEBP_MUX_OK) {
fprintf(stderr, "ERROR (%s): Could not set animation parameters.\n",
ErrorString(err));
goto End;
}
err = WebPMuxAssemble(mux, &webp_data);
if (err != WEBP_MUX_OK) {
fprintf(stderr, "ERROR (%s) assembling the WebP file.\n", ErrorString(err));
goto End;
}
if (out_file != NULL) {
if (!ExUtilWriteFile(out_file, webp_data.bytes, webp_data.size)) {
fprintf(stderr, "Error writing output file: %s\n", out_file);
goto End;
}
if (!quiet) {
printf("Saved output file: %s\n", out_file);
}
} else {
if (!quiet) {
printf("Nothing written; use -o flag to save the result.\n");
}
}
// All OK.
ok = 1;
gif_error = GIF_OK;
End:
WebPDataClear(&webp_data);
WebPMuxDelete(mux);
WebPPictureFree(&picture);
if (out != NULL && out_file != NULL) fclose(out);
if (gif_error != GIF_OK) {
DisplayGifError(gif, gif_error);
}
if (gif != NULL) {
DGifCloseFile(gif);
}
return !ok;
}
//------------------------------------------------------------------------------
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