dany/libwebp
1
0
Fork 0
mirror of https://github.com/webmproject/libwebp.git synced 2025-07-12 22:14:29 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity

gif2webp: Move GIF decoding related code to a support library.

Browse Source 
Change-Id: Ifa5e663eb0db7e1e08174fe6608bd45950281abb
This commit is contained in:
Urvang Joshi
2015-01-13 15:43:31 -08:00
parent 07c39559ea
commit d1c4ffae89
6 changed files with 553 additions and 291 deletions
Download Patch File Download Diff File Expand all files Collapse all files

308
examples/gif2webp.c
View File

@ -27,225 +27,11 @@
#include "webp/encode.h"
#include "webp/mux.h"
#include "./example_util.h"
// GIFLIB_MAJOR is only defined in libgif >= 4.2.0.
#if defined(GIFLIB_MAJOR) && defined(GIFLIB_MINOR)
# define LOCAL_GIF_VERSION ((GIFLIB_MAJOR << 8) | GIFLIB_MINOR)
# define LOCAL_GIF_PREREQ(maj, min) \
(LOCAL_GIF_VERSION >= (((maj) << 8) | (min)))
#else
# define LOCAL_GIF_VERSION 0
# define LOCAL_GIF_PREREQ(maj, min) 0
#endif
#define GIF_TRANSPARENT_MASK 0x01
#define GIF_DISPOSE_MASK 0x07
#define GIF_DISPOSE_SHIFT 2
#define WHITE_COLOR 0xffffffff
#define TRANSPARENT_COLOR 0x00ffffff
#define MAX_CACHE_SIZE 30
typedef enum GIFDisposeMethod {
GIF_DISPOSE_NONE,
GIF_DISPOSE_BACKGROUND,
GIF_DISPOSE_RESTORE_PREVIOUS
} GIFDisposeMethod;
typedef struct {
int x_offset, y_offset, width, height;
} GIFFrameRect;
#include "./gifdec.h"
//------------------------------------------------------------------------------
static int transparent_index = -1; // Opaque frame by default.
static void ClearRectangle(WebPPicture* const picture,
int left, int top, int width, int height) {
int j;
for (j = top; j < top + height; ++j) {
uint32_t* const dst = picture->argb + j * picture->argb_stride;
int i;
for (i = left; i < left + width; ++i) {
dst[i] = TRANSPARENT_COLOR;
}
}
}
static void ClearPic(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);
}
}
// TODO: Also used in picture.c. Move to a common location?
// Copy width x height pixels from 'src' to 'dst' honoring the strides.
static void CopyPlane(const uint8_t* src, int src_stride,
uint8_t* dst, int dst_stride, int width, int height) {
while (height-- > 0) {
memcpy(dst, src, width);
src += src_stride;
dst += dst_stride;
}
}
// Copy pixels from 'src' to 'dst' honoring strides. 'src' and 'dst' are assumed
// to be already allocated.
static void CopyPixels(const WebPPicture* const src, WebPPicture* const dst) {
assert(src->width == dst->width && src->height == dst->height);
CopyPlane((uint8_t*)src->argb, 4 * src->argb_stride, (uint8_t*)dst->argb,
4 * dst->argb_stride, 4 * src->width, src->height);
}
// Given 'src' picture and its frame rectangle 'rect', blend it into 'dst'.
static void BlendPixels(const WebPPicture* const src,
const GIFFrameRect* const rect,
WebPPicture* const dst) {
int j;
assert(src->width == dst->width && src->height == dst->height);
for (j = rect->y_offset; j < rect->y_offset + rect->height; ++j) {
int i;
for (i = rect->x_offset; i < rect->x_offset + rect->width; ++i) {
const uint32_t src_pixel = src->argb[j * src->argb_stride + i];
const int src_alpha = src_pixel >> 24;
if (src_alpha != 0) {
dst->argb[j * dst->argb_stride + i] = src_pixel;
}
}
}
}
static void DisposeFrameRectangle(GIFDisposeMethod dispose_method,
const GIFFrameRect* const rect,
const WebPPicture* const prev_canvas,
WebPPicture* const curr_canvas) {
assert(rect != NULL);
if (dispose_method == GIF_DISPOSE_BACKGROUND) {
ClearPic(curr_canvas, rect);
} else if (dispose_method == GIF_DISPOSE_RESTORE_PREVIOUS) {
const int src_stride = prev_canvas->argb_stride;
const uint32_t* const src =
prev_canvas->argb + rect->x_offset + rect->y_offset * src_stride;
const int 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);
CopyPlane((uint8_t*)src, 4 * src_stride, (uint8_t*)dst, 4 * dst_stride,
4 * rect->width, rect->height);
}
}
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);
}
}
// Read the GIF image frame.
static int ReadFrame(GifFileType* const gif, GIFFrameRect* const gif_rect,
WebPPicture* const webp_frame) {
WebPPicture sub_image;
const GifImageDesc* const image_desc = &gif->Image;
uint32_t* dst = NULL;
uint8_t* tmp = NULL;
int ok = 0;
GIFFrameRect rect = {
image_desc->Left, image_desc->Top, image_desc->Width, image_desc->Height
};
*gif_rect = rect;
// Use a view for the sub-picture:
if (!WebPPictureView(webp_frame, 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) {
int y;
for (y = interlace_offsets[pass]; y < rect.height;
y += interlace_jumps[pass]) {
if (DGifGetLine(gif, tmp, rect.width) == GIF_ERROR) goto End;
Remap(tmp, gif, dst + y * sub_image.argb_stride, rect.width);
}
}
} else { // Non-interlaced image.
int y;
for (y = 0; y < rect.height; ++y) {
if (DGifGetLine(gif, tmp, rect.width) == GIF_ERROR) goto End;
Remap(tmp, gif, dst + y * sub_image.argb_stride, rect.width);
}
}
ok = 1;
End:
if (!ok) webp_frame->error_code = sub_image.error_code;
WebPPictureFree(&sub_image);
free(tmp);
return ok;
}
static void GetBackgroundColor(const ColorMapObject* const color_map,
int bgcolor_idx, uint32_t* const bgcolor) {
if (transparent_index != -1 && bgcolor_idx == transparent_index) {
*bgcolor = TRANSPARENT_COLOR; // Special case.
} else if (color_map == NULL || color_map->Colors == NULL
|| bgcolor_idx >= color_map->ColorCount) {
*bgcolor = WHITE_COLOR;
fprintf(stderr,
"GIF decode warning: invalid background color index. Assuming "
"white background.\n");
} else {
const GifColorType color = color_map->Colors[bgcolor_idx];
*bgcolor = (0xff << 24)
| (color.Red << 16)
| (color.Green << 8)
| (color.Blue << 0);
}
}
static void DisplayGifError(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
}
static int transparent_index = GIF_INDEX_INVALID; // Opaque by default.
static const char* const kErrorMessages[-WEBP_MUX_NOT_ENOUGH_DATA + 1] = {
"WEBP_MUX_NOT_FOUND", "WEBP_MUX_INVALID_ARGUMENT", "WEBP_MUX_BAD_DATA",
@ -514,14 +300,15 @@ int main(int argc, const char *argv[]) {
frame.height = gif->SHeight;
frame.use_argb = 1;
if (!WebPPictureAlloc(&frame)) goto End;
ClearPic(&frame, NULL);
GIFClearPic(&frame, NULL);
WebPPictureCopy(&frame, &curr_canvas);
WebPPictureCopy(&frame, &prev_canvas);
WebPPictureCopy(&frame, &prev_to_prev_canvas);
// Background color.
GetBackgroundColor(gif->SColorMap, gif->SBackGroundColor,
&enc_options.anim_params.bgcolor);
GIFGetBackgroundColor(gif->SColorMap, gif->SBackGroundColor,
transparent_index,
&enc_options.anim_params.bgcolor);
// Initialize encoder.
enc = WebPAnimEncoderNew(curr_canvas.width, curr_canvas.height,
@ -536,12 +323,12 @@ int main(int argc, const char *argv[]) {
image_desc->Height = gif->SHeight;
}
if (!ReadFrame(gif, &gif_rect, &frame)) {
if (!GIFReadFrame(gif, transparent_index, &gif_rect, &frame)) {
goto End;
}
// Blend frame rectangle with previous canvas to compose full canvas.
// Note that 'curr_canvas' is same as 'prev_canvas' at this point.
BlendPixels(&frame, &gif_rect, &curr_canvas);
GIFBlendFrames(&frame, &gif_rect, &curr_canvas);
if (!WebPAnimEncoderAdd(enc, &curr_canvas, duration, &config)) {
fprintf(stderr, "Error! Cannot encode frame as WebP\n");
@ -549,17 +336,16 @@ int main(int argc, const char *argv[]) {
}
// Update canvases.
CopyPixels(&prev_canvas, &prev_to_prev_canvas);
DisposeFrameRectangle(orig_dispose, &gif_rect, &prev_canvas,
&curr_canvas);
CopyPixels(&curr_canvas, &prev_canvas);
GIFCopyPixels(&prev_canvas, &prev_to_prev_canvas);
GIFDisposeFrame(orig_dispose, &gif_rect, &prev_canvas, &curr_canvas);
GIFCopyPixels(&curr_canvas, &prev_canvas);
// In GIF, graphic control extensions are optional for a frame, so we
// may not get one before reading the next frame. To handle this case,
// we reset frame properties to reasonable defaults for the next frame.
orig_dispose = GIF_DISPOSE_NONE;
duration = 0;
transparent_index = -1; // Opaque frame by default.
transparent_index = GIF_INDEX_INVALID;
break;
}
case EXTENSION_RECORD_TYPE: {
@ -573,25 +359,10 @@ int main(int argc, const char *argv[]) {
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;
duration = delay * 10; // Duration is in 1 ms units for WebP.
switch (dispose) {
case 3:
orig_dispose = GIF_DISPOSE_RESTORE_PREVIOUS;
break;
case 2:
orig_dispose = GIF_DISPOSE_BACKGROUND;
break;
case 1:
case 0:
default:
orig_dispose = GIF_DISPOSE_NONE;
break;
if (!GIFReadGraphicsExtension(data, &duration, &orig_dispose,
&transparent_index)) {
goto End;
}
transparent_index = (flags & GIF_TRANSPARENT_MASK) ? data[4] : -1;
break;
}
case PLAINTEXT_EXT_FUNC_CODE: {
@ -601,11 +372,9 @@ int main(int argc, const char *argv[]) {
if (data[0] != 11) break; // Chunk is too short
if (!memcmp(data + 1, "NETSCAPE2.0", 11) ||
!memcmp(data + 1, "ANIMEXTS1.0", 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
loop_count = data[2] | (data[3] << 8);
if (!GIFReadLoopCount(gif, &data, &loop_count)) {
goto End;
}
if (verbose) {
fprintf(stderr, "Loop count: %d\n", loop_count);
}
@ -620,42 +389,9 @@ int main(int argc, const char *argv[]) {
!stored_icc &&
!memcmp(data + 1, "ICCRGBG1012", 11);
if (is_xmp || is_icc) {
WebPData* const metadata = is_xmp ? &xmp_data : &icc_data;
// 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, &data) == GIF_ERROR) {
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;
// 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) {
goto End;
}
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;
}
if (!GIFReadMetadata(gif, &data,
is_xmp ? &xmp_data : &icc_data)) {
goto End;
}
if (is_icc) {
stored_icc = 1;
@ -783,7 +519,7 @@ int main(int argc, const char *argv[]) {
if (out != NULL && out_file != NULL) fclose(out);
if (gif_error != GIF_OK) {
DisplayGifError(gif, gif_error);
GIFDisplayError(gif, gif_error);
}
if (gif != NULL) {
#if LOCAL_GIF_PREREQ(5,1)