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03fb75221c
libwebp/examples/anim_util.cc
Pascal Massimino acb297e9c2 anim_diff: add a -raw_comparison flag 
If this flag is not used, RGB is premultiplied before comparison.
Otherwise, the raw R/G/B values are compared, which can be a problem
in transparent area (alpha=0 R/G/B=anything)

Change-Id: I131cc10ec92414ad508b81f599a60d0097cac470
2015-08-06 20:29:14 -07:00

860 lines
31 KiB
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// Copyright 2015 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.
// -----------------------------------------------------------------------------
//
// Utilities for animated images
#include "./anim_util.h"
#include <assert.h>
#include <math.h>
#include <stdio.h>
#include <string.h>
#include <fstream>
#include <sstream> // for 'ostringstream'.
#ifdef WEBP_HAVE_GIF
#include <gif_lib.h>
#endif
#include "webp/format_constants.h"
#include "webp/decode.h"
#include "webp/demux.h"
using std::ifstream;
using std::ios;
using std::ofstream;
using std::ostringstream;
static const int kNumChannels = 4;
// -----------------------------------------------------------------------------
// Common utilities.
// Returns true if the frame covers the full canvas.
static bool IsFullFrame(int width, int height,
int canvas_width, int canvas_height) {
return (width == canvas_width && height == canvas_height);
}
static void AllocateFrames(AnimatedImage* const image, uint32_t frame_count) {
image->frames.resize(frame_count);
for (size_t i = 0; i < image->frames.size(); ++i) {
const size_t rgba_size =
image->canvas_width * kNumChannels * image->canvas_height;
image->frames[i].rgba.resize(rgba_size);
}
}
// Clear the canvas to transparent.
static void ZeroFillCanvas(uint8_t* rgba,
uint32_t canvas_width, uint32_t canvas_height) {
memset(rgba, 0, canvas_width * kNumChannels * canvas_height);
}
// Clear given frame rectangle to transparent.
static void ZeroFillFrameRect(uint8_t* rgba, int rgba_stride, int x_offset,
int y_offset, int width, int height) {
assert(width * kNumChannels <= rgba_stride);
rgba += y_offset * rgba_stride + x_offset * kNumChannels;
for (int j = 0; j < height; ++j) {
memset(rgba, 0, width * kNumChannels);
rgba += rgba_stride;
}
}
// Copy width * height pixels from 'src' to 'dst'.
static void CopyCanvas(const uint8_t* src, uint8_t* dst,
uint32_t width, uint32_t height) {
assert(src != NULL && dst != NULL);
memcpy(dst, src, width * kNumChannels * height);
}
// Copy pixels in the given rectangle from 'src' to 'dst' honoring the 'stride'.
static void CopyFrameRectangle(const uint8_t* src, uint8_t* dst, int stride,
int x_offset, int y_offset,
int width, int height) {
const int width_in_bytes = width * kNumChannels;
assert(width_in_bytes <= stride);
const size_t offset = y_offset * stride + x_offset * kNumChannels;
src += offset;
dst += offset;
for (int j = 0; j < height; ++j) {
memcpy(dst, src, width_in_bytes);
src += stride;
dst += stride;
}
}
// Canonicalize all transparent pixels to transparent black to aid comparison.
static void CleanupTransparentPixels(uint32_t* rgba,
uint32_t width, uint32_t height) {
const uint32_t* const rgba_end = rgba + width * height;
while (rgba < rgba_end) {
const uint8_t alpha = (*rgba >> 24) & 0xff;
if (alpha == 0) {
*rgba = 0;
}
++rgba;
}
}
// Dump frame to a PAM file.
// Returns true on success.
static bool DumpFrame(const char filename[], const char dump_folder[],
uint32_t frame_num, const uint8_t rgba[],
int canvas_width, int canvas_height) {
const std::string filename_str = filename;
const size_t slash_idx = filename_str.find_last_of("/\\");
const std::string base_name = (slash_idx != std::string::npos)
? filename_str.substr(slash_idx + 1)
: filename_str;
ostringstream dump_file;
dump_file << dump_folder << "/" << base_name << "_frame_" << frame_num
<< ".pam";
ofstream fout(dump_file.str().c_str(), ios::binary | ios::out);
if (!fout.good()) {
fprintf(stderr, "Error opening file for writing: %s\n",
dump_file.str().c_str());
return false;
}
fout << "P7\nWIDTH " << canvas_width << "\nHEIGHT " << canvas_height
<< "\nDEPTH 4\nMAXVAL 255\nTUPLTYPE RGB_ALPHA\nENDHDR\n";
for (int y = 0; y < canvas_height; ++y) {
fout.write(
reinterpret_cast<const char*>(rgba) + y * canvas_width * kNumChannels,
canvas_width * kNumChannels);
if (!fout.good()) {
fprintf(stderr, "Error writing to file: %s\n", dump_file.str().c_str());
return 0;
}
}
fout.close();
return true;
}
// -----------------------------------------------------------------------------
// WebP Decoding.
// Returns true if this is a valid WebP bitstream.
static bool IsWebP(const std::string& file_str) {
return WebPGetInfo(reinterpret_cast<const uint8_t*>(file_str.c_str()),
file_str.length(), NULL, NULL) != 0;
}
// Returns true if the current frame is a key-frame.
static bool IsKeyFrameWebP(const WebPIterator& curr, const WebPIterator& prev,
const DecodedFrame* const prev_frame,
int canvas_width, int canvas_height) {
if (prev_frame == NULL) {
return true;
} else if ((!curr.has_alpha || curr.blend_method == WEBP_MUX_NO_BLEND) &&
IsFullFrame(curr.width, curr.height,
canvas_width, canvas_height)) {
return true;
} else {
return (prev.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND) &&
(IsFullFrame(prev.width, prev.height, canvas_width, canvas_height) ||
prev_frame->is_key_frame);
}
}
// Blend a single channel of 'src' over 'dst', given their alpha channel values.
static uint8_t BlendChannelWebP(uint32_t src, uint8_t src_a, uint32_t dst,
uint8_t dst_a, uint32_t scale, int shift) {
const uint8_t src_channel = (src >> shift) & 0xff;
const uint8_t dst_channel = (dst >> shift) & 0xff;
const uint32_t blend_unscaled = src_channel * src_a + dst_channel * dst_a;
assert(blend_unscaled < (1ULL << 32) / scale);
return (blend_unscaled * scale) >> 24;
}
// Blend 'src' over 'dst' assuming they are NOT pre-multiplied by alpha.
static uint32_t BlendPixelWebP(uint32_t src, uint32_t dst) {
const uint8_t src_a = (src >> 24) & 0xff;
if (src_a == 0) {
return dst;
} else {
const uint8_t dst_a = (dst >> 24) & 0xff;
// This is the approximate integer arithmetic for the actual formula:
// dst_factor_a = (dst_a * (255 - src_a)) / 255.
const uint8_t dst_factor_a = (dst_a * (256 - src_a)) >> 8;
assert(src_a + dst_factor_a < 256);
const uint8_t blend_a = src_a + dst_factor_a;
const uint32_t scale = (1UL << 24) / blend_a;
const uint8_t blend_r =
BlendChannelWebP(src, src_a, dst, dst_factor_a, scale, 0);
const uint8_t blend_g =
BlendChannelWebP(src, src_a, dst, dst_factor_a, scale, 8);
const uint8_t blend_b =
BlendChannelWebP(src, src_a, dst, dst_factor_a, scale, 16);
return (blend_r << 0) | (blend_g << 8) | (blend_b << 16) | (blend_a << 24);
}
}
// Returns two ranges (<left, width> pairs) at row 'canvas_y', that belong to
// 'src' but not 'dst'. A point range is empty if the corresponding width is 0.
static void FindBlendRangeAtRowWebP(const WebPIterator* const src,
const WebPIterator* const dst, int canvas_y,
int* const left1, int* const width1,
int* const left2, int* const width2) {
const int src_max_x = src->x_offset + src->width;
const int dst_max_x = dst->x_offset + dst->width;
const int dst_max_y = dst->y_offset + dst->height;
assert(canvas_y >= src->y_offset && canvas_y < (src->y_offset + src->height));
*left1 = -1;
*width1 = 0;
*left2 = -1;
*width2 = 0;
if (canvas_y < dst->y_offset || canvas_y >= dst_max_y ||
src->x_offset >= dst_max_x || src_max_x <= dst->x_offset) {
*left1 = src->x_offset;
*width1 = src->width;
return;
}
if (src->x_offset < dst->x_offset) {
*left1 = src->x_offset;
*width1 = dst->x_offset - src->x_offset;
}
if (src_max_x > dst_max_x) {
*left2 = dst_max_x;
*width2 = src_max_x - dst_max_x;
}
}
// Blend 'num_pixels' in 'src' over 'dst'.
static void BlendPixelRowWebP(uint32_t* const src, const uint32_t* const dst,
int num_pixels) {
for (int i = 0; i < num_pixels; ++i) {
uint32_t* const src_pixel_ptr = &src[i];
const uint8_t src_alpha = (*src_pixel_ptr >> 24) & 0xff;
if (src_alpha != 0xff) {
const uint32_t dst_pixel = dst[i];
*src_pixel_ptr = BlendPixelWebP(*src_pixel_ptr, dst_pixel);
}
}
}
// Read animated WebP bitstream 'file_str' into 'AnimatedImage' struct.
static bool ReadAnimatedWebP(const char filename[], const std::string& file_str,
AnimatedImage* const image, bool dump_frames,
const char dump_folder[]) {
bool ok = true;
const WebPData webp_data = {
reinterpret_cast<const uint8_t*>(file_str.data()), file_str.size()
};
WebPDemuxer* const demux = WebPDemux(&webp_data);
if (demux == NULL) return false;
// Animation properties.
image->canvas_width = WebPDemuxGetI(demux, WEBP_FF_CANVAS_WIDTH);
image->canvas_height = WebPDemuxGetI(demux, WEBP_FF_CANVAS_HEIGHT);
image->loop_count = WebPDemuxGetI(demux, WEBP_FF_LOOP_COUNT);
image->bgcolor = WebPDemuxGetI(demux, WEBP_FF_BACKGROUND_COLOR);
const uint32_t frame_count = WebPDemuxGetI(demux, WEBP_FF_FRAME_COUNT);
const uint32_t canvas_width = image->canvas_width;
const uint32_t canvas_height = image->canvas_height;
// Allocate frames.
AllocateFrames(image, frame_count);
// Decode and reconstruct frames.
WebPIterator prev_iter = WebPIterator();
WebPIterator curr_iter = WebPIterator();
for (uint32_t i = 0; i < frame_count; ++i) {
prev_iter = curr_iter;
// Get frame.
if (!WebPDemuxGetFrame(demux, i + 1, &curr_iter)) {
fprintf(stderr, "Error retrieving frame #%u\n", i);
return false;
}
DecodedFrame* const prev_frame = (i > 0) ? &image->frames[i - 1] : NULL;
uint8_t* const prev_rgba =
(prev_frame != NULL) ? prev_frame->rgba.data() : NULL;
DecodedFrame* const curr_frame = &image->frames[i];
uint8_t* const curr_rgba = curr_frame->rgba.data();
curr_frame->duration = curr_iter.duration;
curr_frame->is_key_frame = IsKeyFrameWebP(curr_iter, prev_iter, prev_frame,
canvas_width, canvas_height);
// TODO(urvang): The logic of decoding and reconstructing the next animated
// frame given the previous one should be a single library call (ideally a
// user-facing API), which takes care of frame disposal, blending etc.
// Initialize.
if (curr_frame->is_key_frame) {
ZeroFillCanvas(curr_rgba, canvas_width, canvas_height);
} else {
CopyCanvas(prev_rgba, curr_rgba, canvas_width, canvas_height);
if (prev_iter.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND) {
ZeroFillFrameRect(curr_rgba, canvas_width * kNumChannels,
prev_iter.x_offset, prev_iter.y_offset,
prev_iter.width, prev_iter.height);
}
}
// Decode.
const uint8_t* input = curr_iter.fragment.bytes;
const size_t input_size = curr_iter.fragment.size;
const size_t output_offset =
(curr_iter.y_offset * canvas_width + curr_iter.x_offset) * kNumChannels;
uint8_t* output = curr_rgba + output_offset;
const int output_stride = kNumChannels * canvas_width;
const size_t output_size = output_stride * curr_iter.height;
if (WebPDecodeRGBAInto(input, input_size, output, output_size,
output_stride) == NULL) {
ok = false;
break;
}
// During the decoding of current frame, we may have set some pixels to be
// transparent (i.e. alpha < 255). However, the value of each of these
// pixels should have been determined by blending it against the value of
// that pixel in the previous frame if blending method of is WEBP_MUX_BLEND.
if (i > 0 && curr_iter.blend_method == WEBP_MUX_BLEND &&
!curr_frame->is_key_frame) {
if (prev_iter.dispose_method == WEBP_MUX_DISPOSE_NONE) {
// Blend transparent pixels with pixels in previous canvas.
for (int y = 0; y < curr_iter.height; ++y) {
const size_t offset =
(curr_iter.y_offset + y) * canvas_width + curr_iter.x_offset;
BlendPixelRowWebP(reinterpret_cast<uint32_t*>(curr_rgba) + offset,
reinterpret_cast<uint32_t*>(prev_rgba) + offset,
curr_iter.width);
}
} else {
assert(prev_iter.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND);
// We need to blend a transparent pixel with its value just after
// initialization. That is, blend it with:
// * Fully transparent pixel if it belongs to prevRect <-- No-op.
// * The pixel in the previous canvas otherwise <-- Need alpha-blending.
for (int y = 0; y < curr_iter.height; ++y) {
const int canvas_y = curr_iter.y_offset + y;
int left1, width1, left2, width2;
FindBlendRangeAtRowWebP(&curr_iter, &prev_iter, canvas_y, &left1,
&width1, &left2, &width2);
if (width1 > 0) {
const size_t offset1 = canvas_y * canvas_width + left1;
BlendPixelRowWebP(reinterpret_cast<uint32_t*>(curr_rgba) + offset1,
reinterpret_cast<uint32_t*>(prev_rgba) + offset1,
width1);
}
if (width2 > 0) {
const size_t offset2 = canvas_y * canvas_width + left2;
BlendPixelRowWebP(reinterpret_cast<uint32_t*>(curr_rgba) + offset2,
reinterpret_cast<uint32_t*>(prev_rgba) + offset2,
width2);
}
}
}
}
// Needed only because we may want to compare with GIF later.
CleanupTransparentPixels(reinterpret_cast<uint32_t*>(curr_rgba),
canvas_width, canvas_height);
if (dump_frames) {
ok = ok && DumpFrame(filename, dump_folder, i, curr_rgba,
canvas_width, canvas_height);
}
}
WebPDemuxReleaseIterator(&prev_iter);
WebPDemuxReleaseIterator(&curr_iter);
WebPDemuxDelete(demux);
return ok;
}
// -----------------------------------------------------------------------------
// GIF Decoding.
// Returns true if this is a valid GIF bitstream.
static bool IsGIF(const std::string& file_str) {
const char* const cstr = file_str.c_str();
return file_str.length() > GIF_STAMP_LEN &&
(!memcmp(GIF_STAMP, cstr, GIF_STAMP_LEN) ||
!memcmp(GIF87_STAMP, cstr, GIF_STAMP_LEN) ||
!memcmp(GIF89_STAMP, cstr, GIF_STAMP_LEN));
}
#ifdef WEBP_HAVE_GIF
// 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
#if !LOCAL_GIF_PREREQ(5, 0)
// Added in v5.0
typedef struct GraphicsControlBlock {
int DisposalMode;
#define DISPOSAL_UNSPECIFIED 0 // No disposal specified
#define DISPOSE_DO_NOT 1 // Leave image in place
#define DISPOSE_BACKGROUND 2 // Set area to background color
#define DISPOSE_PREVIOUS 3 // Restore to previous content
bool UserInputFlag; // User confirmation required before disposal
int DelayTime; // Pre-display delay in 0.01sec units
int TransparentColor; // Palette index for transparency, -1 if none
#define NO_TRANSPARENT_COLOR -1
} GraphicsControlBlock;
static int DGifExtensionToGCB(const size_t GifExtensionLength,
const GifByteType* GifExtension,
GraphicsControlBlock* gcb) {
if (GifExtensionLength != 4) {
return GIF_ERROR;
}
gcb->DisposalMode = (GifExtension[0] >> 2) & 0x07;
gcb->UserInputFlag = (GifExtension[0] & 0x02) != 0;
gcb->DelayTime = GifExtension[1] | (GifExtension[2] << 8);
if (GifExtension[0] & 0x01) {
gcb->TransparentColor = static_cast<int>(GifExtension[3]);
} else {
gcb->TransparentColor = NO_TRANSPARENT_COLOR;
}
return GIF_OK;
}
static int DGifSavedExtensionToGCB(GifFileType* GifFile, int ImageIndex,
GraphicsControlBlock* gcb) {
int i;
if (ImageIndex < 0 || ImageIndex > GifFile->ImageCount - 1) {
return GIF_ERROR;
}
gcb->DisposalMode = DISPOSAL_UNSPECIFIED;
gcb->UserInputFlag = false;
gcb->DelayTime = 0;
gcb->TransparentColor = NO_TRANSPARENT_COLOR;
for (i = 0; i < GifFile->SavedImages[ImageIndex].ExtensionBlockCount; i++) {
ExtensionBlock* ep = &GifFile->SavedImages[ImageIndex].ExtensionBlocks[i];
if (ep->Function == GRAPHICS_EXT_FUNC_CODE) {
return DGifExtensionToGCB(
ep->ByteCount, reinterpret_cast<const GifByteType*>(ep->Bytes), gcb);
}
}
return GIF_ERROR;
}
#define CONTINUE_EXT_FUNC_CODE 0x00
// Signature was changed in v5.0
#define DGifOpenFileName(a, b) DGifOpenFileName(a)
#endif // !LOCAL_GIF_PREREQ(5, 0)
// Signature changed in v5.1
#if !LOCAL_GIF_PREREQ(5, 1)
#define DGifCloseFile(a, b) DGifCloseFile(a)
#endif
static 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
}
static bool IsKeyFrameGIF(const GifImageDesc& prev_desc, int prev_dispose,
const DecodedFrame* const prev_frame,
int canvas_width, int canvas_height) {
if (prev_frame == NULL) return true;
if (prev_dispose == DISPOSE_BACKGROUND) {
if (IsFullFrame(prev_desc.Width, prev_desc.Height,
canvas_width, canvas_height)) {
return true;
}
if (prev_frame->is_key_frame) return true;
}
return false;
}
static int GetTransparentIndexGIF(GifFileType* gif) {
GraphicsControlBlock first_gcb = GraphicsControlBlock();
DGifSavedExtensionToGCB(gif, 0, &first_gcb);
return first_gcb.TransparentColor;
}
static uint32_t GetBackgroundColorGIF(GifFileType* gif) {
const int transparent_index = GetTransparentIndexGIF(gif);
const ColorMapObject* const color_map = gif->SColorMap;
if (transparent_index != NO_TRANSPARENT_COLOR &&
gif->SBackGroundColor == transparent_index) {
return 0x00ffffff; // Special case: transparent white.
} else if (color_map == NULL || color_map->Colors == NULL
|| gif->SBackGroundColor >= color_map->ColorCount) {
return 0xffffffff; // Invalid: assume white.
} else {
const GifColorType color = color_map->Colors[gif->SBackGroundColor];
return (0xff << 24) |
(color.Red << 16) |
(color.Green << 8) |
(color.Blue << 0);
}
}
// Find appropriate app extension and get loop count from the next extension.
static uint32_t GetLoopCountGIF(const GifFileType* const gif) {
for (int i = 0; i < gif->ImageCount; ++i) {
const SavedImage* const image = &gif->SavedImages[i];
for (int j = 0; (j + 1) < image->ExtensionBlockCount; ++j) {
const ExtensionBlock* const eb1 = image->ExtensionBlocks + j;
const ExtensionBlock* const eb2 = image->ExtensionBlocks + j + 1;
const char* const signature = reinterpret_cast<const char*>(eb1->Bytes);
const bool signature_is_ok =
(eb1->Function == APPLICATION_EXT_FUNC_CODE) &&
(eb1->ByteCount == 11) &&
(!memcmp(signature, "NETSCAPE2.0", 11) ||
!memcmp(signature, "ANIMEXTS1.0", 11));
if (signature_is_ok &&
eb2->Function == CONTINUE_EXT_FUNC_CODE && eb2->ByteCount >= 3 &&
eb2->Bytes[0] == 1) {
return (static_cast<uint32_t>(eb2->Bytes[2]) << 8) +
(static_cast<uint32_t>(eb2->Bytes[1]) << 0);
}
}
}
return 0; // Default.
}
// Get duration of 'n'th frame in milliseconds.
static int GetFrameDurationGIF(GifFileType* gif, int n) {
GraphicsControlBlock gcb = GraphicsControlBlock();
DGifSavedExtensionToGCB(gif, n, &gcb);
return gcb.DelayTime * 10;
}
// Returns true if frame 'target' completely covers 'covered'.
static bool CoversFrameGIF(const GifImageDesc& target,
const GifImageDesc& covered) {
return target.Left <= covered.Left &&
covered.Left + covered.Width <= target.Left + target.Width &&
target.Top <= covered.Top &&
covered.Top + covered.Height <= target.Top + target.Height;
}
static void RemapPixelsGIF(const uint8_t* const src,
const ColorMapObject* const cmap,
int transparent_color, int len, uint8_t* dst) {
int i;
for (i = 0; i < len; ++i) {
if (src[i] != transparent_color) {
// If a pixel in the current frame is transparent, we don't modify it, so
// that we can see-through the corresponding pixel from an earlier frame.
const GifColorType c = cmap->Colors[src[i]];
dst[4 * i + 0] = c.Red;
dst[4 * i + 1] = c.Green;
dst[4 * i + 2] = c.Blue;
dst[4 * i + 3] = 0xff;
}
}
}
static bool ReadFrameGIF(const SavedImage* const gif_image,
const ColorMapObject* cmap, int transparent_color,
int out_stride, uint8_t* const dst) {
const GifImageDesc& image_desc = gif_image->ImageDesc;
if (image_desc.ColorMap) {
cmap = image_desc.ColorMap;
}
if (cmap == NULL || cmap->ColorCount != (1 << cmap->BitsPerPixel)) {
fprintf(stderr, "Potentially corrupt color map.\n");
return false;
}
const uint8_t* in = reinterpret_cast<uint8_t*>(gif_image->RasterBits);
uint8_t* out =
dst + image_desc.Top * out_stride + image_desc.Left * kNumChannels;
for (int j = 0; j < image_desc.Height; ++j) {
RemapPixelsGIF(in, cmap, transparent_color, image_desc.Width, out);
in += image_desc.Width;
out += out_stride;
}
return true;
}
// Read animated GIF bitstream from 'filename' into 'AnimatedImage' struct.
static bool ReadAnimatedGIF(const char filename[], AnimatedImage* const image,
bool dump_frames, const char dump_folder[]) {
GifFileType* gif = DGifOpenFileName(filename, NULL);
if (gif == NULL) {
fprintf(stderr, "Could not read file: %s.\n", filename);
return false;
}
const int gif_error = DGifSlurp(gif);
if (gif_error != GIF_OK) {
fprintf(stderr, "Could not parse image: %s.\n", filename);
GIFDisplayError(gif, gif_error);
DGifCloseFile(gif, NULL);
return false;
}
// Animation properties.
image->canvas_width = static_cast<uint32_t>(gif->SWidth);
image->canvas_height = static_cast<uint32_t>(gif->SHeight);
if (image->canvas_width > MAX_CANVAS_SIZE ||
image->canvas_height > MAX_CANVAS_SIZE) {
fprintf(stderr, "Invalid canvas dimension: %d x %d\n",
image->canvas_width, image->canvas_height);
DGifCloseFile(gif, NULL);
return false;
}
image->loop_count = GetLoopCountGIF(gif);
image->bgcolor = GetBackgroundColorGIF(gif);
const uint32_t frame_count = static_cast<uint32_t>(gif->ImageCount);
if (frame_count == 0) {
DGifCloseFile(gif, NULL);
return false;
}
if (image->canvas_width == 0 || image->canvas_height == 0) {
image->canvas_width = gif->SavedImages[0].ImageDesc.Width;
image->canvas_height = gif->SavedImages[0].ImageDesc.Height;
gif->SavedImages[0].ImageDesc.Left = 0;
gif->SavedImages[0].ImageDesc.Top = 0;
if (image->canvas_width == 0 || image->canvas_height == 0) {
fprintf(stderr, "Invalid canvas size in GIF.\n");
DGifCloseFile(gif, NULL);
return false;
}
}
// Allocate frames.
AllocateFrames(image, frame_count);
const uint32_t canvas_width = image->canvas_width;
const uint32_t canvas_height = image->canvas_height;
// Decode and reconstruct frames.
for (uint32_t i = 0; i < frame_count; ++i) {
const int canvas_width_in_bytes = canvas_width * kNumChannels;
const SavedImage* const curr_gif_image = &gif->SavedImages[i];
GraphicsControlBlock curr_gcb = GraphicsControlBlock();
DGifSavedExtensionToGCB(gif, i, &curr_gcb);
DecodedFrame* const curr_frame = &image->frames[i];
uint8_t* const curr_rgba = curr_frame->rgba.data();
curr_frame->duration = GetFrameDurationGIF(gif, i);
if (i == 0) { // Initialize as transparent.
curr_frame->is_key_frame = true;
ZeroFillCanvas(curr_rgba, canvas_width, canvas_height);
} else {
DecodedFrame* const prev_frame = &image->frames[i - 1];
const GifImageDesc& prev_desc = gif->SavedImages[i - 1].ImageDesc;
GraphicsControlBlock prev_gcb = GraphicsControlBlock();
DGifSavedExtensionToGCB(gif, i - 1, &prev_gcb);
curr_frame->is_key_frame =
IsKeyFrameGIF(prev_desc, prev_gcb.DisposalMode, prev_frame,
canvas_width, canvas_height);
if (curr_frame->is_key_frame) { // Initialize as transparent.
ZeroFillCanvas(curr_rgba, canvas_width, canvas_height);
} else {
// Initialize with previous canvas.
uint8_t* const prev_rgba = image->frames[i - 1].rgba.data();
CopyCanvas(prev_rgba, curr_rgba, canvas_width, canvas_height);
// Dispose previous frame rectangle.
bool prev_frame_disposed =
(prev_gcb.DisposalMode == DISPOSE_BACKGROUND ||
prev_gcb.DisposalMode == DISPOSE_PREVIOUS);
bool curr_frame_opaque =
(curr_gcb.TransparentColor == NO_TRANSPARENT_COLOR);
bool prev_frame_completely_covered =
curr_frame_opaque &&
CoversFrameGIF(curr_gif_image->ImageDesc, prev_desc);
if (prev_frame_disposed && !prev_frame_completely_covered) {
switch (prev_gcb.DisposalMode) {
case DISPOSE_BACKGROUND: {
ZeroFillFrameRect(curr_rgba, canvas_width_in_bytes,
prev_desc.Left, prev_desc.Top,
prev_desc.Width, prev_desc.Height);
break;
}
case DISPOSE_PREVIOUS: {
int src_frame_num = i - 2;
while (src_frame_num >= 0) {
GraphicsControlBlock src_frame_gcb = GraphicsControlBlock();
DGifSavedExtensionToGCB(gif, src_frame_num, &src_frame_gcb);
if (src_frame_gcb.DisposalMode != DISPOSE_PREVIOUS) break;
--src_frame_num;
}
if (src_frame_num >= 0) {
// Restore pixels inside previous frame rectangle to
// corresponding pixels in source canvas.
uint8_t* const src_frame_rgba =
image->frames[src_frame_num].rgba.data();
CopyFrameRectangle(src_frame_rgba, curr_rgba,
canvas_width_in_bytes,
prev_desc.Left, prev_desc.Top,
prev_desc.Width, prev_desc.Height);
} else {
// Source canvas doesn't exist. So clear previous frame
// rectangle to background.
ZeroFillFrameRect(curr_rgba, canvas_width_in_bytes,
prev_desc.Left, prev_desc.Top,
prev_desc.Width, prev_desc.Height);
}
break;
}
default:
break; // Nothing to do.
}
}
}
}
// Decode current frame.
if (!ReadFrameGIF(curr_gif_image, gif->SColorMap, curr_gcb.TransparentColor,
canvas_width_in_bytes, curr_rgba)) {
DGifCloseFile(gif, NULL);
return false;
}
if (dump_frames) {
if (!DumpFrame(filename, dump_folder, i, curr_rgba,
canvas_width, canvas_height)) {
DGifCloseFile(gif, NULL);
return false;
}
}
}
DGifCloseFile(gif, NULL);
return true;
}
#else
static bool ReadAnimatedGIF(const char filename[], AnimatedImage* const image,
bool dump_frames, const char dump_folder[]) {
(void)filename;
(void)image;
(void)dump_frames;
(void)dump_folder;
fprintf(stderr, "GIF support not compiled. Please install the libgif-dev "
"package before building.\n");
return false;
}
#endif // WEBP_HAVE_GIF
// -----------------------------------------------------------------------------
static bool ReadFile(const char filename[], std::string* filestr) {
ifstream fin(filename, ios::binary);
if (!fin.good()) return false;
ostringstream strout;
strout << fin.rdbuf();
*filestr = strout.str();
fin.close();
return true;
}
bool ReadAnimatedImage(const char filename[], AnimatedImage* const image,
bool dump_frames, const char dump_folder[]) {
std::string file_str;
if (!ReadFile(filename, &file_str)) {
fprintf(stderr, "Error reading file: %s\n", filename);
return false;
}
if (IsWebP(file_str)) {
return ReadAnimatedWebP(filename, file_str, image, dump_frames,
dump_folder);
} else if (IsGIF(file_str)) {
return ReadAnimatedGIF(filename, image, dump_frames, dump_folder);
} else {
fprintf(stderr,
"Unknown file type: %s. Supported file types are WebP and GIF\n",
filename);
return false;
}
}
static void Accumulate(double v1, double v2, double* const max_diff,
double* const sse) {
const double diff = fabs(v1 - v2);
if (diff > *max_diff) *max_diff = diff;
*sse += diff * diff;
}
void GetDiffAndPSNR(const uint8_t rgba1[], const uint8_t rgba2[],
uint32_t width, uint32_t height, bool premultiply,
int* const max_diff, double* const psnr) {
const uint32_t stride = width * kNumChannels;
const int kAlphaChannel = kNumChannels - 1;
double f_max_diff = 0.;
double sse = 0.;
for (uint32_t y = 0; y < height; ++y) {
for (uint32_t x = 0; x < stride; x += kNumChannels) {
const size_t offset = y * stride + x;
const int alpha1 = rgba1[offset + kAlphaChannel];
const int alpha2 = rgba2[offset + kAlphaChannel];
Accumulate(alpha1, alpha2, &f_max_diff, &sse);
if (!premultiply) {
for (int k = 0; k < kAlphaChannel; ++k) {
Accumulate(rgba1[offset + k], rgba2[offset + k], &f_max_diff, &sse);
}
} else {
// premultiply R/G/B channels with alpha value
for (int k = 0; k < kAlphaChannel; ++k) {
Accumulate(rgba1[offset + k] * alpha1 / 255.,
rgba2[offset + k] * alpha2 / 255.,
&f_max_diff, &sse);
}
}
}
}
*max_diff = static_cast<int>(f_max_diff);
if (*max_diff == 0) {
*psnr = 99.; // PSNR when images are identical.
} else {
sse /= stride * height;
*psnr = 10. * log10(255. * 255. / sse);
}
}
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