mirror of
https://github.com/webmproject/libwebp.git
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839 lines
30 KiB
C++
839 lines
30 KiB
C++
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// Copyright 2015 Google Inc. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the COPYING file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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// -----------------------------------------------------------------------------
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//
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// Utilities for animated images
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#include "./anim_util.h"
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#include <assert.h>
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#include <math.h>
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#include <stdio.h>
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#include <string.h>
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#include <fstream>
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#include <sstream> // for 'ostringstream'.
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#ifdef WEBP_HAVE_GIF
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#include <gif_lib.h>
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#endif
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#include "webp/format_constants.h"
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#include "webp/decode.h"
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#include "webp/demux.h"
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using std::ifstream;
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using std::ios;
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using std::ofstream;
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using std::ostringstream;
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static const int kNumChannels = 4;
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// -----------------------------------------------------------------------------
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// Common utilities.
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// Returns true if the frame covers the full canvas.
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static bool IsFullFrame(int width, int height,
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int canvas_width, int canvas_height) {
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return (width == canvas_width && height == canvas_height);
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}
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static void AllocateFrames(AnimatedImage* const image, uint32_t frame_count) {
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image->frames.resize(frame_count);
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for (size_t i = 0; i < image->frames.size(); ++i) {
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const size_t rgba_size =
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image->canvas_width * kNumChannels * image->canvas_height;
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image->frames[i].rgba.resize(rgba_size);
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}
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}
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// Clear the canvas to transparent.
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static void ZeroFillCanvas(uint8_t* rgba,
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uint32_t canvas_width, uint32_t canvas_height) {
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memset(rgba, 0, canvas_width * kNumChannels * canvas_height);
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}
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// Clear given frame rectangle to transparent.
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static void ZeroFillFrameRect(uint8_t* rgba, int rgba_stride, int x_offset,
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int y_offset, int width, int height) {
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assert(width * kNumChannels <= rgba_stride);
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rgba += y_offset * rgba_stride + x_offset * kNumChannels;
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for (int j = 0; j < height; ++j) {
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memset(rgba, 0, width * kNumChannels);
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rgba += rgba_stride;
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}
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}
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// Copy width * height pixels from 'src' to 'dst'.
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static void CopyCanvas(const uint8_t* src, uint8_t* dst,
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uint32_t width, uint32_t height) {
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assert(src != NULL && dst != NULL);
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memcpy(dst, src, width * kNumChannels * height);
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}
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// Copy pixels in the given rectangle from 'src' to 'dst' honoring the 'stride'.
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static void CopyFrameRectangle(const uint8_t* src, uint8_t* dst, int stride,
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int x_offset, int y_offset,
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int width, int height) {
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const int width_in_bytes = width * kNumChannels;
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assert(width_in_bytes <= stride);
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const size_t offset = y_offset * stride + x_offset * kNumChannels;
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src += offset;
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dst += offset;
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for (int j = 0; j < height; ++j) {
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memcpy(dst, src, width_in_bytes);
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src += stride;
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dst += stride;
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}
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}
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// Canonicalize all transparent pixels to transparent black to aid comparison.
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static void CleanupTransparentPixels(uint32_t* rgba,
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uint32_t width, uint32_t height) {
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const uint32_t* const rgba_end = rgba + width * height;
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while (rgba < rgba_end) {
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const uint8_t alpha = (*rgba >> 24) & 0xff;
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if (alpha == 0) {
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*rgba = 0;
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}
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++rgba;
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}
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}
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// Dump frame to a PAM file.
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// Returns true on success.
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static bool DumpFrame(const char filename[], const char dump_folder[],
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uint32_t frame_num, const uint8_t rgba[],
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int canvas_width, int canvas_height) {
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const std::string filename_str = filename;
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const size_t slash_idx = filename_str.find_last_of("/\\");
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const std::string base_name = (slash_idx != std::string::npos)
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? filename_str.substr(slash_idx + 1)
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: filename_str;
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ostringstream dump_file;
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dump_file << dump_folder << "/" << base_name << "_frame_" << frame_num
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<< ".pam";
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ofstream fout(dump_file.str().c_str(), ios::binary | ios::out);
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if (!fout.good()) {
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fprintf(stderr, "Error opening file for writing: %s\n",
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dump_file.str().c_str());
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return false;
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}
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fout << "P7\nWIDTH " << canvas_width << "\nHEIGHT " << canvas_height
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<< "\nDEPTH 4\nMAXVAL 255\nTUPLTYPE RGB_ALPHA\nENDHDR\n";
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for (int y = 0; y < canvas_height; ++y) {
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fout.write(
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reinterpret_cast<const char*>(rgba) + y * canvas_width * kNumChannels,
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canvas_width * kNumChannels);
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if (!fout.good()) {
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fprintf(stderr, "Error writing to file: %s\n", dump_file.str().c_str());
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return 0;
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}
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}
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fout.close();
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return true;
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}
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// -----------------------------------------------------------------------------
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// WebP Decoding.
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// Returns true if this is a valid WebP bitstream.
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static bool IsWebP(const std::string& file_str) {
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return WebPGetInfo(reinterpret_cast<const uint8_t*>(file_str.c_str()),
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file_str.length(), NULL, NULL) != 0;
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}
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// Returns true if the current frame is a key-frame.
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static bool IsKeyFrameWebP(const WebPIterator& curr, const WebPIterator& prev,
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const DecodedFrame* const prev_frame,
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int canvas_width, int canvas_height) {
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if (prev_frame == NULL) {
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return true;
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} else if ((!curr.has_alpha || curr.blend_method == WEBP_MUX_NO_BLEND) &&
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IsFullFrame(curr.width, curr.height,
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canvas_width, canvas_height)) {
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return true;
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} else {
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return (prev.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND) &&
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(IsFullFrame(prev.width, prev.height, canvas_width, canvas_height) ||
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prev_frame->is_key_frame);
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}
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}
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// Blend a single channel of 'src' over 'dst', given their alpha channel values.
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static uint8_t BlendChannelWebP(uint32_t src, uint8_t src_a, uint32_t dst,
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uint8_t dst_a, uint32_t scale, int shift) {
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const uint8_t src_channel = (src >> shift) & 0xff;
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const uint8_t dst_channel = (dst >> shift) & 0xff;
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const uint32_t blend_unscaled = src_channel * src_a + dst_channel * dst_a;
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assert(blend_unscaled < (1ULL << 32) / scale);
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return (blend_unscaled * scale) >> 24;
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}
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// Blend 'src' over 'dst' assuming they are NOT pre-multiplied by alpha.
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static uint32_t BlendPixelWebP(uint32_t src, uint32_t dst) {
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const uint8_t src_a = (src >> 24) & 0xff;
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if (src_a == 0) {
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return dst;
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} else {
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const uint8_t dst_a = (dst >> 24) & 0xff;
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// This is the approximate integer arithmetic for the actual formula:
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// dst_factor_a = (dst_a * (255 - src_a)) / 255.
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const uint8_t dst_factor_a = (dst_a * (256 - src_a)) >> 8;
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assert(src_a + dst_factor_a < 256);
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const uint8_t blend_a = src_a + dst_factor_a;
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const uint32_t scale = (1UL << 24) / blend_a;
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const uint8_t blend_r =
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BlendChannelWebP(src, src_a, dst, dst_factor_a, scale, 0);
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const uint8_t blend_g =
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BlendChannelWebP(src, src_a, dst, dst_factor_a, scale, 8);
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const uint8_t blend_b =
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BlendChannelWebP(src, src_a, dst, dst_factor_a, scale, 16);
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return (blend_r << 0) | (blend_g << 8) | (blend_b << 16) | (blend_a << 24);
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}
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}
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// Returns two ranges (<left, width> pairs) at row 'canvas_y', that belong to
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// 'src' but not 'dst'. A point range is empty if the corresponding width is 0.
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static void FindBlendRangeAtRowWebP(const WebPIterator* const src,
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const WebPIterator* const dst, int canvas_y,
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int* const left1, int* const width1,
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int* const left2, int* const width2) {
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const int src_max_x = src->x_offset + src->width;
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const int dst_max_x = dst->x_offset + dst->width;
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const int dst_max_y = dst->y_offset + dst->height;
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assert(canvas_y >= src->y_offset && canvas_y < (src->y_offset + src->height));
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*left1 = -1;
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*width1 = 0;
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*left2 = -1;
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*width2 = 0;
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if (canvas_y < dst->y_offset || canvas_y >= dst_max_y ||
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src->x_offset >= dst_max_x || src_max_x <= dst->x_offset) {
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*left1 = src->x_offset;
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*width1 = src->width;
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return;
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}
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if (src->x_offset < dst->x_offset) {
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*left1 = src->x_offset;
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*width1 = dst->x_offset - src->x_offset;
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}
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if (src_max_x > dst_max_x) {
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*left2 = dst_max_x;
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*width2 = src_max_x - dst_max_x;
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}
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}
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// Blend 'num_pixels' in 'src' over 'dst'.
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static void BlendPixelRowWebP(uint32_t* const src, const uint32_t* const dst,
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int num_pixels) {
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for (int i = 0; i < num_pixels; ++i) {
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uint32_t* const src_pixel_ptr = &src[i];
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const uint8_t src_alpha = (*src_pixel_ptr >> 24) & 0xff;
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if (src_alpha != 0xff) {
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const uint32_t dst_pixel = dst[i];
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*src_pixel_ptr = BlendPixelWebP(*src_pixel_ptr, dst_pixel);
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}
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}
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}
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// Read animated WebP bitstream 'file_str' into 'AnimatedImage' struct.
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static bool ReadAnimatedWebP(const char filename[], const std::string& file_str,
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AnimatedImage* const image, bool dump_frames,
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const char dump_folder[]) {
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bool ok = true;
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const WebPData webp_data = {
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reinterpret_cast<const uint8_t*>(file_str.data()), file_str.size()
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};
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WebPDemuxer* const demux = WebPDemux(&webp_data);
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if (demux == NULL) return false;
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// Animation properties.
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image->canvas_width = WebPDemuxGetI(demux, WEBP_FF_CANVAS_WIDTH);
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image->canvas_height = WebPDemuxGetI(demux, WEBP_FF_CANVAS_HEIGHT);
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image->loop_count = WebPDemuxGetI(demux, WEBP_FF_LOOP_COUNT);
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image->bgcolor = WebPDemuxGetI(demux, WEBP_FF_BACKGROUND_COLOR);
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const uint32_t frame_count = WebPDemuxGetI(demux, WEBP_FF_FRAME_COUNT);
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const uint32_t canvas_width = image->canvas_width;
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const uint32_t canvas_height = image->canvas_height;
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// Allocate frames.
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AllocateFrames(image, frame_count);
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// Decode and reconstruct frames.
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WebPIterator prev_iter = WebPIterator();
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WebPIterator curr_iter = WebPIterator();
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for (uint32_t i = 0; i < frame_count; ++i) {
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prev_iter = curr_iter;
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// Get frame.
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if (!WebPDemuxGetFrame(demux, i + 1, &curr_iter)) {
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fprintf(stderr, "Error retrieving frame #%u\n", i);
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return false;
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}
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DecodedFrame* const prev_frame = (i > 0) ? &image->frames[i - 1] : NULL;
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uint8_t* const prev_rgba =
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(prev_frame != NULL) ? prev_frame->rgba.data() : NULL;
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DecodedFrame* const curr_frame = &image->frames[i];
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uint8_t* const curr_rgba = curr_frame->rgba.data();
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curr_frame->duration = curr_iter.duration;
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curr_frame->is_key_frame = IsKeyFrameWebP(curr_iter, prev_iter, prev_frame,
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canvas_width, canvas_height);
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// TODO(urvang): The logic of decoding and reconstructing the next animated
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// frame given the previous one should be a single library call (ideally a
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// user-facing API), which takes care of frame disposal, blending etc.
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// Initialize.
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if (curr_frame->is_key_frame) {
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ZeroFillCanvas(curr_rgba, canvas_width, canvas_height);
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} else {
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CopyCanvas(prev_rgba, curr_rgba, canvas_width, canvas_height);
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if (prev_iter.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND) {
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ZeroFillFrameRect(curr_rgba, canvas_width * kNumChannels,
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prev_iter.x_offset, prev_iter.y_offset,
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prev_iter.width, prev_iter.height);
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}
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}
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// Decode.
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const uint8_t* input = curr_iter.fragment.bytes;
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const size_t input_size = curr_iter.fragment.size;
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const size_t output_offset =
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(curr_iter.y_offset * canvas_width + curr_iter.x_offset) * kNumChannels;
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uint8_t* output = curr_rgba + output_offset;
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const int output_stride = kNumChannels * canvas_width;
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const size_t output_size = output_stride * curr_iter.height;
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if (WebPDecodeRGBAInto(input, input_size, output, output_size,
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output_stride) == NULL) {
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ok = false;
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break;
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}
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// During the decoding of current frame, we may have set some pixels to be
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// transparent (i.e. alpha < 255). However, the value of each of these
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// pixels should have been determined by blending it against the value of
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// that pixel in the previous frame if blending method of is WEBP_MUX_BLEND.
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if (i > 0 && curr_iter.blend_method == WEBP_MUX_BLEND &&
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!curr_frame->is_key_frame) {
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if (prev_iter.dispose_method == WEBP_MUX_DISPOSE_NONE) {
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// Blend transparent pixels with pixels in previous canvas.
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for (int y = 0; y < curr_iter.height; ++y) {
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const size_t offset =
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(curr_iter.y_offset + y) * canvas_width + curr_iter.x_offset;
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BlendPixelRowWebP(reinterpret_cast<uint32_t*>(curr_rgba) + offset,
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reinterpret_cast<uint32_t*>(prev_rgba) + offset,
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curr_iter.width);
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}
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} else {
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assert(prev_iter.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND);
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// We need to blend a transparent pixel with its value just after
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// initialization. That is, blend it with:
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// * Fully transparent pixel if it belongs to prevRect <-- No-op.
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// * The pixel in the previous canvas otherwise <-- Need alpha-blending.
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for (int y = 0; y < curr_iter.height; ++y) {
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const int canvas_y = curr_iter.y_offset + y;
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int left1, width1, left2, width2;
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FindBlendRangeAtRowWebP(&curr_iter, &prev_iter, canvas_y, &left1,
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&width1, &left2, &width2);
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if (width1 > 0) {
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const size_t offset1 = canvas_y * canvas_width + left1;
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BlendPixelRowWebP(reinterpret_cast<uint32_t*>(curr_rgba) + offset1,
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reinterpret_cast<uint32_t*>(prev_rgba) + offset1,
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width1);
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}
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if (width2 > 0) {
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const size_t offset2 = canvas_y * canvas_width + left2;
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BlendPixelRowWebP(reinterpret_cast<uint32_t*>(curr_rgba) + offset2,
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reinterpret_cast<uint32_t*>(prev_rgba) + offset2,
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width2);
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}
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}
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}
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}
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// Needed only because we may want to compare with GIF later.
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CleanupTransparentPixels(reinterpret_cast<uint32_t*>(curr_rgba),
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canvas_width, canvas_height);
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||
|
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;
|
||
|
}
|
||
|
}
|
||
|
|
||
|
void GetDiffAndPSNR(const uint8_t rgba1[], const uint8_t rgba2[],
|
||
|
uint32_t width, uint32_t height, int* const max_diff,
|
||
|
double* const psnr) {
|
||
|
const uint32_t stride = width * kNumChannels;
|
||
|
*max_diff = 0;
|
||
|
double sse = 0.;
|
||
|
for (uint32_t y = 0; y < height; ++y) {
|
||
|
for (uint32_t x = 0; x < stride; ++x) {
|
||
|
const size_t offset = y * stride + x;
|
||
|
const int diff = abs(rgba1[offset] - rgba2[offset]);
|
||
|
if (diff > *max_diff) *max_diff = diff;
|
||
|
sse += diff * diff;
|
||
|
}
|
||
|
}
|
||
|
if (*max_diff == 0) {
|
||
|
*psnr = 99.; // PSNR when images are identical.
|
||
|
} else {
|
||
|
sse /= stride * height;
|
||
|
*psnr = 10. * log10(255. * 255. / sse);
|
||
|
}
|
||
|
}
|