Add support for encoding/decoding WebP images.

blimp/client/feature/compositor/decoding_image_generator.cc

Index: blimp/client/feature/compositor/decoding_image_generator.cc
diff --git a/blimp/client/feature/compositor/decoding_image_generator.cc b/blimp/client/feature/compositor/decoding_image_generator.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b2239c538ddd5a12aeb4c4872516f0e2f67c6992
--- /dev/null
+++ b/blimp/client/feature/compositor/decoding_image_generator.cc
@@ -0,0 +1,58 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "blimp/client/feature/compositor/decoding_image_generator.h"
+
+#include "blimp/common/compositor/webp_decoder.h"
+#include "third_party/libwebp/webp/decode.h"
+#include "third_party/libwebp/webp/demux.h"
+#include "third_party/skia/include/core/SkData.h"
+
+namespace blimp {
+namespace client {
+
+SkImageGenerator* DecodingImageGenerator::create(SkData* data) {
+  WebPData inputData = {reinterpret_cast<const uint8_t*>(data->data()),
+                        data->size()};
+  WebPDemuxState demuxState(WEBP_DEMUX_PARSING_HEADER);
+  WebPDemuxer* demux = WebPDemuxPartial(&inputData, &demuxState);
+
+  uint32_t width = WebPDemuxGetI(demux, WEBP_FF_CANVAS_WIDTH);
+  uint32_t height = WebPDemuxGetI(demux, WEBP_FF_CANVAS_HEIGHT);
+
+  const SkImageInfo info = SkImageInfo::MakeN32Premul(width, height);
+  return new DecodingImageGenerator(info, data->data(), data->size());
+}
+
+DecodingImageGenerator::DecodingImageGenerator(const SkImageInfo info,
+                                               const void* data,
+                                               size_t size)
+    : SkImageGenerator(info) {
+  WebPDecoder(data, size, &decoded_bitmap_);
+}
+
+DecodingImageGenerator::~DecodingImageGenerator() {}
+
+bool DecodingImageGenerator::onGetPixels(const SkImageInfo& info,
+                                         void* pixels,
+                                         size_t rowBytes,
+                                         SkPMColor table[],
+                                         int* tableCount) {
+  SkAutoLockPixels bitmapLock(decoded_bitmap_);
+  if (decoded_bitmap_.getPixels() != pixels) {
+    return decoded_bitmap_.copyPixelsTo(pixels, rowBytes * info.height(),
+                                        rowBytes);
+  }
+  return true;
+}
+
+bool DecodingImageGenerator::onGetYUV8Planes(SkISize sizes[3],
+                                             void* planes[3],
+                                             size_t rowBytes[3],
+                                             SkYUVColorSpace*) {
+  return false;
+}
+
+}  // namespace client
+}  // namespace blimp