cc/resources/display_item_list.cc

// Copyright 2014 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 "cc/resources/display_item_list.h"

#include <string>

#include "base/trace_event/trace_event.h"
#include "base/trace_event/trace_event_argument.h"
#include "cc/base/math_util.h"
#include "cc/debug/picture_debug_util.h"
#include "cc/debug/traced_picture.h"
#include "cc/debug/traced_value.h"
#include "third_party/skia/include/core/SkCanvas.h"
#include "third_party/skia/include/core/SkDrawPictureCallback.h"
#include "third_party/skia/include/core/SkPictureRecorder.h"
#include "third_party/skia/include/utils/SkPictureUtils.h"
#include "ui/gfx/skia_util.h"

namespace cc {

DisplayItemList::DisplayItemList()
    : is_suitable_for_gpu_rasterization_(true), approximate_op_count_(0) {
}

scoped_refptr<DisplayItemList> DisplayItemList::Create() {
  return make_scoped_refptr(new DisplayItemList());
}

DisplayItemList::~DisplayItemList() {
}

void DisplayItemList::Raster(SkCanvas* canvas,
                             SkDrawPictureCallback* callback,
                             float contents_scale) const {
  if (!picture_) {
    canvas->save();
    canvas->scale(contents_scale, contents_scale);
    for (size_t i = 0; i < items_.size(); ++i) {
      items_[i]->Raster(canvas, callback);
    }
    canvas->restore();
  } else {
    DCHECK(picture_);

    canvas->save();
    canvas->scale(contents_scale, contents_scale);
    if (callback) {
      // If we have a callback, we need to call |draw()|, |drawPicture()|
      // doesn't take a callback.  This is used by |AnalysisCanvas| to early
      // out.
      picture_->playback(canvas, callback);
    } else {
      // Prefer to call |drawPicture()| on the canvas since it could place the
      // entire picture on the canvas instead of parsing the skia operations.
      canvas->drawPicture(picture_.get());
    }
    canvas->restore();
  }
}

void DisplayItemList::CreateAndCacheSkPicture() {
  // Convert to an SkPicture for faster rasterization. Code is identical to
  // that in Picture::Record.
  SkRTreeFactory factory;
  SkPictureRecorder recorder;
  skia::RefPtr<SkCanvas> canvas;
  canvas = skia::SharePtr(recorder.beginRecording(
      layer_rect_.width(), layer_rect_.height(), &factory));
  canvas->translate(-layer_rect_.x(), -layer_rect_.y());
  canvas->clipRect(gfx::RectToSkRect(layer_rect_));
  for (size_t i = 0; i < items_.size(); ++i)
    items_[i]->Raster(canvas.get(), NULL);
  picture_ = skia::AdoptRef(recorder.endRecording());
  DCHECK(picture_);
}

void DisplayItemList::AppendItem(scoped_ptr<DisplayItem> item) {
  is_suitable_for_gpu_rasterization_ &= item->IsSuitableForGpuRasterization();
  approximate_op_count_ += item->ApproximateOpCount();
  items_.push_back(item.Pass());
}

bool DisplayItemList::IsSuitableForGpuRasterization() const {
  // This is more permissive than Picture's implementation, since none of the
  // items might individually trigger a veto even though they collectively have
  // enough "bad" operations that a corresponding Picture would get vetoed.
  return is_suitable_for_gpu_rasterization_;
}

int DisplayItemList::ApproximateOpCount() const {
  return approximate_op_count_;
}

size_t DisplayItemList::PictureMemoryUsage() const {
  size_t total_size = 0;

  for (const auto& item : items_) {
    total_size += item->PictureMemoryUsage();
  }

  if (picture_)
    total_size += SkPictureUtils::ApproximateBytesUsed(picture_.get());

  return total_size;
}

scoped_refptr<base::trace_event::ConvertableToTraceFormat>
DisplayItemList::AsValue() const {
  scoped_refptr<base::trace_event::TracedValue> state =
      new base::trace_event::TracedValue();

  state->SetInteger("length", items_.size());
  state->BeginArray("params.items");
  for (const DisplayItem* item : items_) {
    item->AsValueInto(state.get());
  }
  state->EndArray();
  state->SetValue("params.layer_rect",
                  MathUtil::AsValue(layer_rect_).release());

  SkPictureRecorder recorder;
  SkCanvas* canvas =
      recorder.beginRecording(layer_rect_.width(), layer_rect_.height());
  canvas->translate(-layer_rect_.x(), -layer_rect_.y());
  canvas->clipRect(gfx::RectToSkRect(layer_rect_));
  for (size_t i = 0; i < items_.size(); ++i)
    items_[i]->RasterForTracing(canvas);
  skia::RefPtr<SkPicture> picture = skia::AdoptRef(recorder.endRecording());

  std::string b64_picture;
  PictureDebugUtil::SerializeAsBase64(picture.get(), &b64_picture);
  state->SetString("skp64", b64_picture);

  return state;
}

void DisplayItemList::EmitTraceSnapshot() const {
  TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(
      TRACE_DISABLED_BY_DEFAULT("cc.debug") "," TRACE_DISABLED_BY_DEFAULT(
          "devtools.timeline.picture"),
      "cc::DisplayItemList", this, AsValue());
}

}  // namespace cc