Browser side changes for software compositing

content/renderer/gpu/compositor_software_output_device.cc

+// Copyright (c) 2013 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 "content/renderer/gpu/compositor_software_output_device.h"
+
+#include "base/logging.h"
+#include "cc/output/software_frame_data.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "third_party/skia/include/core/SkDevice.h"
+#include "third_party/skia/include/core/SkPixelRef.h"
+#include "ui/gfx/skia_util.h"
+
+namespace content {
+
+namespace {
+
+class CompareById {
+ public:
+  CompareById(const TransportDIB::Id& id)
+      : id_(id) {
+  }
+
+  bool operator()(const TransportDIB* dib) const {
+    return dib->id() == id_;
+  }
+
+ private:
+  TransportDIB::Id id_;
+};
+
+}  // namespace
+
+CompositorSoftwareOutputDevice::CompositorSoftwareOutputDevice()
+    : front_buffer_(0),
+      last_buffer_(-1),
+      num_free_buffers_(0),
+      sequence_num_(0) {
+  DetachFromThread();
+}
+
+CompositorSoftwareOutputDevice::~CompositorSoftwareOutputDevice() {
+  DCHECK(CalledOnValidThread());
+}
+
+TransportDIB* CompositorSoftwareOutputDevice::CreateDIB() {
+  const size_t size = 4 * viewport_size_.GetArea();
+  TransportDIB* dib = TransportDIB::Create(size, sequence_num_++);
+  CHECK(dib);
+  bool success = dib->Map();
+  CHECK(success);
+  return dib;
+}
+
+void CompositorSoftwareOutputDevice::Resize(gfx::Size viewport_size) {
+  DCHECK(CalledOnValidThread());
+
+  // Reset last_buffer_ so that we don't copy over old damage.
+  last_buffer_ = -1;
+
+  if (viewport_size_ == viewport_size)
+    return;
+  viewport_size_ = viewport_size;
+
+  // Reallocate dibs_.
+  dibs_.clear();
+  for (size_t i = 0; i < kNumBuffers; i++)
+    dibs_.push_back(CreateDIB());
+
+  front_buffer_ = 0;
+  num_free_buffers_ = kNumBuffers;
+}
+
+SkCanvas* CompositorSoftwareOutputDevice::BeginPaint(gfx::Rect damage_rect) {
+  DCHECK(CalledOnValidThread());
+
+  if (num_free_buffers_ == 0) {
+    dibs_.insert(dibs_.begin() + front_buffer_, CreateDIB());
+    num_free_buffers_++;
+  }
+
+  TransportDIB* front_dib = dibs_[front_buffer_];
+  DCHECK(front_dib);
+  DCHECK(front_dib->memory());
+
+  // Set up a canvas for the front_dib.
+  bitmap_.setConfig(SkBitmap::kARGB_8888_Config,
+                    viewport_size_.width(),
+                    viewport_size_.height());
+  bitmap_.setPixels(front_dib->memory());
+  device_ = skia::AdoptRef(new SkDevice(bitmap_));
+  canvas_ = skia::AdoptRef(new SkCanvas(device_.get()));
+
+  // Copy damage_rect_ from last_buffer_ to front_buffer_.
+  if (last_buffer_ != -1 && !damage_rect.Contains(damage_rect_)) {
+    DCHECK_EQ(std::abs(front_buffer_ - last_buffer_ - 1) % dibs_.size(), 0u);
+
+    TransportDIB* last_dib = dibs_[last_buffer_];
+    SkBitmap back_bitmap;
+    back_bitmap.setConfig(SkBitmap::kARGB_8888_Config,
+                          viewport_size_.width(),
+                          viewport_size_.height());
+    back_bitmap.setPixels(last_dib->memory());
+
+    SkRect last_damage = gfx::RectToSkRect(damage_rect_);
+    canvas_->drawBitmapRectToRect(back_bitmap, &last_damage, last_damage, NULL);
+  }
+  damage_rect_ = damage_rect;
+
+  return canvas_.get();
+}
+
+void CompositorSoftwareOutputDevice::EndPaint(
+    cc::SoftwareFrameData* frame_data) {
+  DCHECK(CalledOnValidThread());
+  DCHECK_GE(kNumBuffers, dibs_.size());
+
+  if (frame_data) {
+    frame_data->size = viewport_size_;
+    frame_data->damage_rect = damage_rect_;
+    frame_data->dib_id = dibs_[front_buffer_]->id();
+  }
+
+  last_buffer_ = front_buffer_;
+  front_buffer_ = (front_buffer_ + 1) % dibs_.size();
+  --num_free_buffers_;
+  DCHECK_GE(num_free_buffers_, 0);
+}
+
+void CompositorSoftwareOutputDevice::ReclaimDIB(const TransportDIB::Id& id) {
+  DCHECK(CalledOnValidThread());
+
+  // The reclaimed handle might not be among the currently
+  // active dibs if we got a resize event in the mean time.
+  ScopedVector<TransportDIB>::iterator it =
+      std::find_if(dibs_.begin(), dibs_.end(), CompareById(id));
+  if (it != dibs_.end())
+    ++num_free_buffers_;
+
+  DCHECK_LE(static_cast<size_t>(num_free_buffers_), dibs_.size());
+}
+
+}  // namespace content