text: // 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 "chrome/browser/android/thumbnail/thumbnail.h"
  
  #include "base/bind.h"
  #include "base/location.h"
  #include "base/logging.h"
  #include "base/memory/ptr_util.h"
  #include "base/threading/thread_task_runner_handle.h"
  #include "third_party/skia/include/core/SkBitmap.h"
  #include "third_party/skia/include/core/SkCanvas.h"
  #include "ui/android/resources/ui_resource_provider.h"
  #include "ui/gfx/geometry/size_conversions.h"
  
  namespace {
  
  SkBitmap CreateSmallHolderBitmap() {
    SkBitmap small_bitmap;
    small_bitmap.allocPixels(
        SkImageInfo::Make(1, 1, kRGBA_8888_SkColorType, kOpaque_SkAlphaType));
    SkCanvas canvas(small_bitmap);
    canvas.drawColor(SK_ColorWHITE);
    small_bitmap.setImmutable();
    return small_bitmap;
  }
  
  }  // anonymous namespace
  
  std::unique_ptr<Thumbnail> Thumbnail::Create(
      TabId tab_id,
      const base::Time& time_stamp,
      float scale,
      ui::UIResourceProvider* ui_resource_provider,
      ThumbnailDelegate* thumbnail_delegate) {
    return base::WrapUnique(new Thumbnail(
        tab_id, time_stamp, scale, ui_resource_provider, thumbnail_delegate));
  }
  
  Thumbnail::Thumbnail(TabId tab_id,
                       const base::Time& time_stamp,
                       float scale,
                       ui::UIResourceProvider* ui_resource_provider,
                       ThumbnailDelegate* thumbnail_delegate)
      : tab_id_(tab_id),
        time_stamp_(time_stamp),
        scale_(scale),
        bitmap_(gfx::Size(1, 1), true),
        ui_resource_id_(0),
        retrieved_(false),
        ui_resource_provider_(ui_resource_provider),
        thumbnail_delegate_(thumbnail_delegate),
        weak_factory_(this) {
  }
  
  Thumbnail::~Thumbnail() {
    ClearUIResourceId();
  }
  
  void Thumbnail::SetBitmap(const SkBitmap& bitmap) {
    DCHECK(!bitmap.empty());
    retrieved_ = false;
    ClearUIResourceId();
    scaled_content_size_ =
        gfx::ScaleSize(gfx::SizeF(bitmap.width(), bitmap.height()), 1.f / scale_);
    scaled_data_size_ = scaled_content_size_;
    bitmap_ = cc::UIResourceBitmap(bitmap);
  }
  
  void Thumbnail::SetCompressedBitmap(sk_sp<SkPixelRef> compressed_bitmap,
                                      const gfx::Size& content_size) {
    DCHECK(compressed_bitmap);
    DCHECK(!content_size.IsEmpty());
    retrieved_ = false;
    ClearUIResourceId();
    gfx::Size data_size(compressed_bitmap->width(), compressed_bitmap->height());
    scaled_content_size_ = gfx::ScaleSize(gfx::SizeF(content_size), 1.f / scale_);
    scaled_data_size_ = gfx::ScaleSize(gfx::SizeF(data_size), 1.f / scale_);
    bitmap_ = cc::UIResourceBitmap(std::move(compressed_bitmap), data_size);
  }
  
  void Thumbnail::CreateUIResource() {
    DCHECK(ui_resource_provider_);
    if (!ui_resource_id_)
      ui_resource_id_ = ui_resource_provider_->CreateUIResource(this);
  }
  
  cc::UIResourceBitmap Thumbnail::GetBitmap(cc::UIResourceId uid,
                                            bool resource_lost) {
    if (retrieved_) {
      // InvalidateCachedThumbnail() causes |this| to be deleted, so
      // don't delete the resource while LayerTeeHost calls into |this|
      // to avoid reentry there.
      base::ThreadTaskRunnerHandle::Get()->PostTask(
          FROM_HERE,
          base::Bind(&Thumbnail::DoInvalidate, weak_factory_.GetWeakPtr()));
      return bitmap_;
    }
  
    retrieved_ = true;
  
    cc::UIResourceBitmap old_bitmap(bitmap_);
    // Return a place holder for all other calls to GetBitmap.
    bitmap_ = cc::UIResourceBitmap(CreateSmallHolderBitmap());
    return old_bitmap;
  }
  
  void Thumbnail::DoInvalidate() {
    if (thumbnail_delegate_)
      thumbnail_delegate_->InvalidateCachedThumbnail(this);
  }
  
  void Thumbnail::ClearUIResourceId() {
    if (ui_resource_id_ && ui_resource_provider_)
      ui_resource_provider_->DeleteUIResource(ui_resource_id_);
    ui_resource_id_ = 0;
  }
  