cc/paint/discardable_image_map.cc - chromium/src - Git at Google

 // Copyright 2015 The Chromium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "cc/paint/discardable_image_map.h"

 #include <stddef.h>

 #include <algorithm>
 #include <limits>

 #include "base/auto_reset.h"
 #include "base/check.h"
 #include "base/containers/adapters.h"
 #include "base/memory/raw_ptr.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/no_destructor.h"
 #include "base/sequence_checker.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/paint/image_provider.h"
 #include "cc/paint/paint_filter.h"
 #include "cc/paint/paint_op_buffer.h"
 #include "cc/paint/paint_op_buffer_iterator.h"
 #include "cc/paint/skottie_wrapper.h"
 #include "third_party/skia/include/utils/SkNoDrawCanvas.h"
 #include "ui/gfx/display_color_spaces.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/geometry/skia_conversions.h"

 namespace cc {
 namespace {
 const int kMaxRectsSize = 256;

 class DiscardableImageGenerator {
  public:
   DiscardableImageGenerator(int width,
                             int height,
                             const PaintOpBuffer& buffer) {
     SkNoDrawCanvas canvas(width, height);
     GatherDiscardableImages(buffer, nullptr, &canvas);
   }
   ~DiscardableImageGenerator() = default;

   std::vector<std::pair<DrawImage, gfx::Rect>> TakeImages() {
     return std::move(image_set_);
   }
   base::flat_map<PaintImage::Id, DiscardableImageMap::Rects>
   TakeImageIdToRectsMap() {
     return std::move(image_id_to_rects_);
   }
   base::flat_map<PaintImage::Id, PaintImage::DecodingMode>
   TakeDecodingModeMap() {
     return std::move(decoding_mode_map_);
   }
   std::vector<DiscardableImageMap::AnimatedImageMetadata>
   TakeAnimatedImagesMetadata() {
     return std::move(animated_images_metadata_);
   }
   std::vector<DiscardableImageMap::PaintWorkletInputWithImageId>
   TakePaintWorkletInputs() {
     return std::move(paint_worklet_inputs_);
   }

   gfx::ContentColorUsage content_color_usage() const {
     return content_color_usage_;
   }
   bool contains_hbd_images() const { return contains_hbd_images_; }

  private:
   class ImageGatheringProvider : public ImageProvider {
    public:
     ImageGatheringProvider(DiscardableImageGenerator* generator,
                            const gfx::Rect& op_rect)
         : generator_(generator), op_rect_(op_rect) {}
     ~ImageGatheringProvider() override = default;

     ScopedResult GetRasterContent(const DrawImage& draw_image) override {
       generator_->AddImage(draw_image.paint_image(), false,
                            SkRect::Make(draw_image.src_rect()), op_rect_,
                            SkM44(), draw_image.filter_quality());
       return ScopedResult();
     }

    private:
     raw_ptr<DiscardableImageGenerator> generator_;
     gfx::Rect op_rect_;
   };

   // Adds discardable images from |buffer| to the set of images tracked by
   // this generator. If |buffer| is being used in a DrawOp that requires
   // rasterization of the buffer as a pre-processing step for execution of the
   // op (for instance, with PaintRecord backed PaintShaders),
   // |top_level_op_rect| is set to the rect for that op. If provided, the
   // |top_level_op_rect| will be used as the rect for tracking the position of
   // this image in the top-level buffer.
   void GatherDiscardableImages(const PaintOpBuffer& buffer,
                                const gfx::Rect* top_level_op_rect,
                                SkNoDrawCanvas* canvas) {
     if (!buffer.HasDiscardableImages())
       return;

     // Prevent PaintOpBuffers from having side effects back into the canvas.
     SkAutoCanvasRestore save_restore(canvas, true);

     PlaybackParams params(nullptr, canvas->getLocalToDevice());
     // TODO(khushalsagar): Optimize out save/restore blocks if there are no
     // images in the draw ops between them.
     for (const PaintOp& op : buffer) {
       // We need to play non-draw ops on the SkCanvas since they can affect the
       // transform/clip state.
       if (!op.IsDrawOp())
         op.Raster(canvas, params);

       if (!PaintOp::OpHasDiscardableImages(op))
         continue;

       gfx::Rect op_rect;
       std::optional<gfx::Rect> local_op_rect;

       if (top_level_op_rect) {
         op_rect = *top_level_op_rect;
       } else {
         const SkRect& clip_rect = SkRect::Make(canvas->getDeviceClipBounds());
         const SkMatrix& ctm = canvas->getTotalMatrix();

         local_op_rect = PaintOp::ComputePaintRect(op, clip_rect, ctm);
         if (local_op_rect.value().IsEmpty())
           continue;

         op_rect = local_op_rect.value();
       }

       const SkM44& ctm = canvas->getLocalToDevice();
       if (op.IsPaintOpWithFlags()) {
         AddImageFromFlags(op_rect,
                           static_cast<const PaintOpWithFlags&>(op).flags, ctm);
       }

       PaintOpType op_type = static_cast<PaintOpType>(op.type);
       if (op_type == PaintOpType::kDrawImage) {
         const auto& image_op = static_cast<const DrawImageOp&>(op);
         AddImage(
             image_op.image, image_op.flags.useDarkModeForImage(),
             SkRect::MakeIWH(image_op.image.width(), image_op.image.height()),
             op_rect, ctm, image_op.flags.getFilterQuality());
       } else if (op_type == PaintOpType::kDrawImageRect) {
         const auto& image_rect_op = static_cast<const DrawImageRectOp&>(op);
         // TODO(crbug.com/1155544): Make a RectToRect method that uses SkM44s
         // in MathUtil.
         SkM44 matrix = ctm * SkM44(SkMatrix::RectToRect(image_rect_op.src,
                                                         image_rect_op.dst));
         AddImage(image_rect_op.image, image_rect_op.flags.useDarkModeForImage(),
                  image_rect_op.src, op_rect, matrix,
                  image_rect_op.flags.getFilterQuality());
       } else if (op_type == PaintOpType::kDrawSkottie) {
         const auto& skottie_op = static_cast<const DrawSkottieOp&>(op);
         for (const auto& image_pair : skottie_op.images) {
           const SkottieFrameData& frame_data = image_pair.second;
           // Add the whole image (no cropping).
           SkRect image_src_rect = SkRect::MakeIWH(frame_data.image.width(),
                                                   frame_data.image.height());
           // It is too difficult to tell which specific portion of the animation
           // frame this image will ultimately occupy. So just assume it occupies
           // the whole animation frame for the purposes of finding which images
           // overlap with a given rectangle on the screen.
           gfx::Rect dst_rect = op_rect;
           // Skottie ultimately takes care of scaling and positioning the image
           // internally within the animation frame. However, the image that gets
           // cached in the ImageDecodeCache should have dimensions that at least
           // roughly reflect the ultimate output both for cache space
           // consumption reasons and to make Skottie's scaling job easier
           // (performance). For this reason, the DrawImage submitted to the
           // cache is scaled by the same amount that the entire animation frame
           // itself is scaled. This should get the image dimensions in the right
           // ballpark in the event that the animation's native size and the
           // destination's size differ drastically.
           //
           // Do not allow stretching the image in 1 dimension when scaling. This
           // matches Skottie's scaling behavior.
           static constexpr SkMatrix::ScaleToFit kScalingMode =
               SkMatrix::kCenter_ScaleToFit;
           SkRect skottie_frame_native_size =
               SkRect::MakeSize(skottie_op.skottie->size());
           SkM44 matrix = ctm * SkM44(SkMatrix::RectToRect(
                                    skottie_frame_native_size,
                                    gfx::RectToSkRect(dst_rect), kScalingMode));
           AddImage(frame_data.image, /*use_dark_mode=*/false,
                    std::move(image_src_rect), std::move(dst_rect), matrix,
                    frame_data.quality);
         }
       } else if (op_type == PaintOpType::kDrawRecord) {
         GatherDiscardableImages(
             static_cast<const DrawRecordOp&>(op).record.buffer(),
             top_level_op_rect, canvas);
       }
     }
   }

   void AddImageFromFlags(const gfx::Rect& op_rect,
                          const PaintFlags& flags,
                          const SkM44& ctm) {
     // TODO(prashant.n): Add dark mode support for images from shaders/filters.
     AddImageFromShader(op_rect, flags.getShader(), ctm,
                        flags.getFilterQuality());
     AddImageFromFilter(op_rect, flags.getImageFilter().get());
   }

   void AddImageFromShader(const gfx::Rect& op_rect,
                           const PaintShader* shader,
                           const SkM44& ctm,
                           PaintFlags::FilterQuality filter_quality) {
     if (!shader || !shader->has_discardable_images())
       return;

     if (shader->shader_type() == PaintShader::Type::kImage) {
       const PaintImage& paint_image = shader->paint_image();
       SkM44 matrix = ctm * SkM44(shader->GetLocalMatrix());
       // TODO(prashant.n): Add dark mode support for images from shader.
       AddImage(paint_image, false,
                SkRect::MakeWH(paint_image.width(), paint_image.height()),
                op_rect, matrix, filter_quality);
       return;
     }

     if (shader->shader_type() == PaintShader::Type::kPaintRecord) {
       // For record backed shaders, only analyze them if they have animated
       // images.
       if (shader->image_analysis_state() ==
           ImageAnalysisState::kNoAnimatedImages) {
         return;
       }

       SkRect scaled_tile_rect;
       if (!shader->GetRasterizationTileRect(ctm.asM33(), &scaled_tile_rect)) {
         return;
       }

       SkNoDrawCanvas canvas(scaled_tile_rect.width(),
                             scaled_tile_rect.height());
       canvas.setMatrix(SkMatrix::RectToRect(shader->tile(), scaled_tile_rect));
       base::AutoReset<bool> auto_reset(&only_gather_animated_images_, true);
       size_t prev_image_set_size = image_set_.size();
       GatherDiscardableImages(shader->paint_record()->buffer(), &op_rect,
                               &canvas);

       // We only track animated images for PaintShaders. If we added any entry
       // to the |image_set_|, this shader any has animated images.
       // Note that it is thread-safe to set the |has_animated_images| bit on
       // PaintShader here since the analysis is done on the main thread, before
       // the PaintOpBuffer is used for rasterization.
       DCHECK_GE(image_set_.size(), prev_image_set_size);
       const bool has_animated_images = image_set_.size() > prev_image_set_size;
       const_cast<PaintShader*>(shader)->set_has_animated_images(
           has_animated_images);
     }
   }

   void AddImageFromFilter(const gfx::Rect& op_rect, const PaintFilter* filter) {
     // Only analyze filters if they have animated images.
     if (!filter || !filter->has_discardable_images() ||
         filter->image_analysis_state() ==
             ImageAnalysisState::kNoAnimatedImages) {
       return;
     }

     base::AutoReset<bool> auto_reset(&only_gather_animated_images_, true);
     size_t prev_image_set_size = image_set_.size();
     ImageGatheringProvider image_provider(this, op_rect);
     filter->SnapshotWithImages(&image_provider);

     DCHECK_GE(image_set_.size(), prev_image_set_size);
     const bool has_animated_images = image_set_.size() > prev_image_set_size;
     const_cast<PaintFilter*>(filter)->set_has_animated_images(
         has_animated_images);
   }

   void AddImage(PaintImage paint_image,
                 bool use_dark_mode,
                 const SkRect& src_rect,
                 const gfx::Rect& image_rect,
                 const SkM44& matrix,
                 PaintFlags::FilterQuality filter_quality) {
     if (paint_image.IsTextureBacked())
       return;

     SkIRect src_irect;
     src_rect.roundOut(&src_irect);

     if (paint_image.IsPaintWorklet()) {
       paint_worklet_inputs_.push_back(std::make_pair(
           paint_image.paint_worklet_input(), paint_image.stable_id()));
     } else {
       const auto image_color_usage = paint_image.GetContentColorUsage();
       content_color_usage_ = std::max(content_color_usage_, image_color_usage);

       if (paint_image.is_high_bit_depth())
         contains_hbd_images_ = true;
     }

     auto& rects = image_id_to_rects_[paint_image.stable_id()];
     if (rects.size() >= kMaxRectsSize) {
       rects.back().Union(image_rect);
     } else {
       rects.push_back(image_rect);
     }

     if (paint_image.IsLazyGenerated()) {
       auto decoding_mode_it = decoding_mode_map_.find(paint_image.stable_id());
       // Use the decoding mode if we don't have one yet, otherwise use the more
       // conservative one of the two existing ones.
       if (decoding_mode_it == decoding_mode_map_.end()) {
         decoding_mode_map_[paint_image.stable_id()] =
             paint_image.decoding_mode();
       } else {
         decoding_mode_it->second = PaintImage::GetConservative(
             decoding_mode_it->second, paint_image.decoding_mode());
       }
     }

     if (paint_image.ShouldAnimate()) {
       animated_images_metadata_.emplace_back(
           paint_image.stable_id(), paint_image.completion_state(),
           paint_image.GetFrameMetadata(), paint_image.repetition_count(),
           paint_image.reset_animation_sequence_id());
     }

     bool add_image = true;
     if (paint_image.IsPaintWorklet()) {
       // PaintWorklet-backed images don't go through the image decode pipeline
       // (they are painted pre-raster from LayerTreeHostImpl), so do not need to
       // be added to the |image_set_|.
       add_image = false;
     } else if (only_gather_animated_images_) {
       // If we are iterating images in a record shader, only track them if they
       // are animated. We defer decoding of images in record shaders to skia,
       // but we still need to track animated images to invalidate and advance
       // the animation in cc.
       add_image = paint_image.ShouldAnimate();
     }

     if (add_image) {
       image_set_.emplace_back(DrawImage(std::move(paint_image), use_dark_mode,
                                         src_irect, filter_quality, matrix),
                               image_rect);
     }
   }

   std::vector<std::pair<DrawImage, gfx::Rect>> image_set_;
   base::flat_map<PaintImage::Id, DiscardableImageMap::Rects> image_id_to_rects_;
   std::vector<DiscardableImageMap::AnimatedImageMetadata>
       animated_images_metadata_;
   std::vector<DiscardableImageMap::PaintWorkletInputWithImageId>
       paint_worklet_inputs_;
   PaintImageIdFlatSet paint_worklet_image_ids_;
   base::flat_map<PaintImage::Id, PaintImage::DecodingMode> decoding_mode_map_;
   bool only_gather_animated_images_ = false;

   gfx::ContentColorUsage content_color_usage_ = gfx::ContentColorUsage::kSRGB;
   bool contains_hbd_images_ = false;
 };

 }  // namespace

 DiscardableImageMap::DiscardableImageMap() {
   DETACH_FROM_SEQUENCE(images_rtree_sequence_checker_);
 }
 DiscardableImageMap::~DiscardableImageMap() = default;

 void DiscardableImageMap::Generate(const PaintOpBuffer& paint_op_buffer,
                                    const gfx::Rect& bounds) {
   TRACE_EVENT0("cc", "DiscardableImageMap::Generate");

   if (!paint_op_buffer.HasDiscardableImages()) {
     return;
   }

   DiscardableImageGenerator generator(bounds.right(), bounds.bottom(),
                                       paint_op_buffer);
   image_id_to_rects_ = generator.TakeImageIdToRectsMap();
   images_ = generator.TakeImages();
   animated_images_metadata_ = generator.TakeAnimatedImagesMetadata();
   paint_worklet_inputs_ = generator.TakePaintWorkletInputs();
   decoding_mode_map_ = generator.TakeDecodingModeMap();
   contains_hbd_images_ = generator.contains_hbd_images();
   content_color_usage_ = generator.content_color_usage();
   DCHECK_CALLED_ON_VALID_SEQUENCE(images_rtree_sequence_checker_);
   CHECK(!images_rtree_);
   DETACH_FROM_SEQUENCE(images_rtree_sequence_checker_);
 }

 base::flat_map<PaintImage::Id, PaintImage::DecodingMode>
 DiscardableImageMap::TakeDecodingModeMap() {
   return std::move(decoding_mode_map_);
 }

 void DiscardableImageMap::GetDiscardableImagesInRect(
     const gfx::Rect& rect,
     std::vector<const DrawImage*>* images) const {
   DCHECK_CALLED_ON_VALID_SEQUENCE(images_rtree_sequence_checker_);
   if (!images_rtree_) {
     images_rtree_ = std::make_unique<RTree<const DrawImage*>>();

     images_rtree_->Build(
         images_.size(), [this](size_t index) { return images_[index].second; },
         [this](size_t index) { return &images_[index].first; });
   }
   images_rtree_->Search(rect, images);
 }

 const DiscardableImageMap::Rects& DiscardableImageMap::GetRectsForImage(
     PaintImage::Id image_id) const {
   static const base::NoDestructor<Rects> kEmptyRects;
   auto it = image_id_to_rects_.find(image_id);
   return it == image_id_to_rects_.end() ? *kEmptyRects : it->second;
 }

 void DiscardableImageMap::Reset() {
   image_id_to_rects_.clear();
   image_id_to_rects_.shrink_to_fit();
   DCHECK_CALLED_ON_VALID_SEQUENCE(images_rtree_sequence_checker_);
   images_rtree_.reset();
   images_.clear();
   DETACH_FROM_SEQUENCE(images_rtree_sequence_checker_);
 }

 DiscardableImageMap::AnimatedImageMetadata::AnimatedImageMetadata(
     PaintImage::Id paint_image_id,
     PaintImage::CompletionState completion_state,
     std::vector<FrameMetadata> frames,
     int repetition_count,
     PaintImage::AnimationSequenceId reset_animation_sequence_id)
     : paint_image_id(paint_image_id),
       completion_state(completion_state),
       frames(std::move(frames)),
       repetition_count(repetition_count),
       reset_animation_sequence_id(reset_animation_sequence_id) {}

 DiscardableImageMap::AnimatedImageMetadata::~AnimatedImageMetadata() = default;

 DiscardableImageMap::AnimatedImageMetadata::AnimatedImageMetadata(
     const AnimatedImageMetadata& other) = default;

 }  // namespace cc
	// Copyright 2015 The Chromium Authors
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "cc/paint/discardable_image_map.h"

	#include <stddef.h>

	#include <algorithm>
	#include <limits>

	#include "base/auto_reset.h"
	#include "base/check.h"
	#include "base/containers/adapters.h"
	#include "base/memory/raw_ptr.h"
	#include "base/metrics/histogram_macros.h"
	#include "base/no_destructor.h"
	#include "base/sequence_checker.h"
	#include "base/trace_event/trace_event.h"
	#include "cc/paint/image_provider.h"
	#include "cc/paint/paint_filter.h"
	#include "cc/paint/paint_op_buffer.h"
	#include "cc/paint/paint_op_buffer_iterator.h"
	#include "cc/paint/skottie_wrapper.h"
	#include "third_party/skia/include/utils/SkNoDrawCanvas.h"
	#include "ui/gfx/display_color_spaces.h"
	#include "ui/gfx/geometry/rect_conversions.h"
	#include "ui/gfx/geometry/skia_conversions.h"

	namespace cc {
	namespace {
	const int kMaxRectsSize = 256;

	class DiscardableImageGenerator {
	public:
	DiscardableImageGenerator(int width,
	int height,
	const PaintOpBuffer& buffer) {
	SkNoDrawCanvas canvas(width, height);
	GatherDiscardableImages(buffer, nullptr, &canvas);
	}
	~DiscardableImageGenerator() = default;

	std::vector<std::pair<DrawImage, gfx::Rect>> TakeImages() {
	return std::move(image_set_);
	}
	base::flat_map<PaintImage::Id, DiscardableImageMap::Rects>
	TakeImageIdToRectsMap() {
	return std::move(image_id_to_rects_);
	}
	base::flat_map<PaintImage::Id, PaintImage::DecodingMode>
	TakeDecodingModeMap() {
	return std::move(decoding_mode_map_);
	}
	std::vector<DiscardableImageMap::AnimatedImageMetadata>
	TakeAnimatedImagesMetadata() {
	return std::move(animated_images_metadata_);
	}
	std::vector<DiscardableImageMap::PaintWorkletInputWithImageId>
	TakePaintWorkletInputs() {
	return std::move(paint_worklet_inputs_);
	}

	gfx::ContentColorUsage content_color_usage() const {
	return content_color_usage_;
	}
	bool contains_hbd_images() const { return contains_hbd_images_; }

	private:
	class ImageGatheringProvider : public ImageProvider {
	public:
	ImageGatheringProvider(DiscardableImageGenerator* generator,
	const gfx::Rect& op_rect)
	: generator_(generator), op_rect_(op_rect) {}
	~ImageGatheringProvider() override = default;

	ScopedResult GetRasterContent(const DrawImage& draw_image) override {
	generator_->AddImage(draw_image.paint_image(), false,
	SkRect::Make(draw_image.src_rect()), op_rect_,
	SkM44(), draw_image.filter_quality());
	return ScopedResult();
	}

	private:
	raw_ptr<DiscardableImageGenerator> generator_;
	gfx::Rect op_rect_;
	};

	// Adds discardable images from \|buffer\| to the set of images tracked by
	// this generator. If \|buffer\| is being used in a DrawOp that requires
	// rasterization of the buffer as a pre-processing step for execution of the
	// op (for instance, with PaintRecord backed PaintShaders),
	// \|top_level_op_rect\| is set to the rect for that op. If provided, the
	// \|top_level_op_rect\| will be used as the rect for tracking the position of
	// this image in the top-level buffer.
	void GatherDiscardableImages(const PaintOpBuffer& buffer,
	const gfx::Rect* top_level_op_rect,
	SkNoDrawCanvas* canvas) {
	if (!buffer.HasDiscardableImages())
	return;

	// Prevent PaintOpBuffers from having side effects back into the canvas.
	SkAutoCanvasRestore save_restore(canvas, true);

	PlaybackParams params(nullptr, canvas->getLocalToDevice());
	// TODO(khushalsagar): Optimize out save/restore blocks if there are no
	// images in the draw ops between them.
	for (const PaintOp& op : buffer) {
	// We need to play non-draw ops on the SkCanvas since they can affect the
	// transform/clip state.
	if (!op.IsDrawOp())
	op.Raster(canvas, params);

	if (!PaintOp::OpHasDiscardableImages(op))
	continue;

	gfx::Rect op_rect;
	std::optional<gfx::Rect> local_op_rect;

	if (top_level_op_rect) {
	op_rect = *top_level_op_rect;
	} else {
	const SkRect& clip_rect = SkRect::Make(canvas->getDeviceClipBounds());
	const SkMatrix& ctm = canvas->getTotalMatrix();

	local_op_rect = PaintOp::ComputePaintRect(op, clip_rect, ctm);
	if (local_op_rect.value().IsEmpty())
	continue;

	op_rect = local_op_rect.value();
	}

	const SkM44& ctm = canvas->getLocalToDevice();
	if (op.IsPaintOpWithFlags()) {
	AddImageFromFlags(op_rect,
	static_cast<const PaintOpWithFlags&>(op).flags, ctm);
	}

	PaintOpType op_type = static_cast<PaintOpType>(op.type);
	if (op_type == PaintOpType::kDrawImage) {
	const auto& image_op = static_cast<const DrawImageOp&>(op);
	AddImage(
	image_op.image, image_op.flags.useDarkModeForImage(),
	SkRect::MakeIWH(image_op.image.width(), image_op.image.height()),
	op_rect, ctm, image_op.flags.getFilterQuality());
	} else if (op_type == PaintOpType::kDrawImageRect) {
	const auto& image_rect_op = static_cast<const DrawImageRectOp&>(op);
	// TODO(crbug.com/1155544): Make a RectToRect method that uses SkM44s
	// in MathUtil.
	SkM44 matrix = ctm * SkM44(SkMatrix::RectToRect(image_rect_op.src,
	image_rect_op.dst));
	AddImage(image_rect_op.image, image_rect_op.flags.useDarkModeForImage(),
	image_rect_op.src, op_rect, matrix,
	image_rect_op.flags.getFilterQuality());
	} else if (op_type == PaintOpType::kDrawSkottie) {
	const auto& skottie_op = static_cast<const DrawSkottieOp&>(op);
	for (const auto& image_pair : skottie_op.images) {
	const SkottieFrameData& frame_data = image_pair.second;
	// Add the whole image (no cropping).
	SkRect image_src_rect = SkRect::MakeIWH(frame_data.image.width(),
	frame_data.image.height());
	// It is too difficult to tell which specific portion of the animation
	// frame this image will ultimately occupy. So just assume it occupies
	// the whole animation frame for the purposes of finding which images
	// overlap with a given rectangle on the screen.
	gfx::Rect dst_rect = op_rect;
	// Skottie ultimately takes care of scaling and positioning the image
	// internally within the animation frame. However, the image that gets
	// cached in the ImageDecodeCache should have dimensions that at least
	// roughly reflect the ultimate output both for cache space
	// consumption reasons and to make Skottie's scaling job easier
	// (performance). For this reason, the DrawImage submitted to the
	// cache is scaled by the same amount that the entire animation frame
	// itself is scaled. This should get the image dimensions in the right
	// ballpark in the event that the animation's native size and the
	// destination's size differ drastically.
	//
	// Do not allow stretching the image in 1 dimension when scaling. This
	// matches Skottie's scaling behavior.
	static constexpr SkMatrix::ScaleToFit kScalingMode =
	SkMatrix::kCenter_ScaleToFit;
	SkRect skottie_frame_native_size =
	SkRect::MakeSize(skottie_op.skottie->size());
	SkM44 matrix = ctm * SkM44(SkMatrix::RectToRect(
	skottie_frame_native_size,
	gfx::RectToSkRect(dst_rect), kScalingMode));
	AddImage(frame_data.image, /use_dark_mode=/false,
	std::move(image_src_rect), std::move(dst_rect), matrix,
	frame_data.quality);
	}
	} else if (op_type == PaintOpType::kDrawRecord) {
	GatherDiscardableImages(
	static_cast<const DrawRecordOp&>(op).record.buffer(),
	top_level_op_rect, canvas);
	}
	}
	}

	void AddImageFromFlags(const gfx::Rect& op_rect,
	const PaintFlags& flags,
	const SkM44& ctm) {
	// TODO(prashant.n): Add dark mode support for images from shaders/filters.
	AddImageFromShader(op_rect, flags.getShader(), ctm,
	flags.getFilterQuality());
	AddImageFromFilter(op_rect, flags.getImageFilter().get());
	}

	void AddImageFromShader(const gfx::Rect& op_rect,
	const PaintShader* shader,
	const SkM44& ctm,
	PaintFlags::FilterQuality filter_quality) {
	if (!shader \|\| !shader->has_discardable_images())
	return;

	if (shader->shader_type() == PaintShader::Type::kImage) {
	const PaintImage& paint_image = shader->paint_image();
	SkM44 matrix = ctm * SkM44(shader->GetLocalMatrix());
	// TODO(prashant.n): Add dark mode support for images from shader.
	AddImage(paint_image, false,
	SkRect::MakeWH(paint_image.width(), paint_image.height()),
	op_rect, matrix, filter_quality);
	return;
	}

	if (shader->shader_type() == PaintShader::Type::kPaintRecord) {
	// For record backed shaders, only analyze them if they have animated
	// images.
	if (shader->image_analysis_state() ==
	ImageAnalysisState::kNoAnimatedImages) {
	return;
	}

	SkRect scaled_tile_rect;
	if (!shader->GetRasterizationTileRect(ctm.asM33(), &scaled_tile_rect)) {
	return;
	}

	SkNoDrawCanvas canvas(scaled_tile_rect.width(),
	scaled_tile_rect.height());
	canvas.setMatrix(SkMatrix::RectToRect(shader->tile(), scaled_tile_rect));
	base::AutoReset<bool> auto_reset(&only_gather_animated_images_, true);
	size_t prev_image_set_size = image_set_.size();
	GatherDiscardableImages(shader->paint_record()->buffer(), &op_rect,
	&canvas);

	// We only track animated images for PaintShaders. If we added any entry
	// to the \|image_set_\|, this shader any has animated images.
	// Note that it is thread-safe to set the \|has_animated_images\| bit on
	// PaintShader here since the analysis is done on the main thread, before
	// the PaintOpBuffer is used for rasterization.
	DCHECK_GE(image_set_.size(), prev_image_set_size);
	const bool has_animated_images = image_set_.size() > prev_image_set_size;
	const_cast<PaintShader*>(shader)->set_has_animated_images(
	has_animated_images);
	}
	}

	void AddImageFromFilter(const gfx::Rect& op_rect, const PaintFilter* filter) {
	// Only analyze filters if they have animated images.
	if (!filter \|\| !filter->has_discardable_images() \|\|
	filter->image_analysis_state() ==
	ImageAnalysisState::kNoAnimatedImages) {
	return;
	}

	base::AutoReset<bool> auto_reset(&only_gather_animated_images_, true);
	size_t prev_image_set_size = image_set_.size();
	ImageGatheringProvider image_provider(this, op_rect);
	filter->SnapshotWithImages(&image_provider);

	DCHECK_GE(image_set_.size(), prev_image_set_size);
	const bool has_animated_images = image_set_.size() > prev_image_set_size;
	const_cast<PaintFilter*>(filter)->set_has_animated_images(
	has_animated_images);
	}

	void AddImage(PaintImage paint_image,
	bool use_dark_mode,
	const SkRect& src_rect,
	const gfx::Rect& image_rect,
	const SkM44& matrix,
	PaintFlags::FilterQuality filter_quality) {
	if (paint_image.IsTextureBacked())
	return;

	SkIRect src_irect;
	src_rect.roundOut(&src_irect);

	if (paint_image.IsPaintWorklet()) {
	paint_worklet_inputs_.push_back(std::make_pair(
	paint_image.paint_worklet_input(), paint_image.stable_id()));
	} else {
	const auto image_color_usage = paint_image.GetContentColorUsage();
	content_color_usage_ = std::max(content_color_usage_, image_color_usage);

	if (paint_image.is_high_bit_depth())
	contains_hbd_images_ = true;
	}

	auto& rects = image_id_to_rects_[paint_image.stable_id()];
	if (rects.size() >= kMaxRectsSize) {
	rects.back().Union(image_rect);
	} else {
	rects.push_back(image_rect);
	}

	if (paint_image.IsLazyGenerated()) {
	auto decoding_mode_it = decoding_mode_map_.find(paint_image.stable_id());
	// Use the decoding mode if we don't have one yet, otherwise use the more
	// conservative one of the two existing ones.
	if (decoding_mode_it == decoding_mode_map_.end()) {
	decoding_mode_map_[paint_image.stable_id()] =
	paint_image.decoding_mode();
	} else {
	decoding_mode_it->second = PaintImage::GetConservative(
	decoding_mode_it->second, paint_image.decoding_mode());
	}
	}

	if (paint_image.ShouldAnimate()) {
	animated_images_metadata_.emplace_back(
	paint_image.stable_id(), paint_image.completion_state(),
	paint_image.GetFrameMetadata(), paint_image.repetition_count(),
	paint_image.reset_animation_sequence_id());
	}

	bool add_image = true;
	if (paint_image.IsPaintWorklet()) {
	// PaintWorklet-backed images don't go through the image decode pipeline
	// (they are painted pre-raster from LayerTreeHostImpl), so do not need to
	// be added to the \|image_set_\|.
	add_image = false;
	} else if (only_gather_animated_images_) {
	// If we are iterating images in a record shader, only track them if they
	// are animated. We defer decoding of images in record shaders to skia,
	// but we still need to track animated images to invalidate and advance
	// the animation in cc.
	add_image = paint_image.ShouldAnimate();
	}

	if (add_image) {
	image_set_.emplace_back(DrawImage(std::move(paint_image), use_dark_mode,
	src_irect, filter_quality, matrix),
	image_rect);
	}
	}

	std::vector<std::pair<DrawImage, gfx::Rect>> image_set_;
	base::flat_map<PaintImage::Id, DiscardableImageMap::Rects> image_id_to_rects_;
	std::vector<DiscardableImageMap::AnimatedImageMetadata>
	animated_images_metadata_;
	std::vector<DiscardableImageMap::PaintWorkletInputWithImageId>
	paint_worklet_inputs_;
	PaintImageIdFlatSet paint_worklet_image_ids_;
	base::flat_map<PaintImage::Id, PaintImage::DecodingMode> decoding_mode_map_;
	bool only_gather_animated_images_ = false;

	gfx::ContentColorUsage content_color_usage_ = gfx::ContentColorUsage::kSRGB;
	bool contains_hbd_images_ = false;
	};

	} // namespace

	DiscardableImageMap::DiscardableImageMap() {
	DETACH_FROM_SEQUENCE(images_rtree_sequence_checker_);
	}
	DiscardableImageMap::~DiscardableImageMap() = default;

	void DiscardableImageMap::Generate(const PaintOpBuffer& paint_op_buffer,
	const gfx::Rect& bounds) {
	TRACE_EVENT0("cc", "DiscardableImageMap::Generate");

	if (!paint_op_buffer.HasDiscardableImages()) {
	return;
	}

	DiscardableImageGenerator generator(bounds.right(), bounds.bottom(),
	paint_op_buffer);
	image_id_to_rects_ = generator.TakeImageIdToRectsMap();
	images_ = generator.TakeImages();
	animated_images_metadata_ = generator.TakeAnimatedImagesMetadata();
	paint_worklet_inputs_ = generator.TakePaintWorkletInputs();
	decoding_mode_map_ = generator.TakeDecodingModeMap();
	contains_hbd_images_ = generator.contains_hbd_images();
	content_color_usage_ = generator.content_color_usage();
	DCHECK_CALLED_ON_VALID_SEQUENCE(images_rtree_sequence_checker_);
	CHECK(!images_rtree_);
	DETACH_FROM_SEQUENCE(images_rtree_sequence_checker_);
	}

	base::flat_map<PaintImage::Id, PaintImage::DecodingMode>
	DiscardableImageMap::TakeDecodingModeMap() {
	return std::move(decoding_mode_map_);
	}

	void DiscardableImageMap::GetDiscardableImagesInRect(
	const gfx::Rect& rect,
	std::vector<const DrawImage> images) const {
	DCHECK_CALLED_ON_VALID_SEQUENCE(images_rtree_sequence_checker_);
	if (!images_rtree_) {
	images_rtree_ = std::make_unique<RTree<const DrawImage*>>();

	images_rtree_->Build(
	images_.size(), [this](size_t index) { return images_[index].second; },
	[this](size_t index) { return &images_[index].first; });
	}
	images_rtree_->Search(rect, images);
	}

	const DiscardableImageMap::Rects& DiscardableImageMap::GetRectsForImage(
	PaintImage::Id image_id) const {
	static const base::NoDestructor<Rects> kEmptyRects;
	auto it = image_id_to_rects_.find(image_id);
	return it == image_id_to_rects_.end() ? *kEmptyRects : it->second;
	}

	void DiscardableImageMap::Reset() {
	image_id_to_rects_.clear();
	image_id_to_rects_.shrink_to_fit();
	DCHECK_CALLED_ON_VALID_SEQUENCE(images_rtree_sequence_checker_);
	images_rtree_.reset();
	images_.clear();
	DETACH_FROM_SEQUENCE(images_rtree_sequence_checker_);
	}

	DiscardableImageMap::AnimatedImageMetadata::AnimatedImageMetadata(
	PaintImage::Id paint_image_id,
	PaintImage::CompletionState completion_state,
	std::vector<FrameMetadata> frames,
	int repetition_count,
	PaintImage::AnimationSequenceId reset_animation_sequence_id)
	: paint_image_id(paint_image_id),
	completion_state(completion_state),
	frames(std::move(frames)),
	repetition_count(repetition_count),
	reset_animation_sequence_id(reset_animation_sequence_id) {}

	DiscardableImageMap::AnimatedImageMetadata::~AnimatedImageMetadata() = default;

	DiscardableImageMap::AnimatedImageMetadata::AnimatedImageMetadata(
	const AnimatedImageMetadata& other) = default;

	} // namespace cc