cc/tiles/software_image_decode_cache_utils.cc - chromium/src - Git at Google

 // Copyright 2018 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/tiles/software_image_decode_cache_utils.h"

 #include "base/atomic_sequence_num.h"
 #include "base/hash.h"
 #include "base/memory/discardable_memory_allocator.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/tiles/mipmap_util.h"
 #include "ui/gfx/skia_util.h"

 namespace cc {
 namespace {
 // If the size of the original sized image breaches kMemoryRatioToSubrect but we
 // don't need to scale the image, consider caching only the needed subrect.
 // The second part that much be true is that we cache only the needed subrect if
 // the total size needed for the subrect is at most kMemoryRatioToSubrect *
 // (size needed for the full original image).
 // Note that at least one of the dimensions has to be at least
 // kMinDimensionToSubrect before an image can breach the threshold.
 const size_t kMemoryThresholdToSubrect = 64 * 1024 * 1024;
 const int kMinDimensionToSubrect = 4 * 1024;
 const float kMemoryRatioToSubrect = 0.5f;

 // Tracing ID sequence for use in CacheEntry.
 base::AtomicSequenceNumber g_next_tracing_id_;

 gfx::Rect GetSrcRect(const DrawImage& image) {
   const SkIRect& src_rect = image.src_rect();
   int x = std::max(0, src_rect.x());
   int y = std::max(0, src_rect.y());
   int right = std::min(image.paint_image().width(), src_rect.right());
   int bottom = std::min(image.paint_image().height(), src_rect.bottom());
   if (x >= right || y >= bottom)
     return gfx::Rect();
   return gfx::Rect(x, y, right - x, bottom - y);
 }

 SkImageInfo CreateImageInfo(const SkISize& size, SkColorType color_type) {
   return SkImageInfo::Make(size.width(), size.height(), color_type,
                            kPremul_SkAlphaType);
 }

 std::unique_ptr<base::DiscardableMemory> AllocateDiscardable(
     const SkImageInfo& info) {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("cc.debug"), "AllocateDiscardable");
   return base::DiscardableMemoryAllocator::GetInstance()
       ->AllocateLockedDiscardableMemory(info.minRowBytes() * info.height());
 }

 }  // namespace

 // static
 std::unique_ptr<SoftwareImageDecodeCacheUtils::CacheEntry>
 SoftwareImageDecodeCacheUtils::DoDecodeImage(
     const CacheKey& key,
     const PaintImage& paint_image,
     SkColorType color_type,
     PaintImage::GeneratorClientId client_id) {
   SkISize target_size =
       SkISize::Make(key.target_size().width(), key.target_size().height());
   DCHECK(target_size == paint_image.GetSupportedDecodeSize(target_size));

   SkImageInfo target_info = CreateImageInfo(target_size, color_type);
   std::unique_ptr<base::DiscardableMemory> target_pixels =
       AllocateDiscardable(target_info);
   if (!target_pixels || !target_pixels->data())
     return nullptr;

   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("cc.debug"),
                "SoftwareImageDecodeCacheUtils::DoDecodeImage - "
                "decode");
   bool result = paint_image.Decode(target_pixels->data(), &target_info,
                                    key.target_color_space().ToSkColorSpace(),
                                    key.frame_key().frame_index(), client_id);
   if (!result) {
     target_pixels->Unlock();
     return nullptr;
   }
   return std::make_unique<CacheEntry>(target_info, std::move(target_pixels),
                                       SkSize::Make(0, 0));
 }

 // static
 std::unique_ptr<SoftwareImageDecodeCacheUtils::CacheEntry>
 SoftwareImageDecodeCacheUtils::GenerateCacheEntryFromCandidate(
     const CacheKey& key,
     const DecodedDrawImage& candidate_image,
     bool needs_extract_subset,
     SkColorType color_type) {
   SkISize target_size =
       SkISize::Make(key.target_size().width(), key.target_size().height());
   SkImageInfo target_info = CreateImageInfo(target_size, color_type);
   std::unique_ptr<base::DiscardableMemory> target_pixels =
       AllocateDiscardable(target_info);
   DCHECK(target_pixels);

   if (key.type() == CacheKey::kSubrectOriginal) {
     DCHECK(needs_extract_subset);
     TRACE_EVENT0(
         TRACE_DISABLED_BY_DEFAULT("cc.debug"),
         "SoftwareImageDecodeCacheUtils::GenerateCacheEntryFromCandidate - "
         "subrect");
     bool result = candidate_image.image()->readPixels(
         target_info, target_pixels->data(), target_info.minRowBytes(),
         key.src_rect().x(), key.src_rect().y(), SkImage::kDisallow_CachingHint);
     // We have a decoded image, and we're reading into already allocated memory.
     // This should never fail.
     DCHECK(result) << key.ToString();
     return std::make_unique<CacheEntry>(
         target_info.makeColorSpace(candidate_image.image()->refColorSpace()),
         std::move(target_pixels),
         SkSize::Make(-key.src_rect().x(), -key.src_rect().y()));
   }

   DCHECK_EQ(key.type(), CacheKey::kSubrectAndScale);
   TRACE_EVENT0(
       TRACE_DISABLED_BY_DEFAULT("cc.debug"),
       "SoftwareImageDecodeCacheUtils::GenerateCacheEntryFromCandidate - "
       "scale");
   SkPixmap decoded_pixmap;
   // We don't need to subrect this image, since all candidates passed in would
   // already have a src_rect applied to them.
   bool result = candidate_image.image()->peekPixels(&decoded_pixmap);
   DCHECK(result) << key.ToString();
   if (needs_extract_subset) {
     result = decoded_pixmap.extractSubset(&decoded_pixmap,
                                           gfx::RectToSkIRect(key.src_rect()));
     DCHECK(result) << key.ToString();
   }

   // Nearest neighbor would only be set in the unscaled case.
   DCHECK(!key.is_nearest_neighbor());
   SkPixmap target_pixmap(target_info, target_pixels->data(),
                          target_info.minRowBytes());
   SkFilterQuality filter_quality = kMedium_SkFilterQuality;
   if (decoded_pixmap.colorType() == kRGBA_F16_SkColorType &&
       !ImageDecodeCacheUtils::CanResizeF16Image(filter_quality)) {
     result = ImageDecodeCacheUtils::ScaleToHalfFloatPixmapUsingN32Intermediate(
         decoded_pixmap, &target_pixmap, filter_quality);
   } else {
     result = decoded_pixmap.scalePixels(target_pixmap, filter_quality);
   }
   DCHECK(result) << key.ToString();

   return std::make_unique<CacheEntry>(
       target_info.makeColorSpace(candidate_image.image()->refColorSpace()),
       std::move(target_pixels),
       SkSize::Make(-key.src_rect().x(), -key.src_rect().y()));
 }

 // CacheKey --------------------------------------------------------------------
 // static
 SoftwareImageDecodeCacheUtils::CacheKey
 SoftwareImageDecodeCacheUtils::CacheKey::FromDrawImage(const DrawImage& image,
                                                        SkColorType color_type) {
   DCHECK(!image.paint_image().GetSkImage()->isTextureBacked());

   const PaintImage::FrameKey frame_key = image.frame_key();
   const PaintImage::Id stable_id = image.paint_image().stable_id();

   const SkSize& scale = image.scale();
   // If the src_rect falls outside of the image, we need to clip it since
   // otherwise we might end up with uninitialized memory in the decode process.
   // Note that the scale is still unchanged and the target size is now a
   // function of the new src_rect.
   const gfx::Rect& src_rect = GetSrcRect(image);

   // Start with the exact target size. However, this will be adjusted below to
   // be either a mip level, the original size, or a subrect size. This is done
   // to keep memory accounting correct.
   gfx::Size target_size(
       SkScalarRoundToInt(std::abs(src_rect.width() * scale.width())),
       SkScalarRoundToInt(std::abs(src_rect.height() * scale.height())));

   // If the target size is empty, then we'll be skipping the decode anyway, so
   // the filter quality doesn't matter. Early out instead.
   if (target_size.IsEmpty()) {
     return CacheKey(frame_key, stable_id, kSubrectAndScale, false, src_rect,
                     target_size, image.target_color_space());
   }

   ProcessingType type = kOriginal;
   bool is_nearest_neighbor = image.filter_quality() == kNone_SkFilterQuality;
   int mip_level = MipMapUtil::GetLevelForSize(src_rect.size(), target_size);
   // If any of the following conditions hold, then use at most low filter
   // quality and adjust the target size to match the original image:
   // - Quality is none: We need a pixelated image, so we can't upgrade it.
   // - Mip level is 0: The required mip is the original image, so just use low
   //   filter quality.
   // - Matrix is not decomposable: There's perspective on this image and we
   //   can't determine the size, so use the original.
   if (is_nearest_neighbor || mip_level == 0 ||
       !image.matrix_is_decomposable()) {
     type = kOriginal;
     // Update the size to be the original image size.
     target_size =
         gfx::Size(image.paint_image().width(), image.paint_image().height());
   } else {
     type = kSubrectAndScale;
     // Update the target size to be a mip level size.
     // TODO(vmpstr): MipMapUtil and JPEG decoders disagree on what to do with
     // odd sizes. If width = 2k + 1, and the mip level is 1, then this will
     // return width = k; JPEG decoder, however, will support decoding to width =
     // k + 1. We need to figure out what to do in this case.
     SkSize mip_scale_adjustment =
         MipMapUtil::GetScaleAdjustmentForLevel(src_rect.size(), mip_level);
     target_size.set_width(src_rect.width() * mip_scale_adjustment.width());
     target_size.set_height(src_rect.height() * mip_scale_adjustment.height());
   }

   // If the original image is large, we might want to do a subrect instead if
   // the subrect would be kMemoryRatioToSubrect times smaller.
   if (type == kOriginal &&
       (image.paint_image().width() >= kMinDimensionToSubrect ||
        image.paint_image().height() >= kMinDimensionToSubrect)) {
     base::CheckedNumeric<size_t> checked_original_size = 4u;
     checked_original_size *= image.paint_image().width();
     checked_original_size *= image.paint_image().height();
     size_t original_size = checked_original_size.ValueOrDefault(
         std::numeric_limits<size_t>::max());

     base::CheckedNumeric<size_t> checked_src_rect_size = 4u;
     checked_src_rect_size *= src_rect.width();
     checked_src_rect_size *= src_rect.height();
     size_t src_rect_size = checked_src_rect_size.ValueOrDefault(
         std::numeric_limits<size_t>::max());

     // If the sizes are such that we get good savings by subrecting, then do
     // that. Also update the target size to be the src rect size since that's
     // the rect we want to use.
     if (original_size > kMemoryThresholdToSubrect &&
         src_rect_size <= original_size * kMemoryRatioToSubrect) {
       type = kSubrectOriginal;
       target_size = src_rect.size();
     }
   }

   return CacheKey(frame_key, stable_id, type, is_nearest_neighbor, src_rect,
                   target_size, image.target_color_space());
 }

 SoftwareImageDecodeCacheUtils::CacheKey::CacheKey(
     PaintImage::FrameKey frame_key,
     PaintImage::Id stable_id,
     ProcessingType type,
     bool is_nearest_neighbor,
     const gfx::Rect& src_rect,
     const gfx::Size& target_size,
     const gfx::ColorSpace& target_color_space)
     : frame_key_(frame_key),
       stable_id_(stable_id),
       type_(type),
       is_nearest_neighbor_(is_nearest_neighbor),
       src_rect_(src_rect),
       target_size_(target_size),
       target_color_space_(target_color_space) {
   if (type == kOriginal) {
     hash_ = frame_key_.hash();
   } else {
     // TODO(vmpstr): This is a mess. Maybe it's faster to just search the vector
     // always (forwards or backwards to account for LRU).
     uint64_t src_rect_hash = base::HashInts(
         static_cast<uint64_t>(base::HashInts(src_rect_.x(), src_rect_.y())),
         static_cast<uint64_t>(
             base::HashInts(src_rect_.width(), src_rect_.height())));

     uint64_t target_size_hash =
         base::HashInts(target_size_.width(), target_size_.height());

     hash_ = base::HashInts(base::HashInts(src_rect_hash, target_size_hash),
                            frame_key_.hash());
   }
   // Include the target color space in the hash regardless of scaling.
   hash_ = base::HashInts(hash_, target_color_space.GetHash());
 }

 SoftwareImageDecodeCacheUtils::CacheKey::CacheKey(const CacheKey& other) =
     default;

 std::string SoftwareImageDecodeCacheUtils::CacheKey::ToString() const {
   std::ostringstream str;
   str << "frame_key[" << frame_key_.ToString() << "]\ntype[";
   switch (type_) {
     case kOriginal:
       str << "Original";
       break;
     case kSubrectOriginal:
       str << "SubrectOriginal";
       break;
     case kSubrectAndScale:
       str << "SubrectAndScale";
       break;
   }
   str << "]\nis_nearest_neightbor[" << is_nearest_neighbor_ << "]\nsrc_rect["
       << src_rect_.ToString() << "]\ntarget_size[" << target_size_.ToString()
       << "]\ntarget_color_space[" << target_color_space_.ToString()
       << "]\nhash[" << hash_ << "]";
   return str.str();
 }

 // CacheEntry ------------------------------------------------------------------
 SoftwareImageDecodeCacheUtils::CacheEntry::CacheEntry()
     : tracing_id_(g_next_tracing_id_.GetNext()) {}
 SoftwareImageDecodeCacheUtils::CacheEntry::CacheEntry(
     const SkImageInfo& info,
     std::unique_ptr<base::DiscardableMemory> in_memory,
     const SkSize& src_rect_offset)
     : is_locked(true),
       memory(std::move(in_memory)),
       image_info_(info),
       src_rect_offset_(src_rect_offset),
       tracing_id_(g_next_tracing_id_.GetNext()) {
   DCHECK(memory);
   SkPixmap pixmap(image_info_, memory->data(), image_info_.minRowBytes());
   image_ = SkImage::MakeFromRaster(
       pixmap, [](const void* pixels, void* context) {}, nullptr);
 }

 SoftwareImageDecodeCacheUtils::CacheEntry::~CacheEntry() {
   DCHECK(!is_locked);

   // We create temporary CacheEntries as a part of decoding. However, we move
   // the memory to cache entries that actually live in the cache. Destroying the
   // temporaries should not cause any of the stats to be recorded. Specifically,
   // if allowed to report, they would report every single temporary entry as
   // wasted, which is misleading. As a fix, don't report on a cache entry that
   // has never been in the cache.
   if (!cached_)
     return;

   // lock_count | used  | last lock failed | result state
   // ===========+=======+==================+==================
   //  1         | false | false            | WASTED
   //  1         | false | true             | WASTED
   //  1         | true  | false            | USED
   //  1         | true  | true             | USED_RELOCK_FAILED
   //  >1        | false | false            | WASTED_RELOCKED
   //  >1        | false | true             | WASTED_RELOCKED
   //  >1        | true  | false            | USED_RELOCKED
   //  >1        | true  | true             | USED_RELOCKED
   // Note that it's important not to reorder the following enums, since the
   // numerical values are used in the histogram code.
   enum State : int {
     DECODED_IMAGE_STATE_WASTED,
     DECODED_IMAGE_STATE_USED,
     DECODED_IMAGE_STATE_USED_RELOCK_FAILED,
     DECODED_IMAGE_STATE_WASTED_RELOCKED,
     DECODED_IMAGE_STATE_USED_RELOCKED,
     DECODED_IMAGE_STATE_COUNT
   } state = DECODED_IMAGE_STATE_WASTED;

   if (usage_stats_.lock_count == 1) {
     if (!usage_stats_.used)
       state = DECODED_IMAGE_STATE_WASTED;
     else if (usage_stats_.last_lock_failed)
       state = DECODED_IMAGE_STATE_USED_RELOCK_FAILED;
     else
       state = DECODED_IMAGE_STATE_USED;
   } else {
     if (usage_stats_.used)
       state = DECODED_IMAGE_STATE_USED_RELOCKED;
     else
       state = DECODED_IMAGE_STATE_WASTED_RELOCKED;
   }

   UMA_HISTOGRAM_ENUMERATION("Renderer4.SoftwareImageDecodeState", state,
                             DECODED_IMAGE_STATE_COUNT);
   UMA_HISTOGRAM_BOOLEAN("Renderer4.SoftwareImageDecodeState.FirstLockWasted",
                         usage_stats_.first_lock_wasted);
   if (usage_stats_.first_lock_out_of_raster)
     UMA_HISTOGRAM_BOOLEAN(
         "Renderer4.SoftwareImageDecodeState.FirstLockWasted.OutOfRaster",
         usage_stats_.first_lock_wasted);
 }

 void SoftwareImageDecodeCacheUtils::CacheEntry::MoveImageMemoryTo(
     CacheEntry* entry) {
   DCHECK(!is_budgeted);
   DCHECK_EQ(ref_count, 0);

   // Copy/move most things except budgeted and ref counts.
   entry->decode_failed = decode_failed;
   entry->is_locked = is_locked;
   is_locked = false;

   entry->memory = std::move(memory);
   entry->image_info_ = std::move(image_info_);
   entry->src_rect_offset_ = std::move(src_rect_offset_);
   entry->image_ = std::move(image_);
 }

 bool SoftwareImageDecodeCacheUtils::CacheEntry::Lock() {
   if (!memory)
     return false;

   DCHECK(!is_locked);
   bool success = memory->Lock();
   if (!success) {
     memory = nullptr;
     usage_stats_.last_lock_failed = true;
     return false;
   }
   is_locked = true;
   ++usage_stats_.lock_count;
   return true;
 }

 void SoftwareImageDecodeCacheUtils::CacheEntry::Unlock() {
   if (!memory)
     return;

   DCHECK(is_locked);
   memory->Unlock();
   is_locked = false;
   if (usage_stats_.lock_count == 1)
     usage_stats_.first_lock_wasted = !usage_stats_.used;
 }

 }  // namespace cc
	// Copyright 2018 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/tiles/software_image_decode_cache_utils.h"

	#include "base/atomic_sequence_num.h"
	#include "base/hash.h"
	#include "base/memory/discardable_memory_allocator.h"
	#include "base/metrics/histogram_macros.h"
	#include "base/trace_event/trace_event.h"
	#include "cc/tiles/mipmap_util.h"
	#include "ui/gfx/skia_util.h"

	namespace cc {
	namespace {
	// If the size of the original sized image breaches kMemoryRatioToSubrect but we
	// don't need to scale the image, consider caching only the needed subrect.
	// The second part that much be true is that we cache only the needed subrect if
	// the total size needed for the subrect is at most kMemoryRatioToSubrect *
	// (size needed for the full original image).
	// Note that at least one of the dimensions has to be at least
	// kMinDimensionToSubrect before an image can breach the threshold.
	const size_t kMemoryThresholdToSubrect = 64 * 1024 * 1024;
	const int kMinDimensionToSubrect = 4 * 1024;
	const float kMemoryRatioToSubrect = 0.5f;

	// Tracing ID sequence for use in CacheEntry.
	base::AtomicSequenceNumber g_next_tracing_id_;

	gfx::Rect GetSrcRect(const DrawImage& image) {
	const SkIRect& src_rect = image.src_rect();
	int x = std::max(0, src_rect.x());
	int y = std::max(0, src_rect.y());
	int right = std::min(image.paint_image().width(), src_rect.right());
	int bottom = std::min(image.paint_image().height(), src_rect.bottom());
	if (x >= right \|\| y >= bottom)
	return gfx::Rect();
	return gfx::Rect(x, y, right - x, bottom - y);
	}

	SkImageInfo CreateImageInfo(const SkISize& size, SkColorType color_type) {
	return SkImageInfo::Make(size.width(), size.height(), color_type,
	kPremul_SkAlphaType);
	}

	std::unique_ptr<base::DiscardableMemory> AllocateDiscardable(
	const SkImageInfo& info) {
	TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("cc.debug"), "AllocateDiscardable");
	return base::DiscardableMemoryAllocator::GetInstance()
	->AllocateLockedDiscardableMemory(info.minRowBytes() * info.height());
	}

	} // namespace

	// static
	std::unique_ptr<SoftwareImageDecodeCacheUtils::CacheEntry>
	SoftwareImageDecodeCacheUtils::DoDecodeImage(
	const CacheKey& key,
	const PaintImage& paint_image,
	SkColorType color_type,
	PaintImage::GeneratorClientId client_id) {
	SkISize target_size =
	SkISize::Make(key.target_size().width(), key.target_size().height());
	DCHECK(target_size == paint_image.GetSupportedDecodeSize(target_size));

	SkImageInfo target_info = CreateImageInfo(target_size, color_type);
	std::unique_ptr<base::DiscardableMemory> target_pixels =
	AllocateDiscardable(target_info);
	if (!target_pixels \|\| !target_pixels->data())
	return nullptr;

	TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("cc.debug"),
	"SoftwareImageDecodeCacheUtils::DoDecodeImage - "
	"decode");
	bool result = paint_image.Decode(target_pixels->data(), &target_info,
	key.target_color_space().ToSkColorSpace(),
	key.frame_key().frame_index(), client_id);
	if (!result) {
	target_pixels->Unlock();
	return nullptr;
	}
	return std::make_unique<CacheEntry>(target_info, std::move(target_pixels),
	SkSize::Make(0, 0));
	}

	// static
	std::unique_ptr<SoftwareImageDecodeCacheUtils::CacheEntry>
	SoftwareImageDecodeCacheUtils::GenerateCacheEntryFromCandidate(
	const CacheKey& key,
	const DecodedDrawImage& candidate_image,
	bool needs_extract_subset,
	SkColorType color_type) {
	SkISize target_size =
	SkISize::Make(key.target_size().width(), key.target_size().height());
	SkImageInfo target_info = CreateImageInfo(target_size, color_type);
	std::unique_ptr<base::DiscardableMemory> target_pixels =
	AllocateDiscardable(target_info);
	DCHECK(target_pixels);

	if (key.type() == CacheKey::kSubrectOriginal) {
	DCHECK(needs_extract_subset);
	TRACE_EVENT0(
	TRACE_DISABLED_BY_DEFAULT("cc.debug"),
	"SoftwareImageDecodeCacheUtils::GenerateCacheEntryFromCandidate - "
	"subrect");
	bool result = candidate_image.image()->readPixels(
	target_info, target_pixels->data(), target_info.minRowBytes(),
	key.src_rect().x(), key.src_rect().y(), SkImage::kDisallow_CachingHint);
	// We have a decoded image, and we're reading into already allocated memory.
	// This should never fail.
	DCHECK(result) << key.ToString();
	return std::make_unique<CacheEntry>(
	target_info.makeColorSpace(candidate_image.image()->refColorSpace()),
	std::move(target_pixels),
	SkSize::Make(-key.src_rect().x(), -key.src_rect().y()));
	}

	DCHECK_EQ(key.type(), CacheKey::kSubrectAndScale);
	TRACE_EVENT0(
	TRACE_DISABLED_BY_DEFAULT("cc.debug"),
	"SoftwareImageDecodeCacheUtils::GenerateCacheEntryFromCandidate - "
	"scale");
	SkPixmap decoded_pixmap;
	// We don't need to subrect this image, since all candidates passed in would
	// already have a src_rect applied to them.
	bool result = candidate_image.image()->peekPixels(&decoded_pixmap);
	DCHECK(result) << key.ToString();
	if (needs_extract_subset) {
	result = decoded_pixmap.extractSubset(&decoded_pixmap,
	gfx::RectToSkIRect(key.src_rect()));
	DCHECK(result) << key.ToString();
	}

	// Nearest neighbor would only be set in the unscaled case.
	DCHECK(!key.is_nearest_neighbor());
	SkPixmap target_pixmap(target_info, target_pixels->data(),
	target_info.minRowBytes());
	SkFilterQuality filter_quality = kMedium_SkFilterQuality;
	if (decoded_pixmap.colorType() == kRGBA_F16_SkColorType &&
	!ImageDecodeCacheUtils::CanResizeF16Image(filter_quality)) {
	result = ImageDecodeCacheUtils::ScaleToHalfFloatPixmapUsingN32Intermediate(
	decoded_pixmap, &target_pixmap, filter_quality);
	} else {
	result = decoded_pixmap.scalePixels(target_pixmap, filter_quality);
	}
	DCHECK(result) << key.ToString();

	return std::make_unique<CacheEntry>(
	target_info.makeColorSpace(candidate_image.image()->refColorSpace()),
	std::move(target_pixels),
	SkSize::Make(-key.src_rect().x(), -key.src_rect().y()));
	}

	// CacheKey --------------------------------------------------------------------
	// static
	SoftwareImageDecodeCacheUtils::CacheKey
	SoftwareImageDecodeCacheUtils::CacheKey::FromDrawImage(const DrawImage& image,
	SkColorType color_type) {
	DCHECK(!image.paint_image().GetSkImage()->isTextureBacked());

	const PaintImage::FrameKey frame_key = image.frame_key();
	const PaintImage::Id stable_id = image.paint_image().stable_id();

	const SkSize& scale = image.scale();
	// If the src_rect falls outside of the image, we need to clip it since
	// otherwise we might end up with uninitialized memory in the decode process.
	// Note that the scale is still unchanged and the target size is now a
	// function of the new src_rect.
	const gfx::Rect& src_rect = GetSrcRect(image);

	// Start with the exact target size. However, this will be adjusted below to
	// be either a mip level, the original size, or a subrect size. This is done
	// to keep memory accounting correct.
	gfx::Size target_size(
	SkScalarRoundToInt(std::abs(src_rect.width() * scale.width())),
	SkScalarRoundToInt(std::abs(src_rect.height() * scale.height())));

	// If the target size is empty, then we'll be skipping the decode anyway, so
	// the filter quality doesn't matter. Early out instead.
	if (target_size.IsEmpty()) {
	return CacheKey(frame_key, stable_id, kSubrectAndScale, false, src_rect,
	target_size, image.target_color_space());
	}

	ProcessingType type = kOriginal;
	bool is_nearest_neighbor = image.filter_quality() == kNone_SkFilterQuality;
	int mip_level = MipMapUtil::GetLevelForSize(src_rect.size(), target_size);
	// If any of the following conditions hold, then use at most low filter
	// quality and adjust the target size to match the original image:
	// - Quality is none: We need a pixelated image, so we can't upgrade it.
	// - Mip level is 0: The required mip is the original image, so just use low
	// filter quality.
	// - Matrix is not decomposable: There's perspective on this image and we
	// can't determine the size, so use the original.
	if (is_nearest_neighbor \|\| mip_level == 0 \|\|
	!image.matrix_is_decomposable()) {
	type = kOriginal;
	// Update the size to be the original image size.
	target_size =
	gfx::Size(image.paint_image().width(), image.paint_image().height());
	} else {
	type = kSubrectAndScale;
	// Update the target size to be a mip level size.
	// TODO(vmpstr): MipMapUtil and JPEG decoders disagree on what to do with
	// odd sizes. If width = 2k + 1, and the mip level is 1, then this will
	// return width = k; JPEG decoder, however, will support decoding to width =
	// k + 1. We need to figure out what to do in this case.
	SkSize mip_scale_adjustment =
	MipMapUtil::GetScaleAdjustmentForLevel(src_rect.size(), mip_level);
	target_size.set_width(src_rect.width() * mip_scale_adjustment.width());
	target_size.set_height(src_rect.height() * mip_scale_adjustment.height());
	}

	// If the original image is large, we might want to do a subrect instead if
	// the subrect would be kMemoryRatioToSubrect times smaller.
	if (type == kOriginal &&
	(image.paint_image().width() >= kMinDimensionToSubrect \|\|
	image.paint_image().height() >= kMinDimensionToSubrect)) {
	base::CheckedNumeric<size_t> checked_original_size = 4u;
	checked_original_size *= image.paint_image().width();
	checked_original_size *= image.paint_image().height();
	size_t original_size = checked_original_size.ValueOrDefault(
	std::numeric_limits<size_t>::max());

	base::CheckedNumeric<size_t> checked_src_rect_size = 4u;
	checked_src_rect_size *= src_rect.width();
	checked_src_rect_size *= src_rect.height();
	size_t src_rect_size = checked_src_rect_size.ValueOrDefault(
	std::numeric_limits<size_t>::max());

	// If the sizes are such that we get good savings by subrecting, then do
	// that. Also update the target size to be the src rect size since that's
	// the rect we want to use.
	if (original_size > kMemoryThresholdToSubrect &&
	src_rect_size <= original_size * kMemoryRatioToSubrect) {
	type = kSubrectOriginal;
	target_size = src_rect.size();
	}
	}

	return CacheKey(frame_key, stable_id, type, is_nearest_neighbor, src_rect,
	target_size, image.target_color_space());
	}

	SoftwareImageDecodeCacheUtils::CacheKey::CacheKey(
	PaintImage::FrameKey frame_key,
	PaintImage::Id stable_id,
	ProcessingType type,
	bool is_nearest_neighbor,
	const gfx::Rect& src_rect,
	const gfx::Size& target_size,
	const gfx::ColorSpace& target_color_space)
	: frame_key_(frame_key),
	stable_id_(stable_id),
	type_(type),
	is_nearest_neighbor_(is_nearest_neighbor),
	src_rect_(src_rect),
	target_size_(target_size),
	target_color_space_(target_color_space) {
	if (type == kOriginal) {
	hash_ = frame_key_.hash();
	} else {
	// TODO(vmpstr): This is a mess. Maybe it's faster to just search the vector
	// always (forwards or backwards to account for LRU).
	uint64_t src_rect_hash = base::HashInts(
	static_cast<uint64_t>(base::HashInts(src_rect_.x(), src_rect_.y())),
	static_cast<uint64_t>(
	base::HashInts(src_rect_.width(), src_rect_.height())));

	uint64_t target_size_hash =
	base::HashInts(target_size_.width(), target_size_.height());

	hash_ = base::HashInts(base::HashInts(src_rect_hash, target_size_hash),
	frame_key_.hash());
	}
	// Include the target color space in the hash regardless of scaling.
	hash_ = base::HashInts(hash_, target_color_space.GetHash());
	}

	SoftwareImageDecodeCacheUtils::CacheKey::CacheKey(const CacheKey& other) =
	default;

	std::string SoftwareImageDecodeCacheUtils::CacheKey::ToString() const {
	std::ostringstream str;
	str << "frame_key[" << frame_key_.ToString() << "]\ntype[";
	switch (type_) {
	case kOriginal:
	str << "Original";
	break;
	case kSubrectOriginal:
	str << "SubrectOriginal";
	break;
	case kSubrectAndScale:
	str << "SubrectAndScale";
	break;
	}
	str << "]\nis_nearest_neightbor[" << is_nearest_neighbor_ << "]\nsrc_rect["
	<< src_rect_.ToString() << "]\ntarget_size[" << target_size_.ToString()
	<< "]\ntarget_color_space[" << target_color_space_.ToString()
	<< "]\nhash[" << hash_ << "]";
	return str.str();
	}

	// CacheEntry ------------------------------------------------------------------
	SoftwareImageDecodeCacheUtils::CacheEntry::CacheEntry()
	: tracing_id_(g_next_tracing_id_.GetNext()) {}
	SoftwareImageDecodeCacheUtils::CacheEntry::CacheEntry(
	const SkImageInfo& info,
	std::unique_ptr<base::DiscardableMemory> in_memory,
	const SkSize& src_rect_offset)
	: is_locked(true),
	memory(std::move(in_memory)),
	image_info_(info),
	src_rect_offset_(src_rect_offset),
	tracing_id_(g_next_tracing_id_.GetNext()) {
	DCHECK(memory);
	SkPixmap pixmap(image_info_, memory->data(), image_info_.minRowBytes());
	image_ = SkImage::MakeFromRaster(
	pixmap, [](const void* pixels, void* context) {}, nullptr);
	}

	SoftwareImageDecodeCacheUtils::CacheEntry::~CacheEntry() {
	DCHECK(!is_locked);

	// We create temporary CacheEntries as a part of decoding. However, we move
	// the memory to cache entries that actually live in the cache. Destroying the
	// temporaries should not cause any of the stats to be recorded. Specifically,
	// if allowed to report, they would report every single temporary entry as
	// wasted, which is misleading. As a fix, don't report on a cache entry that
	// has never been in the cache.
	if (!cached_)
	return;

	// lock_count \| used \| last lock failed \| result state
	// ===========+=======+==================+==================
	// 1 \| false \| false \| WASTED
	// 1 \| false \| true \| WASTED
	// 1 \| true \| false \| USED
	// 1 \| true \| true \| USED_RELOCK_FAILED
	// >1 \| false \| false \| WASTED_RELOCKED
	// >1 \| false \| true \| WASTED_RELOCKED
	// >1 \| true \| false \| USED_RELOCKED
	// >1 \| true \| true \| USED_RELOCKED
	// Note that it's important not to reorder the following enums, since the
	// numerical values are used in the histogram code.
	enum State : int {
	DECODED_IMAGE_STATE_WASTED,
	DECODED_IMAGE_STATE_USED,
	DECODED_IMAGE_STATE_USED_RELOCK_FAILED,
	DECODED_IMAGE_STATE_WASTED_RELOCKED,
	DECODED_IMAGE_STATE_USED_RELOCKED,
	DECODED_IMAGE_STATE_COUNT
	} state = DECODED_IMAGE_STATE_WASTED;

	if (usage_stats_.lock_count == 1) {
	if (!usage_stats_.used)
	state = DECODED_IMAGE_STATE_WASTED;
	else if (usage_stats_.last_lock_failed)
	state = DECODED_IMAGE_STATE_USED_RELOCK_FAILED;
	else
	state = DECODED_IMAGE_STATE_USED;
	} else {
	if (usage_stats_.used)
	state = DECODED_IMAGE_STATE_USED_RELOCKED;
	else
	state = DECODED_IMAGE_STATE_WASTED_RELOCKED;
	}

	UMA_HISTOGRAM_ENUMERATION("Renderer4.SoftwareImageDecodeState", state,
	DECODED_IMAGE_STATE_COUNT);
	UMA_HISTOGRAM_BOOLEAN("Renderer4.SoftwareImageDecodeState.FirstLockWasted",
	usage_stats_.first_lock_wasted);
	if (usage_stats_.first_lock_out_of_raster)
	UMA_HISTOGRAM_BOOLEAN(
	"Renderer4.SoftwareImageDecodeState.FirstLockWasted.OutOfRaster",
	usage_stats_.first_lock_wasted);
	}

	void SoftwareImageDecodeCacheUtils::CacheEntry::MoveImageMemoryTo(
	CacheEntry* entry) {
	DCHECK(!is_budgeted);
	DCHECK_EQ(ref_count, 0);

	// Copy/move most things except budgeted and ref counts.
	entry->decode_failed = decode_failed;
	entry->is_locked = is_locked;
	is_locked = false;

	entry->memory = std::move(memory);
	entry->image_info_ = std::move(image_info_);
	entry->src_rect_offset_ = std::move(src_rect_offset_);
	entry->image_ = std::move(image_);
	}

	bool SoftwareImageDecodeCacheUtils::CacheEntry::Lock() {
	if (!memory)
	return false;

	DCHECK(!is_locked);
	bool success = memory->Lock();
	if (!success) {
	memory = nullptr;
	usage_stats_.last_lock_failed = true;
	return false;
	}
	is_locked = true;
	++usage_stats_.lock_count;
	return true;
	}

	void SoftwareImageDecodeCacheUtils::CacheEntry::Unlock() {
	if (!memory)
	return;

	DCHECK(is_locked);
	memory->Unlock();
	is_locked = false;
	if (usage_stats_.lock_count == 1)
	usage_stats_.first_lock_wasted = !usage_stats_.used;
	}

	} // namespace cc