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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef FLUTTER_FLOW_RASTER_CACHE_H_
#define FLUTTER_FLOW_RASTER_CACHE_H_
#include <memory>
#include <unordered_map>
#include "flutter/display_list/display_list.h"
#include "flutter/display_list/display_list_complexity.h"
#include "flutter/flow/raster_cache_key.h"
#include "flutter/fml/macros.h"
#include "flutter/fml/memory/weak_ptr.h"
#include "flutter/fml/trace_event.h"
#include "third_party/skia/include/core/SkImage.h"
#include "third_party/skia/include/core/SkSize.h"
class SkColorSpace;
namespace flutter {
enum class RasterCacheLayerStrategy { kLayer, kLayerChildren };
class RasterCacheResult {
public:
RasterCacheResult(sk_sp<SkImage> image,
const SkRect& logical_rect,
const char* type);
virtual ~RasterCacheResult() = default;
virtual void draw(SkCanvas& canvas, const SkPaint* paint) const;
virtual SkISize image_dimensions() const {
return image_ ? image_->dimensions() : SkISize::Make(0, 0);
};
virtual int64_t image_bytes() const {
return image_ ? image_->imageInfo().computeMinByteSize() : 0;
};
private:
sk_sp<SkImage> image_;
SkRect logical_rect_;
fml::tracing::TraceFlow flow_;
};
class Layer;
struct PrerollContext;
struct RasterCacheMetrics {
/**
* The number of cache entries with images evicted in this frame.
*/
size_t eviction_count = 0;
/**
* The size of all of the images evicted in this frame.
*/
size_t eviction_bytes = 0;
/**
* The number of cache entries with images used in this frame.
*/
size_t in_use_count = 0;
/**
* The size of all of the images used in this frame.
*/
size_t in_use_bytes = 0;
/**
* The total cache entries that had images during this frame whether
* they were used in the frame or held memory during the frame and then
* were evicted after it ended.
*/
size_t total_count() const { return in_use_count + eviction_count; }
/**
* The size of all of the cached images during this frame whether
* they were used in the frame or held memory during the frame and then
* were evicted after it ended.
*/
size_t total_bytes() const { return in_use_bytes + eviction_bytes; }
};
class RasterCache {
public:
// The default max number of picture and display list raster caches to be
// generated per frame. Generating too many caches in one frame may cause jank
// on that frame. This limit allows us to throttle the cache and distribute
// the work across multiple frames.
static constexpr int kDefaultPictureAndDispLayListCacheLimitPerFrame = 3;
explicit RasterCache(size_t access_threshold = 3,
size_t picture_and_display_list_cache_limit_per_frame =
kDefaultPictureAndDispLayListCacheLimitPerFrame);
virtual ~RasterCache() = default;
/**
* @brief Rasterize a picture object and produce a RasterCacheResult
* to be stored in the cache.
*
* @param picture the SkPicture object to be cached.
* @param context the GrDirectContext used for rendering.
* @param ctm the transformation matrix used for rendering.
* @param dst_color_space the destination color space that the cached
* rendering will be drawn into
* @param checkerboard a flag indicating whether or not a checkerboard
* pattern should be rendered into the cached image for debug
* analysis
* @return a RasterCacheResult that can draw the rendered picture into
* the destination using a simple image blit
*/
virtual std::unique_ptr<RasterCacheResult> RasterizePicture(
SkPicture* picture,
GrDirectContext* context,
const SkMatrix& ctm,
SkColorSpace* dst_color_space,
bool checkerboard) const;
virtual std::unique_ptr<RasterCacheResult> RasterizeDisplayList(
DisplayList* display_list,
GrDirectContext* context,
const SkMatrix& ctm,
SkColorSpace* dst_color_space,
bool checkerboard) const;
/**
* @brief Rasterize an engine Layer and produce a RasterCacheResult
* to be stored in the cache.
*
* @param context the PrerollContext containing important information
* needed for rendering a layer.
* @param layer the Layer object to be cached.
* @param ctm the transformation matrix used for rendering.
* @param checkerboard a flag indicating whether or not a checkerboard
* pattern should be rendered into the cached image for debug
* analysis
* @return a RasterCacheResult that can draw the rendered layer into
* the destination using a simple image blit
*/
virtual std::unique_ptr<RasterCacheResult> RasterizeLayer(
PrerollContext* context,
Layer* layer,
RasterCacheLayerStrategy strategy,
const SkMatrix& ctm,
bool checkerboard) const;
static SkIRect GetDeviceBounds(const SkRect& rect, const SkMatrix& ctm) {
SkRect device_rect;
ctm.mapRect(&device_rect, rect);
SkIRect bounds;
device_rect.roundOut(&bounds);
return bounds;
}
/**
* @brief Snap the translation components of the matrix to integers.
*
* The snapping will only happen if the matrix only has scale and translation
* transformations.
*
* @param ctm the current transformation matrix.
* @return SkMatrix the snapped transformation matrix.
*/
static SkMatrix GetIntegralTransCTM(const SkMatrix& ctm) {
// Avoid integral snapping if the matrix has complex transformation to avoid
// the artifact observed in https://github.com/flutter/flutter/issues/41654.
if (!ctm.isScaleTranslate()) {
return ctm;
}
SkMatrix result = ctm;
result[SkMatrix::kMTransX] = SkScalarRoundToScalar(ctm.getTranslateX());
result[SkMatrix::kMTransY] = SkScalarRoundToScalar(ctm.getTranslateY());
return result;
}
// Return true if the cache is generated.
//
// We may return false and not generate the cache if
// 1. There are too many pictures to be cached in the current frame.
// (See also kDefaultPictureAndDispLayListCacheLimitPerFrame.)
// 2. The picture is not worth rasterizing
// 3. The matrix is singular
// 4. The picture is accessed too few times
bool Prepare(PrerollContext* context,
SkPicture* picture,
bool is_complex,
bool will_change,
const SkMatrix& untranslated_matrix,
const SkPoint& offset = SkPoint());
bool Prepare(PrerollContext* context,
DisplayList* display_list,
bool is_complex,
bool will_change,
const SkMatrix& untranslated_matrix,
const SkPoint& offset = SkPoint());
// If there is cache entry for this picture, display list or layer, mark it as
// used for this frame in order to not get evicted. This is needed during
// partial repaint for layers that are outside of current clip and are culled
// away.
void Touch(SkPicture* picture, const SkMatrix& transformation_matrix);
void Touch(DisplayList* display_list, const SkMatrix& transformation_matrix);
void Touch(
Layer* layer,
const SkMatrix& ctm,
RasterCacheLayerStrategy strategey = RasterCacheLayerStrategy::kLayer);
void Prepare(
PrerollContext* context,
Layer* layer,
const SkMatrix& ctm,
RasterCacheLayerStrategy strategey = RasterCacheLayerStrategy::kLayer);
// Find the raster cache for the picture and draw it to the canvas.
//
// Return true if it's found and drawn.
bool Draw(const SkPicture& picture,
SkCanvas& canvas,
const SkPaint* paint = nullptr) const;
// Find the raster cache for the display list and draw it to the canvas.
//
// Return true if it's found and drawn.
bool Draw(const DisplayList& display_list,
SkCanvas& canvas,
const SkPaint* paint = nullptr) const;
// Find the raster cache for the layer and draw it to the canvas.
//
// Additional paint can be given to change how the raster cache is drawn
// (e.g., draw the raster cache with some opacity).
//
// Return true if the layer raster cache is found and drawn.
bool Draw(
const Layer* layer,
SkCanvas& canvas,
RasterCacheLayerStrategy strategey = RasterCacheLayerStrategy::kLayer,
const SkPaint* paint = nullptr) const;
void PrepareNewFrame();
void CleanupAfterFrame();
void Clear();
void SetCheckboardCacheImages(bool checkerboard);
const RasterCacheMetrics& picture_metrics() const { return picture_metrics_; }
const RasterCacheMetrics& layer_metrics() const { return layer_metrics_; }
size_t GetCachedEntriesCount() const;
/**
* Return the number of map entries in the layer cache regardless of whether
* the entries have been populated with an image.
*/
size_t GetLayerCachedEntriesCount() const;
/**
* Return the number of map entries in the picture caches (SkPicture and
* DisplayList) regardless of whether the entries have been populated with
* an image.
*/
size_t GetPictureCachedEntriesCount() const;
/**
* @brief Estimate how much memory is used by picture raster cache entries in
* bytes, including cache entries in the SkPicture cache and the DisplayList
* cache.
*
* Only SkImage's memory usage is counted as other objects are often much
* smaller compared to SkImage. SkImageInfo::computeMinByteSize is used to
* estimate the SkImage memory usage.
*/
size_t EstimatePictureCacheByteSize() const;
/**
* @brief Estimate how much memory is used by layer raster cache entries in
* bytes.
*
* Only SkImage's memory usage is counted as other objects are often much
* smaller compared to SkImage. SkImageInfo::computeMinByteSize is used to
* estimate the SkImage memory usage.
*/
size_t EstimateLayerCacheByteSize() const;
/**
* @brief Return the number of frames that a picture must be prepared
* before it will be cached. If the number is 0, then no picture will
* ever be cached.
*
* If the number is one, then it must be prepared and drawn on 1 frame
* and it will then be cached on the next frame if it is prepared.
*/
int access_threshold() const { return access_threshold_; }
private:
struct Entry {
bool used_this_frame = false;
size_t access_count = 0;
std::unique_ptr<RasterCacheResult> image;
};
void Touch(const RasterCacheKey& cache_key);
bool Draw(const RasterCacheKey& cache_key,
SkCanvas& canvas,
const SkPaint* paint) const;
void SweepOneCacheAfterFrame(RasterCacheKey::Map<Entry>& cache,
RasterCacheMetrics& picture_metrics,
RasterCacheMetrics& layer_metrics);
bool GenerateNewCacheInThisFrame() const {
// Disabling caching when access_threshold is zero is historic behavior.
return access_threshold_ != 0 &&
picture_cached_this_frame_ + display_list_cached_this_frame_ <
picture_and_display_list_cache_limit_per_frame_;
}
std::optional<RasterCacheKey> TryToMakeRasterCacheKeyForLayer(
const Layer* layer,
RasterCacheLayerStrategy strategy,
const SkMatrix& ctm) const;
const SkRect& GetPaintBoundsFromLayer(
Layer* layer,
RasterCacheLayerStrategy strategy) const;
const size_t access_threshold_;
const size_t picture_and_display_list_cache_limit_per_frame_;
size_t picture_cached_this_frame_ = 0;
size_t display_list_cached_this_frame_ = 0;
RasterCacheMetrics layer_metrics_;
RasterCacheMetrics picture_metrics_;
mutable RasterCacheKey::Map<Entry> cache_;
bool checkerboard_images_;
void TraceStatsToTimeline() const;
FML_DISALLOW_COPY_AND_ASSIGN(RasterCache);
};
} // namespace flutter
#endif // FLUTTER_FLOW_RASTER_CACHE_H_