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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/flow/display_list.h"
#include "flutter/flow/raster_cache_key.h"
#include "flutter/fml/macros.h"
#include "flutter/fml/memory/weak_ptr.h"
#include "third_party/skia/include/core/SkImage.h"
#include "third_party/skia/include/core/SkSize.h"
namespace flutter {
class RasterCacheResult {
public:
RasterCacheResult(sk_sp<SkImage> image, const SkRect& logical_rect);
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_;
};
struct PrerollContext;
class RasterCache {
public:
// The default max number of picture 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 kDefaultPictureCacheLimitPerFrame = 3;
explicit RasterCache(
size_t access_threshold = 3,
size_t picture_cache_limit_per_frame = kDefaultPictureCacheLimitPerFrame);
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,
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. The picture is not worth rasterizing
// 2. The matrix is singular
// 3. The picture is accessed too few times
// 4. There are too many pictures to be cached in the current frame.
// (See also kDefaultPictureCacheLimitPerFrame.)
bool Prepare(GrDirectContext* context,
SkPicture* picture,
const SkMatrix& transformation_matrix,
SkColorSpace* dst_color_space,
bool is_complex,
bool will_change);
bool Prepare(GrDirectContext* context,
DisplayList* display_list,
const SkMatrix& transformation_matrix,
SkColorSpace* dst_color_space,
bool is_complex,
bool will_change);
void Prepare(PrerollContext* context, Layer* layer, const SkMatrix& ctm);
// 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;
// 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;
// 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,
SkPaint* paint = nullptr) const;
void SweepAfterFrame();
void Clear();
void SetCheckboardCacheImages(bool checkerboard);
size_t GetCachedEntriesCount() const;
size_t GetLayerCachedEntriesCount() const;
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 count of cache sweeps that have occured.
*
* The sweep count will help to determine if a sweep of the cache may have
* removed expired entries since the last time the method was called.
* The count will increment even if the sweep performs no evictions.
*/
int sweep_count() const { return sweep_count_; }
/**
* @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;
};
template <class Cache>
static void SweepOneCacheAfterFrame(Cache& cache) {
std::vector<typename Cache::iterator> dead;
for (auto it = cache.begin(); it != cache.end(); ++it) {
Entry& entry = it->second;
if (!entry.used_this_frame) {
dead.push_back(it);
}
entry.used_this_frame = false;
}
for (auto it : dead) {
cache.erase(it);
}
}
const size_t access_threshold_;
const size_t picture_cache_limit_per_frame_;
size_t picture_cached_this_frame_ = 0;
int sweep_count_ = 0;
mutable PictureRasterCacheKey::Map<Entry> picture_cache_;
mutable DisplayListRasterCacheKey::Map<Entry> display_list_cache_;
mutable LayerRasterCacheKey::Map<Entry> layer_cache_;
bool checkerboard_images_;
void TraceStatsToTimeline() const;
FML_DISALLOW_COPY_AND_ASSIGN(RasterCache);
};
} // namespace flutter
#endif // FLUTTER_FLOW_RASTER_CACHE_H_