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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.
#include "flutter/flow/raster_cache.h"
#include <vector>
#include "flutter/flow/layers/layer.h"
#include "flutter/flow/paint_utils.h"
#include "flutter/fml/logging.h"
#include "flutter/fml/trace_event.h"
#include "third_party/skia/include/core/SkCanvas.h"
#include "third_party/skia/include/core/SkImage.h"
#include "third_party/skia/include/core/SkPicture.h"
#include "third_party/skia/include/core/SkSurface.h"
namespace flutter {
RasterCacheResult::RasterCacheResult(sk_sp<SkImage> image,
const SkRect& logical_rect)
: image_(std::move(image)), logical_rect_(logical_rect) {}
void RasterCacheResult::draw(SkCanvas& canvas, const SkPaint* paint) const {
TRACE_EVENT0("flutter", "RasterCacheResult::draw");
SkAutoCanvasRestore auto_restore(&canvas, true);
SkIRect bounds =
RasterCache::GetDeviceBounds(logical_rect_, canvas.getTotalMatrix());
FML_DCHECK(
std::abs(bounds.size().width() - image_->dimensions().width()) <= 1 &&
std::abs(bounds.size().height() - image_->dimensions().height()) <= 1);
canvas.resetMatrix();
canvas.drawImage(image_, bounds.fLeft, bounds.fTop, paint);
}
RasterCache::RasterCache(size_t access_threshold,
size_t picture_cache_limit_per_frame)
: access_threshold_(access_threshold),
picture_cache_limit_per_frame_(picture_cache_limit_per_frame),
checkerboard_images_(false) {}
static bool CanRasterizePicture(SkPicture* picture) {
if (picture == nullptr) {
return false;
}
const SkRect cull_rect = picture->cullRect();
if (cull_rect.isEmpty()) {
// No point in ever rasterizing an empty picture.
return false;
}
if (!cull_rect.isFinite()) {
// Cannot attempt to rasterize into an infinitely large surface.
return false;
}
return true;
}
static bool IsPictureWorthRasterizing(SkPicture* picture,
bool will_change,
bool is_complex) {
if (will_change) {
// If the picture is going to change in the future, there is no point in
// doing to extra work to rasterize.
return false;
}
if (!CanRasterizePicture(picture)) {
// No point in deciding whether the picture is worth rasterizing if it
// cannot be rasterized at all.
return false;
}
if (is_complex) {
// The caller seems to have extra information about the picture and thinks
// the picture is always worth rasterizing.
return true;
}
// TODO(abarth): We should find a better heuristic here that lets us avoid
// wasting memory on trivial layers that are easy to re-rasterize every frame.
return picture->approximateOpCount() > 5;
}
/// @note Procedure doesn't copy all closures.
static RasterCacheResult Rasterize(
GrContext* context,
const SkMatrix& ctm,
SkColorSpace* dst_color_space,
bool checkerboard,
const SkRect& logical_rect,
const std::function<void(SkCanvas*)>& draw_function) {
TRACE_EVENT0("flutter", "RasterCachePopulate");
SkIRect cache_rect = RasterCache::GetDeviceBounds(logical_rect, ctm);
const SkImageInfo image_info = SkImageInfo::MakeN32Premul(
cache_rect.width(), cache_rect.height(), sk_ref_sp(dst_color_space));
sk_sp<SkSurface> surface =
context
? SkSurface::MakeRenderTarget(context, SkBudgeted::kYes, image_info)
: SkSurface::MakeRaster(image_info);
if (!surface) {
return {};
}
SkCanvas* canvas = surface->getCanvas();
canvas->clear(SK_ColorTRANSPARENT);
canvas->translate(-cache_rect.left(), -cache_rect.top());
canvas->concat(ctm);
draw_function(canvas);
if (checkerboard) {
DrawCheckerboard(canvas, logical_rect);
}
return {surface->makeImageSnapshot(), logical_rect};
}
RasterCacheResult RasterizePicture(SkPicture* picture,
GrContext* context,
const SkMatrix& ctm,
SkColorSpace* dst_color_space,
bool checkerboard) {
return Rasterize(context, ctm, dst_color_space, checkerboard,
picture->cullRect(),
[=](SkCanvas* canvas) { canvas->drawPicture(picture); });
}
void RasterCache::Prepare(PrerollContext* context,
Layer* layer,
const SkMatrix& ctm) {
LayerRasterCacheKey cache_key(layer->unique_id(), ctm);
Entry& entry = layer_cache_[cache_key];
entry.access_count++;
entry.used_this_frame = true;
if (!entry.image.is_valid()) {
entry.image = Rasterize(
context->gr_context, ctm, context->dst_color_space,
checkerboard_images_, layer->paint_bounds(),
[layer, context](SkCanvas* canvas) {
SkISize canvas_size = canvas->getBaseLayerSize();
SkNWayCanvas internal_nodes_canvas(canvas_size.width(),
canvas_size.height());
internal_nodes_canvas.addCanvas(canvas);
Layer::PaintContext paintContext = {
(SkCanvas*)&internal_nodes_canvas,
canvas,
context->gr_context,
nullptr,
context->raster_time,
context->ui_time,
context->texture_registry,
context->has_platform_view ? nullptr : context->raster_cache,
context->checkerboard_offscreen_layers,
context->frame_physical_depth,
context->frame_device_pixel_ratio};
if (layer->needs_painting()) {
layer->Paint(paintContext);
}
});
}
}
bool RasterCache::Prepare(GrContext* context,
SkPicture* picture,
const SkMatrix& transformation_matrix,
SkColorSpace* dst_color_space,
bool is_complex,
bool will_change) {
// Disabling caching when access_threshold is zero is historic behavior.
if (access_threshold_ == 0) {
return false;
}
if (picture_cached_this_frame_ >= picture_cache_limit_per_frame_) {
return false;
}
if (!IsPictureWorthRasterizing(picture, will_change, is_complex)) {
// We only deal with pictures that are worthy of rasterization.
return false;
}
// Decompose the matrix (once) for all subsequent operations. We want to make
// sure to avoid volumetric distortions while accounting for scaling.
const MatrixDecomposition matrix(transformation_matrix);
if (!matrix.IsValid()) {
// The matrix was singular. No point in going further.
return false;
}
PictureRasterCacheKey cache_key(picture->uniqueID(), transformation_matrix);
// Creates an entry, if not present prior.
Entry& entry = picture_cache_[cache_key];
if (entry.access_count < access_threshold_) {
// Frame threshold has not yet been reached.
return false;
}
if (!entry.image.is_valid()) {
entry.image = RasterizePicture(picture, context, transformation_matrix,
dst_color_space, checkerboard_images_);
picture_cached_this_frame_++;
}
return true;
}
RasterCacheResult RasterCache::Get(const SkPicture& picture,
const SkMatrix& ctm) const {
PictureRasterCacheKey cache_key(picture.uniqueID(), ctm);
auto it = picture_cache_.find(cache_key);
if (it == picture_cache_.end()) {
return RasterCacheResult();
}
Entry& entry = it->second;
entry.access_count++;
entry.used_this_frame = true;
return entry.image;
}
RasterCacheResult RasterCache::Get(Layer* layer, const SkMatrix& ctm) const {
LayerRasterCacheKey cache_key(layer->unique_id(), ctm);
auto it = layer_cache_.find(cache_key);
if (it == layer_cache_.end()) {
return RasterCacheResult();
}
Entry& entry = it->second;
entry.access_count++;
entry.used_this_frame = true;
return entry.image;
}
void RasterCache::SweepAfterFrame() {
SweepOneCacheAfterFrame(picture_cache_);
SweepOneCacheAfterFrame(layer_cache_);
picture_cached_this_frame_ = 0;
TraceStatsToTimeline();
}
void RasterCache::Clear() {
picture_cache_.clear();
layer_cache_.clear();
}
size_t RasterCache::GetCachedEntriesCount() const {
return layer_cache_.size() + picture_cache_.size();
}
void RasterCache::SetCheckboardCacheImages(bool checkerboard) {
if (checkerboard_images_ == checkerboard) {
return;
}
checkerboard_images_ = checkerboard;
// Clear all existing entries so previously rasterized items (with or without
// a checkerboard) will be refreshed in subsequent passes.
Clear();
}
void RasterCache::TraceStatsToTimeline() const {
#if !FLUTTER_RELEASE
size_t layer_cache_count = 0;
size_t layer_cache_bytes = 0;
size_t picture_cache_count = 0;
size_t picture_cache_bytes = 0;
for (const auto& item : layer_cache_) {
const auto dimensions = item.second.image.image_dimensions();
layer_cache_count++;
layer_cache_bytes += dimensions.width() * dimensions.height() * 4;
}
for (const auto& item : picture_cache_) {
const auto dimensions = item.second.image.image_dimensions();
picture_cache_count++;
picture_cache_bytes += dimensions.width() * dimensions.height() * 4;
}
FML_TRACE_COUNTER("flutter", "RasterCache",
reinterpret_cast<int64_t>(this), //
"LayerCount", layer_cache_count, //
"LayerMBytes", layer_cache_bytes * 1e-6, //
"PictureCount", picture_cache_count, //
"PictureMBytes", picture_cache_bytes * 1e-6 //
);
#endif // !FLUTTER_RELEASE
}
} // namespace flutter