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// Copyright 2017 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "cobalt/renderer/rasterizer/egl/offscreen_target_manager.h"
#include <algorithm>
#include <unordered_map>
#include "cobalt/renderer/rasterizer/egl/rect_allocator.h"
#include "third_party/skia/include/core/SkRefCnt.h"
namespace cobalt {
namespace renderer {
namespace rasterizer {
namespace egl {
namespace {
struct AllocationMapValue {
AllocationMapValue(const OffscreenTargetManager::ErrorData& in_error_data,
const math::RectF& in_target_region)
: error_data(in_error_data), target_region(in_target_region) {}
OffscreenTargetManager::ErrorData error_data;
math::RectF target_region;
};
typedef std::unordered_multimap<int64_t, AllocationMapValue> AllocationMap;
int32_t NextPowerOf2(int32_t num) {
// Return the smallest power of 2 that is greater than or equal to num.
// This flips on all bits <= num, then num+1 will be the next power of 2.
--num;
num |= num >> 1;
num |= num >> 2;
num |= num >> 4;
num |= num >> 8;
num |= num >> 16;
return num + 1;
}
bool IsPowerOf2(int32_t num) {
return (num & (num - 1)) == 0;
}
size_t GetMemorySize(const math::Size& target_size) {
// RGBA uses 4 bytes per pixel. Assume no rounding to the nearest power of 2.
return target_size.width() * target_size.height() * 4;
}
} // namespace
struct OffscreenTargetManager::OffscreenAtlas {
explicit OffscreenAtlas(const math::Size& size)
: allocator(size),
allocations_used(0),
needs_flush(false) {}
RectAllocator allocator;
AllocationMap allocation_map;
size_t allocations_used;
scoped_refptr<backend::FramebufferRenderTargetEGL> framebuffer;
sk_sp<SkSurface> skia_surface;
bool needs_flush;
};
OffscreenTargetManager::OffscreenTargetManager(
backend::GraphicsContextEGL* graphics_context,
const CreateFallbackSurfaceFunction& create_fallback_surface,
size_t memory_limit)
: graphics_context_(graphics_context),
create_fallback_surface_(create_fallback_surface),
offscreen_target_size_mask_(0, 0),
memory_limit_(memory_limit),
cache_error_threshold_(1.0f) {
}
OffscreenTargetManager::~OffscreenTargetManager() {
}
void OffscreenTargetManager::Update(const math::Size& frame_size) {
if (offscreen_atlases_.empty()) {
DCHECK(offscreen_atlases_1d_.empty());
InitializeTargets(frame_size);
}
SelectAtlasCache(&offscreen_atlases_, &offscreen_cache_);
SelectAtlasCache(&offscreen_atlases_1d_, &offscreen_cache_1d_);
// Delete uncached targets that were not used in the previous render frame.
for (size_t index = 0; index < uncached_targets_.size();) {
if (uncached_targets_[index]->allocations_used == 0) {
uncached_targets_.erase(uncached_targets_.begin() + index);
} else {
uncached_targets_[index]->allocations_used = 0;
++index;
}
}
}
void OffscreenTargetManager::SelectAtlasCache(
ScopedVector<OffscreenAtlas>* atlases_ptr,
scoped_ptr<OffscreenAtlas>* cache_ptr) {
ScopedVector<OffscreenAtlas>& atlases = *atlases_ptr;
scoped_ptr<OffscreenAtlas>& cache = *cache_ptr;
// If any of the current atlases have more allocations used than the
// current cache, then use that as the new cache.
size_t most_used_atlas_index = 0;
for (size_t index = 1; index < atlases.size(); ++index) {
if (atlases[most_used_atlas_index]->allocations_used <
atlases[index]->allocations_used) {
most_used_atlas_index = index;
}
}
OffscreenAtlas* most_used_atlas = atlases[most_used_atlas_index];
if (cache->allocations_used < most_used_atlas->allocations_used) {
OffscreenAtlas* new_atlas = cache.release();
cache.reset(atlases[most_used_atlas_index]);
atlases.weak_erase(atlases.begin() + most_used_atlas_index);
atlases.push_back(new_atlas);
}
cache->allocations_used = 0;
// Reset all current atlases for use this frame.
for (size_t index = 0; index < atlases.size(); ++index) {
OffscreenAtlas* atlas = atlases[index];
atlas->allocator.Reset();
atlas->allocation_map.clear();
atlas->allocations_used = 0;
}
}
void OffscreenTargetManager::Flush() {
if (offscreen_cache_->needs_flush) {
offscreen_cache_->needs_flush = false;
offscreen_cache_->skia_surface->getCanvas()->flush();
}
for (size_t index = 0; index < offscreen_atlases_.size(); ++index) {
if (offscreen_atlases_[index]->needs_flush) {
offscreen_atlases_[index]->needs_flush = false;
offscreen_atlases_[index]->skia_surface->getCanvas()->flush();
}
}
}
void OffscreenTargetManager::SetCacheErrorThreshold(float threshold) {
DCHECK_GE(threshold, 0.0f);
cache_error_threshold_ = threshold;
}
bool OffscreenTargetManager::GetCachedTarget(const render_tree::Node* node,
const CacheErrorFunction& error_function, TargetInfo* out_target_info) {
// Find the cache of the given node (if any) with the lowest error.
AllocationMap::iterator best_iter = offscreen_cache_->allocation_map.end();
float best_error = 2.0f;
auto range = offscreen_cache_->allocation_map.equal_range(node->GetId());
for (auto iter = range.first; iter != range.second; ++iter) {
float error = error_function.Run(iter->second.error_data);
if (best_error > error) {
best_error = error;
best_iter = iter;
}
}
// A cache entry matches the caller's criteria only if error < threshold.
if (best_error < cache_error_threshold_) {
offscreen_cache_->allocations_used += 1;
out_target_info->framebuffer = offscreen_cache_->framebuffer.get();
out_target_info->skia_canvas = offscreen_cache_->skia_surface->getCanvas();
out_target_info->region = best_iter->second.target_region;
return true;
}
return false;
}
bool OffscreenTargetManager::GetCachedTarget(const render_tree::Node* node,
const CacheErrorFunction1D& error_function, TargetInfo* out_target_info) {
// Find the cache of the given node (if any) with the lowest error.
AllocationMap::iterator best_iter = offscreen_cache_1d_->allocation_map.end();
float best_error = 2.0f;
auto range = offscreen_cache_1d_->allocation_map.equal_range(node->GetId());
for (auto iter = range.first; iter != range.second; ++iter) {
float error = error_function.Run(iter->second.error_data.width());
if (best_error > error) {
best_error = error;
best_iter = iter;
}
}
// A cache entry matches the caller's criteria only if error < threshold.
if (best_error < cache_error_threshold_) {
offscreen_cache_1d_->allocations_used += 1;
out_target_info->framebuffer = offscreen_cache_1d_->framebuffer.get();
out_target_info->skia_canvas = nullptr;
out_target_info->region = best_iter->second.target_region;
return true;
}
return false;
}
void OffscreenTargetManager::AllocateCachedTarget(
const render_tree::Node* node, const math::SizeF& size,
const ErrorData& error_data, TargetInfo* out_target_info) {
// Pad the offscreen target size to prevent interpolation with unwanted
// texels when rendering the results.
const int kInterpolatePad = 1;
// Get an offscreen target for rendering. Align up the requested target size
// to improve usage of the atlas (since more requests will have the same
// aligned width or height).
math::Size target_size(
(static_cast<int>(std::ceil(size.width())) + 2 * kInterpolatePad +
offscreen_target_size_mask_.width()) &
~offscreen_target_size_mask_.width(),
(static_cast<int>(std::ceil(size.height())) + 2 * kInterpolatePad +
offscreen_target_size_mask_.height()) &
~offscreen_target_size_mask_.height());
math::RectF target_rect(0.0f, 0.0f, 0.0f, 0.0f);
OffscreenAtlas* atlas = NULL;
// See if there's room in the offscreen cache for additional targets.
atlas = offscreen_cache_.get();
target_rect = atlas->allocator.Allocate(target_size);
if (target_rect.IsEmpty()) {
// See if there's room in the other atlases.
for (size_t index = offscreen_atlases_.size(); index > 0;) {
atlas = offscreen_atlases_[--index];
target_rect = atlas->allocator.Allocate(target_size);
if (!target_rect.IsEmpty()) {
break;
}
}
}
if (target_rect.IsEmpty()) {
// There wasn't enough room for the requested offscreen target.
out_target_info->framebuffer = nullptr;
out_target_info->skia_canvas = nullptr;
out_target_info->region.SetRect(0, 0, 0, 0);
} else {
// Inset to prevent interpolation with unwanted pixels at the edge.
target_rect.Inset(kInterpolatePad, kInterpolatePad);
DCHECK_LE(size.width(), target_rect.width());
DCHECK_LE(size.height(), target_rect.height());
target_rect.set_size(size);
// Clear the atlas if this will be the first draw into it.
if (atlas->allocation_map.empty()) {
atlas->skia_surface->getCanvas()->clear(SK_ColorTRANSPARENT);
}
atlas->allocation_map.insert(AllocationMap::value_type(
node->GetId(), AllocationMapValue(error_data, target_rect)));
atlas->allocations_used += 1;
atlas->needs_flush = true;
out_target_info->framebuffer = atlas->framebuffer.get();
out_target_info->skia_canvas = atlas->skia_surface->getCanvas();
out_target_info->region = target_rect;
}
}
void OffscreenTargetManager::AllocateCachedTarget(
const render_tree::Node* node, float size,
const ErrorData1D& error_data, TargetInfo* out_target_info) {
// 1D targets do not use any padding to avoid interpolation with neighboring
// allocations in the atlas.
math::Size target_size(static_cast<int>(std::ceil(size)), 1);
math::RectF target_rect(0.0f, 0.0f, 0.0f, 0.0f);
OffscreenAtlas* atlas = NULL;
// See if there's room in the offscreen cache for additional targets.
atlas = offscreen_cache_1d_.get();
target_rect = atlas->allocator.Allocate(target_size);
if (target_rect.IsEmpty()) {
// See if there's room in the other atlases.
for (size_t index = offscreen_atlases_1d_.size(); index > 0;) {
atlas = offscreen_atlases_1d_[--index];
target_rect = atlas->allocator.Allocate(target_size);
if (!target_rect.IsEmpty()) {
break;
}
}
}
if (target_rect.IsEmpty()) {
// There wasn't enough room for the requested offscreen target.
out_target_info->framebuffer = nullptr;
out_target_info->skia_canvas = nullptr;
out_target_info->region.SetRect(0, 0, 0, 0);
} else {
DCHECK_LE(size, target_rect.width());
target_rect.set_width(size);
atlas->allocation_map.insert(AllocationMap::value_type(
node->GetId(), AllocationMapValue(
ErrorData(error_data, 1), target_rect)));
atlas->allocations_used += 1;
atlas->needs_flush = false;
out_target_info->framebuffer = atlas->framebuffer.get();
out_target_info->skia_canvas = nullptr;
out_target_info->region = target_rect;
}
}
void OffscreenTargetManager::AllocateUncachedTarget(const math::SizeF& size,
TargetInfo* out_target_info) {
// Align up the requested target size to increase the chances that it can
// be reused in subsequent frames.
math::Size target_size(
(static_cast<int>(std::ceil(size.width())) +
offscreen_target_size_mask_.width()) &
~offscreen_target_size_mask_.width(),
(static_cast<int>(std::ceil(size.height())) +
offscreen_target_size_mask_.height()) &
~offscreen_target_size_mask_.height());
// Find a render target that meets the size requirement. However, do not
// select anything that is too big.
const int kMaxTargetSize = target_size.GetArea() * 2;
OffscreenAtlas* atlas = nullptr;
for (size_t index = 0; index < uncached_targets_.size(); ++index) {
OffscreenAtlas* current = uncached_targets_[index];
if (current->allocations_used == 0) {
const math::Size& current_size = current->framebuffer->GetSize();
if (current_size.width() >= target_size.width() &&
current_size.height() >= target_size.height() &&
current_size.GetArea() <= kMaxTargetSize) {
// Pick the smallest render target that meets the requirements.
if (atlas && atlas->framebuffer->GetSize().GetArea() <
current_size.GetArea()) {
continue;
}
atlas = current;
}
}
}
if (!atlas) {
atlas = CreateOffscreenAtlas(target_size, true).release();
if (!atlas) {
// If there was an error allocating the offscreen atlas, indicate by
// marking framebuffer and skia canvas as null and returning early.
out_target_info->framebuffer = nullptr;
out_target_info->skia_canvas = nullptr;
return;
}
uncached_targets_.push_back(atlas);
}
atlas->allocations_used = 1;
out_target_info->framebuffer = atlas->framebuffer.get();
out_target_info->skia_canvas = atlas->skia_surface->getCanvas();
out_target_info->region.SetRect(0.0f, 0.0f, size.width(), size.height());
}
void OffscreenTargetManager::InitializeTargets(const math::Size& frame_size) {
DLOG(INFO) << "offscreen render target memory limit: " << memory_limit_;
if (frame_size.width() >= 64 && frame_size.height() >= 64) {
offscreen_target_size_mask_.SetSize(
NextPowerOf2(frame_size.width() / 64) - 1,
NextPowerOf2(frame_size.height() / 64) - 1);
} else {
offscreen_target_size_mask_.SetSize(0, 0);
}
DCHECK(IsPowerOf2(offscreen_target_size_mask_.width() + 1));
DCHECK(IsPowerOf2(offscreen_target_size_mask_.height() + 1));
// Allow offscreen targets to be as large as the frame.
math::Size max_size(std::max(frame_size.width(), 1),
std::max(frame_size.height(), 1));
// Offscreen render targets are optional but highly recommended. These
// allow caching of render results for improved performance. At least two
// must exist -- one for the cache and the other a working scratch.
size_t half_memory_limit = memory_limit_ / 2;
math::Size atlas_size(1, 1);
for (;;) {
// See if the next atlas size will fit in the memory budget.
// Try to keep the atlas square-ish.
math::Size next_size(atlas_size);
if (atlas_size.width() < max_size.width() &&
(atlas_size.width() <= atlas_size.height() ||
atlas_size.height() >= max_size.height())) {
next_size.set_width(
std::min(atlas_size.width() * 2, max_size.width()));
} else if (atlas_size.height() < max_size.height()) {
next_size.set_height(
std::min(atlas_size.height() * 2, max_size.height()));
} else {
break;
}
if (GetMemorySize(next_size) > half_memory_limit) {
break;
}
atlas_size = next_size;
}
// It is better to have fewer, large atlases than many small atlases to
// minimize the cost of switching render targets. Consider changing the
// max_size logic if there's plenty of memory to spare.
const int kMaxAtlases = 4;
int num_atlases = memory_limit_ / GetMemorySize(atlas_size);
if (num_atlases < 2) {
// Must have at least two atlases -- even if they are of a token size.
// This simplifies code elsewhere.
DCHECK(atlas_size.width() == 1 && atlas_size.height() == 1);
num_atlases = 2;
} else if (num_atlases > kMaxAtlases) {
DCHECK(atlas_size == max_size);
num_atlases = kMaxAtlases;
DLOG(WARNING) << "More memory was allotted for offscreen render targets"
<< " than will be used.";
}
offscreen_cache_ = CreateOffscreenAtlas(atlas_size, true);
CHECK(offscreen_cache_);
for (int i = 1; i < num_atlases; ++i) {
offscreen_atlases_.push_back(
CreateOffscreenAtlas(atlas_size, true).release());
CHECK(offscreen_atlases_.back());
}
DLOG(INFO) << "Created " << num_atlases << " offscreen atlases of size "
<< atlas_size.width() << " x " << atlas_size.height();
// Create 1D texture atlases. These are just regular 2D textures that will
// be used as 1D row textures. These atlases are not intended to be used by
// skia.
const int kAtlasHeight1D =
std::min(std::min(16, frame_size.width()), frame_size.height());
math::Size atlas_size_1d(
std::max(frame_size.width(), frame_size.height()), kAtlasHeight1D);
offscreen_atlases_1d_.push_back(
CreateOffscreenAtlas(atlas_size_1d, false).release());
CHECK(offscreen_atlases_1d_.back());
offscreen_cache_1d_ = CreateOffscreenAtlas(atlas_size_1d, false);
CHECK(offscreen_cache_1d_);
DLOG(INFO) << "Created " << offscreen_atlases_1d_.size() + 1
<< " offscreen atlases of size " << atlas_size_1d.width() << " x "
<< atlas_size_1d.height();
}
scoped_ptr<OffscreenTargetManager::OffscreenAtlas>
OffscreenTargetManager::CreateOffscreenAtlas(const math::Size& size,
bool create_canvas) {
scoped_ptr<OffscreenAtlas> atlas(new OffscreenAtlas(size));
// Create a new framebuffer.
atlas->framebuffer = new backend::FramebufferRenderTargetEGL(
graphics_context_, size);
if (atlas->framebuffer->CreationError()) {
return scoped_ptr<OffscreenAtlas>();
}
if (create_canvas) {
// Wrap the framebuffer as a skia surface.
atlas->skia_surface = create_fallback_surface_.Run(atlas->framebuffer);
}
return atlas.Pass();
}
} // namespace egl
} // namespace rasterizer
} // namespace renderer
} // namespace cobalt