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// Copyright 2021 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.
#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_PAINT_CULL_RECT_UPDATER_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_PAINT_CULL_RECT_UPDATER_H_
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/platform/graphics/paint/cull_rect.h"
#include "third_party/blink/renderer/platform/graphics/paint/property_tree_state.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
namespace blink {
class FragmentData;
class LayoutObject;
class PaintLayer;
struct PaintPropertiesChangeInfo;
// This class is used for updating the cull rects of PaintLayer fragments (see:
// |FragmentData::cull_rect_| and |FragmentData::contents_cull_rect_|.
// Cull rects are used as an optimization to limit painting to areas "near" the
// viewport. This update should happen during the PrePaint lifecycle stage.
//
// Dirty bits (see: |PaintLayer::NeedsCullRectUpdate()| and
// PaintLayer::DescendantNeedsCullRectUpdate()|) are used to optimize this
// update, and are cleared at the end.
class CORE_EXPORT CullRectUpdater {
STACK_ALLOCATED();
public:
explicit CullRectUpdater(PaintLayer& starting_layer)
: starting_layer_(starting_layer) {}
void Update();
static void PaintPropertiesChanged(const LayoutObject&,
const PaintPropertiesChangeInfo&);
private:
friend class OverriddenCullRectScope;
struct ContainerInfo {
const PaintLayer* container = nullptr;
bool subtree_is_out_of_cull_rect = false;
bool subtree_should_use_infinite_cull_rect = false;
bool force_proactive_update = false;
bool force_update_children = false;
STACK_ALLOCATED();
};
struct Context {
ContainerInfo current;
ContainerInfo absolute;
ContainerInfo fixed;
STACK_ALLOCATED();
};
void UpdateInternal(const CullRect& input_cull_rect);
void UpdateRecursively(const Context&, PaintLayer&);
// Returns true if the contents cull rect changed which requires forced update
// for children.
bool UpdateForSelf(Context&, PaintLayer&);
void UpdateForDescendants(const Context&, PaintLayer&);
CullRect ComputeFragmentCullRect(Context&,
PaintLayer&,
const FragmentData& fragment,
const FragmentData& parent_fragment);
CullRect ComputeFragmentContentsCullRect(Context&,
PaintLayer&,
const FragmentData& fragment,
const CullRect& cull_rect);
bool ShouldProactivelyUpdate(const Context&, const PaintLayer&) const;
PaintLayer& starting_layer_;
PropertyTreeState root_state_ = PropertyTreeState::Uninitialized();
};
// Used when painting with a custom top-level cull rect, e.g. when printing a
// page. It temporarily overrides the cull rect on the PaintLayer (which must be
// a stacking context) and marks the PaintLayer as needing to recalculate the
// cull rect when leaving this scope.
// TODO(crbug.com/1215251): Avoid repaint after the scope if the scope is used
// to paint into a separate PaintController.
class CORE_EXPORT OverriddenCullRectScope {
STACK_ALLOCATED();
public:
OverriddenCullRectScope(PaintLayer&, const CullRect&);
~OverriddenCullRectScope();
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_CORE_PAINT_CULL_RECT_UPDATER_H_
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