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d117ac979c
* Remove erroneous ChildView opacity * Wire frame metrics through contexts * Maintain layer stack inside of SceneBuilder * Remove EnsureSingleChild * Centralize system-composite and elevation logic * Wire up OpacityLayer to Scenic
76 lines
2.5 KiB
C++
76 lines
2.5 KiB
C++
// Copyright 2013 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef FLUTTER_FLOW_LAYERS_OPACITY_LAYER_H_
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#define FLUTTER_FLOW_LAYERS_OPACITY_LAYER_H_
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#include "flutter/flow/layers/elevated_container_layer.h"
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#if defined(OS_FUCHSIA)
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#include "flutter/flow/layers/fuchsia_system_composited_layer.h"
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#endif
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namespace flutter {
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#if !defined(OS_FUCHSIA)
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class OpacityLayerBase : public ContainerLayer {
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public:
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static bool can_system_composite() { return false; }
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OpacityLayerBase(SkColor color, SkAlpha opacity, float elevation)
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: color_(color), opacity_(opacity) {}
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void Preroll(PrerollContext* context, const SkMatrix& matrix) override;
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void set_dimensions(SkRRect rrect) {}
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SkColor color() const { return color_; }
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SkAlpha opacity() const { return opacity_; }
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float elevation() const { return 0; }
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private:
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SkColor color_;
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SkAlpha opacity_;
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};
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#else
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using OpacityLayerBase = FuchsiaSystemCompositedLayer;
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#endif
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// Don't add an OpacityLayer with no children to the layer tree. Painting an
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// OpacityLayer is very costly due to the saveLayer call. If there's no child,
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// having the OpacityLayer or not has the same effect. In debug_unopt build,
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// |Preroll| will assert if there are no children.
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class OpacityLayer : public OpacityLayerBase {
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public:
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// An offset is provided here because OpacityLayer.addToScene method in the
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// Flutter framework can take an optional offset argument.
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//
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// By default, that offset is always zero, and all the offsets are handled by
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// some parent TransformLayers. But we allow the offset to be non-zero for
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// backward compatibility. If it's non-zero, the old behavior is to propage
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// that offset to all the leaf layers (e.g., PictureLayer). That will make
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// the retained rendering inefficient as a small offset change could propagate
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// to many leaf layers. Therefore we try to capture that offset here to stop
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// the propagation as repainting the OpacityLayer is expensive.
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OpacityLayer(SkAlpha alpha, const SkPoint& offset);
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void Add(std::shared_ptr<Layer> layer) override;
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void Preroll(PrerollContext* context, const SkMatrix& matrix) override;
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#if defined(OS_FUCHSIA)
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void UpdateScene(SceneUpdateContext& context) override;
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#endif
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void Paint(PaintContext& context) const override;
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private:
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ContainerLayer* GetChildContainer() const;
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SkPoint offset_;
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FML_DISALLOW_COPY_AND_ASSIGN(OpacityLayer);
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};
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} // namespace flutter
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#endif // FLUTTER_FLOW_LAYERS_OPACITY_LAYER_H_
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