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authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
commit5f8de423f190bbb79a62f804151bc24824fa32d8 (patch)
tree10027f336435511475e392454359edea8e25895d /gfx/layers/ReadbackLayer.h
parent49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff)
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Add m-esr52 at 52.6.0
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+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef GFX_READBACKLAYER_H
+#define GFX_READBACKLAYER_H
+
+#include <stdint.h> // for uint64_t
+#include "Layers.h" // for Layer, etc
+#include "mozilla/gfx/Rect.h" // for gfxRect
+#include "mozilla/gfx/Point.h" // for IntPoint
+#include "mozilla/mozalloc.h" // for operator delete
+#include "nsAutoPtr.h" // for nsAutoPtr
+#include "nsCOMPtr.h" // for already_AddRefed
+#include "nsDebug.h" // for NS_ASSERTION
+#include "nsPoint.h" // for nsIntPoint
+#include "nscore.h" // for nsACString
+
+class gfxContext;
+
+namespace mozilla {
+namespace layers {
+
+class ReadbackProcessor;
+
+namespace layerscope {
+class LayersPacket;
+} // namespace layerscope
+
+/**
+ * A ReadbackSink receives a stream of updates to a rectangle of pixels.
+ * These update callbacks are always called on the main thread, either during
+ * EndTransaction or from the event loop.
+ */
+class ReadbackSink {
+public:
+ ReadbackSink() {}
+ virtual ~ReadbackSink() {}
+
+ /**
+ * Sends an update to indicate that the background is currently unknown.
+ */
+ virtual void SetUnknown(uint64_t aSequenceNumber) = 0;
+ /**
+ * Called by the layer system to indicate that the contents of part of
+ * the readback area are changing.
+ * @param aRect is the rectangle of content that is being updated,
+ * in the coordinate system of the ReadbackLayer.
+ * @param aSequenceNumber updates issued out of order should be ignored.
+ * Only use updates whose sequence counter is greater than all other updates
+ * seen so far. Return null when a non-fresh sequence value is given.
+ * @return a context into which the update should be drawn. This should be
+ * set up to clip to aRect. Zero should never be passed as a sequence number.
+ * If this returns null, EndUpdate should NOT be called. If it returns
+ * non-null, EndUpdate must be called.
+ *
+ * We don't support partially unknown backgrounds. Therefore, the
+ * first BeginUpdate after a SetUnknown will have the complete background.
+ */
+ virtual already_AddRefed<gfx::DrawTarget>
+ BeginUpdate(const gfx::IntRect& aRect, uint64_t aSequenceNumber) = 0;
+ /**
+ * EndUpdate must be called immediately after BeginUpdate, without returning
+ * to the event loop.
+ * @param aContext the context returned by BeginUpdate
+ * Implicitly Restore()s the state of aContext.
+ */
+ virtual void EndUpdate(const gfx::IntRect& aRect) = 0;
+};
+
+/**
+ * A ReadbackLayer never renders anything. It enables clients to extract
+ * the rendered contents of the layer tree below the ReadbackLayer.
+ * The rendered contents are delivered asynchronously via calls to a
+ * ReadbackSink object supplied by the client.
+ *
+ * This is a "best effort" API; it is possible for the layer system to tell
+ * the ReadbackSink that the contents of the readback area are unknown.
+ *
+ * This API exists to work around the limitations of transparent windowless
+ * plugin rendering APIs. It should not be used for anything else.
+ */
+class ReadbackLayer : public Layer {
+public:
+ MOZ_LAYER_DECL_NAME("ReadbackLayer", TYPE_READBACK)
+
+ virtual void ComputeEffectiveTransforms(const gfx::Matrix4x4& aTransformToSurface) override
+ {
+ // Snap our local transform first, and snap the inherited transform as well.
+ // This makes our snapping equivalent to what would happen if our content
+ // was drawn into a PaintedLayer (gfxContext would snap using the local
+ // transform, then we'd snap again when compositing the PaintedLayer).
+ mEffectiveTransform =
+ SnapTransform(GetLocalTransform(), gfxRect(0, 0, mSize.width, mSize.height),
+ nullptr)*
+ SnapTransformTranslation(aTransformToSurface, nullptr);
+ }
+
+ /**
+ * CONSTRUCTION PHASE ONLY
+ * Set the callback object to which readback updates will be delivered.
+ * This also resets the "needed rectangle" so that on the next layer tree
+ * transaction we will try to deliver the full contents of the readback
+ * area to the sink.
+ * This layer takes ownership of the sink. It will be deleted when the
+ * layer is destroyed or when a new sink is set.
+ * Initially the contents of the readback area are completely unknown.
+ */
+ void SetSink(ReadbackSink* aSink)
+ {
+ SetUnknown();
+ mSink = aSink;
+ }
+ ReadbackSink* GetSink() { return mSink; }
+
+ /**
+ * CONSTRUCTION PHASE ONLY
+ * Set the size of content that should be read back. The readback area
+ * has its top-left at 0,0 and has size aSize.
+ * Can only be called while the sink is null!
+ */
+ void SetSize(const gfx::IntSize& aSize)
+ {
+ NS_ASSERTION(!mSink, "Should have no sink while changing size!");
+ mSize = aSize;
+ }
+ const gfx::IntSize& GetSize() { return mSize; }
+ gfx::IntRect GetRect() { return gfx::IntRect(gfx::IntPoint(0, 0), mSize); }
+
+ bool IsBackgroundKnown()
+ {
+ return mBackgroundLayer || mBackgroundColor.a == 1.f;
+ }
+
+ void NotifyRemoved() {
+ SetUnknown();
+ mSink = nullptr;
+ }
+
+ void NotifyPaintedLayerRemoved(PaintedLayer* aLayer)
+ {
+ if (mBackgroundLayer == aLayer) {
+ mBackgroundLayer = nullptr;
+ }
+ }
+
+ const nsIntPoint& GetBackgroundLayerOffset() { return mBackgroundLayerOffset; }
+
+ uint64_t AllocateSequenceNumber() { return ++mSequenceCounter; }
+
+ void SetUnknown()
+ {
+ if (IsBackgroundKnown()) {
+ if (mSink) {
+ mSink->SetUnknown(AllocateSequenceNumber());
+ }
+ mBackgroundLayer = nullptr;
+ mBackgroundColor = gfx::Color();
+ }
+ }
+
+protected:
+ friend class ReadbackProcessor;
+
+ ReadbackLayer(LayerManager* aManager, void* aImplData) :
+ Layer(aManager, aImplData),
+ mSequenceCounter(0),
+ mSize(0,0),
+ mBackgroundLayer(nullptr),
+ mBackgroundLayerOffset(0, 0),
+ mBackgroundColor(gfx::Color())
+ {}
+
+ virtual void PrintInfo(std::stringstream& aStream, const char* aPrefix) override;
+
+ virtual void DumpPacket(layerscope::LayersPacket* aPacket, const void* aParent) override;
+
+ uint64_t mSequenceCounter;
+ nsAutoPtr<ReadbackSink> mSink;
+ gfx::IntSize mSize;
+
+ // This can refer to any (earlier) sibling PaintedLayer. That PaintedLayer
+ // must have mUsedForReadback set on it. If the PaintedLayer is removed
+ // for the container, this will be set to null by NotifyPaintedLayerRemoved.
+ // This PaintedLayer contains the contents which have previously been reported
+ // to mSink. The PaintedLayer had only an integer translation transform,
+ // and it covered the entire readback area. This layer also had only an
+ // integer translation transform.
+ PaintedLayer* mBackgroundLayer;
+ // When mBackgroundLayer is non-null, this is the offset to add to
+ // convert from the coordinates of mBackgroundLayer to the coordinates
+ // of this layer.
+ nsIntPoint mBackgroundLayerOffset;
+ // When mBackgroundColor is opaque, this is the color of the ColorLayer
+ // that contained the contents we reported to mSink, which covered the
+ // entire readback area.
+ gfx::Color mBackgroundColor;
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif /* GFX_READBACKLAYER_H */