/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- * ***** BEGIN LICENSE BLOCK ***** * Version: MPL 1.1/GPL 2.0/LGPL 2.1 * * The contents of this file are subject to the Mozilla Public License Version * 1.1 (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.mozilla.org/MPL/ * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the * License. * * The Original Code is Mozilla Corporation code. * * The Initial Developer of the Original Code is Mozilla Foundation. * Portions created by the Initial Developer are Copyright (C) 2011 * the Initial Developer. All Rights Reserved. * * Contributor(s): * Robert O'Callahan * * Alternatively, the contents of this file may be used under the terms of * either the GNU General Public License Version 2 or later (the "GPL"), or * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), * in which case the provisions of the GPL or the LGPL are applicable instead * of those above. If you wish to allow use of your version of this file only * under the terms of either the GPL or the LGPL, and not to allow others to * use your version of this file under the terms of the MPL, indicate your * decision by deleting the provisions above and replace them with the notice * and other provisions required by the GPL or the LGPL. If you do not delete * the provisions above, a recipient may use your version of this file under * the terms of any one of the MPL, the GPL or the LGPL. * * ***** END LICENSE BLOCK ***** */ #ifndef GFX_READBACKLAYER_H #define GFX_READBACKLAYER_H #include "Layers.h" namespace mozilla { namespace layers { class ReadbackProcessor; /** * 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 THEBES_API ReadbackSink { public: ReadbackSink() {} virtual ~ReadbackSink() {} /** * Sends an update to indicate that the background is currently unknown. */ virtual void SetUnknown(PRUint64 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 BeginUpdate(const nsIntRect& aRect, PRUint64 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(gfxContext* aContext, const nsIntRect& 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 THEBES_API ReadbackLayer : public Layer { public: MOZ_LAYER_DECL_NAME("ReadbackLayer", TYPE_READBACK) virtual void ComputeEffectiveTransforms(const gfx3DMatrix& aTransformToSurface) { // 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 ThebesLayer (gfxContext would snap using the local // transform, then we'd snap again when compositing the ThebesLayer). mEffectiveTransform = SnapTransform(GetLocalTransform(), gfxRect(0, 0, mSize.width, mSize.height), nsnull)* SnapTransform(aTransformToSurface, gfxRect(0, 0, 0, 0), nsnull); } /** * 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 nsIntSize& aSize) { NS_ASSERTION(!mSink, "Should have no sink while changing size!"); mSize = aSize; } const nsIntSize& GetSize() { return mSize; } nsIntRect GetRect() { return nsIntRect(nsIntPoint(0, 0), mSize); } PRBool IsBackgroundKnown() { return mBackgroundLayer || mBackgroundColor.a == 1.0; } void NotifyRemoved() { SetUnknown(); mSink = nsnull; } void NotifyThebesLayerRemoved(ThebesLayer* aLayer) { if (mBackgroundLayer == aLayer) { mBackgroundLayer = nsnull; } } const nsIntPoint& GetBackgroundLayerOffset() { return mBackgroundLayerOffset; } PRUint64 AllocateSequenceNumber() { return ++mSequenceCounter; } void SetUnknown() { if (IsBackgroundKnown()) { if (mSink) { mSink->SetUnknown(AllocateSequenceNumber()); } mBackgroundLayer = nsnull; mBackgroundColor = gfxRGBA(0,0,0,0); } } protected: friend class ReadbackProcessor; ReadbackLayer(LayerManager* aManager, void* aImplData) : Layer(aManager, aImplData), mSequenceCounter(0), mSize(0,0), mBackgroundLayer(nsnull), mBackgroundLayerOffset(0, 0), mBackgroundColor(gfxRGBA(0,0,0,0)) {} // Print interesting information about this into aTo. Internally // used to implement Dump*() and Log*(). virtual nsACString& PrintInfo(nsACString& aTo, const char* aPrefix); PRUint64 mSequenceCounter; nsAutoPtr mSink; nsIntSize mSize; // This can refer to any (earlier) sibling ThebesLayer. That ThebesLayer // must have mUsedForReadback set on it. If the ThebesLayer is removed // for the container, this will be set to null by NotifyThebesLayerRemoved. // This ThebesLayer contains the contents which have previously been reported // to mSink. The ThebesLayer had only an integer translation transform, // and it covered the entire readback area. This layer also had only an // integer translation transform. ThebesLayer* 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. gfxRGBA mBackgroundColor; }; } } #endif /* GFX_READBACKLAYER_H */