From c764b148d3fe99b12b2c70a74d1cc676b359ce39 Mon Sep 17 00:00:00 2001
From: Matt Woodrow <mwoodrow@mozilla.com>
Date: Tue, 18 Jun 2013 19:58:43 +1200
Subject: [PATCH] Bug 873944 - Add FlushRendering API to the compositor
 interface. r=nrc

---
 gfx/layers/Layers.h                      |  9 +++++++++
 gfx/layers/client/ClientLayerManager.cpp | 10 ++++++++++
 gfx/layers/client/ClientLayerManager.h   |  2 ++
 gfx/layers/ipc/CompositorParent.cpp      | 13 +++++++++++++
 gfx/layers/ipc/CompositorParent.h        |  1 +
 gfx/layers/ipc/PCompositor.ipdl          |  4 ++++
 6 files changed, 39 insertions(+)

diff --git a/gfx/layers/Layers.h b/gfx/layers/Layers.h
index 29aef1df13c..95c8bd864b1 100644
--- a/gfx/layers/Layers.h
+++ b/gfx/layers/Layers.h
@@ -466,6 +466,15 @@ public:
    */
   virtual void SetIsFirstPaint() {}
 
+  /**
+   * Make sure that the previous transaction has been entirely
+   * completed.
+   *
+   * Note: This may sychronously wait on a remote compositor
+   * to complete rendering.
+   */
+  virtual void FlushRendering() { }
+
   // We always declare the following logging symbols, because it's
   // extremely tricky to conditionally declare them.  However, for
   // ifndef MOZ_LAYERS_HAVE_LOG builds, they only have trivial
diff --git a/gfx/layers/client/ClientLayerManager.cpp b/gfx/layers/client/ClientLayerManager.cpp
index 0ceb44f9d14..bd041160fa4 100644
--- a/gfx/layers/client/ClientLayerManager.cpp
+++ b/gfx/layers/client/ClientLayerManager.cpp
@@ -260,6 +260,16 @@ ClientLayerManager::MakeSnapshotIfRequired()
   mShadowTarget = nullptr;
 }
 
+void
+ClientLayerManager::FlushRendering()
+{
+  if (mWidget) {
+    if (CompositorChild* remoteRenderer = mWidget->GetRemoteRenderer()) {
+      remoteRenderer->SendFlushRendering();
+    }
+  }
+}
+
 void
 ClientLayerManager::ForwardTransaction()
 {
diff --git a/gfx/layers/client/ClientLayerManager.h b/gfx/layers/client/ClientLayerManager.h
index 08c64b20d0e..774a57c807f 100644
--- a/gfx/layers/client/ClientLayerManager.h
+++ b/gfx/layers/client/ClientLayerManager.h
@@ -53,6 +53,8 @@ public:
   virtual already_AddRefed<ColorLayer> CreateColorLayer();
   virtual already_AddRefed<RefLayer> CreateRefLayer();
 
+  virtual void FlushRendering() MOZ_OVERRIDE;
+
   ShadowableLayer* Hold(Layer* aLayer);
 
   bool HasShadowManager() const { return ShadowLayerForwarder::HasShadowManager(); }
diff --git a/gfx/layers/ipc/CompositorParent.cpp b/gfx/layers/ipc/CompositorParent.cpp
index d807d567bf9..be6dbf779c3 100644
--- a/gfx/layers/ipc/CompositorParent.cpp
+++ b/gfx/layers/ipc/CompositorParent.cpp
@@ -249,6 +249,18 @@ CompositorParent::RecvMakeSnapshot(const SurfaceDescriptor& aInSnapshot,
   return true;
 }
 
+bool
+CompositorParent::RecvFlushRendering()
+{
+  // If we're waiting to do a composite, then cancel it
+  // and do it immediately instead.
+  if (mCurrentCompositeTask) {
+    mCurrentCompositeTask->Cancel();
+    ComposeToTarget(nullptr);
+  }
+  return true;
+}
+
 void
 CompositorParent::ActorDestroy(ActorDestroyReason why)
 {
@@ -743,6 +755,7 @@ public:
   virtual bool RecvMakeSnapshot(const SurfaceDescriptor& aInSnapshot,
                                 SurfaceDescriptor* aOutSnapshot)
   { return true; }
+  virtual bool RecvFlushRendering() MOZ_OVERRIDE { return true; }
 
   virtual PLayerTransactionParent*
     AllocPLayerTransaction(const LayersBackend& aBackendType,
diff --git a/gfx/layers/ipc/CompositorParent.h b/gfx/layers/ipc/CompositorParent.h
index fba4cbff667..4f25a4201af 100644
--- a/gfx/layers/ipc/CompositorParent.h
+++ b/gfx/layers/ipc/CompositorParent.h
@@ -55,6 +55,7 @@ public:
   virtual bool RecvResume() MOZ_OVERRIDE;
   virtual bool RecvMakeSnapshot(const SurfaceDescriptor& aInSnapshot,
                                 SurfaceDescriptor* aOutSnapshot);
+  virtual bool RecvFlushRendering() MOZ_OVERRIDE;
 
   virtual void ActorDestroy(ActorDestroyReason why) MOZ_OVERRIDE;
 
diff --git a/gfx/layers/ipc/PCompositor.ipdl b/gfx/layers/ipc/PCompositor.ipdl
index cc78eba14cc..72e1ea00f01 100644
--- a/gfx/layers/ipc/PCompositor.ipdl
+++ b/gfx/layers/ipc/PCompositor.ipdl
@@ -53,6 +53,10 @@ parent:
   sync MakeSnapshot(SurfaceDescriptor inSnapshot)
     returns (SurfaceDescriptor outSnapshot);
 
+  // Make sure any pending composites are started immediately and
+  // block until they are completed.
+  sync FlushRendering();
+
   sync PLayerTransaction(LayersBackend layersBackendHint, uint64_t id)
     returns (TextureFactoryIdentifier textureFactoryIdentifier);
 };