# HG changeset patch
# User Kartikaya Gupta <kgupta@mozilla.com>
Add InputEventContext


diff --git a/gfx/layers/apz/util/InputEventContext.cpp b/gfx/layers/apz/util/InputEventContext.cpp
new file mode 100644
index 0000000..76a205f
--- /dev/null
+++ b/gfx/layers/apz/util/InputEventContext.cpp
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 2; 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/. */
+
+#include "InputEventContext.h"
+
+namespace mozilla {
+namespace layers {
+
+ScrollableLayerGuid InputEventContext::sGuid;
+uint64_t InputEventContext::sBlockId = 0;
+
+/*static*/ ScrollableLayerGuid
+InputEventContext::GetTargetLayerGuid()
+{
+  return sGuid;
+}
+
+/*static*/ uint64_t
+InputEventContext::GetInputBlockId()
+{
+  return sBlockId;
+}
+
+InputEventContext::InputEventContext(const ScrollableLayerGuid& aGuid,
+                                     const uint64_t& aBlockId)
+  : mOldGuid(sGuid)
+  , mOldBlockId(sBlockId)
+{
+  sGuid = aGuid;
+  sBlockId = aBlockId;
+}
+
+InputEventContext::~InputEventContext()
+{
+  sGuid = mOldGuid;
+  sBlockId = mOldBlockId;
+}
+
+}
+}
diff --git a/gfx/layers/apz/util/InputEventContext.h b/gfx/layers/apz/util/InputEventContext.h
new file mode 100644
index 0000000..3af9f3d
--- /dev/null
+++ b/gfx/layers/apz/util/InputEventContext.h
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 2; 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 mozilla_layers_InputEventContext_h
+#define mozilla_layers_InputEventContext_h
+
+#include "FrameMetrics.h"
+
+namespace mozilla {
+namespace layers {
+
+/* This class contains some helper methods that facilitate implementing the
+   GeckoContentController callback interface required by the AsyncPanZoomController.
+   Since different platforms need to implement this interface in similar-but-
+   not-quite-the-same ways, this utility class provides some helpful methods
+   to hold code that can be shared across the different platform implementations.
+ */
+class MOZ_STACK_CLASS InputEventContext
+{
+private:
+  static ScrollableLayerGuid sGuid;
+  static uint64_t sBlockId;
+
+public:
+  static ScrollableLayerGuid GetTargetLayerGuid();
+  static uint64_t GetInputBlockId();
+
+  InputEventContext(const ScrollableLayerGuid& aGuid,
+                    const uint64_t& aBlockId);
+  ~InputEventContext();
+
+private:
+  ScrollableLayerGuid mOldGuid;
+  uint64_t mOldBlockId;
+};
+
+}
+}
+
+#endif /* mozilla_layers_InputEventContext_h */
diff --git a/gfx/layers/moz.build b/gfx/layers/moz.build
index de95569..c88db65 100644
--- a/gfx/layers/moz.build
+++ b/gfx/layers/moz.build
@@ -109,16 +109,17 @@ EXPORTS.mozilla.layers += [
     'apz/public/GeckoContentController.h',
     # exporting things from apz/src is temporary until we extract a
     # proper interface for the code there
     'apz/src/APZCTreeManager.h',
     'apz/testutil/APZTestData.h',
     'apz/util/ActiveElementManager.h',
     'apz/util/APZCCallbackHelper.h',
     'apz/util/ChromeProcessController.h',
+    'apz/util/InputEventContext.h',
     'AtomicRefCountedWithFinalize.h',
     'AxisPhysicsModel.h',
     'AxisPhysicsMSDModel.h',
     'basic/BasicCompositor.h',
     'basic/MacIOSurfaceTextureHostBasic.h',
     'basic/TextureHostBasic.h',
     'client/CanvasClient.h',
     'client/CompositableClient.h',
@@ -241,16 +242,17 @@ UNIFIED_SOURCES += [
     'apz/src/InputBlockState.cpp',
     'apz/src/InputQueue.cpp',
     'apz/src/OverscrollHandoffState.cpp',
     'apz/src/TaskThrottler.cpp',
     'apz/testutil/APZTestData.cpp',
     'apz/util/ActiveElementManager.cpp',
     'apz/util/APZCCallbackHelper.cpp',
     'apz/util/ChromeProcessController.cpp',
+    'apz/util/InputEventContext.cpp',
     'AxisPhysicsModel.cpp',
     'AxisPhysicsMSDModel.cpp',
     'basic/BasicCanvasLayer.cpp',
     'basic/BasicColorLayer.cpp',
     'basic/BasicCompositor.cpp',
     'basic/BasicContainerLayer.cpp',
     'basic/BasicImages.cpp',
     'basic/BasicLayerManager.cpp',