Bug 1194876 - Extract a TouchCounter class. r=botond

--HG--
extra : commitid : Au3xHqP2lQW

gfx/layers/apz/src/APZCTreeManager.cpp

@@ -95,7 +95,6 @@ APZCTreeManager::APZCTreeManager()
       mTreeLock("APZCTreeLock"),
       mHitResultForInputBlock(HitNothing),
       mRetainedTouchIdentifier(-1),
-      mTouchCount(0),
       mApzcTreeLog("apzctree")
 {
   MOZ_ASSERT(NS_IsMainThread());
@@ -730,9 +729,6 @@ APZCTreeManager::ProcessTouchInput(MultiTouchInput& aInput,
       return nsEventStatus_eConsumeNoDefault;
     }
 
-    // NS_TOUCH_START event contains all active touches of the current
-    // session thus resetting mTouchCount.
-    mTouchCount = aInput.mTouches.Length();
     mHitResultForInputBlock = HitNothing;
     nsRefPtr<AsyncPanZoomController> apzc = GetTouchInputBlockAPZC(aInput, &mHitResultForInputBlock);
     // XXX the following check assumes mHitResultForInputBlock == HitLayer
@@ -802,21 +798,11 @@ APZCTreeManager::ProcessTouchInput(MultiTouchInput& aInput,
     }
   }
 
-  if (aInput.mType == MultiTouchInput::MULTITOUCH_END) {
-    if (mTouchCount >= aInput.mTouches.Length()) {
-      // NS_TOUCH_END event contains only released touches thus decrementing.
-      mTouchCount -= aInput.mTouches.Length();
-    } else {
-      NS_WARNING("Got an unexpected touchend/touchcancel");
-      mTouchCount = 0;
-    }
-  } else if (aInput.mType == MultiTouchInput::MULTITOUCH_CANCEL) {
-    mTouchCount = 0;
-  }
+  mTouchCounter.Update(aInput);
 
   // If it's the end of the touch sequence then clear out variables so we
   // don't keep dangling references and leak things.
-  if (mTouchCount == 0) {
+  if (mTouchCounter.GetActiveTouchCount() == 0) {
     mApzcForInputBlock = nullptr;
     mHitResultForInputBlock = HitNothing;
     mRetainedTouchIdentifier = -1;

gfx/layers/apz/src/APZCTreeManager.h

@@ -8,20 +8,22 @@
 
 #include <stdint.h>                     // for uint64_t, uint32_t
 #include <map>                          // for std::map
+
 #include "FrameMetrics.h"               // for FrameMetrics, etc
-#include "Units.h"                      // for CSSPoint, CSSRect, etc
 #include "gfxPoint.h"                   // for gfxPoint
 #include "mozilla/Assertions.h"         // for MOZ_ASSERT_HELPER2
 #include "mozilla/EventForwards.h"      // for WidgetInputEvent, nsEventStatus
-#include "mozilla/Monitor.h"            // for Monitor
+#include "mozilla/gfx/Logging.h"        // for gfx::TreeLog
 #include "mozilla/gfx/Matrix.h"         // for Matrix4x4
+#include "mozilla/layers/APZUtils.h"    // for HitTestResult
+#include "mozilla/layers/TouchCounter.h"// for TouchCounter
+#include "mozilla/Monitor.h"            // for Monitor
+#include "mozilla/Vector.h"             // for mozilla::Vector
 #include "nsAutoPtr.h"                  // for nsRefPtr
 #include "nsCOMPtr.h"                   // for already_AddRefed
 #include "nsISupportsImpl.h"            // for MOZ_COUNT_CTOR, etc
-#include "mozilla/Vector.h"             // for mozilla::Vector
 #include "nsTArrayForwardDeclare.h"     // for nsTArray, nsTArray_Impl, etc
-#include "mozilla/gfx/Logging.h"        // for gfx::TreeLog
-#include "mozilla/layers/APZUtils.h"    // for HitTestResult
+#include "Units.h"                      // for CSSPoint, CSSRect, etc
 
 namespace mozilla {
 class InputData;
@@ -520,8 +522,9 @@ private:
    * this is set to -1.
    */
   int32_t mRetainedTouchIdentifier;
-  /* The number of touch points we are tracking that are currently on the screen. */
-  uint32_t mTouchCount;
+  /* Tracks the number of touch points we are tracking that are currently on
+   * the screen. */
+  TouchCounter mTouchCounter;
   /* For logging the APZC tree for debugging (enabled by the apz.printtree
    * pref). */
   gfx::TreeLog mApzcTreeLog;

gfx/layers/apz/src/TouchCounter.cpp

@@ -0,0 +1,50 @@
+/* -*- 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 "TouchCounter.h"
+
+#include "InputData.h"
+
+namespace mozilla {
+namespace layers {
+
+TouchCounter::TouchCounter()
+  : mActiveTouchCount(0)
+{
+}
+
+void
+TouchCounter::Update(const MultiTouchInput& aInput)
+{
+  switch (aInput.mType) {
+    case MultiTouchInput::MULTITOUCH_START:
+      // touch-start event contains all active touches of the current session
+      mActiveTouchCount = aInput.mTouches.Length();
+      break;
+    case MultiTouchInput::MULTITOUCH_END:
+      if (mActiveTouchCount >= aInput.mTouches.Length()) {
+        // touch-end event contains only released touches
+        mActiveTouchCount -= aInput.mTouches.Length();
+      } else {
+        NS_WARNING("Got an unexpected touchend/touchcancel");
+        mActiveTouchCount = 0;
+      }
+      break;
+    case MultiTouchInput::MULTITOUCH_CANCEL:
+      mActiveTouchCount = 0;
+      break;
+    default:
+      break;
+  }
+}
+
+uint32_t
+TouchCounter::GetActiveTouchCount() const
+{
+  return mActiveTouchCount;
+}
+
+} // namespace layers
+} // namespace mozilla

gfx/layers/apz/src/TouchCounter.h

@@ -0,0 +1,33 @@
+/* -*- 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_TouchCounter_h
+#define mozilla_layers_TouchCounter_h
+
+#include "mozilla/EventForwards.h"
+
+namespace mozilla {
+
+class MultiTouchInput;
+
+namespace layers {
+
+// TouchCounter simply tracks the number of active touch points. Feed it
+// your input events to update the internal state.
+class TouchCounter
+{
+public:
+  TouchCounter();
+  void Update(const MultiTouchInput& aInput);
+  uint32_t GetActiveTouchCount() const;
+
+private:
+  uint32_t mActiveTouchCount;
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif /* mozilla_layers_TouchCounter_h */

gfx/layers/moz.build

@@ -98,6 +98,7 @@ EXPORTS.mozilla.layers += [
     'apz/src/APZCTreeManager.h',
     'apz/src/APZUtils.h',
     'apz/src/AsyncPanZoomAnimation.h',
+    'apz/src/TouchCounter.h',
     'apz/testutil/APZTestData.h',
     'apz/util/ActiveElementManager.h',
     'apz/util/APZCCallbackHelper.h',
@@ -241,6 +242,7 @@ UNIFIED_SOURCES += [
     'apz/src/InputQueue.cpp',
     'apz/src/OverscrollHandoffState.cpp',
     'apz/src/TaskThrottler.cpp',
+    'apz/src/TouchCounter.cpp',
     'apz/src/WheelScrollAnimation.cpp',
     'apz/testutil/APZTestData.cpp',
     'apz/util/ActiveElementManager.cpp',