1 files changed, 50 insertions, 0 deletions
diff --git a/gfx/layers/apz/src/TouchCounter.cpp b/gfx/layers/apz/src/TouchCounter.cpp
new file mode 100644
index 0000000000..96dc35dc71
--- /dev/null
+++ b/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