Bug 1121353 - Implement SynthesizeNativeTouchPoint in the gonk widget to allow injecting touch events into APZ. r=mwu

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -664,8 +664,8 @@ interface nsIDOMWindowUtils : nsISupports {
    * drag - msg1-n:TOUCH_CONTACT (moving), msgn+1:TOUCH_REMOVE
    * hover drag - msg1-n:TOUCH_HOVER (moving), msgn+1:TOUCH_REMOVE
    *
-   * Widget support: Windows 8.0+, Winrt/Win32. Other widgets will
-   * throw.
+   * Widget support: Windows 8.0+, Winrt/Win32. Gonk supports CONTACT, REMOVE,
+   * and CANCEL but no HOVER. Other widgets will throw.
    *
    * @param aPointerId The touch point id to create or update.
    * @param aTouchState one or more of the touch states listed above

widget/InputData.cpp

@@ -158,6 +158,17 @@ MultiTouchInput::ToWidgetMouseEvent(nsIWidget* aWidget) const
   return event;
 }
 
+int32_t
+MultiTouchInput::IndexOfTouch(int32_t aTouchIdentifier)
+{
+  for (size_t i = 0; i < mTouches.Length(); i++) {
+    if (mTouches[i].mIdentifier == aTouchIdentifier) {
+      return (int32_t)i;
+    }
+  }
+  return -1;
+}
+
 // This conversion from WidgetMouseEvent to MultiTouchInput is needed because on
 // the B2G emulator we can only receive mouse events, but we need to be able
 // to pan correctly. To do this, we convert the events into a format that the

widget/InputData.h

@@ -222,6 +222,10 @@ public:
   WidgetTouchEvent ToWidgetTouchEvent(nsIWidget* aWidget) const;
   WidgetMouseEvent ToWidgetMouseEvent(nsIWidget* aWidget) const;
 
+  // Return the index into mTouches of the SingleTouchData with the given
+  // identifier, or -1 if there is no such SingleTouchData.
+  int32_t IndexOfTouch(int32_t aTouchIdentifier);
+
   // This conversion from WidgetMouseEvent to MultiTouchInput is needed because
   // on the B2G emulator we can only receive mouse events, but we need to be
   // able to pan correctly. To do this, we convert the events into a format that

widget/gonk/GeckoTouchDispatcher.cpp

@@ -224,19 +224,15 @@ Interpolate(int start, int end, TimeDuration aFrameDiff, TimeDuration aTouchDiff
 static const SingleTouchData&
 GetTouchByID(const SingleTouchData& aCurrentTouch, MultiTouchInput& aOtherTouch)
 {
-  int32_t id = aCurrentTouch.mIdentifier;
-  for (size_t i = 0; i < aOtherTouch.mTouches.Length(); i++) {
-    SingleTouchData& touch = aOtherTouch.mTouches[i];
-    if (touch.mIdentifier == id) {
-      return touch;
-    }
+  int32_t index = aOtherTouch.IndexOfTouch(aCurrentTouch.mIdentifier);
+  if (index < 0) {
+    // We can have situations where a previous touch event had 2 fingers
+    // and we lift 1 finger off. In those cases, we won't find the touch event
+    // with given id, so just return the current touch, which will be resampled
+    // without modification and dispatched.
+    return aCurrentTouch;
   }
-
-  // We can have situations where a previous touch event had 2 fingers
-  // and we lift 1 finger off. In those cases, we won't find the touch event
-  // with given id, so just return the current touch, which will be resampled
-  // without modification and dispatched.
-  return aCurrentTouch;
+  return aOtherTouch.mTouches[index];
 }
 
 

widget/gonk/nsWindow.cpp

@@ -300,6 +300,71 @@ nsWindow::DispatchTouchInputViaAPZ(MultiTouchInput& aInput)
     }
 }
 
+
+nsresult
+nsWindow::SynthesizeNativeTouchPoint(uint32_t aPointerId,
+                                     TouchPointerState aPointerState,
+                                     nsIntPoint aPointerScreenPoint,
+                                     double aPointerPressure,
+                                     uint32_t aPointerOrientation)
+{
+    if (aPointerState == TOUCH_HOVER) {
+        return NS_ERROR_UNEXPECTED;
+    }
+
+    if (!mSynthesizedTouchInput) {
+        mSynthesizedTouchInput = new MultiTouchInput();
+    }
+
+    // We can't dispatch mSynthesizedTouchInput directly because (a) dispatching
+    // it might inadvertently modify it and (b) in the case of touchend or
+    // touchcancel events mSynthesizedTouchInput will hold the touches that are
+    // still down whereas the input dispatched needs to hold the removed
+    // touch(es). We use |inputToDispatch| for this purpose.
+    MultiTouchInput inputToDispatch;
+    inputToDispatch.mInputType = MULTITOUCH_INPUT;
+
+    int32_t index = mSynthesizedTouchInput->IndexOfTouch((int32_t)aPointerId);
+    if (aPointerState == TOUCH_CONTACT) {
+        if (index >= 0) {
+            // found an existing touch point, update it
+            SingleTouchData& point = mSynthesizedTouchInput->mTouches[index];
+            point.mScreenPoint = ScreenIntPoint::FromUntyped(aPointerScreenPoint);
+            point.mRotationAngle = (float)aPointerOrientation;
+            point.mForce = (float)aPointerPressure;
+            inputToDispatch.mType = MultiTouchInput::MULTITOUCH_MOVE;
+        } else {
+            // new touch point, add it
+            mSynthesizedTouchInput->mTouches.AppendElement(SingleTouchData(
+                (int32_t)aPointerId,
+                ScreenIntPoint::FromUntyped(aPointerScreenPoint),
+                ScreenSize(0, 0),
+                (float)aPointerOrientation,
+                (float)aPointerPressure));
+            inputToDispatch.mType = MultiTouchInput::MULTITOUCH_START;
+        }
+        inputToDispatch.mTouches = mSynthesizedTouchInput->mTouches;
+    } else {
+        MOZ_ASSERT(aPointerState == TOUCH_REMOVE || aPointerState == TOUCH_CANCEL);
+        // a touch point is being lifted, so remove it from the stored list
+        if (index >= 0) {
+            mSynthesizedTouchInput->mTouches.RemoveElementAt(index);
+        }
+        inputToDispatch.mType = (aPointerState == TOUCH_REMOVE
+            ? MultiTouchInput::MULTITOUCH_END
+            : MultiTouchInput::MULTITOUCH_CANCEL);
+        inputToDispatch.mTouches.AppendElement(SingleTouchData(
+            (int32_t)aPointerId,
+            ScreenIntPoint::FromUntyped(aPointerScreenPoint),
+            ScreenSize(0, 0),
+            (float)aPointerOrientation,
+            (float)aPointerPressure));
+    }
+
+    DispatchTouchInputViaAPZ(inputToDispatch);
+    return NS_OK;
+}
+
 NS_IMETHODIMP
 nsWindow::Create(nsIWidget *aParent,
                  void *aNativeParent,

widget/gonk/nsWindow.h

@@ -90,6 +90,12 @@ public:
     void DispatchTouchInputViaAPZ(mozilla::MultiTouchInput& aInput);
     NS_IMETHOD DispatchEvent(mozilla::WidgetGUIEvent* aEvent,
                              nsEventStatus& aStatus);
+    virtual nsresult SynthesizeNativeTouchPoint(uint32_t aPointerId,
+                                                TouchPointerState aPointerState,
+                                                nsIntPoint aPointerScreenPoint,
+                                                double aPointerPressure,
+                                                uint32_t aPointerOrientation) MOZ_OVERRIDE;
+
     NS_IMETHOD CaptureRollupEvents(nsIRollupListener *aListener,
                                    bool aDoCapture)
     {
@@ -147,6 +153,11 @@ protected:
     // Call this function when the users activity is the direct cause of an
     // event (like a keypress or mouse click).
     void UserActivity();
+
+private:
+    // This is used by SynthesizeNativeTouchPoint to maintain state between
+    // multiple synthesized points
+    nsAutoPtr<mozilla::MultiTouchInput> mSynthesizedTouchInput;
 };
 
 #endif /* nsWindow_h */