Forward GenericMotionEvent to EventForwarder

ui/android/java/src/org/chromium/ui/base/EventForwarder.java

Index: ui/android/java/src/org/chromium/ui/base/EventForwarder.java
diff --git a/ui/android/java/src/org/chromium/ui/base/EventForwarder.java b/ui/android/java/src/org/chromium/ui/base/EventForwarder.java
index ee52e3c37f6ee49b8cea47d6798c2a2ea8400210..85b6428f78260c4276ab08c8d7f12399d7034dad 100644
--- a/ui/android/java/src/org/chromium/ui/base/EventForwarder.java
+++ b/ui/android/java/src/org/chromium/ui/base/EventForwarder.java
@@ -7,10 +7,12 @@ package org.chromium.ui.base;
 import android.annotation.TargetApi;
 import android.os.Build;
 import android.view.MotionEvent;
+import android.view.View;
 
 import org.chromium.base.TraceEvent;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
+import org.chromium.ui.input.JoystickScrollProvider;
 
 /**
  * Class used to forward view, input events down to native.
@@ -23,6 +25,9 @@ public class EventForwarder {
     private float mCurrentTouchOffsetX;
     private float mCurrentTouchOffsetY;
 
+    // Provides smooth gamepad joystick-driven scrolling.
+    private JoystickScrollProvider mJoystickScrollProvider;
+
     @CalledByNative
     private static EventForwarder create(long nativeEventForwarder) {
         return new EventForwarder(nativeEventForwarder);
@@ -35,6 +40,7 @@ public class EventForwarder {
     @CalledByNative
     private void destroy() {
         mNativeEventForwarder = 0;
+        mJoystickScrollProvider = null;
     }
 
     /**
@@ -181,6 +187,47 @@ public class EventForwarder {
                 orientation, tilt, actionButton, buttonState, metaState, toolType);
     }
 
+    /**
+     * Handles motion event of type {@code SOURCE_CLASS_POINTER}.
+     *
+     * @param event {@link MotionEvent} instance.
+     * @param event scrollFactor scale factor used to convert wheel tick to pixel.
+     */
+    public boolean onPointerDeviceEvent(MotionEvent event, float scrollFactor) {
+        switch (event.getActionMasked()) {
+            case MotionEvent.ACTION_SCROLL:
+                assert mNativeEventForwarder != 0;
+
+                nativeOnMouseWheelEvent(mNativeEventForwarder, event.getEventTime(), event.getX(),
+                        event.getY(), event.getAxisValue(MotionEvent.AXIS_HSCROLL),
+                        event.getAxisValue(MotionEvent.AXIS_VSCROLL), scrollFactor);
+                return true;
+            case MotionEvent.ACTION_BUTTON_PRESS:
+            case MotionEvent.ACTION_BUTTON_RELEASE:
+                // TODO(mustaq): Should we include MotionEvent.TOOL_TYPE_STYLUS here?
+                // crbug.com/592082
+                if (event.getToolType(0) == MotionEvent.TOOL_TYPE_MOUSE) return onMouseEvent(event);
+        }
+
+        return false;
+    }
+
+    public JoystickScrollProvider createJoystickScrollProvider(

[boliu, 2017/03/27 17:44:44]

Having JoystickScrollProvider and whatnot in ui makes no sense to me. Why can't
these things just stay in content?

[Jinsuk Kim, 2017/03/27 22:42:06]

The motivation is to migrate these input events flow from CVC to EventForwarder.
Unlike simple touch events, generic motion events need to take care of a few
other stuff. One of them is joystick events. Without moving this, it seems not
possible (at least to me) to do the migration. 

Got any other idea?

[boliu, 2017/03/27 22:54:22]

afaict, the dependency (from higher to lower) is content -> JoyStick ->
ui/EventHandler. Is that correct? ie I don't see anything in ui or EventHandler
actually using any of this JoyStick code. So why is it in ui at all?

Pulling joystick stuff out of CVC is fine, but I don't see why it has to be in
ui?

[Jinsuk Kim, 2017/03/27 22:59:51]

.. wish it had been discussed in the crbug.com/703023 before, which I had
created just for that. EventForwarder has a reference to it. So it needs to be
where ui can have an access to, not in content any more.

[Jinsuk Kim, 2017/03/27 23:04:24]

May I was not clear. I meant that EventForwarder provides the path to native for
JoystickScrollProvider here. 

[boliu, 2017/03/27 23:19:17]

You can just make onMouseWheelEvent public here then?

[Jinsuk Kim, 2017/03/28 02:40:33]

Done. Moved Joystick.+Provider classes back to content/

+            View containerView, WindowAndroid windowAndroid) {
+        if (mJoystickScrollProvider != null) return mJoystickScrollProvider;
+        mJoystickScrollProvider = new JoystickScrollProvider(
+                containerView, windowAndroid, new JoystickScrollProvider.ScrollEmulator() {
+                    // Joystick scroll is translated to mouse wheel event.
+                    @Override
+                    public void scroll(long timeMillis, float dx, float dy) {
+                        assert mNativeEventForwarder != 0;
+                        nativeOnMouseWheelEvent(
+                                mNativeEventForwarder, timeMillis, 0, 0, -dx, -dy, 1.0f);
+                    }
+                });
+        return mJoystickScrollProvider;
+    }
+
     // All touch events (including flings, scrolls etc) accept coordinates in physical pixels.
     private native boolean nativeOnTouchEvent(long nativeEventForwarder, MotionEvent event,
             long timeMs, int action, int pointerCount, int historySize, int actionIndex, float x0,
@@ -192,4 +239,6 @@ public class EventForwarder {
     private native void nativeOnMouseEvent(long nativeEventForwarder, long timeMs, int action,
             float x, float y, int pointerId, float pressure, float orientation, float tilt,
             int changedButton, int buttonState, int metaState, int toolType);
+    private native void nativeOnMouseWheelEvent(long nativeEventForwarder, long timeMs, float x,
+            float y, float ticksX, float ticksY, float pixelsPerTick);
 }