Add EventForwarder for routing touch events

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

Index: ui/android/java/src/org/chromium/ui/base/EventHandler.java
diff --git a/ui/android/java/src/org/chromium/ui/base/EventHandler.java b/ui/android/java/src/org/chromium/ui/base/EventHandler.java
new file mode 100644
index 0000000000000000000000000000000000000000..71f160e5849f6e640e8fa8b586e3e8ec926b6b1b
--- /dev/null
+++ b/ui/android/java/src/org/chromium/ui/base/EventHandler.java
@@ -0,0 +1,207 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.ui.base;
+
+import android.annotation.TargetApi;
+import android.os.Build;
+import android.view.MotionEvent;
+
+import org.chromium.base.TraceEvent;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+
+/**
+ * Class used to forward view, input events down to native.
+ */
+@JNINamespace("ui")
+public class EventHandler {
+    private final long mNativeEventHandler;
+
+    // Offsets for the events that passes through.
+    private float mCurrentTouchOffsetX;
+    private float mCurrentTouchOffsetY;
+
+    private EventNotifier mEventNotifier;
+
+    /**
+     * Interface that allows embedder to have a chance to handle certain events.
+     */
+    public interface EventNotifier {
+        /**
+         * Called when a touch event occurs.
+         */
+        void onTouchEvent(MotionEvent event);
+    }
+
+    @CalledByNative
+    private static EventHandler create(long nativeEventHandler) {
+        return new EventHandler(nativeEventHandler);
+    }
+
+    private EventHandler(long nativeEventHandler) {
+        mNativeEventHandler = nativeEventHandler;
+    }
+
+    public void setEventNotifier(EventNotifier notifier) {
+        mEventNotifier = notifier;
+    }
+
+    /**
+     * @see View#onTouchEvent(MotionEvent)
+     */
+    public boolean onTouchEvent(MotionEvent event) {
+        // TODO(mustaq): Should we include MotionEvent.TOOL_TYPE_STYLUS here?
+        // crbug.com/592082
+        if (event.getToolType(0) == MotionEvent.TOOL_TYPE_MOUSE) {
+            // Mouse button info is incomplete on L and below
+            int apiVersion = Build.VERSION.SDK_INT;
+            if (apiVersion >= android.os.Build.VERSION_CODES.M) {
+                return onMouseEvent(event);
+            }
+        }
+
+        final boolean isTouchHandleEvent = false;
+        return sendTouchEvent(event, isTouchHandleEvent);
+    }
+
+    /**
+     * Called by PopupWindow-based touch handles.
+     * @param event the MotionEvent targeting the handle.
+     */
+    public boolean onTouchHandleEvent(MotionEvent event) {
+        final boolean isTouchHandleEvent = true;
+        return sendTouchEvent(event, isTouchHandleEvent);
+    }
+
+    private boolean sendTouchEvent(MotionEvent event, boolean isTouchHandleEvent) {
+        TraceEvent.begin("sendTouchEvent");
+        try {
+            int eventAction = event.getActionMasked();
+
+            if (mEventNotifier != null) mEventNotifier.onTouchEvent(event);
+
+            eventAction = SPenSupport.convertSPenEventAction(eventAction);
+
+            if (!isValidTouchEventActionForNative(eventAction)) return false;
+
+            // A zero offset is quite common, in which case the unnecessary copy should be avoided.
+            MotionEvent offset = null;
+            if (mCurrentTouchOffsetX != 0 || mCurrentTouchOffsetY != 0) {
+                offset = createOffsetMotionEvent(event);
+                event = offset;
+            }
+
+            final int pointerCount = event.getPointerCount();
+
+            float[] touchMajor = {
+                    event.getTouchMajor(), pointerCount > 1 ? event.getTouchMajor(1) : 0};
+            float[] touchMinor = {
+                    event.getTouchMinor(), pointerCount > 1 ? event.getTouchMinor(1) : 0};
+
+            for (int i = 0; i < 2; i++) {
+                if (touchMajor[i] < touchMinor[i]) {
+                    float tmp = touchMajor[i];
+                    touchMajor[i] = touchMinor[i];
+                    touchMinor[i] = tmp;
+                }
+            }
+
+            final boolean consumed = nativeOnTouchEvent(mNativeEventHandler, event,
+                    event.getEventTime(), eventAction, pointerCount, event.getHistorySize(),
+                    event.getActionIndex(), event.getX(), event.getY(),
+                    pointerCount > 1 ? event.getX(1) : 0, pointerCount > 1 ? event.getY(1) : 0,
+                    event.getPointerId(0), pointerCount > 1 ? event.getPointerId(1) : -1,
+                    touchMajor[0], touchMajor[1], touchMinor[0], touchMinor[1],
+                    event.getOrientation(), pointerCount > 1 ? event.getOrientation(1) : 0,
+                    event.getAxisValue(MotionEvent.AXIS_TILT),
+                    pointerCount > 1 ? event.getAxisValue(MotionEvent.AXIS_TILT, 1) : 0,
+                    event.getRawX(), event.getRawY(), event.getToolType(0),
+                    pointerCount > 1 ? event.getToolType(1) : MotionEvent.TOOL_TYPE_UNKNOWN,
+                    event.getButtonState(), event.getMetaState(), isTouchHandleEvent);
+
+            if (offset != null) offset.recycle();
+            return consumed;
+        } finally {
+            TraceEvent.end("sendTouchEvent");
+        }
+    }
+
+    /**
+     * Sets the current amount to offset incoming touch events by (including MotionEvent and
+     * DragEvent). This is used to handle content moving and not lining up properly with the
+     * android input system.
+     * @param dx The X offset in pixels to shift touch events.
+     * @param dy The Y offset in pixels to shift touch events.
+     */
+    public void setCurrentTouchEventOffsets(float dx, float dy) {
+        mCurrentTouchOffsetX = dx;
+        mCurrentTouchOffsetY = dy;
+    }
+
+    private MotionEvent createOffsetMotionEvent(MotionEvent src) {
+        MotionEvent dst = MotionEvent.obtain(src);
+        dst.offsetLocation(mCurrentTouchOffsetX, mCurrentTouchOffsetY);
+        return dst;
+    }
+
+    private static boolean isValidTouchEventActionForNative(int eventAction) {
+        // Only these actions have any effect on gesture detection.  Other
+        // actions have no corresponding WebTouchEvent type and may confuse the
+        // touch pipline, so we ignore them entirely.
+        return eventAction == MotionEvent.ACTION_DOWN || eventAction == MotionEvent.ACTION_UP
+                || eventAction == MotionEvent.ACTION_CANCEL
+                || eventAction == MotionEvent.ACTION_MOVE
+                || eventAction == MotionEvent.ACTION_POINTER_DOWN
+                || eventAction == MotionEvent.ACTION_POINTER_UP;
+    }
+
+    @TargetApi(Build.VERSION_CODES.M)
+    public boolean onMouseEvent(MotionEvent event) {
+        TraceEvent.begin("sendMouseEvent");
+
+        MotionEvent offsetEvent = createOffsetMotionEvent(event);
+        try {
+            if (mNativeEventHandler == 0) return false;

[boliu, 2017/02/28 22:44:54]

ditto not required

[Jinsuk Kim, 2017/03/02 04:08:34]

Done.

+
+            int eventAction = event.getActionMasked();
+
+            // For mousedown and mouseup events, we use ACTION_BUTTON_PRESS
+            // and ACTION_BUTTON_RELEASE respectively because they provide
+            // info about the changed-button.
+            if (eventAction == MotionEvent.ACTION_DOWN || eventAction == MotionEvent.ACTION_UP) {
+                return false;
+            }
+            sendMouseEvent(event.getEventTime(), eventAction, offsetEvent.getX(),
+                    offsetEvent.getY(), event.getPointerId(0), event.getPressure(0),
+                    event.getOrientation(0), event.getAxisValue(MotionEvent.AXIS_TILT, 0),
+                    event.getActionButton(), event.getButtonState(), event.getMetaState(),
+                    event.getToolType(0));
+            return true;

[boliu, 2017/02/28 22:44:54]

this is not totally clear to me, why is the native method not returning anything
now, and this is just always returning true?

[Jinsuk Kim, 2017/03/02 04:08:34]

Unlike OnTouchEvent, OnMouseEvent (before refactoring) simply was returning
true. I just made it simpler. 

+        } finally {
+            offsetEvent.recycle();
+            TraceEvent.end("sendMouseEvent");
+        }
+    }
+
+    @TargetApi(Build.VERSION_CODES.M)
+    public void sendMouseEvent(long timeMs, int action, float x, float y, int pointerId,
+            float pressure, float orientation, float tilt, int actionButton, int buttonState,
+            int metaState, int toolType) {
+        nativeOnMouseEvent(mNativeEventHandler, timeMs, action, x, y, pointerId, pressure,
+                orientation, tilt, actionButton, buttonState, metaState, toolType);
+    }
+
+    // All touch events (including flings, scrolls etc) accept coordinates in physical pixels.
+    private native boolean nativeOnTouchEvent(long nativeEventHandler, MotionEvent event,
+            long timeMs, int action, int pointerCount, int historySize, int actionIndex, float x0,
+            float y0, float x1, float y1, int pointerId0, int pointerId1, float touchMajor0,
+            float touchMajor1, float touchMinor0, float touchMinor1, float orientation0,
+            float orientation1, float tilt0, float tilt1, float rawX, float rawY,
+            int androidToolType0, int androidToolType1, int androidButtonState,
+            int androidMetaState, boolean isTouchHandleEvent);
+    private native void nativeOnMouseEvent(long nativeEventHandler, long timeMs, int action,
+            float x, float y, int pointerId, float pressure, float orientation, float tilt,
+            int changedButton, int buttonState, int metaState, int toolType);
+}