ViewRoot class for event forwarding on Android

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

+// 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.view.MotionEvent;
+
+import org.chromium.base.annotations.JNINamespace;
+
+/**
+ * Class used to forward view, input events down to native.
+ * TODO(jinsukkim): Hook this up to UI event forwarding flow and substitute WindowAndroid.
+ */
+@JNINamespace("ui")
+public class ViewRoot {
+
+    private final WindowAndroid mWindowAndroid;
+
+    // The corresponding native instance. This class can only be used while
+    // the native instance is alive.
+    // This is initialized lazily. Use {@link getNativePtr()} rather than
+    // accessing it directly.
+    private long mNativeView;
+
+    public static ViewRoot create(WindowAndroid window) {
+        if (window == null) throw new IllegalArgumentException("WindowAndroid should not be null");
+        return new ViewRoot(window);
+    }
+
+    private ViewRoot(WindowAndroid window) {
+        mWindowAndroid = window;
+    }
+
+    public WindowAndroid getWindowAndroid() {
+        return mWindowAndroid;
+    }
+
+    public boolean onTouchEvent(MotionEvent event, boolean isTouchHandleEvent) {
+        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;
+            }
+        }
+
+        return nativeOnTouchEvent(getNativePtr(), event,
+                event.getEventTime(), event.getActionMasked(),
+                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);
+    }
+
+    public long getNativePtr() {
+        if (mNativeView == 0) mNativeView = nativeInit(mWindowAndroid.getNativePointer());
+        return mNativeView;
+    }
+
+    public void destroy() {
+        if (mNativeView != 0) {
+            nativeDestroy(mNativeView);
+            mNativeView = 0;
+        }
+    }
+
+    private native long nativeInit(long windowNativePointer);
+    private native void nativeDestroy(long nativeViewRoot);
+
+    // All touch events (including flings, scrolls etc) accept coordinates in physical pixels.
+    private native boolean nativeOnTouchEvent(
+            long nativeViewRoot, 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);
+}