Pass MotionEvent tilt angles to Blink on Android.

ui/events/blink/blink_event_util.cc

 // Copyright 2015 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.
 
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 
 #include "ui/events/blink/blink_event_util.h"
 
 #include <cmath>
@@ skipping 81 matching lines @@
   // using two radii along x- & y-axes and a positive acute rotation angle in
   // degrees. See:
   // http://dvcs.w3.org/hg/webevents/raw-file/default/touchevents.html
 
   float major_radius = event.GetTouchMajor(pointer_index) / 2.f;
   float minor_radius = event.GetTouchMinor(pointer_index) / 2.f;
 
   DCHECK_LE(minor_radius, major_radius);
   DCHECK_IMPLIES(major_radius, minor_radius);
 
-  float orientation_deg = event.GetOrientation(pointer_index) * 180.f / M_PI;
+  float orientation_rad = event.GetOrientation(pointer_index);
+  float orientation_deg = orientation_rad * 180.f / M_PI;
   DCHECK_GE(major_radius, 0);
   DCHECK_GE(minor_radius, 0);
   DCHECK_GE(major_radius, minor_radius);
   if (event.GetToolType(pointer_index) == MotionEvent::TOOL_TYPE_STYLUS) {
     // Orientation lies in [-180, 180] for a stylus. Normalise to [-90, 90).
     // Allow a small bound tolerance to account for floating point conversion.
-    // TODO(e_hakkinen): crbug.com/493728: Pass also unaltered orientation
-    //                   to touch in order not to lose quadrant information.
     DCHECK_GT(orientation_deg, -180.01f);
     DCHECK_LT(orientation_deg, 180.01f);
     if (orientation_deg >= 90.f)
       orientation_deg -= 180.f;
     else if (orientation_deg < -90.f)
       orientation_deg += 180.f;
+
+    // A stylus points to a direction specified by orientation and tilts to
+    // the opposite direction. Coordinate system is left-handed.
+    float tilt_rad = event.GetTilt(pointer_index);
+    float r = sin(tilt_rad);
+    float z = cos(tilt_rad);
+    touch.tiltX = atan2(sin(-orientation_rad) * r, z) * 180.f / M_PI;
+    touch.tiltY = atan2(cos(-orientation_rad) * r, z) * 180.f / M_PI;
   } else {
     // Orientation lies in [-90, 90] for a touch. Normalise to [-90, 90).
     // Allow a small bound tolerance to account for floating point conversion.
     DCHECK_GT(orientation_deg, -90.01f);
     DCHECK_LT(orientation_deg, 90.01f);
     if (orientation_deg >= 90.f)
       orientation_deg -= 180.f;
+
+    touch.tiltX = touch.tiltY = 0;
   }
   if (orientation_deg >= 0) {
     // The case orientation_deg == 0 is handled here on purpose: although the
     // 'else' block is equivalent in this case, we want to pass the 0 value
     // unchanged (and 0 is the default value for many devices that don't
     // report elliptical touches).
     touch.radiusX = minor_radius;
     touch.radiusY = major_radius;
     touch.rotationAngle = orientation_deg;
   } else {
@@ skipping 176 matching lines @@
 }
 
 WebGestureEvent CreateWebGestureEventFromGestureEventData(
     const GestureEventData& data) {
   return CreateWebGestureEvent(data.details, data.time - base::TimeTicks(),
                                gfx::PointF(data.x, data.y),
                                gfx::PointF(data.raw_x, data.raw_y), data.flags);
 }
 
 }  // namespace ui