Pass MotionEvent tilt angles to Blink on Android.

content/browser/renderer_host/input/motion_event_web.cc

 // Copyright 2014 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 "content/browser/renderer_host/input/motion_event_web.h"
 
 #include <cmath>
@@ skipping 112 matching lines @@
 
 float MotionEventWeb::GetTouchMinor(size_t pointer_index) const {
   DCHECK_LT(pointer_index, GetPointerCount());
   return 2.f * std::min(event_.touches[pointer_index].radiusX,
                         event_.touches[pointer_index].radiusY);
 }
 
 float MotionEventWeb::GetOrientation(size_t pointer_index) const {
   DCHECK_LT(pointer_index, GetPointerCount());
 
-  float rotation_angle_rad = event_.touches[pointer_index].rotationAngle
+  float orientation_rad = event_.touches[pointer_index].rotationAngle
       * M_PI / 180.f;
-  DCHECK(0 <= rotation_angle_rad && rotation_angle_rad <= M_PI_2)
+  DCHECK(0 <= orientation_rad && orientation_rad <= M_PI_2)
       << "Unexpected touch rotation angle";
 
-  if (event_.touches[pointer_index].radiusX
-      > event_.touches[pointer_index].radiusY) {
+  if (GetToolType(pointer_index) == TOOL_TYPE_STYLUS) {
+    const WebPointerProperties& pointer = event_.touches[pointer_index];
+

[jdduke (slow), 2015/08/12 17:00:12]

I think we'll want some basic test coverage for this. Doesn't need to be
exhaustive, but we should have at least a couple smoke test cases.

+    if (pointer.tiltY < 0) {
+      if (pointer.tiltX < 0)
+        orientation_rad += M_PI_2;
+      else
+        orientation_rad -= M_PI;
+    } else {
+      if (pointer.tiltX > 0)
+        orientation_rad -= M_PI_2;
+    }
+  } else if (event_.touches[pointer_index].radiusX
+             > event_.touches[pointer_index].radiusY) {
     // The case radiusX == radiusY is omitted from here on purpose: for circles,
     // we want to pass the angle (which could be any value in such cases but
     // always seem to be set to zero) unchanged.
-    rotation_angle_rad -= (float) M_PI_2;
+    orientation_rad -= (float) M_PI_2;
   }
 
-  return rotation_angle_rad;
+  return orientation_rad;
 }
 
 float MotionEventWeb::GetPressure(size_t pointer_index) const {
   return 0.f;
 }
 
+float MotionEventWeb::GetTilt(size_t pointer_index) const {
+  DCHECK_LT(pointer_index, GetPointerCount());
+
+  if (GetToolType(pointer_index) != TOOL_TYPE_STYLUS)
+    return 0.f;
+

[jdduke (slow), 2015/08/12 17:00:13]

Same here, a few basic test cases would be nice. We haven't added tests for this
class until now as most of the getters are trivial, but it's probably time we
add some coverage.

Ideally we'd have a case where we construct a MotionEventGeneric with some
tilt/orientation values, we run that through
CreateWebTouchEventFromMotionEvent(), then create a MotionEventWeb from the
result. The result of GetTilt/GetOrientation should be the same.

+  const WebPointerProperties& pointer = event_.touches[pointer_index];
+
+  float tilt_x_r = sin(pointer.tiltX * M_PI / 180.f);
+  float tilt_x_z = cos(pointer.tiltX * M_PI / 180.f);
+  float tilt_y_r = sin(pointer.tiltY * M_PI / 180.f);
+  float tilt_y_z = cos(pointer.tiltY * M_PI / 180.f);
+  float r_x = tilt_x_r * tilt_y_z;
+  float r_y = tilt_y_r * tilt_x_z;
+  float r = sqrt(r_x * r_x + r_y * r_y);
+  float z = tilt_x_z * tilt_y_z;
+
+  return atan2(r, z);
+}
+
 base::TimeTicks MotionEventWeb::GetEventTime() const {
   return base::TimeTicks() +
          base::TimeDelta::FromMicroseconds(event_.timeStampSeconds *
                                            base::Time::kMicrosecondsPerSecond);
 }
 
 ui::MotionEvent::ToolType MotionEventWeb::GetToolType(
     size_t pointer_index) const {
   DCHECK_LT(pointer_index, GetPointerCount());
 
@@ skipping 16 matching lines @@
 
 int MotionEventWeb::GetButtonState() const {
   return 0;
 }
 
 int MotionEventWeb::GetFlags() const {
   return WebEventModifiersToEventFlags(event_.modifiers);
 }
 
 }  // namespace content