Separate motion event touch geometry orientation from stylus orientation.

content/browser/renderer_host/input/motion_event_android.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.
 
 #include "content/browser/renderer_host/input/motion_event_android.h"
 
 #include <android/input.h>
 
 #include <cmath>
 
@@ skipping 240 matching lines @@
 }
 
 float MotionEventAndroid::GetOrientation(size_t pointer_index) const {
   DCHECK_LT(pointer_index, cached_pointer_count_);
   if (pointer_index < MAX_POINTERS_TO_CACHE)
     return cached_pointers_[pointer_index].orientation;
   return ToValidFloat(Java_MotionEvent_getOrientationF_I(
       AttachCurrentThread(), event_.obj(), pointer_index));
 }
 
+float MotionEventAndroid::GetTouchOrientation(size_t pointer_index) const {
+  float orientation = GetOrientation(pointer_index);
+  // The meaning of the motion event orientation is overloaded on Android.
+  // * For a touch screen or pad, it's the orientation of the touch major axis
+  //   clockwise from vertical. The value lies in [-PI/1, PI/2].
+  // * For a stylus, it indicates the direction in which the stylus is pointing
+  //   clockwise from top. The value lies in [-PI, PI].
+  // Map to touch major axis orientation.
+  if (orientation <= -M_PI_2)
+    return orientation + M_PI;
+  if (orientation >= M_PI_2)
+    return orientation - M_PI;
+  return orientation;
+}
+
 float MotionEventAndroid::GetPressure(size_t pointer_index) const {
   DCHECK_LT(pointer_index, cached_pointer_count_);
   // Note that this early return is a special case exercised only in testing, as
   // caching the pressure values is not a worthwhile optimization (they're
   // accessed at most once per event instance).
   if (!event_.obj())
     return 0.f;
   return Java_MotionEvent_getPressureF_I(
       AttachCurrentThread(), event_.obj(), pointer_index);
 }
@@ skipping 64 matching lines @@
   result.tool_type = FromAndroidToolType(pointer.tool_type);
   return result;
 }
 
 // static
 bool MotionEventAndroid::RegisterMotionEventAndroid(JNIEnv* env) {
   return JNI_MotionEvent::RegisterNativesImpl(env);
 }
 
 }  // namespace content