Aura on Android: Making events work

ui/events/gesture_detection/gesture_configuration_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 "ui/events/gesture_detection/gesture_configuration.h"
 
 #include "base/android/build_info.h"
 #include "base/memory/singleton.h"
 #include "ui/gfx/android/view_configuration.h"
 #include "ui/gfx/screen.h"
@@ skipping 19 matching lines @@
     return base::Singleton<GestureConfigurationAndroid>::get();
   }
 
  private:
   GestureConfigurationAndroid() : GestureConfiguration() {
     set_double_tap_enabled(true);
     set_double_tap_timeout_in_ms(ViewConfiguration::GetDoubleTapTimeoutInMs());
     // TODO(jdduke): Enable this on Android M after the implicit conflict with
     // stylus selection is resolved.
     set_stylus_scale_enabled(false);
+#if defined(USE_AURA)
+    set_gesture_begin_end_types_enabled(true);
+#else
     set_gesture_begin_end_types_enabled(false);
+#endif

[sadrul, 2015/10/15 19:54:22]

Or would it make sense to actually use GestureConfigurationAura on android-aura?

[mfomitchev, 2015/10/15 20:06:29]

The Android implementation gets a bunch of settings from ViewConfiguration. It
ends up plugging directly into the native Android ViewConfiguration class. So if
we use the Aura implementation here, Chrome's feel will be different than that
of the native apps, which won't be good.

[jdduke (slow), 2015/10/15 20:50:51]

Sorry for the drive-by, but yeah, when we fashioned these classes we never
envisioned a world where Android/Aura intersected =/. Never say never I guess.
I'm fine with this addition, I suppose you could also just set it somewhere
early-on (during the late stages of startup?) in some Aura-specific code?

[mfomitchev, 2015/10/15 21:42:05]

We could, sure. Isn't it preferable though to have all the configuration in one
place so that we don't have to search through the code to understand the default
behavior? Is the concern simply that this pollutes the non-Aura Android logic?
If we get a lot of these ifdefs, we could create a
gesture_configuration_auraandroid.cc, but currently it doesn't seem too bad.

     set_long_press_time_in_ms(ViewConfiguration::GetLongPressTimeoutInMs());
     set_max_distance_between_taps_for_double_tap(
         ViewConfiguration::GetDoubleTapSlopInDips());
     // TODO(jdduke): Set this to 2 after double-click triggers selection only in
     // editable elements, see crbug.com/522268.
     set_max_tap_count(1);
     set_max_fling_velocity(
         ViewConfiguration::GetMaximumFlingVelocityInDipsPerSecond());
     set_max_gesture_bounds_length(kMaxGestureBoundsLengthDips);
     set_max_touch_move_in_pixels_for_click(
@@ skipping 21 matching lines @@
 };
 
 }  // namespace
 
 // Create a GestureConfigurationAura singleton instance when using Android.
 GestureConfiguration* GestureConfiguration::GetPlatformSpecificInstance() {
   return GestureConfigurationAndroid::GetInstance();
 }
 
 }  // namespace ui