Implementing the dispatch of the swipe gesture for one-finger touch swipes.

ui/events/gesture_detection/gesture_detector.cc

Index: ui/events/gesture_detection/gesture_detector.cc
diff --git a/ui/events/gesture_detection/gesture_detector.cc b/ui/events/gesture_detection/gesture_detector.cc
index fdc524bef2cf8e861fde0022dcf604db9fbf354f..9c222e970fd0773880f33898325ae7aad0a6398f 100644
--- a/ui/events/gesture_detection/gesture_detector.cc
+++ b/ui/events/gesture_detection/gesture_detector.cc
@@ -272,29 +272,7 @@ bool GestureDetector::OnTouchEvent(const MotionEvent& ev) {
         vy_total += vy2;
       }
 
-      if (swipe_enabled_ && (vx_total || vy_total)) {
-        float vx = vx_total / count;
-        float vy = vy_total / count;
-        float vx_abs = std::abs(vx);
-        float vy_abs = std::abs(vy);
-
-        if (vx_abs < min_swipe_velocity_)
-          vx_abs = vx = 0;
-        if (vy_abs < min_swipe_velocity_)
-          vy_abs = vy = 0;
-
-        // Note that the ratio will be 0 if both velocites are below the min.
-        float ratio = vx_abs > vy_abs ? vx_abs / std::max(vy_abs, 0.001f)
-                                      : vy_abs / std::max(vx_abs, 0.001f);
-        if (ratio > min_swipe_direction_component_ratio_) {
-          if (vx_abs > vy_abs)
-            vy = 0;
-          else
-            vx = 0;
-
-          handled = listener_->OnSwipe(*current_down_event_, ev, vx, vy);
-        }
-      }
+      handled = handleSwipeIfNeeded(ev, vx_total / count, vy_total / count);
 
       if (two_finger_tap_allowed_for_gesture_ && ev.GetPointerCount() == 2 &&
           (ev.GetEventTime() - secondary_pointer_down_event_->GetEventTime() <=
@@ -433,6 +411,8 @@ bool GestureDetector::OnTouchEvent(const MotionEvent& ev) {
             handled = listener_->OnFling(
                 *current_down_event_, ev, velocity_x, velocity_y);
           }
+
+          handled |= handleSwipeIfNeeded(ev, velocity_x, velocity_y);
         }
 
         previous_up_event_ = ev.Clone();
@@ -554,4 +534,32 @@ bool GestureDetector::IsConsideredDoubleTap(
   return (delta_x * delta_x + delta_y * delta_y < double_tap_slop_square_);
 }
 
+bool GestureDetector::handleSwipeIfNeeded(const MotionEvent& up,
+                                          float vx,
+                                          float vy) {
+  if (!swipe_enabled_ || (!vx && !vy))
+    return false;
+  float vx_abs = std::abs(vx);
+  float vy_abs = std::abs(vy);
+
+  if (vx_abs < min_swipe_velocity_)
+    vx_abs = vx = 0;
+  if (vy_abs < min_swipe_velocity_)
+    vy_abs = vy = 0;
+
+  // Note that the ratio will be 0 if both velocites are below the min.
+  float ratio = vx_abs > vy_abs ? vx_abs / std::max(vy_abs, 0.001f)
+                                : vy_abs / std::max(vx_abs, 0.001f);
+
+  if (ratio > min_swipe_direction_component_ratio_) {

[jdduke (slow), 2014/05/26 21:19:42]

Nit: I would early out here in the unsatisfied case, i.e.,

if (ratio < min_swipe_direction_component_ratio_)
  return false;

...

(Note that the inequality strictness doesn't really matter, either way should
work).

[mfomitchev, 2014/05/26 22:07:14]

Done.

+    if (vx_abs > vy_abs)
+      vy = 0;
+    else
+      vx = 0;
+
+    return listener_->OnSwipe(*current_down_event_, up, vx, vy);
+  }
+  return false;
+}
+
 }  // namespace ui