Add Vector2d classes that represent offsets, instead of using Point.

ui/base/gestures/gesture_recognizer_impl.cc

 // Copyright (c) 2012 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/base/gestures/gesture_recognizer_impl.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time.h"
 #include "ui/base/events/event.h"
@@ skipping 107 matching lines @@
     GestureEvent* event) {
   GestureConsumer* target = NULL;
   int touch_id = event->GetLowestTouchId();
   target = touch_id_target_for_gestures_[touch_id];
   return target;
 }
 
 GestureConsumer* GestureRecognizerImpl::GetTargetForLocation(
     const gfx::Point& location) {
   const GesturePoint* closest_point = NULL;
-  int closest_distance_squared = 0;
+  int64 closest_distance_squared = 0;
   std::map<GestureConsumer*, GestureSequence*>::iterator i;
   for (i = consumer_sequence_.begin(); i != consumer_sequence_.end(); ++i) {
     const GesturePoint* points = i->second->points();
     for (int j = 0; j < GestureSequence::kMaxGesturePoints; ++j) {
       if (!points[j].in_use())
         continue;
-      gfx::Point delta =
-          points[j].last_touch_position().Subtract(location);
-      int distance = delta.x() * delta.x() + delta.y() * delta.y();
-      if (!closest_point || distance < closest_distance_squared) {
+      gfx::Vector2d delta = points[j].last_touch_position() - location;
+      // Relative distance is all we need here, so LengthSquared() is
+      // appropriate, and cheaper than Length().
+      int64 distance_squared = delta.LengthSquared();
+      if (!closest_point || distance_squared < closest_distance_squared) {
         closest_point = &points[j];
-        closest_distance_squared = distance;
+        closest_distance_squared = distance_squared;
       }
     }
   }
 
   const int max_distance =
       GestureConfiguration::max_separation_for_gesture_touches_in_pixels();
 
   if (closest_distance_squared < max_distance * max_distance && closest_point)
     return touch_id_target_[closest_point->touch_id()];
   else
@@ skipping 87 matching lines @@
   RemoveConsumerFromMap(consumer, &touch_id_target_);
   RemoveConsumerFromMap(consumer, &touch_id_target_for_gestures_);
 }
 
 // GestureRecognizer, static
 GestureRecognizer* GestureRecognizer::Create(GestureEventHelper* helper) {
   return new GestureRecognizerImpl(helper);
 }
 
 }  // namespace ui