Add support for rect-based event targeting in views

ui/views/widget/root_view.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/views/widget/root_view.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "ui/base/accessibility/accessible_view_state.h"
 #include "ui/base/dragdrop/drag_drop_types.h"
 #include "ui/compositor/layer.h"
 #include "ui/events/event.h"
 #include "ui/events/keycodes/keyboard_codes.h"
 #include "ui/gfx/canvas.h"
 #include "ui/views/focus/view_storage.h"
 #include "ui/views/layout/fill_layout.h"
+#include "ui/views/views_switches.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/widget/widget_delegate.h"
 #include "ui/views/widget/widget_deletion_observer.h"
 
 #if defined(USE_AURA)
 #include "ui/base/cursor/cursor.h"
 #endif
 
 namespace views {
 namespace internal {
@@ skipping 250 matching lines @@
   // events are not dispatched to any views.
   switch (event->type()) {
     case ui::ET_GESTURE_SCROLL_UPDATE:
     case ui::ET_GESTURE_SCROLL_END:
     case ui::ET_SCROLL_FLING_START:
       return;
     default:
       break;
   }
 
+  View* gesture_handler = NULL;
+  if (views::switches::UseRectBasedTargeting()) {
+    // TODO(tdanderson): Pass in the bounding box to GetEventHandlerForRect()
+    // once crbug.com/313392 is resolved.
+    gfx::Rect touch_rect(event->details().bounding_box());
+    touch_rect.set_origin(event->location());
+    touch_rect.Offset(-touch_rect.width() / 2, -touch_rect.height() / 2);
+    gesture_handler = GetEventHandlerForRect(touch_rect);
+  } else {
+    gesture_handler = GetEventHandlerForPoint(event->location());
+  }
+
   // Walk up the tree until we find a view that wants the gesture event.
-  for (gesture_handler_ = GetEventHandlerForPoint(event->location());
-      gesture_handler_ && (gesture_handler_ != this);
-      gesture_handler_ = gesture_handler_->parent()) {
+  for (gesture_handler_ = gesture_handler;
+       gesture_handler_ && (gesture_handler_ != this);
+       gesture_handler_ = gesture_handler_->parent()) {
     if (!gesture_handler_->enabled()) {
       // Disabled views eat events but are treated as not handled.
       return;
     }
 
     // See if this view wants to handle the Gesture.
     ui::GestureEvent gesture_event(*event, static_cast<View*>(this),
                                    gesture_handler_);
     DispatchEventToTarget(gesture_handler_, &gesture_event);
 
@@ skipping 420 matching lines @@
       return;
   }
 }
 
 bool RootView::CanDispatchToTarget(ui::EventTarget* target) {
   return event_dispatch_target_ == target;
 }
 
 }  // namespace internal
 }  // namespace views