ui/views/widget/root_view_targeter.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "ui/views/widget/root_view_targeter.h"
   6
   7 #include "ui/views/view.h"
   8 #include "ui/views/view_targeter_delegate.h"
   9 #include "ui/views/views_switches.h"
  10 #include "ui/views/widget/root_view.h"
  11 #include "ui/views/widget/widget.h"
  12
  13 namespace views {
  14
  15 RootViewTargeter::RootViewTargeter(ViewTargeterDelegate* delegate,
  16                                    internal::RootView* root_view)
  17     : ViewTargeter(delegate), root_view_(root_view) {
  18 }
  19
  20 RootViewTargeter::~RootViewTargeter() {
  21 }
  22
  23 View* RootViewTargeter::FindTargetForGestureEvent(
  24     View* root,
  25     const ui::GestureEvent& gesture) {
  26   CHECK_EQ(root, root_view_);
  27
  28   // Return the default gesture handler if one is already set.
  29   if (root_view_->gesture_handler_) {
  30     CHECK(root_view_->gesture_handler_set_before_processing_);
  31     return root_view_->gesture_handler_;
  32   }
  33
  34   // If rect-based targeting is enabled, use the gesture's bounding box to
  35   // determine the target. Otherwise use the center point of the gesture's
  36   // bounding box to determine the target.
  37   gfx::Rect rect(gesture.location(), gfx::Size(1, 1));
  38   if (views::switches::IsRectBasedTargetingEnabled() &&
  39       !gesture.details().bounding_box().IsEmpty()) {
  40     // TODO(tdanderson): Pass in the bounding box to GetEventHandlerForRect()
  41     // once crbug.com/313392 is resolved.
  42     rect.set_size(gesture.details().bounding_box().size());
  43     rect.Offset(-rect.width() / 2, -rect.height() / 2);
  44   }
  45
  46   return root->GetEffectiveViewTargeter()->TargetForRect(root, rect);
  47 }
  48
  49 ui::EventTarget* RootViewTargeter::FindNextBestTargetForGestureEvent(
  50     ui::EventTarget* previous_target,
  51     const ui::GestureEvent& gesture) {
  52   // ET_GESTURE_END events should only ever be targeted to the default
  53   // gesture handler set by a previous gesture, if one exists. Thus we do not
  54   // permit any re-targeting of ET_GESTURE_END events.
  55   if (gesture.type() == ui::ET_GESTURE_END)
  56     return NULL;
  57
  58   // Prohibit re-targeting of gesture events (except for GESTURE_SCROLL_BEGIN
  59   // events) if the default gesture handler was set by the dispatch of a
  60   // previous gesture event.
  61   if (root_view_->gesture_handler_set_before_processing_ &&
  62       gesture.type() != ui::ET_GESTURE_SCROLL_BEGIN) {
  63     return NULL;
  64   }
  65
  66   // If |gesture_handler_| is NULL, it is either because the view was removed
  67   // from the tree by the previous dispatch of |gesture| or because |gesture| is
  68   // the GESTURE_END event corresponding to the removal of the last touch
  69   // point. In either case, no further re-targeting of |gesture| should be
  70   // permitted.
  71   if (!root_view_->gesture_handler_)
  72     return NULL;
  73
  74   return previous_target->GetParentTarget();
  75 }
  76
  77 }  // namespace views