Support targeting for gestures in ViewTargeter

ui/views/widget/root_view_targeter.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/views/widget/root_view_targeter.h"
+
+#include "ui/views/view.h"
+#include "ui/views/view_targeter_delegate.h"
+#include "ui/views/views_switches.h"
+#include "ui/views/widget/root_view.h"
+#include "ui/views/widget/widget.h"
+
+namespace views {
+
+RootViewTargeter::RootViewTargeter(ViewTargeterDelegate* delegate,
+                                   internal::RootView* root_view)
+    : ViewTargeter(delegate), root_view_(root_view) {
+}
+
+RootViewTargeter::~RootViewTargeter() {
+}
+
+View* RootViewTargeter::FindTargetForGestureEvent(
+    View* root,
+    const ui::GestureEvent& gesture) {
+  CHECK_EQ(root, root_view_);
+
+  // Return the default gesture handler if one is already set.
+  if (root_view_->gesture_handler_) {
+    CHECK(!root_view_->allow_gesture_event_retargeting_);
+    return root_view_->gesture_handler_;
+  }
+
+  // If rect-based targeting is enabled, use the gesture's bounding box to
+  // determine the target. Otherwise use the center point of the gesture's
+  // bounding box to determine the target.
+  gfx::Rect rect(gesture.location(), gfx::Size(1, 1));
+  if (views::switches::IsRectBasedTargetingEnabled() &&
+      !gesture.details().bounding_box().IsEmpty()) {
+    // TODO(tdanderson): Pass in the bounding box to GetEventHandlerForRect()
+    // once crbug.com/313392 is resolved.
+    rect.set_size(gesture.details().bounding_box().size());
+    rect.Offset(-rect.width() / 2, -rect.height() / 2);
+  }
+
+  return root->GetEffectiveViewTargeter()->TargetForRect(root, rect);
+}
+
+ui::EventTarget* RootViewTargeter::FindNextBestTargetForGestureEvent(
+    ui::EventTarget* previous_target,
+    const ui::GestureEvent& gesture) {
+  // GESTURE_SCROLL_BEGIN events are always permitted to be re-targeted, even
+  // if |allow_gesture_event_retargeting_| is false.
+  if (!root_view_->allow_gesture_event_retargeting_ &&
+      gesture.type() != ui::ET_GESTURE_SCROLL_BEGIN) {
+    return NULL;
+  }
+
+  // If |gesture_handler_| is NULL, it is either because the view was removed
+  // from the tree by the previous dispatch of |gesture| or because |gesture| is
+  // the GESTURE_END event corresponding to the removal of the last touch
+  // point. In either case, no further re-targeting of |gesture| should be
+  // permitted.
+  if (!root_view_->gesture_handler_)
+    return NULL;
+
+  return previous_target->GetParentTarget();
+}
+
+}  // namespace views