Move views event targeting into ViewTargeterDelegate::TargetForRect()

Move the default event-targeting implementation for views from
View::GetEventHandlerForRect() into the new method
ViewTargeterDelegate::TargetForRect() and make the method
View::GetEventHandlerForRect() call into its effective ViewTargeter
instead. The "effective" targeter for a View is the
ViewTargeter installed on that View if one exists, otherwise
it is the ViewTargeter installed on its root view.

Once this change has landed, the overrides of
View::GetEventHandlerForRect() can be removed and their
implementations moved into overrides of
ViewTargeterDelegate::TargetForRect().
View::GetEventHandlerForRect() can then be made
non-virtual.

BUG=391845
TEST=existing coverage in ViewTest.GetEventHandlerForRect

Review URL: https://codereview.chromium.org/401933002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284342 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 90 insertions, 1 deletions

diff --git a/ui/views/view_targeter_delegate.cc b/ui/views/view_targeter_delegate.cc
index 5527742..7d4556a 100644
--- a/ui/views/view_targeter_delegate.cc
+++ b/ui/views/view_targeter_delegate.cc
@@ -2,14 +2,103 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ui/views/view.h"
 #include "ui/views/view_targeter_delegate.h"
 
+#include "ui/gfx/rect_conversions.h"
+#include "ui/views/rect_based_targeting_utils.h"
+#include "ui/views/view.h"
+
+namespace {
+
+// The minimum percentage of a view's area that needs to be covered by a rect
+// representing a touch region in order for that view to be considered by the
+// rect-based targeting algorithm.
+static const float kRectTargetOverlap = 0.6f;
+
+}  // namespace
+
 namespace views {
 
+// TODO(tdanderson): Move the contents of rect_based_targeting_utils.(h|cc)
+//                   into here.
+
 bool ViewTargeterDelegate::DoesIntersectRect(const View* target,
                                              const gfx::Rect& rect) const {
   return target->GetLocalBounds().Intersects(rect);
 }
 
+View* ViewTargeterDelegate::TargetForRect(View* root, const gfx::Rect& rect) {
+  // |rect_view| represents the current best candidate to return
+  // if rect-based targeting (i.e., fuzzing) is used.
+  // |rect_view_distance| is used to keep track of the distance
+  // between the center point of |rect_view| and the center
+  // point of |rect|.
+  View* rect_view = NULL;
+  int rect_view_distance = INT_MAX;
+
+  // |point_view| represents the view that would have been returned
+  // from this function call if point-based targeting were used.
+  View* point_view = NULL;
+
+  for (int i = root->child_count() - 1; i >= 0; --i) {
+    View* child = root->child_at(i);
+
+    if (!child->CanProcessEventsWithinSubtree())
+      continue;
+
+    // Ignore any children which are invisible or do not intersect |rect|.
+    if (!child->visible())
+      continue;
+    gfx::RectF rect_in_child_coords_f(rect);
+    View::ConvertRectToTarget(root, child, &rect_in_child_coords_f);
+    gfx::Rect rect_in_child_coords = gfx::ToEnclosingRect(
+        rect_in_child_coords_f);
+    if (!child->HitTestRect(rect_in_child_coords))
+      continue;
+
+    View* cur_view = child->GetEventHandlerForRect(rect_in_child_coords);
+
+    if (views::UsePointBasedTargeting(rect))
+      return cur_view;
+
+    gfx::RectF cur_view_bounds_f(cur_view->GetLocalBounds());
+    View::ConvertRectToTarget(cur_view, root, &cur_view_bounds_f);
+    gfx::Rect cur_view_bounds = gfx::ToEnclosingRect(
+        cur_view_bounds_f);
+    if (views::PercentCoveredBy(cur_view_bounds, rect) >= kRectTargetOverlap) {
+      // |cur_view| is a suitable candidate for rect-based targeting.
+      // Check to see if it is the closest suitable candidate so far.
+      gfx::Point touch_center(rect.CenterPoint());
+      int cur_dist = views::DistanceSquaredFromCenterToPoint(touch_center,
+                                                             cur_view_bounds);
+      if (!rect_view || cur_dist < rect_view_distance) {
+        rect_view = cur_view;
+        rect_view_distance = cur_dist;
+      }
+    } else if (!rect_view && !point_view) {
+      // Rect-based targeting has not yielded any candidates so far. Check
+      // if point-based targeting would have selected |cur_view|.
+      gfx::Point point_in_child_coords(rect_in_child_coords.CenterPoint());
+      if (child->HitTestPoint(point_in_child_coords))
+        point_view = child->GetEventHandlerForPoint(point_in_child_coords);
+    }
+  }
+
+  if (views::UsePointBasedTargeting(rect) || (!rect_view && !point_view))
+    return root;
+
+  // If |root| is a suitable candidate for rect-based targeting, check to
+  // see if it is closer than the current best suitable candidate so far.
+  gfx::Rect local_bounds(root->GetLocalBounds());
+  if (views::PercentCoveredBy(local_bounds, rect) >= kRectTargetOverlap) {
+    gfx::Point touch_center(rect.CenterPoint());
+    int cur_dist = views::DistanceSquaredFromCenterToPoint(touch_center,
+                                                           local_bounds);
+    if (!rect_view || cur_dist < rect_view_distance)
+      rect_view = root;
+  }
+
+  return rect_view ? rect_view : point_view;
+}
+
 }  // namespace views