Add gesture target fuzzing to views

ui/views/view.cc

Index: ui/views/view.cc
diff --git a/ui/views/view.cc b/ui/views/view.cc
index 078d42a75a3b0855fad2aca1fdbb7eb20fdf0fbb..52ffc0876bb90e0207e73af477e87d9439fa344d 100644
--- a/ui/views/view.cc
+++ b/ui/views/view.cc
@@ -27,6 +27,7 @@
 #include "ui/views/context_menu_controller.h"
 #include "ui/views/drag_controller.h"
 #include "ui/views/layout/layout_manager.h"
+#include "ui/views/view_constants.h"
 #include "ui/views/views_delegate.h"
 #include "ui/views/widget/native_widget_private.h"
 #include "ui/views/widget/root_view.h"
@@ -80,6 +81,44 @@ const views::View* GetHierarchyRoot(const views::View* view) {
   return root;
 }
 
+// Returns the percentage of |rect_1|'s area that is covered by |rect_2|.
+float PercentCoveredBy(const gfx::Rect& rect_1, const gfx::Rect& rect_2) {
+  gfx::Rect intersection(rect_1.Intersect(rect_2));
+  float intersection_area = intersection.size().GetArea();
+  float rect_1_area = rect_1.size().GetArea();
+  return intersection_area / rect_1_area;
+}
+
+int DistanceToInterval(int pos, int start, int end) {
+  if (pos < start)
+    return start - pos;
+  if (pos > end)
+    return end - pos;
+  return 0;
+}
+
+// Returns the square of the distance from |point| to the center line of
+// |target_rect|. The center line of a rectangle is obtained by repeatedly
+// stripping away 1px borders around the rectangle until a line remains.
+int DistanceSquaredFromCenterLineToPoint(const gfx::Point& point,
+                                         const gfx::Rect& target_rect) {
+  gfx::Point center_point = target_rect.CenterPoint();
+  int dx = center_point.x() - point.x();
+  int dy = center_point.y() - point.y();
+
+  if (target_rect.width() > target_rect.height()) {
+    dx = DistanceToInterval(point.x(),
+                            target_rect.x() + (target_rect.height() / 2),
+                            target_rect.right() - (target_rect.height() / 2));
+  } else {
+    dy = DistanceToInterval(point.y(),
+                            target_rect.y() + (target_rect.width() / 2),
+                            target_rect.bottom() - (target_rect.width() / 2));
+  }
+
+  return (dx * dx) + (dy * dy);
+}
+
 }  // namespace
 
 namespace views {
@@ -764,6 +803,42 @@ View* View::GetEventHandlerForPoint(const gfx::Point& point) {
   return this;
 }
 
+View* View::GetEventHandlerForRect(const gfx::Rect& touch_rect) {
+  if (!child_count()) {
+    gfx::Rect view_rect(GetBoundsInScreen());
+    if (PercentCoveredBy(view_rect, touch_rect) >= kFuzzingOverlapPercentage)
+      return this;
+    return NULL;
+  }
+
+  View* closest_view = NULL;
+  int best_dist_so_far = INT_MAX;
+  for (int i = child_count() - 1; i >= 0; --i) {
+    View* child = child_at(i);
+    if (!child->visible())
+      continue;
+
+    gfx::Rect child_rect(child->GetBoundsInScreen());
+    if (!child_rect.Intersects(touch_rect))
+      continue;
+
+    View* cur_view = child->GetEventHandlerForRect(touch_rect);
+    if (!cur_view)
+      continue;
+
+    gfx::Point touch_center(touch_rect.CenterPoint());
+    gfx::Rect cur_rect(cur_view->GetBoundsInScreen());
+    int cur_dist = DistanceSquaredFromCenterLineToPoint(touch_center,
+                                                        cur_rect);
+    if (!closest_view || cur_dist < best_dist_so_far) {
+      closest_view = cur_view;
+      best_dist_so_far = cur_dist;
+    }
+  }
+
+  return closest_view;
+}
+
 gfx::NativeCursor View::GetCursor(const MouseEvent& event) {
 #if defined(OS_WIN) && !defined(USE_AURA)
   static HCURSOR arrow = LoadCursor(NULL, IDC_ARROW);