Fix bounding box calculation for touches with radius of 0.

BUG=None
TEST=GestureProviderTest.ZeroRadiusBoundingBox

Review URL: https://codereview.chromium.org/464013002

Cr-Commit-Position: refs/heads/master@{#289151}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289151 0039d316-1c4b-4281-b951-d872f2087c98

ui/events/gesture_detection/gesture_provider.cc

@@ -31,15 +31,21 @@ const char* GetMotionEventActionName(MotionEvent::Action action) {
 }
 
 gfx::RectF GetBoundingBox(const MotionEvent& event) {
-  gfx::RectF bounds;
+  // Can't use gfx::RectF::Union, as it ignores touches with a radius of 0.
+  float left = std::numeric_limits<float>::max();
+  float top = std::numeric_limits<float>::max();
+  float right = -std::numeric_limits<float>::max();
+  float bottom = -std::numeric_limits<float>::max();
   for (size_t i = 0; i < event.GetPointerCount(); ++i) {
     float diameter = event.GetTouchMajor(i);
-    bounds.Union(gfx::RectF(event.GetX(i) - diameter / 2,
-                            event.GetY(i) - diameter / 2,
-                            diameter,
-                            diameter));
-  }
-  return bounds;
+    float x = event.GetX(i) - diameter / 2;
+    float y = event.GetY(i) - diameter / 2;
+    left = std::min(left, x);
+    right = std::max(right, x + diameter);
+    top = std::min(top, y);
+    bottom = std::max(bottom, y + diameter);
+  }
+  return gfx::RectF(left, top, right - left, bottom - top);
 }
 
 GestureEventData CreateGesture(const GestureEventDetails& details,

ui/events/gesture_detection/gesture_provider_unittest.cc

@@ -823,7 +823,7 @@ TEST_F(GestureProviderTest, FractionalScroll) {
     // Verify that the event co-ordinates are still the precise values we
     // supplied.
     EXPECT_EQ(kFakeCoordX + delta_x * i, gesture.x);
-    EXPECT_EQ(kFakeCoordY + delta_y * i, gesture.y);
+    EXPECT_FLOAT_EQ(kFakeCoordY + delta_y * i, gesture.y);
 
     // Verify that we're scrolling vertically by the expected amount
     // (modulo rounding).
@@ -2340,4 +2340,27 @@ TEST_F(GestureProviderTest, MaxGestureBoundsLength) {
             GetMostRecentGestureEvent().details.bounding_box_f().height());
 }
 
+TEST_F(GestureProviderTest, ZeroRadiusBoundingBox) {
+  base::TimeTicks event_time = base::TimeTicks::Now();
+  MockMotionEvent event =
+      ObtainMotionEvent(event_time, MotionEvent::ACTION_DOWN, 10, 20);
+  event.SetTouchMajor(0);
+  EXPECT_TRUE(gesture_provider_->OnTouchEvent(event));
+  EXPECT_EQ(gfx::RectF(10, 20, 0, 0),
+            GetMostRecentGestureEvent().details.bounding_box());
+
+  event = ObtainMotionEvent(
+      event_time, MotionEvent::ACTION_POINTER_DOWN, 10, 20, 110, 120);
+  event.SetTouchMajor(0);
+  EXPECT_TRUE(gesture_provider_->OnTouchEvent(event));
+
+  event = ObtainMotionEvent(
+      event_time, MotionEvent::ACTION_MOVE, 10, 20, 110, 150);
+  event.SetTouchMajor(0);
+  EXPECT_TRUE(gesture_provider_->OnTouchEvent(event));
+
+  EXPECT_EQ(gfx::RectF(10, 20, 100, 130),
+            GetMostRecentGestureEvent().details.bounding_box());
+}
+
 }  // namespace ui