gesture recognizer: Make sure the pinch/scroll only when the finger is moved for real.

Change in the radius for any of the touch-points changes the bounding box of the points,
but in such cases, we do not want to trigger either scroll or pinch updates.

BUG=none
TBR=ben@chromium.org

Review URL: https://chromiumcodereview.appspot.com/10837107

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@150400 0039d316-1c4b-4281-b951-d872f2087c98

ui/aura/gestures/gesture_recognizer_unittest.cc

@@ -2516,5 +2516,55 @@ TEST_F(GestureRecognizerTest, TwoTapsWithDelayBetween) {
   EXPECT_EQ(1, delegate->tap_count());
 }
 
+// Checks that if the bounding-box of a gesture changes because of change in
+// radius of a touch-point, and not because of change in position, then there
+// are not gesture events from that.
+TEST_F(GestureRecognizerTest, BoundingBoxRadiusChange) {
+  scoped_ptr<GestureEventConsumeDelegate> delegate(
+      new GestureEventConsumeDelegate());
+  const int kWindowWidth = 234;
+  const int kWindowHeight = 345;
+  const int kTouchId = 5, kTouchId2 = 7;
+  gfx::Rect bounds(100, 200, kWindowWidth, kWindowHeight);
+  scoped_ptr<aura::Window> window(CreateTestWindowWithDelegate(
+      delegate.get(), -1234, bounds, NULL));
+
+  TouchEvent press1(ui::ET_TOUCH_PRESSED, gfx::Point(101, 201), kTouchId,
+      GetTime());
+  root_window()->AsRootWindowHostDelegate()->OnHostTouchEvent(&press1);
+  EXPECT_TRUE(delegate->bounding_box().IsEmpty());
+
+  delegate->Reset();
+
+  TouchEvent press2(ui::ET_TOUCH_PRESSED, gfx::Point(201, 201), kTouchId2,
+      press1.time_stamp() + base::TimeDelta::FromMilliseconds(400));
+  press2.set_radius_x(5);
+  root_window()->AsRootWindowHostDelegate()->OnHostTouchEvent(&press2);
+  EXPECT_FALSE(delegate->pinch_begin());
+
+  delegate->Reset();
+
+  TouchEvent move1(ui::ET_TOUCH_MOVED, gfx::Point(141, 201), kTouchId,
+      press1.time_stamp() + base::TimeDelta::FromMilliseconds(40));
+  root_window()->AsRootWindowHostDelegate()->OnHostTouchEvent(&move1);
+  EXPECT_TRUE(delegate->pinch_begin());
+  EXPECT_EQ(gfx::Rect(141, 196, 65, 10).ToString(),
+            delegate->bounding_box().ToString());
+
+  delegate->Reset();
+
+  // The position doesn't move, but the radius changes.
+  TouchEvent move2(ui::ET_TOUCH_MOVED, gfx::Point(101, 201), kTouchId,
+      press2.time_stamp() + base::TimeDelta::FromMilliseconds(40));
+  move2.set_radius_x(50);
+  move2.set_radius_y(60);
+  root_window()->AsRootWindowHostDelegate()->OnHostTouchEvent(&move2);
+  EXPECT_FALSE(delegate->tap());
+  EXPECT_FALSE(delegate->scroll_update());
+  EXPECT_FALSE(delegate->pinch_update());
+
+  delegate->Reset();
+}
+
 }  // namespace test
 }  // namespace aura

ui/base/gestures/gesture_sequence.cc

@@ -675,12 +675,12 @@ void GestureSequence::AppendScrollGestureUpdate(const GesturePoint& point,
   gfx::Point current_center = bounding_box_.CenterPoint();
   int dx = current_center.x() - bounding_box_last_center_.x();
   int dy = current_center.y() - bounding_box_last_center_.y();
-  if (dx == 0 && dy == 0)
-    return;
   if (scroll_type_ == ST_HORIZONTAL)
     dy = 0;
   else if (scroll_type_ == ST_VERTICAL)
     dx = 0;
+  if (dx == 0 && dy == 0)
+    return;
 
   gestures->push_back(CreateGestureEvent(
       GestureEventDetails(ui::ET_GESTURE_SCROLL_UPDATE, dx, dy),
@@ -908,6 +908,22 @@ bool GestureSequence::PinchUpdate(const TouchEvent& event,
     const GesturePoint& point, Gestures* gestures) {
   DCHECK(state_ == GS_PINCH);
 
+  // It is possible that the none of the touch-points changed their position,
+  // but their radii changed, and that caused the bounding box to also change.
+  // But in such cases, we do not want to either pinch or scroll.
+  // To avoid small jiggles, it is also necessary to make sure that at least one
+  // of the fingers moved enough before a pinch or scroll update is created.
+  bool did_scroll = false;
+  for (int i = 0; i < kMaxGesturePoints; ++i) {
+    if (!points_[i].in_use() || !points_[i].DidScroll(event, 2))
+      continue;
+    did_scroll = true;
+    break;
+  }
+
+  if (!did_scroll)
+    return false;
+
   float distance = BoundingBoxDiagonal(bounding_box_);
 
   if (abs(distance - pinch_distance_current_) >=