Implement Wheel Gesture Scrolling on OSX.

ui/events/blink/input_scroll_elasticity_controller_unittest.cc

Index: ui/events/blink/input_scroll_elasticity_controller_unittest.cc
diff --git a/ui/events/blink/input_scroll_elasticity_controller_unittest.cc b/ui/events/blink/input_scroll_elasticity_controller_unittest.cc
index 82b94343f8e061a2c1f14cbdf687b9e7a1df060c..4ce7b9494ed7dee8c1255430b3f0eff45df377a7 100644
--- a/ui/events/blink/input_scroll_elasticity_controller_unittest.cc
+++ b/ui/events/blink/input_scroll_elasticity_controller_unittest.cc
@@ -99,6 +99,53 @@ class ScrollElasticityControllerTest : public testing::Test {
     input_event_count_ += 1;
   }
 
+  void SendGestureScrollBegin(bool inertial) {
+    blink::WebGestureEvent event;
+    event.sourceDevice = blink::WebGestureDeviceTouchpad;
+    event.type = blink::WebInputEvent::GestureScrollBegin;
+    event.data.scrollBegin.inertial = inertial;
+    TickCurrentTime();
+    event.timeStampSeconds = (current_time_ - base::TimeTicks()).InSecondsF();
+
+    controller_.ObserveGestureEventAndResult(event,
+                                             cc::InputHandlerScrollResult());
+    input_event_count_ += 1;
+  }
+
+  void SendGestureScrollUpdate(
+      bool inertial,
+      const gfx::Vector2dF& event_delta = gfx::Vector2dF(),
+      const gfx::Vector2dF& overscroll_delta = gfx::Vector2dF()) {
+    blink::WebGestureEvent event;
+    event.sourceDevice = blink::WebGestureDeviceTouchpad;
+    event.type = blink::WebInputEvent::GestureScrollUpdate;
+    event.data.scrollUpdate.inertial = inertial;
+    event.data.scrollUpdate.deltaX = -event_delta.x();
+    event.data.scrollUpdate.deltaY = -event_delta.y();
+    TickCurrentTime();
+    event.timeStampSeconds = (current_time_ - base::TimeTicks()).InSecondsF();
+
+    cc::InputHandlerScrollResult scroll_result;
+    scroll_result.did_overscroll_root = !overscroll_delta.IsZero();
+    scroll_result.unused_scroll_delta = overscroll_delta;
+
+    controller_.ObserveGestureEventAndResult(event, scroll_result);
+    input_event_count_ += 1;
+  }
+
+  void SendGestureScrollEnd() {
+    blink::WebGestureEvent event;
+    event.sourceDevice = blink::WebGestureDeviceTouchpad;
+    event.type = blink::WebInputEvent::GestureScrollEnd;
+
+    TickCurrentTime();
+    event.timeStampSeconds = (current_time_ - base::TimeTicks()).InSecondsF();
+
+    controller_.ObserveGestureEventAndResult(event,
+                                             cc::InputHandlerScrollResult());
+    input_event_count_ += 1;
+  }
+
   const base::TimeTicks& TickCurrentTime() {
     current_time_ += base::TimeDelta::FromSecondsD(1 / 60.f);
     return current_time_;
@@ -148,6 +195,40 @@ TEST_F(ScrollElasticityControllerTest, Axis) {
   EXPECT_EQ(0, helper_.request_begin_frame_count());
 }
 
+// Verify that stretching only occurs in one axis at a time, and that it
+// is biased to the Y axis.
+TEST_F(ScrollElasticityControllerTest, GestureBased_Axis) {
+  helper_.SetScrollOffsetAndMaxScrollOffset(gfx::ScrollOffset(0, 0),
+                                            gfx::ScrollOffset(0, 0));
+
+  // If we push equally in the X and Y directions, we should see a stretch only
+  // in the Y direction.
+  SendGestureScrollBegin(false);
+  SendGestureScrollUpdate(false, gfx::Vector2dF(10, 10),
+                          gfx::Vector2dF(10, 10));
+  EXPECT_EQ(1, helper_.set_stretch_amount_count());
+  EXPECT_EQ(0.f, helper_.StretchAmount().x());
+  EXPECT_LT(0.f, helper_.StretchAmount().y());
+  helper_.SetStretchAmount(gfx::Vector2dF());
+  EXPECT_EQ(2, helper_.set_stretch_amount_count());
+  SendGestureScrollEnd();
+  EXPECT_EQ(0, helper_.request_begin_frame_count());
+
+  // If we push more in the X direction than the Y direction, we should see a
+  // stretch only in the X direction. This decision should be based on the
+  // input delta, not the actual overscroll delta.
+  SendGestureScrollBegin(false);
+  SendGestureScrollUpdate(false, gfx::Vector2dF(-25, 10),
+                          gfx::Vector2dF(-25, 40));
+  EXPECT_EQ(3, helper_.set_stretch_amount_count());
+  EXPECT_GT(0.f, helper_.StretchAmount().x());
+  EXPECT_EQ(0.f, helper_.StretchAmount().y());
+  helper_.SetStretchAmount(gfx::Vector2dF());
+  EXPECT_EQ(4, helper_.set_stretch_amount_count());
+  SendGestureScrollEnd();
+  EXPECT_EQ(0, helper_.request_begin_frame_count());
+}
+
 // Verify that we need a total overscroll delta of at least 10 in a pinned
 // direction before we start stretching.
 TEST_F(ScrollElasticityControllerTest, MinimumDeltaBeforeStretch) {
@@ -201,7 +282,54 @@ TEST_F(ScrollElasticityControllerTest, MinimumDeltaBeforeStretch) {
   EXPECT_EQ(1, helper_.request_begin_frame_count());
 }
 
-// Verify that an stretch caused by a momentum scroll will switch to the
+// Verify that we need a total overscroll delta of at least 10 in a pinned
+// direction before we start stretching.
+TEST_F(ScrollElasticityControllerTest, GestureBased_MinimumDeltaBeforeStretch) {
+  // We should not start stretching while we are not pinned in the direction
+  // of the scroll (even if there is an overscroll delta). We have to wait for
+  // the regular scroll to eat all of the events.
+  helper_.SetScrollOffsetAndMaxScrollOffset(gfx::ScrollOffset(5, 5),
+                                            gfx::ScrollOffset(10, 10));
+  SendGestureScrollBegin(false);
+  SendGestureScrollUpdate(false, gfx::Vector2dF(0, 10), gfx::Vector2dF(0, 10));
+  SendGestureScrollUpdate(false, gfx::Vector2dF(0, 10), gfx::Vector2dF(0, 10));
+  EXPECT_EQ(0, helper_.set_stretch_amount_count());
+
+  // Now pin the -X and +Y direction. The first event will not generate a
+  // stretch
+  // because it is below the delta threshold of 10.
+  helper_.SetScrollOffsetAndMaxScrollOffset(gfx::ScrollOffset(0, 10),
+                                            gfx::ScrollOffset(10, 10));
+  SendGestureScrollUpdate(false, gfx::Vector2dF(0, 10), gfx::Vector2dF(0, 8));
+  EXPECT_EQ(0, helper_.set_stretch_amount_count());
+
+  // Make the next scroll be in the -X direction more than the +Y direction,
+  // which will erase the memory of the previous unused delta of 8.
+  SendGestureScrollUpdate(false, gfx::Vector2dF(-10, 5),
+                          gfx::Vector2dF(-8, 10));
+  EXPECT_EQ(0, helper_.set_stretch_amount_count());
+
+  // Now push against the pinned +Y direction again by 8. We reset the
+  // previous delta, so this will not generate a stretch.
+  SendGestureScrollUpdate(false, gfx::Vector2dF(0, 10), gfx::Vector2dF(0, 8));
+  EXPECT_EQ(0, helper_.set_stretch_amount_count());
+
+  // Push against +Y by another 8. This gets us above the delta threshold of
+  // 10, so we should now have had the stretch set, and it should be in the
+  // +Y direction. The scroll in the -X direction should have been forgotten.
+  SendGestureScrollUpdate(false, gfx::Vector2dF(0, 10), gfx::Vector2dF(0, 8));
+  EXPECT_EQ(1, helper_.set_stretch_amount_count());
+  EXPECT_EQ(0.f, helper_.StretchAmount().x());
+  EXPECT_LT(0.f, helper_.StretchAmount().y());
+
+  // End the gesture. Because there is a non-zero stretch, we should be in the
+  // animated state, and should have had a frame requested.
+  EXPECT_EQ(0, helper_.request_begin_frame_count());
+  SendGestureScrollEnd();
+  EXPECT_EQ(1, helper_.request_begin_frame_count());
+}
+
+// Verify that a stretch caused by a momentum scroll will switch to the
 // animating mode, where input events are ignored, and the stretch is updated
 // while animating.
 TEST_F(ScrollElasticityControllerTest, MomentumAnimate) {
@@ -297,7 +425,93 @@ TEST_F(ScrollElasticityControllerTest, MomentumAnimate) {
   EXPECT_EQ(begin_frame_count, helper_.request_begin_frame_count());
 }
 
-// Verify that an stretch opposing a scroll is correctly resolved.
+// Verify that a stretch caused by a momentum scroll will switch to the
+// animating mode, where input events are ignored, and the stretch is updated
+// while animating.
+TEST_F(ScrollElasticityControllerTest, GestureBased_MomentumAnimate) {
+  // Do an active scroll, then switch to the momentum phase and scroll for a
+  // bit.
+  helper_.SetScrollOffsetAndMaxScrollOffset(gfx::ScrollOffset(5, 5),
+                                            gfx::ScrollOffset(10, 10));
+  SendGestureScrollBegin(false);
+  SendGestureScrollUpdate(false, gfx::Vector2dF(0, -80), gfx::Vector2dF(0, 0));
+  SendGestureScrollUpdate(false, gfx::Vector2dF(0, -80), gfx::Vector2dF(0, 0));
+  SendGestureScrollUpdate(false, gfx::Vector2dF(0, -80), gfx::Vector2dF(0, 0));
+  SendGestureScrollEnd();
+  SendGestureScrollBegin(true);
+  SendGestureScrollUpdate(true, gfx::Vector2dF(0, -80), gfx::Vector2dF(0, 0));
+  SendGestureScrollUpdate(true, gfx::Vector2dF(0, -80), gfx::Vector2dF(0, 0));
+  SendGestureScrollUpdate(true, gfx::Vector2dF(0, -80), gfx::Vector2dF(0, 0));
+  EXPECT_EQ(0, helper_.set_stretch_amount_count());
+
+  // Hit the -Y edge and overscroll slightly, but not enough to go over the
+  // threshold to cause a stretch.
+  helper_.SetScrollOffsetAndMaxScrollOffset(gfx::ScrollOffset(5, 0),
+                                            gfx::ScrollOffset(10, 10));
+  SendGestureScrollUpdate(true, gfx::Vector2dF(0, -80), gfx::Vector2dF(0, -8));
+  EXPECT_EQ(0, helper_.set_stretch_amount_count());
+  EXPECT_EQ(0, helper_.request_begin_frame_count());
+
+  // Take another step, this time going over the threshold. This should update
+  // the stretch amount, and then switch to the animating mode.
+  SendGestureScrollUpdate(true, gfx::Vector2dF(0, -80), gfx::Vector2dF(0, -80));
+  EXPECT_EQ(1, helper_.set_stretch_amount_count());
+  EXPECT_EQ(1, helper_.request_begin_frame_count());
+  EXPECT_GT(-1.f, helper_.StretchAmount().y());
+
+  // Subsequent momentum events should do nothing.
+  SendGestureScrollUpdate(true, gfx::Vector2dF(0, -80), gfx::Vector2dF(0, -80));
+  SendGestureScrollUpdate(true, gfx::Vector2dF(0, -80), gfx::Vector2dF(0, -80));
+  SendGestureScrollUpdate(true, gfx::Vector2dF(0, -80), gfx::Vector2dF(0, -80));
+  SendGestureScrollEnd();
+  EXPECT_EQ(1, helper_.set_stretch_amount_count());
+  EXPECT_EQ(1, helper_.request_begin_frame_count());
+
+  // Subsequent animate events should update the stretch amount and request
+  // another frame.
+  TickCurrentTimeAndAnimate();
+  EXPECT_EQ(2, helper_.set_stretch_amount_count());
+  EXPECT_EQ(2, helper_.request_begin_frame_count());
+  EXPECT_GT(-1.f, helper_.StretchAmount().y());
+
+  // Touching the trackpad (a PhaseMayBegin event) should disable animation.
+  SendGestureScrollBegin(false);
+  TickCurrentTimeAndAnimate();
+  EXPECT_EQ(2, helper_.set_stretch_amount_count());
+  EXPECT_EQ(2, helper_.request_begin_frame_count());
+
+  // Releasing the trackpad should re-enable animation.
+  SendGestureScrollEnd();
+  EXPECT_EQ(2, helper_.set_stretch_amount_count());
+  EXPECT_EQ(3, helper_.request_begin_frame_count());
+  TickCurrentTimeAndAnimate();
+  EXPECT_EQ(3, helper_.set_stretch_amount_count());
+  EXPECT_EQ(4, helper_.request_begin_frame_count());
+
+  // Keep animating frames until the stretch returns to rest.
+  int stretch_count = 3;
+  int begin_frame_count = 4;
+  while (1) {
+    TickCurrentTimeAndAnimate();
+    if (helper_.StretchAmount().IsZero()) {
+      stretch_count += 1;
+      EXPECT_EQ(stretch_count, helper_.set_stretch_amount_count());
+      EXPECT_EQ(begin_frame_count, helper_.request_begin_frame_count());
+      break;
+    }
+    stretch_count += 1;
+    begin_frame_count += 1;
+    EXPECT_EQ(stretch_count, helper_.set_stretch_amount_count());
+    EXPECT_EQ(begin_frame_count, helper_.request_begin_frame_count());
+  }
+
+  // After coming to rest, no subsequent animate calls change anything.
+  TickCurrentTimeAndAnimate();
+  EXPECT_EQ(stretch_count, helper_.set_stretch_amount_count());
+  EXPECT_EQ(begin_frame_count, helper_.request_begin_frame_count());
+}
+
+// Verify that a stretch opposing a scroll is correctly resolved.
 TEST_F(ScrollElasticityControllerTest, ReconcileStretchAndScroll) {
   SendMouseWheelEvent(PhaseBegan, PhaseNone);
 
@@ -334,14 +548,50 @@ TEST_F(ScrollElasticityControllerTest, ReconcileStretchAndScroll) {
   EXPECT_EQ(helper_.ScrollOffset(), gfx::ScrollOffset(7, 8));
 }
 
+// Verify that a stretch opposing a scroll is correctly resolved.
+TEST_F(ScrollElasticityControllerTest, GestureBased_ReconcileStretchAndScroll) {
+  SendGestureScrollBegin(false);
+
+  // Verify completely knocking out the scroll in the -Y direction.
+  helper_.SetScrollOffsetAndMaxScrollOffset(gfx::ScrollOffset(5, 5),
+                                            gfx::ScrollOffset(10, 10));
+  helper_.SetStretchAmount(gfx::Vector2dF(0, -10));
+  controller_.ReconcileStretchAndScroll();
+  EXPECT_EQ(helper_.StretchAmount(), gfx::Vector2dF(0, -5));
+  EXPECT_EQ(helper_.ScrollOffset(), gfx::ScrollOffset(5, 0));
+
+  // Verify partially knocking out the scroll in the -Y direction.
+  helper_.SetScrollOffsetAndMaxScrollOffset(gfx::ScrollOffset(5, 8),
+                                            gfx::ScrollOffset(10, 10));
+  helper_.SetStretchAmount(gfx::Vector2dF(0, -5));
+  controller_.ReconcileStretchAndScroll();
+  EXPECT_EQ(helper_.StretchAmount(), gfx::Vector2dF(0, 0));
+  EXPECT_EQ(helper_.ScrollOffset(), gfx::ScrollOffset(5, 3));
+
+  // Verify completely knocking out the scroll in the +X direction.
+  helper_.SetScrollOffsetAndMaxScrollOffset(gfx::ScrollOffset(5, 5),
+                                            gfx::ScrollOffset(10, 10));
+  helper_.SetStretchAmount(gfx::Vector2dF(10, 0));
+  controller_.ReconcileStretchAndScroll();
+  EXPECT_EQ(helper_.StretchAmount(), gfx::Vector2dF(5, 0));
+  EXPECT_EQ(helper_.ScrollOffset(), gfx::ScrollOffset(10, 5));
+
+  // Verify partially knocking out the scroll in the +X and +Y directions.
+  helper_.SetScrollOffsetAndMaxScrollOffset(gfx::ScrollOffset(2, 3),
+                                            gfx::ScrollOffset(10, 10));
+  helper_.SetStretchAmount(gfx::Vector2dF(5, 5));
+  controller_.ReconcileStretchAndScroll();
+  EXPECT_EQ(helper_.StretchAmount(), gfx::Vector2dF(0, 0));
+  EXPECT_EQ(helper_.ScrollOffset(), gfx::ScrollOffset(7, 8));
+}
+
 // Verify that stretching only happens when the area is user scrollable.
 TEST_F(ScrollElasticityControllerTest, UserScrollableRequiredForStretch) {
   helper_.SetScrollOffsetAndMaxScrollOffset(gfx::ScrollOffset(0, 0),
                                             gfx::ScrollOffset(10, 10));
   gfx::Vector2dF delta(0, -15);
 
-  // Do an active scroll, and ensure that the stretch amount doesn't change,
-  // and also that the stretch amount isn't even ever changed.
+  // Do an active scroll, and ensure that the stretch amount doesn't change.
   helper_.SetUserScrollable(false);
   SendMouseWheelEvent(PhaseBegan, PhaseNone);
   SendMouseWheelEvent(PhaseChanged, PhaseNone, delta, delta);
@@ -384,5 +634,55 @@ TEST_F(ScrollElasticityControllerTest, UserScrollableRequiredForStretch) {
   EXPECT_GT(ticks_to_zero, 3);
 }
 
+// Verify that stretching only happens when the area is user scrollable.
+TEST_F(ScrollElasticityControllerTest,
+       GestureBased_UserScrollableRequiredForStretch) {
+  helper_.SetScrollOffsetAndMaxScrollOffset(gfx::ScrollOffset(0, 0),
+                                            gfx::ScrollOffset(10, 10));
+  gfx::Vector2dF delta(0, -15);
+
+  // Do an active scroll, and ensure that the stretch amount doesn't change.
+  helper_.SetUserScrollable(false);
+  SendGestureScrollBegin(false);
+  SendGestureScrollUpdate(false, delta, delta);
+  SendGestureScrollUpdate(false, delta, delta);
+  SendGestureScrollEnd();
+  EXPECT_EQ(helper_.StretchAmount(), gfx::Vector2dF(0, 0));
+  EXPECT_EQ(0, helper_.set_stretch_amount_count());
+  SendGestureScrollBegin(true);
+  SendGestureScrollUpdate(true, delta, delta);
+  SendGestureScrollUpdate(true, delta, delta);
+  SendGestureScrollEnd();
+  EXPECT_EQ(helper_.StretchAmount(), gfx::Vector2dF(0, 0));
+  EXPECT_EQ(0, helper_.set_stretch_amount_count());
+
+  // Re-enable user scrolling and ensure that stretching is re-enabled.
+  helper_.SetUserScrollable(true);
+  SendGestureScrollBegin(false);
+  SendGestureScrollUpdate(false, delta, delta);
+  SendGestureScrollUpdate(false, delta, delta);
+  SendGestureScrollEnd();
+  EXPECT_NE(helper_.StretchAmount(), gfx::Vector2dF(0, 0));
+  EXPECT_GT(helper_.set_stretch_amount_count(), 0);
+  SendGestureScrollBegin(true);
+  SendGestureScrollUpdate(true, delta, delta);
+  SendGestureScrollUpdate(true, delta, delta);
+  SendGestureScrollEnd();
+  EXPECT_NE(helper_.StretchAmount(), gfx::Vector2dF(0, 0));
+  EXPECT_GT(helper_.set_stretch_amount_count(), 0);
+
+  // Disable user scrolling and tick the timer until the stretch goes back
+  // to zero. Ensure that the return to zero doesn't happen immediately.
+  helper_.SetUserScrollable(false);
+  int ticks_to_zero = 0;
+  while (1) {
+    TickCurrentTimeAndAnimate();
+    if (helper_.StretchAmount().IsZero())
+      break;
+    ticks_to_zero += 1;
+  }
+  EXPECT_GT(ticks_to_zero, 3);
+}
+
 }  // namespace
 }  // namespace ui