1 files changed, 102 insertions, 0 deletions
diff --git a/gfx/layers/apz/test/gtest/TestSnappingOnMomentum.cpp b/gfx/layers/apz/test/gtest/TestSnappingOnMomentum.cpp
new file mode 100644
index 0000000000..a76d1b2d60
--- /dev/null
+++ b/gfx/layers/apz/test/gtest/TestSnappingOnMomentum.cpp
@@ -0,0 +1,102 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "APZCTreeManagerTester.h"
+#include "APZTestCommon.h"
+
+#include "InputUtils.h"
+#include "mozilla/StaticPrefs_layout.h"
+
+class APZCSnappingOnMomentumTesterMock : public APZCTreeManagerTester {
+ public:
+  APZCSnappingOnMomentumTesterMock() { CreateMockHitTester(); }
+};
+
+TEST_F(APZCSnappingOnMomentumTesterMock, Snap_On_Momentum) {
+  const char* treeShape = "x";
+  LayerIntRect layerVisibleRect[] = {
+      LayerIntRect(0, 0, 100, 100),
+  };
+  CreateScrollData(treeShape, layerVisibleRect);
+  SetScrollableFrameMetrics(root, ScrollableLayerGuid::START_SCROLL_ID,
+                            CSSRect(0, 0, 100, 500));
+
+  // Set up some basic scroll snapping
+  ScrollSnapInfo snap;
+  snap.mScrollSnapStrictnessY = StyleScrollSnapStrictness::Mandatory;
+  snap.mSnapportSize =
+      CSSSize::ToAppUnits(layerVisibleRect[0].Size() * LayerToCSSScale(1.0));
+  snap.mSnapTargets.AppendElement(ScrollSnapInfo::SnapTarget(
+      Nothing(), Some(0 * AppUnitsPerCSSPixel()),
+      CSSRect::ToAppUnits(CSSRect(0, 0, 10, 10)), StyleScrollSnapStop::Normal,
+      ScrollSnapTargetId{1}));
+  snap.mSnapTargets.AppendElement(ScrollSnapInfo::SnapTarget(
+      Nothing(), Some(100 * AppUnitsPerCSSPixel()),
+      CSSRect::ToAppUnits(CSSRect(0, 100, 10, 10)), StyleScrollSnapStop::Normal,
+      ScrollSnapTargetId{2}));
+
+  ModifyFrameMetrics(root, [&](ScrollMetadata& aSm, FrameMetrics&) {
+    aSm.SetSnapInfo(ScrollSnapInfo(snap));
+  });
+
+  UniquePtr<ScopedLayerTreeRegistration> registration =
+      MakeUnique<ScopedLayerTreeRegistration>(LayersId{0}, mcc);
+  UpdateHitTestingTree();
+
+  RefPtr<TestAsyncPanZoomController> apzc = ApzcOf(root);
+
+  TimeStamp now = mcc->Time();
+
+  QueueMockHitResult(ScrollableLayerGuid::START_SCROLL_ID);
+  PanGesture(PanGestureInput::PANGESTURE_START, manager, ScreenIntPoint(50, 80),
+             ScreenPoint(0, 2), now);
+  mcc->AdvanceByMillis(5);
+  apzc->AdvanceAnimations(mcc->GetSampleTime());
+  QueueMockHitResult(ScrollableLayerGuid::START_SCROLL_ID);
+  PanGesture(PanGestureInput::PANGESTURE_PAN, manager, ScreenIntPoint(50, 80),
+             ScreenPoint(0, 25), mcc->Time());
+  mcc->AdvanceByMillis(5);
+  apzc->AdvanceAnimations(mcc->GetSampleTime());
+  QueueMockHitResult(ScrollableLayerGuid::START_SCROLL_ID);
+  PanGesture(PanGestureInput::PANGESTURE_PAN, manager, ScreenIntPoint(50, 80),
+             ScreenPoint(0, 25), mcc->Time());
+
+  // The velocity should be positive when panning with positive displacement.
+  EXPECT_GT(apzc->GetVelocityVector().y, 3.0);
+
+  mcc->AdvanceByMillis(5);
+  apzc->AdvanceAnimations(mcc->GetSampleTime());
+  QueueMockHitResult(ScrollableLayerGuid::START_SCROLL_ID);
+  PanGesture(PanGestureInput::PANGESTURE_END, manager, ScreenIntPoint(50, 80),
+             ScreenPoint(0, 0), mcc->Time());
+
+  // After lifting the fingers, the velocity should be zero and a smooth
+  // animation should have been triggered for scroll snap.
+  EXPECT_EQ(apzc->GetVelocityVector().y, 0);
+  apzc->AssertStateIsSmoothMsdScroll();
+
+  mcc->AdvanceByMillis(5);
+
+  apzc->AdvanceAnimations(mcc->GetSampleTime());
+  QueueMockHitResult(ScrollableLayerGuid::START_SCROLL_ID);
+  PanGesture(PanGestureInput::PANGESTURE_MOMENTUMSTART, manager,
+             ScreenIntPoint(50, 80), ScreenPoint(0, 200), mcc->Time());
+  mcc->AdvanceByMillis(10);
+  apzc->AdvanceAnimations(mcc->GetSampleTime());
+  QueueMockHitResult(ScrollableLayerGuid::START_SCROLL_ID);
+  PanGesture(PanGestureInput::PANGESTURE_MOMENTUMPAN, manager,
+             ScreenIntPoint(50, 80), ScreenPoint(0, 50), mcc->Time());
+  mcc->AdvanceByMillis(10);
+  apzc->AdvanceAnimations(mcc->GetSampleTime());
+  QueueMockHitResult(ScrollableLayerGuid::START_SCROLL_ID);
+  PanGesture(PanGestureInput::PANGESTURE_MOMENTUMEND, manager,
+             ScreenIntPoint(50, 80), ScreenPoint(0, 0), mcc->Time());
+
+  apzc->AdvanceAnimationsUntilEnd();
+  EXPECT_EQ(100.0f, apzc->GetCurrentAsyncScrollOffset(
+                            AsyncTransformConsumer::eForEventHandling)
+                        .y);
+}