1 files changed, 88 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..7ed1992037
--- /dev/null
+++ b/gfx/layers/apz/test/gtest/TestSnappingOnMomentum.cpp
@@ -0,0 +1,88 @@
+/* -*- 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 APZCSnappingOnMomentumTester : public APZCTreeManagerTester {};
+
+TEST_F(APZCSnappingOnMomentumTester, Snap_On_Momentum) {
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
+
+  const char* layerTreeSyntax = "c";
+  nsIntRegion layerVisibleRegion[] = {
+      nsIntRegion(IntRect(0, 0, 100, 100)),
+  };
+  root =
+      CreateLayerTree(layerTreeSyntax, layerVisibleRegion, nullptr, lm, layers);
+  SetScrollableFrameMetrics(root, ScrollableLayerGuid::START_SCROLL_ID,
+                            CSSRect(0, 0, 100, 500));
+
+  // Set up some basic scroll snapping
+  ScrollSnapInfo snap;
+  snap.mScrollSnapStrictnessY = StyleScrollSnapStrictness::Mandatory;
+
+  snap.mSnapPositionY.AppendElement(0 * AppUnitsPerCSSPixel());
+  snap.mSnapPositionY.AppendElement(100 * AppUnitsPerCSSPixel());
+
+  ScrollMetadata metadata = root->GetScrollMetadata(0);
+  metadata.SetSnapInfo(ScrollSnapInfo(snap));
+  root->SetScrollMetadata(metadata);
+
+  UniquePtr<ScopedLayerTreeRegistration> registration =
+      MakeUnique<ScopedLayerTreeRegistration>(manager, LayersId{0}, root, mcc);
+  UpdateHitTestingTree();
+
+  RefPtr<TestAsyncPanZoomController> apzc = ApzcOf(root);
+
+  TimeStamp now = mcc->Time();
+
+  PanGesture(PanGestureInput::PANGESTURE_START, manager, ScreenIntPoint(50, 80),
+             ScreenPoint(0, 2), now);
+  mcc->AdvanceByMillis(5);
+  apzc->AdvanceAnimations(mcc->GetSampleTime());
+  PanGesture(PanGestureInput::PANGESTURE_PAN, manager, ScreenIntPoint(50, 80),
+             ScreenPoint(0, 25), mcc->Time());
+  mcc->AdvanceByMillis(5);
+  apzc->AdvanceAnimations(mcc->GetSampleTime());
+  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());
+  PanGesture(PanGestureInput::PANGESTURE_END, manager, ScreenIntPoint(50, 80),
+             ScreenPoint(0, 0), mcc->Time());
+
+  // After lifting the fingers, the velocity should still be positive.
+  EXPECT_GT(apzc->GetVelocityVector().y, 3.0);
+
+  mcc->AdvanceByMillis(5);
+
+  apzc->AdvanceAnimations(mcc->GetSampleTime());
+  PanGesture(PanGestureInput::PANGESTURE_MOMENTUMSTART, manager,
+             ScreenIntPoint(50, 80), ScreenPoint(0, 200), mcc->Time());
+  mcc->AdvanceByMillis(10);
+  apzc->AdvanceAnimations(mcc->GetSampleTime());
+  PanGesture(PanGestureInput::PANGESTURE_MOMENTUMPAN, manager,
+             ScreenIntPoint(50, 80), ScreenPoint(0, 50), mcc->Time());
+  mcc->AdvanceByMillis(10);
+  apzc->AdvanceAnimations(mcc->GetSampleTime());
+  PanGesture(PanGestureInput::PANGESTURE_MOMENTUMEND, manager,
+             ScreenIntPoint(50, 80), ScreenPoint(0, 0), mcc->Time());
+
+  apzc->AdvanceAnimationsUntilEnd();
+  EXPECT_EQ(
+      100.0f,
+      apzc->GetCurrentAsyncScrollOffset(
+              AsyncPanZoomController::AsyncTransformConsumer::eForHitTesting)
+          .y);
+}