1 files changed, 156 insertions, 0 deletions
diff --git a/layout/generic/ScrollPositionUpdate.cpp b/layout/generic/ScrollPositionUpdate.cpp
new file mode 100644
index 0000000000..9607d2d18a
--- /dev/null
+++ b/layout/generic/ScrollPositionUpdate.cpp
@@ -0,0 +1,156 @@
+/* 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 "ScrollPositionUpdate.h"
+
+#include <ostream>
+
+#include "mozilla/Assertions.h"
+
+namespace mozilla {
+
+static ScrollGenerationCounter sGenerationCounter;
+
+ScrollPositionUpdate::ScrollPositionUpdate()
+    : mType(ScrollUpdateType::Absolute),
+      mScrollMode(ScrollMode::Normal),
+      mScrollOrigin(ScrollOrigin::None),
+      mTriggeredByScript(ScrollTriggeredByScript::No) {}
+
+/*static*/
+ScrollPositionUpdate ScrollPositionUpdate::NewScrollframe(
+    nsPoint aInitialPosition) {
+  ScrollPositionUpdate ret;
+  ret.mScrollGeneration = sGenerationCounter.NewMainThreadGeneration();
+  ret.mScrollMode = ScrollMode::Instant;
+  ret.mDestination = CSSPoint::FromAppUnits(aInitialPosition);
+  return ret;
+}
+
+/*static*/
+ScrollPositionUpdate ScrollPositionUpdate::NewScroll(ScrollOrigin aOrigin,
+                                                     nsPoint aDestination) {
+  MOZ_ASSERT(aOrigin != ScrollOrigin::NotSpecified);
+  MOZ_ASSERT(aOrigin != ScrollOrigin::None);
+
+  ScrollPositionUpdate ret;
+  ret.mScrollGeneration = sGenerationCounter.NewMainThreadGeneration();
+  ret.mType = ScrollUpdateType::Absolute;
+  ret.mScrollMode = ScrollMode::Instant;
+  ret.mScrollOrigin = aOrigin;
+  ret.mDestination = CSSPoint::FromAppUnits(aDestination);
+  return ret;
+}
+
+/*static*/
+ScrollPositionUpdate ScrollPositionUpdate::NewRelativeScroll(
+    nsPoint aSource, nsPoint aDestination) {
+  ScrollPositionUpdate ret;
+  ret.mScrollGeneration = sGenerationCounter.NewMainThreadGeneration();
+  ret.mType = ScrollUpdateType::Relative;
+  ret.mScrollMode = ScrollMode::Instant;
+  ret.mScrollOrigin = ScrollOrigin::Relative;
+  ret.mDestination = CSSPoint::FromAppUnits(aDestination);
+  ret.mSource = CSSPoint::FromAppUnits(aSource);
+  return ret;
+}
+
+/*static*/
+ScrollPositionUpdate ScrollPositionUpdate::NewSmoothScroll(
+    ScrollMode aMode, ScrollOrigin aOrigin, nsPoint aDestination,
+    ScrollTriggeredByScript aTriggeredByScript,
+    UniquePtr<ScrollSnapTargetIds> aSnapTargetIds) {
+  MOZ_ASSERT(aOrigin != ScrollOrigin::NotSpecified);
+  MOZ_ASSERT(aOrigin != ScrollOrigin::None);
+  MOZ_ASSERT(aMode == ScrollMode::Smooth || aMode == ScrollMode::SmoothMsd);
+
+  ScrollPositionUpdate ret;
+  ret.mScrollGeneration = sGenerationCounter.NewMainThreadGeneration();
+  ret.mType = ScrollUpdateType::Absolute;
+  ret.mScrollMode = aMode;
+  ret.mScrollOrigin = aOrigin;
+  ret.mDestination = CSSPoint::FromAppUnits(aDestination);
+  ret.mTriggeredByScript = aTriggeredByScript;
+  if (aSnapTargetIds) {
+    ret.mSnapTargetIds = *aSnapTargetIds;
+  }
+  return ret;
+}
+
+/*static*/
+ScrollPositionUpdate ScrollPositionUpdate::NewPureRelativeScroll(
+    ScrollOrigin aOrigin, ScrollMode aMode, const nsPoint& aDelta) {
+  MOZ_ASSERT(aOrigin != ScrollOrigin::NotSpecified);
+  MOZ_ASSERT(aOrigin != ScrollOrigin::None);
+
+  ScrollPositionUpdate ret;
+  ret.mScrollGeneration = sGenerationCounter.NewMainThreadGeneration();
+  ret.mType = ScrollUpdateType::PureRelative;
+  ret.mScrollMode = aMode;
+  ret.mScrollOrigin = aOrigin;
+  ret.mDelta = CSSPoint::FromAppUnits(aDelta);
+  return ret;
+}
+
+/*static*/
+ScrollPositionUpdate ScrollPositionUpdate::NewMergeableScroll(
+    ScrollOrigin aOrigin, nsPoint aDestination) {
+  MOZ_ASSERT(aOrigin == ScrollOrigin::AnchorAdjustment);
+
+  ScrollPositionUpdate ret;
+  ret.mScrollGeneration = sGenerationCounter.NewMainThreadGeneration();
+  ret.mType = ScrollUpdateType::MergeableAbsolute;
+  ret.mScrollMode = ScrollMode::Instant;
+  ret.mScrollOrigin = aOrigin;
+  ret.mDestination = CSSPoint::FromAppUnits(aDestination);
+  return ret;
+}
+
+bool ScrollPositionUpdate::operator==(
+    const ScrollPositionUpdate& aOther) const {
+  // instances are immutable, and all the fields are set when the generation
+  // is set. So if the generation matches, these instances are identical.
+  return mScrollGeneration == aOther.mScrollGeneration;
+}
+
+MainThreadScrollGeneration ScrollPositionUpdate::GetGeneration() const {
+  return mScrollGeneration;
+}
+
+ScrollUpdateType ScrollPositionUpdate::GetType() const { return mType; }
+
+ScrollMode ScrollPositionUpdate::GetMode() const { return mScrollMode; }
+
+ScrollOrigin ScrollPositionUpdate::GetOrigin() const { return mScrollOrigin; }
+
+CSSPoint ScrollPositionUpdate::GetDestination() const {
+  MOZ_ASSERT(mType == ScrollUpdateType::Absolute ||
+             mType == ScrollUpdateType::MergeableAbsolute ||
+             mType == ScrollUpdateType::Relative);
+  return mDestination;
+}
+
+CSSPoint ScrollPositionUpdate::GetSource() const {
+  MOZ_ASSERT(mType == ScrollUpdateType::Relative);
+  return mSource;
+}
+
+CSSPoint ScrollPositionUpdate::GetDelta() const {
+  MOZ_ASSERT(mType == ScrollUpdateType::PureRelative);
+  return mDelta;
+}
+
+std::ostream& operator<<(std::ostream& aStream,
+                         const ScrollPositionUpdate& aUpdate) {
+  aStream << "{ gen=" << aUpdate.mScrollGeneration
+          << ", type=" << (int)aUpdate.mType
+          << ", mode=" << (int)aUpdate.mScrollMode
+          << ", origin=" << (int)aUpdate.mScrollOrigin
+          << ", dst=" << aUpdate.mDestination << ", src=" << aUpdate.mSource
+          << ", delta=" << aUpdate.mDelta
+          << ", triggered by script=" << aUpdate.WasTriggeredByScript() << " }";
+  return aStream;
+}
+
+}  // namespace mozilla