Bug 1668913 - Audit usages of ScaleFactors2D::ToScaleFactor(). r=botond

Differential Revision: https://phabricator.services.mozilla.com/D106576

gfx/layers/apz/src/AsyncPanZoomController.cpp

@@ -1543,6 +1543,7 @@ nsEventStatus AsyncPanZoomController::OnScale(const PinchGestureInput& aEvent) {
     MOZ_ASSERT(Metrics().IsRootContent());
     MOZ_ASSERT(Metrics().GetZoom().AreScalesSame());
 
+    // TODO: Need to handle different x-and y-scales.
     CSSToParentLayerScale userZoom = Metrics().GetZoom().ToScaleFactor();
     ParentLayerPoint focusPoint =
         aEvent.mLocalFocusPoint - Metrics().GetCompositionBounds().TopLeft();
@@ -5224,6 +5225,7 @@ void AsyncPanZoomController::ZoomToRect(CSSRect aRect, const uint32_t aFlags) {
     ParentLayerRect compositionBounds = Metrics().GetCompositionBounds();
     CSSRect cssPageRect = Metrics().GetScrollableRect();
     CSSPoint scrollOffset = Metrics().GetVisualScrollOffset();
+    // TODO: Need to handle different x-and y-scales.
     CSSToParentLayerScale currentZoom = Metrics().GetZoom().ToScaleFactor();
     CSSToParentLayerScale targetZoom;
 

gfx/layers/apz/src/Axis.cpp

@@ -318,7 +318,7 @@ ParentLayerCoord Axis::DisplacementWillOverscrollAmount(
 CSSCoord Axis::ScaleWillOverscrollAmount(float aScale, CSSCoord aFocus) const {
   // Internally, do computations in ParentLayer coordinates *before* the scale
   // is applied.
-  CSSToParentLayerScale zoom = GetFrameMetrics().GetZoom().ToScaleFactor();
+  CSSToParentLayerScale zoom = GetAxisScale(GetFrameMetrics().GetZoom());
   ParentLayerCoord focus = aFocus * zoom;
   ParentLayerCoord originAfterScale = (GetOrigin() + focus) - (focus / aScale);
 
@@ -433,6 +433,11 @@ ParentLayerCoord AxisX::GetPointOffset(const ParentLayerPoint& aPoint) const {
   return aPoint.x;
 }
 
+CSSToParentLayerScale AxisX::GetAxisScale(
+    const CSSToParentLayerScale2D& aScale) const {
+  return CSSToParentLayerScale(aScale.xScale);
+}
+
 ParentLayerCoord AxisX::GetRectLength(const ParentLayerRect& aRect) const {
   return aRect.Width();
 }
@@ -475,6 +480,11 @@ ParentLayerCoord AxisY::GetPointOffset(const ParentLayerPoint& aPoint) const {
   return aPoint.y;
 }
 
+CSSToParentLayerScale AxisY::GetAxisScale(
+    const CSSToParentLayerScale2D& aScale) const {
+  return CSSToParentLayerScale(aScale.yScale);
+}
+
 ParentLayerCoord AxisY::GetRectLength(const ParentLayerRect& aRect) const {
   return aRect.Height();
 }

gfx/layers/apz/src/Axis.h

@@ -273,6 +273,8 @@ class Axis {
   bool OverscrollBehaviorAllowsHandoff() const;
   bool OverscrollBehaviorAllowsOverscrollEffect() const;
 
+  virtual CSSToParentLayerScale GetAxisScale(
+      const CSSToParentLayerScale2D& aScale) const = 0;
   virtual ParentLayerCoord GetPointOffset(
       const ParentLayerPoint& aPoint) const = 0;
   virtual ParentLayerCoord GetRectLength(
@@ -340,6 +342,8 @@ class Axis {
 class AxisX : public Axis {
  public:
   explicit AxisX(AsyncPanZoomController* mAsyncPanZoomController);
+  CSSToParentLayerScale GetAxisScale(
+      const CSSToParentLayerScale2D& aScale) const override;
   ParentLayerCoord GetPointOffset(
       const ParentLayerPoint& aPoint) const override;
   ParentLayerCoord GetRectLength(const ParentLayerRect& aRect) const override;
@@ -359,6 +363,8 @@ class AxisY : public Axis {
   explicit AxisY(AsyncPanZoomController* mAsyncPanZoomController);
   ParentLayerCoord GetPointOffset(
       const ParentLayerPoint& aPoint) const override;
+  CSSToParentLayerScale GetAxisScale(
+      const CSSToParentLayerScale2D& aScale) const override;
   ParentLayerCoord GetRectLength(const ParentLayerRect& aRect) const override;
   ParentLayerCoord GetRectOffset(const ParentLayerRect& aRect) const override;
   CSSToParentLayerScale GetScaleForAxis(

gfx/layers/ipc/UiCompositorControllerParent.cpp

@@ -217,6 +217,7 @@ void UiCompositorControllerParent::NotifyFirstPaint() {
 void UiCompositorControllerParent::NotifyUpdateScreenMetrics(
     const GeckoViewMetrics& aMetrics) {
 #if defined(MOZ_WIDGET_ANDROID)
+  // TODO: Need to handle different x-and y-scales.
   CSSToScreenScale scale = ViewTargetAs<ScreenPixel>(
       aMetrics.mZoom.ToScaleFactor(),
       PixelCastJustification::ScreenIsParentLayerForRoot);