Bug 1224015 - Part 1: nsLayoutUtils functions do not account for nsPresShell resolution r=tnikkel

dom/base/nsContentUtils.cpp

@@ -7659,7 +7659,7 @@ nsContentUtils::ToWidgetPoint(const CSSPoint& aPoint,
                               nsPresContext* aPresContext)
 {
   return LayoutDeviceIntPoint::FromAppUnitsRounded(
-    CSSPoint::ToAppUnits(aPoint) + aOffset,
+    (CSSPoint::ToAppUnits(aPoint) + aOffset).ApplyResolution(aPresContext->PresShell()->GetCumulativeScaleResolution()),
     aPresContext->AppUnitsPerDevPixel());
 }
 

dom/events/Event.cpp

@@ -935,6 +935,10 @@ Event::GetScreenCoords(nsPresContext* aPresContext,
   nsPoint pt =
     LayoutDevicePixel::ToAppUnits(aPoint, aPresContext->DeviceContext()->AppUnitsPerDevPixelAtUnitFullZoom());
 
+  if (aPresContext->PresShell()) {
+    pt = pt.RemoveResolution(aPresContext->PresShell()->GetCumulativeScaleResolution());
+  }
+
   pt += LayoutDevicePixel::ToAppUnits(guiEvent->widget->WidgetToScreenOffset(),
                                       aPresContext->DeviceContext()->AppUnitsPerDevPixelAtUnitFullZoom());
 

gfx/layers/apz/util/APZCCallbackHelper.cpp

@@ -422,21 +422,7 @@ APZCCallbackHelper::ApplyCallbackTransform(const CSSPoint& aInput,
     if (aGuid.mScrollId == FrameMetrics::NULL_SCROLL_ID) {
         return input;
     }
-    nsCOMPtr<nsIContent> content = nsLayoutUtils::FindContentFor(aGuid.mScrollId);
-    if (!content) {
-        return input;
-    }
-
-    // First, scale inversely by the root content document's pres shell
-    // resolution to cancel the scale-to-resolution transform that the
-    // compositor adds to the layer with the pres shell resolution. The points
-    // sent to Gecko by APZ don't have this transform unapplied (unlike other
-    // compositor-side transforms) because APZ doesn't know about it.
-    if (nsIPresShell* shell = GetRootContentDocumentPresShellForContent(content)) {
-        input = input / shell->GetResolution();
-    }
-
-    // Now apply the callback-transform.
+    // Apply the callback-transform.
     // XXX: technically we need to walk all the way up the layer tree from the layer
     // represented by |aGuid.mScrollId| up to the root of the layer tree and apply
     // the input transforms at each level in turn. However, it is quite difficult
@@ -447,9 +433,19 @@ APZCCallbackHelper::ApplyCallbackTransform(const CSSPoint& aInput,
     // some things transformed improperly. In practice we should rarely hit scenarios
     // where any of this matters, so I'm skipping it for now and just doing the single
     // transform for the layer that the input hit.
-    void* property = content->GetProperty(nsGkAtoms::apzCallbackTransform);
-    if (property) {
-        CSSPoint delta = (*static_cast<CSSPoint*>(property));
+    nsCOMPtr<nsIContent> content = nsLayoutUtils::FindContentFor(aGuid.mScrollId);
+    if (content) {
+        void* property = content->GetProperty(nsGkAtoms::apzCallbackTransform);
+        CSSPoint delta = property ? (*static_cast<CSSPoint*>(property)) : CSSPoint(0.0f, 0.0f);
+        // The delta is in root content document coordinate space while the
+        // aInput point is in root document coordinate space so convert the
+        // delta to root document space before adding it to the aInput point.
+        float resolution = 1.0f;
+        if (nsIPresShell* shell = GetRootContentDocumentPresShellForContent(content)) {
+            resolution = shell->GetResolution();
+        }
+        delta.x = delta.x * resolution;
+        delta.y = delta.y * resolution;
         input += delta;
     }
     return input;

gfx/layers/apz/util/ChromeProcessController.cpp

@@ -147,6 +147,14 @@ ChromeProcessController::HandleDoubleTap(const mozilla::CSSPoint& aPoint,
   }
 
   CSSPoint point = APZCCallbackHelper::ApplyCallbackTransform(aPoint, aGuid);
+  // CalculateRectToZoomTo performs a hit test on the frame associated with the
+  // Root Content Document. Unfortunately that frame does not know about the
+  // resolution of the document and so we must remove it before calculating
+  // the zoomToRect.
+  nsIPresShell* presShell = document->GetShell();
+  const float resolution = presShell->ScaleToResolution() ? presShell->GetResolution () : 1.0f;
+  point.x = point.x / resolution;
+  point.y = point.y / resolution;
   CSSRect zoomToRect = CalculateRectToZoomTo(document, point);
 
   uint32_t presShellId;

gfx/src/nsPoint.h

@@ -37,6 +37,11 @@ struct nsPoint : public mozilla::gfx::BasePoint<nscoord, nsPoint> {
    */
   MOZ_WARN_UNUSED_RESULT inline nsPoint
     ScaleToOtherAppUnits(int32_t aFromAPP, int32_t aToAPP) const;
+
+  MOZ_WARN_UNUSED_RESULT inline nsPoint
+    RemoveResolution(const float resolution) const;
+  MOZ_WARN_UNUSED_RESULT inline nsPoint
+    ApplyResolution(const float resolution) const;
 };
 
 inline nsPoint ToAppUnits(const nsIntPoint& aPoint, nscoord aAppUnitsPerPixel);
@@ -68,6 +73,28 @@ nsPoint::ScaleToOtherAppUnits(int32_t aFromAPP, int32_t aToAPP) const
   return *this;
 }
 
+inline nsPoint
+nsPoint::RemoveResolution(const float resolution) const {
+  if (resolution != 1.0f) {
+    nsPoint point;
+    point.x = NSToCoordRound(NSCoordToFloat(x) / resolution);
+    point.y = NSToCoordRound(NSCoordToFloat(y) / resolution);
+    return point;
+  }
+  return *this;
+}
+
+inline nsPoint
+nsPoint::ApplyResolution(const float resolution) const {
+  if (resolution != 1.0f) {
+    nsPoint point;
+    point.x = NSToCoordRound(NSCoordToFloat(x) * resolution);
+    point.y = NSToCoordRound(NSCoordToFloat(y) * resolution);
+    return point;
+  }
+  return *this;
+}
+
 // app units are integer multiples of pixels, so no rounding needed
 inline nsPoint
 ToAppUnits(const nsIntPoint& aPoint, nscoord aAppUnitsPerPixel)

layout/base/nsIPresShell.h

@@ -140,10 +140,10 @@ typedef struct CapturingContentInfo {
   mozilla::StaticRefPtr<nsIContent> mContent;
 } CapturingContentInfo;
 
-// 327d78a0-0680-4709-b209-1cf9578720e6
+// 5023beaa-0e54-4fc7-b9dc-0344dc4fb8be
 #define NS_IPRESSHELL_IID \
-{ 0x327d78a0, 0x0680, 0x4709, \
-  { 0xb2, 0x09, 0x1c, 0xf9, 0x57, 0x87, 0x20, 0xe6 } }
+{ 0x5023beaa, 0x0e54, 0x4fc7, \
+  { 0xb9, 0xdc, 0x03, 0x44, 0xdc, 0x4f, 0xb8, 0xbe } }
 
 // debug VerifyReflow flags
 #define VERIFY_REFLOW_ON                    0x01
@@ -1416,6 +1416,7 @@ public:
   virtual nsresult SetResolution(float aResolution) = 0;
   float GetResolution() { return mResolution.valueOr(1.0); }
   virtual float GetCumulativeResolution() = 0;
+  virtual float GetCumulativeScaleResolution() = 0;
 
   /**
    * Was the current resolution set by the user or just default initialized?

layout/base/nsLayoutUtils.cpp

@@ -2111,7 +2111,9 @@ nsLayoutUtils::GetEventCoordinatesRelativeTo(nsIWidget* aWidget,
       nsPresContext* presContext = aFrame->PresContext();
       nsPoint pt(presContext->DevPixelsToAppUnits(aPoint.x),
                  presContext->DevPixelsToAppUnits(aPoint.y));
-      return pt - view->ViewToWidgetOffset();
+      pt = pt - view->ViewToWidgetOffset();
+      pt = pt.RemoveResolution(presContext->PresShell()->GetCumulativeScaleResolution());
+      return pt;
     }
   }
 
@@ -2146,6 +2148,10 @@ nsLayoutUtils::GetEventCoordinatesRelativeTo(nsIWidget* aWidget,
   int32_t rootAPD = rootFrame->PresContext()->AppUnitsPerDevPixel();
   int32_t localAPD = aFrame->PresContext()->AppUnitsPerDevPixel();
   widgetToView = widgetToView.ScaleToOtherAppUnits(rootAPD, localAPD);
+  nsIPresShell* shell = aFrame->PresContext()->PresShell();
+
+  // XXX Bug 1224748 - Update nsLayoutUtils functions to correctly handle nsPresShell resolution
+  widgetToView = widgetToView.RemoveResolution(shell->GetCumulativeScaleResolution());
 
   /* If we encountered a transform, we can't do simple arithmetic to figure
    * out how to convert back to aFrame's coordinates and must use the CTM.
@@ -2893,8 +2899,9 @@ nsLayoutUtils::TranslateViewToWidget(nsPresContext* aPresContext,
     return LayoutDeviceIntPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
   }
 
-  LayoutDeviceIntPoint relativeToViewWidget(aPresContext->AppUnitsToDevPixels(aPt.x + viewOffset.x),
-                                            aPresContext->AppUnitsToDevPixels(aPt.y + viewOffset.y));
+  nsPoint pt = (aPt + viewOffset).ApplyResolution(aPresContext->PresShell()->GetCumulativeScaleResolution());
+  LayoutDeviceIntPoint relativeToViewWidget(aPresContext->AppUnitsToDevPixels(pt.x),
+                                            aPresContext->AppUnitsToDevPixels(pt.y));
   return relativeToViewWidget + WidgetToWidgetOffset(viewWidget, aWidget);
 }
 

layout/base/nsPresShell.cpp

@@ -5351,6 +5351,22 @@ float PresShell::GetCumulativeResolution()
   return resolution;
 }
 
+float PresShell::GetCumulativeScaleResolution()
+{
+  float resolution = 1.0;
+  nsIPresShell* currentShell = this;
+  while (currentShell) {
+    resolution *=  currentShell->ScaleToResolution() ? currentShell->GetResolution() : 1.0f;
+    nsPresContext* parentCtx = currentShell->GetPresContext()->GetParentPresContext();
+    if (parentCtx) {
+      currentShell = parentCtx->PresShell();
+    } else {
+      currentShell = nullptr;
+    }
+  }
+  return resolution;
+}
+
 void PresShell::SetRenderingState(const RenderingState& aState)
 {
   if (mRenderFlags != aState.mRenderFlags) {
@@ -7097,8 +7113,9 @@ PresShell::HandleEvent(nsIFrame* aFrame,
       // document that is being captured.
       retargetEventDoc = capturingContent->GetCrossShadowCurrentDoc();
 #ifdef ANDROID
-    } else if (aEvent->mClass == eTouchEventClass ||
-              (aEvent->AsMouseEvent() && aEvent->AsMouseEvent()->inputSource == nsIDOMMouseEvent::MOZ_SOURCE_TOUCH)) {
+    } else if ((aEvent->mClass == eTouchEventClass) ||
+               (aEvent->mClass == eMouseEventClass) ||
+               (aEvent->mClass == eWheelEventClass)) {
       retargetEventDoc = GetTouchEventTargetDocument();
 #endif
     }

layout/base/nsPresShell.h

@@ -218,6 +218,7 @@ public:
   }
   virtual bool ScaleToResolution() const override;
   virtual float GetCumulativeResolution() override;
+  virtual float GetCumulativeScaleResolution() override;
 
   //nsIViewObserver interface