Bug 1558482 - Apply visibleRect and scaling when painting. r=mattwoodrow

visibleRect should affect both WR/layers, and scaling will only affect
layers.

Differential Revision: https://phabricator.services.mozilla.com/D34525

--HG--
extra : rebase_source : 49273db3e10088c9493f693d5f8b58864dcb01aa

dom/ipc/BrowserChild.cpp

@@ -60,6 +60,7 @@
 #include "mozilla/TextEvents.h"
 #include "mozilla/TouchEvents.h"
 #include "mozilla/Unused.h"
+#include "Units.h"
 #include "nsBrowserStatusFilter.h"
 #include "nsContentUtils.h"
 #include "nsDocShell.h"
@@ -3328,6 +3329,17 @@ ScreenIntSize BrowserChild::GetInnerSize() {
       innerSize, PixelCastJustification::LayoutDeviceIsScreenForTabDims);
 };
 
+nsRect BrowserChild::GetVisibleRect() {
+  bool isForceRendering = mIsTopLevel && mRenderLayers;
+  if (isForceRendering && !mEffectsInfo.IsVisible()) {
+    // We are forced to render even though we are not visible. In this case, we
+    // don't have an accurate visible rect, so we must be conservative.
+    return nsRect(nsPoint(), CSSPixel::ToAppUnits(mUnscaledInnerSize));
+  } else {
+    return mEffectsInfo.mVisibleRect;
+  }
+}
+
 ScreenIntRect BrowserChild::GetOuterRect() {
   LayoutDeviceIntRect outerRect =
       RoundedToInt(mUnscaledOuterRect * mPuppetWidget->GetDefaultScale());

dom/ipc/BrowserChild.h

@@ -418,6 +418,8 @@ class BrowserChild final : public nsMessageManagerScriptExecutor,
 
   bool IsTransparent() const { return mIsTransparent; }
 
+  const EffectsInfo& GetEffectsInfo() const { return mEffectsInfo; }
+
   void GetMaxTouchPoints(uint32_t* aTouchPoints) {
     *aTouchPoints = mMaxTouchPoints;
   }
@@ -547,6 +549,8 @@ class BrowserChild final : public nsMessageManagerScriptExecutor,
 
   ScreenIntSize GetInnerSize();
 
+  nsRect GetVisibleRect();
+
   // Call RecvShow(nsIntSize(0, 0)) and block future calls to RecvShow().
   void DoFakeShow(const ShowInfo& aShowInfo);
 

layout/base/nsLayoutUtils.cpp

@@ -26,6 +26,7 @@
 #include "mozilla/StaticPrefs.h"
 #include "mozilla/Unused.h"
 #include "nsCharTraits.h"
+#include "mozilla/dom/BrowserChild.h"
 #include "mozilla/dom/Document.h"
 #include "mozilla/dom/DocumentInlines.h"
 #include "nsFontMetrics.h"
@@ -3786,12 +3787,20 @@ nsresult nsLayoutUtils::PaintFrame(gfxContext* aRenderingContext,
     builder->SetInActiveDocShell(isActive);
   }
 
+  nsRect rootVisualOverflow = aFrame->GetVisualOverflowRectRelativeToSelf();
+
+  // If we are in a remote browser, then apply clipping from ancestor browsers
+  if (BrowserChild* browserChild = BrowserChild::GetFrom(presShell)) {
+    rootVisualOverflow.IntersectRect(rootVisualOverflow,
+                                     browserChild->GetVisibleRect());
+  }
+
   nsIFrame* rootScrollFrame = presShell->GetRootScrollFrame();
   if (rootScrollFrame && !aFrame->GetParent()) {
     nsIScrollableFrame* rootScrollableFrame =
         presShell->GetRootScrollFrameAsScrollable();
     MOZ_ASSERT(rootScrollableFrame);
-    nsRect displayPortBase = aFrame->GetVisualOverflowRectRelativeToSelf();
+    nsRect displayPortBase = rootVisualOverflow;
     nsRect temp = displayPortBase;
     Unused << rootScrollableFrame->DecideScrollableLayer(
         builder, &displayPortBase, &temp,
@@ -3806,7 +3815,7 @@ nsresult nsLayoutUtils::PaintFrame(gfxContext* aRenderingContext,
     // |ignoreViewportScrolling| and |usingDisplayPort| are persistent
     // document-rendering state.  We rely on PresShell to flush
     // retained layers as needed when that persistent state changes.
-    visibleRegion = aFrame->GetVisualOverflowRectRelativeToSelf();
+    visibleRegion = rootVisualOverflow;
   } else {
     visibleRegion = aDirtyRegion;
   }

layout/painting/RetainedDisplayListBuilder.h

@@ -101,7 +101,8 @@ enum class PartialUpdateFailReason {
   RebuildLimit,
   FrameType,
   Disabled,
-  Content
+  Content,
+  VisibleRect,
 };
 
 struct RetainedDisplayListMetrics {
@@ -146,6 +147,8 @@ struct RetainedDisplayListMetrics {
         return "Disabled";
       case PartialUpdateFailReason::Content:
         return "Content";
+      case PartialUpdateFailReason::VisibleRect:
+        return "VisibleRect";
       default:
         MOZ_ASSERT_UNREACHABLE("Enum value not handled!");
     }
@@ -254,6 +257,7 @@ struct RetainedDisplayListBuilder {
 
   nsDisplayListBuilder mBuilder;
   RetainedDisplayList mList;
+  nsRect mPreviousVisibleRect;
   WeakFrame mPreviousCaret;
   RetainedDisplayListMetrics mMetrics;
 };

layout/painting/nsDisplayList.cpp

@@ -2882,11 +2882,19 @@ FrameLayerBuilder* nsDisplayList::BuildLayers(nsDisplayListBuilder* aBuilder,
       rootLayer->SetScrollMetadata(nsTArray<ScrollMetadata>());
     }
 
-    float rootLayerResolution = StaticPrefs::LayoutUseContainersForRootFrames()
+    float resolutionUniform = StaticPrefs::LayoutUseContainersForRootFrames()
                                   ? presShell->GetResolution()
                                   : 1.0f;
-    ContainerLayerParameters containerParameters(rootLayerResolution,
-                                                 rootLayerResolution);
+    float resolutionX = resolutionUniform;
+    float resolutionY = resolutionUniform;
+
+    // If we are in a remote browser, then apply scaling from ancestor browsers
+    if (BrowserChild* browserChild = BrowserChild::GetFrom(presShell)) {
+      resolutionX *= browserChild->GetEffectsInfo().mScaleX;
+      resolutionY *= browserChild->GetEffectsInfo().mScaleY;
+    }
+
+    ContainerLayerParameters containerParameters(resolutionX, resolutionY);
 
     {
       PaintTelemetry::AutoRecord record(PaintTelemetry::Metric::Layerization);
@@ -2906,11 +2914,10 @@ FrameLayerBuilder* nsDisplayList::BuildLayers(nsDisplayListBuilder* aBuilder,
     if (!root) {
       return nullptr;
     }
-    if (StaticPrefs::LayoutUseContainersForRootFrames()) {
     // Root is being scaled up by the X/Y resolution. Scale it back down.
-      root->SetPostScale(1.0f / containerParameters.mXScale,
-                         1.0f / containerParameters.mYScale);
-      root->SetScaleToResolution(containerParameters.mXScale);
+    root->SetPostScale(1.0f / resolutionX, 1.0f / resolutionY);
+    if (StaticPrefs::LayoutUseContainersForRootFrames()) {
+      root->SetScaleToResolution(resolutionUniform);
     }
 
     auto callback = [root](ScrollableLayerGuid::ViewID aScrollId) -> bool {