1 files changed, 416 insertions, 0 deletions
diff --git a/layout/generic/nsViewportFrame.cpp b/layout/generic/nsViewportFrame.cpp
new file mode 100644
index 0000000000..39491a0edc
--- /dev/null
+++ b/layout/generic/nsViewportFrame.cpp
@@ -0,0 +1,416 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+/*
+ * rendering object that is the root of the frame tree, which contains
+ * the document's scrollbars and contains fixed-positioned elements
+ */
+
+#include "nsViewportFrame.h"
+#include "nsGkAtoms.h"
+#include "nsIScrollableFrame.h"
+#include "nsSubDocumentFrame.h"
+#include "nsCanvasFrame.h"
+#include "nsAbsoluteContainingBlock.h"
+#include "GeckoProfiler.h"
+#include "nsIMozBrowserFrame.h"
+
+using namespace mozilla;
+typedef nsAbsoluteContainingBlock::AbsPosReflowFlags AbsPosReflowFlags;
+
+ViewportFrame*
+NS_NewViewportFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) ViewportFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(ViewportFrame)
+NS_QUERYFRAME_HEAD(ViewportFrame)
+  NS_QUERYFRAME_ENTRY(ViewportFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsContainerFrame)
+
+void
+ViewportFrame::Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow)
+{
+  nsContainerFrame::Init(aContent, aParent, aPrevInFlow);
+
+  nsIFrame* parent = nsLayoutUtils::GetCrossDocParentFrame(this);
+  if (parent) {
+    nsFrameState state = parent->GetStateBits();
+
+    mState |= state & (NS_FRAME_IN_POPUP);
+  }
+}
+
+void
+ViewportFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists)
+{
+  PROFILER_LABEL("ViewportFrame", "BuildDisplayList",
+    js::ProfileEntry::Category::GRAPHICS);
+
+  if (nsIFrame* kid = mFrames.FirstChild()) {
+    // make the kid's BorderBackground our own. This ensures that the canvas
+    // frame's background becomes our own background and therefore appears
+    // below negative z-index elements.
+    BuildDisplayListForChild(aBuilder, kid, aDirtyRect, aLists);
+  }
+
+  nsDisplayList topLayerList;
+  BuildDisplayListForTopLayer(aBuilder, &topLayerList);
+  if (!topLayerList.IsEmpty()) {
+    // Wrap the whole top layer in a single item with maximum z-index,
+    // and append it at the very end, so that it stays at the topmost.
+    nsDisplayWrapList* wrapList =
+      new (aBuilder) nsDisplayWrapList(aBuilder, this, &topLayerList);
+    wrapList->SetOverrideZIndex(
+      std::numeric_limits<decltype(wrapList->ZIndex())>::max());
+    aLists.PositionedDescendants()->AppendNewToTop(wrapList);
+  }
+}
+
+#ifdef DEBUG
+/**
+ * Returns whether we are going to put an element in the top layer for
+ * fullscreen. This function should matches the CSS rule in ua.css.
+ */
+static bool
+ShouldInTopLayerForFullscreen(Element* aElement)
+{
+  if (!aElement->GetParent()) {
+    return false;
+  }
+  nsCOMPtr<nsIMozBrowserFrame> browserFrame = do_QueryInterface(aElement);
+  if (browserFrame && browserFrame->GetReallyIsBrowserOrApp()) {
+    return false;
+  }
+  return true;
+}
+#endif // DEBUG
+
+static void
+BuildDisplayListForTopLayerFrame(nsDisplayListBuilder* aBuilder,
+                                 nsIFrame* aFrame,
+                                 nsDisplayList* aList)
+{
+  nsRect dirty;
+  DisplayListClipState::AutoClipMultiple clipState(aBuilder);
+  nsDisplayListBuilder::OutOfFlowDisplayData*
+    savedOutOfFlowData = nsDisplayListBuilder::GetOutOfFlowData(aFrame);
+  if (savedOutOfFlowData) {
+    dirty = savedOutOfFlowData->mDirtyRect;
+    clipState.SetClipForContainingBlockDescendants(
+      &savedOutOfFlowData->mContainingBlockClip);
+    clipState.SetScrollClipForContainingBlockDescendants(
+      aBuilder, savedOutOfFlowData->mContainingBlockScrollClip);
+  }
+  nsDisplayList list;
+  aFrame->BuildDisplayListForStackingContext(aBuilder, dirty, &list);
+  aList->AppendToTop(&list);
+}
+
+void
+ViewportFrame::BuildDisplayListForTopLayer(nsDisplayListBuilder* aBuilder,
+                                           nsDisplayList* aList)
+{
+  nsIDocument* doc = PresContext()->Document();
+  nsTArray<Element*> fullscreenStack = doc->GetFullscreenStack();
+  for (Element* elem : fullscreenStack) {
+    if (nsIFrame* frame = elem->GetPrimaryFrame()) {
+      // There are two cases where an element in fullscreen is not in
+      // the top layer:
+      // 1. When building display list for purpose other than painting,
+      //    it is possible that there is inconsistency between the style
+      //    info and the content tree.
+      // 2. This is an element which we are not going to put in the top
+      //    layer for fullscreen. See ShouldInTopLayerForFullscreen().
+      // In both cases, we want to skip the frame here and paint it in
+      // the normal path.
+      if (frame->StyleDisplay()->mTopLayer == NS_STYLE_TOP_LAYER_NONE) {
+        MOZ_ASSERT(!aBuilder->IsForPainting() ||
+                   !ShouldInTopLayerForFullscreen(elem));
+        continue;
+      }
+      MOZ_ASSERT(ShouldInTopLayerForFullscreen(elem));
+      // Inner SVG, MathML elements, as well as children of some XUL
+      // elements are not allowed to be out-of-flow. They should not
+      // be handled as top layer element here.
+      if (!(frame->GetStateBits() & NS_FRAME_OUT_OF_FLOW)) {
+        MOZ_ASSERT(!elem->GetParent()->IsHTMLElement(), "HTML element "
+                   "should always be out-of-flow if in the top layer");
+        continue;
+      }
+      if (nsIFrame* backdropPh =
+          frame->GetChildList(kBackdropList).FirstChild()) {
+        MOZ_ASSERT(backdropPh->GetType() == nsGkAtoms::placeholderFrame);
+        nsIFrame* backdropFrame =
+          static_cast<nsPlaceholderFrame*>(backdropPh)->GetOutOfFlowFrame();
+        MOZ_ASSERT(backdropFrame);
+        BuildDisplayListForTopLayerFrame(aBuilder, backdropFrame, aList);
+      }
+      BuildDisplayListForTopLayerFrame(aBuilder, frame, aList);
+    }
+  }
+
+  nsIPresShell* shell = PresContext()->PresShell();
+  if (nsCanvasFrame* canvasFrame = shell->GetCanvasFrame()) {
+    if (Element* container = canvasFrame->GetCustomContentContainer()) {
+      if (nsIFrame* frame = container->GetPrimaryFrame()) {
+        BuildDisplayListForTopLayerFrame(aBuilder, frame, aList);
+      }
+    }
+  }
+}
+
+#ifdef DEBUG
+void
+ViewportFrame::AppendFrames(ChildListID     aListID,
+                            nsFrameList&    aFrameList)
+{
+  NS_ASSERTION(aListID == kPrincipalList, "unexpected child list");
+  NS_ASSERTION(GetChildList(aListID).IsEmpty(), "Shouldn't have any kids!");
+  nsContainerFrame::AppendFrames(aListID, aFrameList);
+}
+
+void
+ViewportFrame::InsertFrames(ChildListID     aListID,
+                            nsIFrame*       aPrevFrame,
+                            nsFrameList&    aFrameList)
+{
+  NS_ASSERTION(aListID == kPrincipalList, "unexpected child list");
+  NS_ASSERTION(GetChildList(aListID).IsEmpty(), "Shouldn't have any kids!");
+  nsContainerFrame::InsertFrames(aListID, aPrevFrame, aFrameList);
+}
+
+void
+ViewportFrame::RemoveFrame(ChildListID     aListID,
+                           nsIFrame*       aOldFrame)
+{
+  NS_ASSERTION(aListID == kPrincipalList, "unexpected child list");
+  nsContainerFrame::RemoveFrame(aListID, aOldFrame);
+}
+#endif
+
+/* virtual */ nscoord
+ViewportFrame::GetMinISize(nsRenderingContext *aRenderingContext)
+{
+  nscoord result;
+  DISPLAY_MIN_WIDTH(this, result);
+  if (mFrames.IsEmpty())
+    result = 0;
+  else
+    result = mFrames.FirstChild()->GetMinISize(aRenderingContext);
+
+  return result;
+}
+
+/* virtual */ nscoord
+ViewportFrame::GetPrefISize(nsRenderingContext *aRenderingContext)
+{
+  nscoord result;
+  DISPLAY_PREF_WIDTH(this, result);
+  if (mFrames.IsEmpty())
+    result = 0;
+  else
+    result = mFrames.FirstChild()->GetPrefISize(aRenderingContext);
+
+  return result;
+}
+
+nsPoint
+ViewportFrame::AdjustReflowInputForScrollbars(ReflowInput* aReflowInput) const
+{
+  // Get our prinicpal child frame and see if we're scrollable
+  nsIFrame* kidFrame = mFrames.FirstChild();
+  nsIScrollableFrame* scrollingFrame = do_QueryFrame(kidFrame);
+
+  if (scrollingFrame) {
+    WritingMode wm = aReflowInput->GetWritingMode();
+    LogicalMargin scrollbars(wm, scrollingFrame->GetActualScrollbarSizes());
+    aReflowInput->SetComputedISize(aReflowInput->ComputedISize() -
+                                   scrollbars.IStartEnd(wm));
+    aReflowInput->AvailableISize() -= scrollbars.IStartEnd(wm);
+    aReflowInput->SetComputedBSizeWithoutResettingResizeFlags(
+      aReflowInput->ComputedBSize() - scrollbars.BStartEnd(wm));
+    return nsPoint(scrollbars.Left(wm), scrollbars.Top(wm));
+  }
+  return nsPoint(0, 0);
+}
+
+nsRect
+ViewportFrame::AdjustReflowInputAsContainingBlock(ReflowInput* aReflowInput) const
+{
+#ifdef DEBUG
+  nsPoint offset =
+#endif
+    AdjustReflowInputForScrollbars(aReflowInput);
+
+  NS_ASSERTION(GetAbsoluteContainingBlock()->GetChildList().IsEmpty() ||
+               (offset.x == 0 && offset.y == 0),
+               "We don't handle correct positioning of fixed frames with "
+               "scrollbars in odd positions");
+
+  // If a scroll position clamping scroll-port size has been set, layout
+  // fixed position elements to this size instead of the computed size.
+  nsRect rect(0, 0, aReflowInput->ComputedWidth(), aReflowInput->ComputedHeight());
+  nsIPresShell* ps = PresContext()->PresShell();
+  if (ps->IsScrollPositionClampingScrollPortSizeSet()) {
+    rect.SizeTo(ps->GetScrollPositionClampingScrollPortSize());
+  }
+
+  return rect;
+}
+
+void
+ViewportFrame::Reflow(nsPresContext*           aPresContext,
+                      ReflowOutput&     aDesiredSize,
+                      const ReflowInput& aReflowInput,
+                      nsReflowStatus&          aStatus)
+{
+  MarkInReflow();
+  DO_GLOBAL_REFLOW_COUNT("ViewportFrame");
+  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
+  NS_FRAME_TRACE_REFLOW_IN("ViewportFrame::Reflow");
+
+  // Initialize OUT parameters
+  aStatus = NS_FRAME_COMPLETE;
+
+  // Because |Reflow| sets ComputedBSize() on the child to our
+  // ComputedBSize().
+  AddStateBits(NS_FRAME_CONTAINS_RELATIVE_BSIZE);
+
+  // Set our size up front, since some parts of reflow depend on it
+  // being already set.  Note that the computed height may be
+  // unconstrained; that's ok.  Consumers should watch out for that.
+  SetSize(nsSize(aReflowInput.ComputedWidth(), aReflowInput.ComputedHeight()));
+
+  // Reflow the main content first so that the placeholders of the
+  // fixed-position frames will be in the right places on an initial
+  // reflow.
+  nscoord kidBSize = 0;
+  WritingMode wm = aReflowInput.GetWritingMode();
+
+  if (mFrames.NotEmpty()) {
+    // Deal with a non-incremental reflow or an incremental reflow
+    // targeted at our one-and-only principal child frame.
+    if (aReflowInput.ShouldReflowAllKids() ||
+        aReflowInput.IsBResize() ||
+        NS_SUBTREE_DIRTY(mFrames.FirstChild())) {
+      // Reflow our one-and-only principal child frame
+      nsIFrame*           kidFrame = mFrames.FirstChild();
+      ReflowOutput kidDesiredSize(aReflowInput);
+      WritingMode         wm = kidFrame->GetWritingMode();
+      LogicalSize         availableSpace = aReflowInput.AvailableSize(wm);
+      ReflowInput   kidReflowInput(aPresContext, aReflowInput,
+                                         kidFrame, availableSpace);
+
+      // Reflow the frame
+      kidReflowInput.SetComputedBSize(aReflowInput.ComputedBSize());
+      ReflowChild(kidFrame, aPresContext, kidDesiredSize, kidReflowInput,
+                  0, 0, 0, aStatus);
+      kidBSize = kidDesiredSize.BSize(wm);
+
+      FinishReflowChild(kidFrame, aPresContext, kidDesiredSize, nullptr, 0, 0, 0);
+    } else {
+      kidBSize = LogicalSize(wm, mFrames.FirstChild()->GetSize()).BSize(wm);
+    }
+  }
+
+  NS_ASSERTION(aReflowInput.AvailableISize() != NS_UNCONSTRAINEDSIZE,
+               "shouldn't happen anymore");
+
+  // Return the max size as our desired size
+  LogicalSize maxSize(wm, aReflowInput.AvailableISize(),
+                      // Being flowed initially at an unconstrained block size
+                      // means we should return our child's intrinsic size.
+                      aReflowInput.ComputedBSize() != NS_UNCONSTRAINEDSIZE
+                        ? aReflowInput.ComputedBSize()
+                        : kidBSize);
+  aDesiredSize.SetSize(wm, maxSize);
+  aDesiredSize.SetOverflowAreasToDesiredBounds();
+
+  if (HasAbsolutelyPositionedChildren()) {
+    // Make a copy of the reflow state and change the computed width and height
+    // to reflect the available space for the fixed items
+    ReflowInput reflowInput(aReflowInput);
+
+    if (reflowInput.AvailableBSize() == NS_UNCONSTRAINEDSIZE) {
+      // We have an intrinsic-height document with abs-pos/fixed-pos children.
+      // Set the available height and mComputedHeight to our chosen height.
+      reflowInput.AvailableBSize() = maxSize.BSize(wm);
+      // Not having border/padding simplifies things
+      NS_ASSERTION(reflowInput.ComputedPhysicalBorderPadding() == nsMargin(0,0,0,0),
+                   "Viewports can't have border/padding");
+      reflowInput.SetComputedBSize(maxSize.BSize(wm));
+    }
+
+    nsRect rect = AdjustReflowInputAsContainingBlock(&reflowInput);
+    nsOverflowAreas* overflowAreas = &aDesiredSize.mOverflowAreas;
+    nsIScrollableFrame* rootScrollFrame =
+                    aPresContext->PresShell()->GetRootScrollFrameAsScrollable();
+    if (rootScrollFrame && !rootScrollFrame->IsIgnoringViewportClipping()) {
+      overflowAreas = nullptr;
+    }
+    AbsPosReflowFlags flags =
+      AbsPosReflowFlags::eCBWidthAndHeightChanged; // XXX could be optimized
+    GetAbsoluteContainingBlock()->Reflow(this, aPresContext, reflowInput, aStatus,
+                                         rect, flags, overflowAreas);
+  }
+
+  if (mFrames.NotEmpty()) {
+    ConsiderChildOverflow(aDesiredSize.mOverflowAreas, mFrames.FirstChild());
+  }
+
+  // If we were dirty then do a repaint
+  if (GetStateBits() & NS_FRAME_IS_DIRTY) {
+    InvalidateFrame();
+  }
+
+  // Clipping is handled by the document container (e.g., nsSubDocumentFrame),
+  // so we don't need to change our overflow areas.
+  bool overflowChanged = FinishAndStoreOverflow(&aDesiredSize);
+  if (overflowChanged) {
+    // We may need to alert our container to get it to pick up the
+    // overflow change.
+    nsSubDocumentFrame* container = static_cast<nsSubDocumentFrame*>
+      (nsLayoutUtils::GetCrossDocParentFrame(this));
+    if (container && !container->ShouldClipSubdocument()) {
+      container->PresContext()->PresShell()->
+        FrameNeedsReflow(container, nsIPresShell::eResize, NS_FRAME_IS_DIRTY);
+    }
+  }
+
+  NS_FRAME_TRACE_REFLOW_OUT("ViewportFrame::Reflow", aStatus);
+  NS_FRAME_SET_TRUNCATION(aStatus, aReflowInput, aDesiredSize);
+}
+
+bool
+ViewportFrame::ComputeCustomOverflow(nsOverflowAreas& aOverflowAreas)
+{
+  nsIScrollableFrame* rootScrollFrame =
+    PresContext()->PresShell()->GetRootScrollFrameAsScrollable();
+  if (rootScrollFrame && !rootScrollFrame->IsIgnoringViewportClipping()) {
+    return false;
+  }
+
+  return nsContainerFrame::ComputeCustomOverflow(aOverflowAreas);
+}
+
+nsIAtom*
+ViewportFrame::GetType() const
+{
+  return nsGkAtoms::viewportFrame;
+}
+
+#ifdef DEBUG_FRAME_DUMP
+nsresult
+ViewportFrame::GetFrameName(nsAString& aResult) const
+{
+  return MakeFrameName(NS_LITERAL_STRING("Viewport"), aResult);
+}
+#endif