Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 936 insertions, 0 deletions

diff --git a/layout/generic/TextOverflow.cpp b/layout/generic/TextOverflow.cpp
new file mode 100644
index 0000000000..f529a2268d
--- /dev/null
+++ b/layout/generic/TextOverflow.cpp
@@ -0,0 +1,936 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 "TextOverflow.h"
+#include <algorithm>
+
+// Please maintain alphabetical order below
+#include "gfxContext.h"
+#include "nsBlockFrame.h"
+#include "nsCaret.h"
+#include "nsContentUtils.h"
+#include "nsCSSAnonBoxes.h"
+#include "nsFontMetrics.h"
+#include "nsGfxScrollFrame.h"
+#include "nsIScrollableFrame.h"
+#include "nsLayoutUtils.h"
+#include "nsPresContext.h"
+#include "nsRect.h"
+#include "nsTextFrame.h"
+#include "nsIFrameInlines.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/Likely.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/dom/Selection.h"
+#include "TextDrawTarget.h"
+
+using mozilla::layout::TextDrawTarget;
+
+namespace mozilla {
+namespace css {
+
+class LazyReferenceRenderingDrawTargetGetterFromFrame final
+    : public gfxFontGroup::LazyReferenceDrawTargetGetter {
+ public:
+  typedef mozilla::gfx::DrawTarget DrawTarget;
+
+  explicit LazyReferenceRenderingDrawTargetGetterFromFrame(nsIFrame* aFrame)
+      : mFrame(aFrame) {}
+  virtual already_AddRefed<DrawTarget> GetRefDrawTarget() override {
+    UniquePtr<gfxContext> ctx =
+        mFrame->PresShell()->CreateReferenceRenderingContext();
+    RefPtr<DrawTarget> dt = ctx->GetDrawTarget();
+    return dt.forget();
+  }
+
+ private:
+  nsIFrame* mFrame;
+};
+
+static gfxTextRun* GetEllipsisTextRun(nsIFrame* aFrame) {
+  RefPtr<nsFontMetrics> fm =
+      nsLayoutUtils::GetInflatedFontMetricsForFrame(aFrame);
+  LazyReferenceRenderingDrawTargetGetterFromFrame lazyRefDrawTargetGetter(
+      aFrame);
+  return fm->GetThebesFontGroup()->GetEllipsisTextRun(
+      aFrame->PresContext()->AppUnitsPerDevPixel(),
+      nsLayoutUtils::GetTextRunOrientFlagsForStyle(aFrame->Style()),
+      lazyRefDrawTargetGetter);
+}
+
+static nsIFrame* GetSelfOrNearestBlock(nsIFrame* aFrame) {
+  MOZ_ASSERT(aFrame);
+  return aFrame->IsBlockFrameOrSubclass()
+             ? aFrame
+             : nsLayoutUtils::FindNearestBlockAncestor(aFrame);
+}
+
+// Return true if the frame is an atomic inline-level element.
+// It's not supposed to be called for block frames since we never
+// process block descendants for text-overflow.
+static bool IsAtomicElement(nsIFrame* aFrame, LayoutFrameType aFrameType) {
+  MOZ_ASSERT(!aFrame->IsBlockFrameOrSubclass() || !aFrame->IsBlockOutside(),
+             "unexpected block frame");
+  MOZ_ASSERT(aFrameType != LayoutFrameType::Placeholder,
+             "unexpected placeholder frame");
+  return !aFrame->IsLineParticipant();
+}
+
+static bool IsFullyClipped(nsTextFrame* aFrame, nscoord aLeft, nscoord aRight,
+                           nscoord* aSnappedLeft, nscoord* aSnappedRight) {
+  *aSnappedLeft = aLeft;
+  *aSnappedRight = aRight;
+  if (aLeft <= 0 && aRight <= 0) {
+    return false;
+  }
+  return !aFrame->MeasureCharClippedText(aLeft, aRight, aSnappedLeft,
+                                         aSnappedRight);
+}
+
+static bool IsInlineAxisOverflowVisible(nsIFrame* aFrame) {
+  MOZ_ASSERT(aFrame && aFrame->IsBlockFrameOrSubclass(),
+             "expected a block frame");
+
+  nsIFrame* f = aFrame;
+  while (f && f->Style()->IsAnonBox() && !f->IsScrollFrame()) {
+    f = f->GetParent();
+  }
+  if (!f) {
+    return true;
+  }
+  auto overflow = aFrame->GetWritingMode().IsVertical()
+                      ? f->StyleDisplay()->mOverflowY
+                      : f->StyleDisplay()->mOverflowX;
+  return overflow == StyleOverflow::Visible;
+}
+
+static void ClipMarker(const nsRect& aContentArea, const nsRect& aMarkerRect,
+                       DisplayListClipState::AutoSaveRestore& aClipState) {
+  nscoord rightOverflow = aMarkerRect.XMost() - aContentArea.XMost();
+  nsRect markerRect = aMarkerRect;
+  if (rightOverflow > 0) {
+    // Marker overflows on the right side (content width < marker width).
+    markerRect.width -= rightOverflow;
+    aClipState.ClipContentDescendants(markerRect);
+  } else {
+    nscoord leftOverflow = aContentArea.x - aMarkerRect.x;
+    if (leftOverflow > 0) {
+      // Marker overflows on the left side
+      markerRect.width -= leftOverflow;
+      markerRect.x += leftOverflow;
+      aClipState.ClipContentDescendants(markerRect);
+    }
+  }
+}
+
+static void InflateIStart(WritingMode aWM, LogicalRect* aRect, nscoord aDelta) {
+  nscoord iend = aRect->IEnd(aWM);
+  aRect->IStart(aWM) -= aDelta;
+  aRect->ISize(aWM) = std::max(iend - aRect->IStart(aWM), 0);
+}
+
+static void InflateIEnd(WritingMode aWM, LogicalRect* aRect, nscoord aDelta) {
+  aRect->ISize(aWM) = std::max(aRect->ISize(aWM) + aDelta, 0);
+}
+
+static bool IsFrameDescendantOfAny(
+    nsIFrame* aChild, const TextOverflow::FrameHashtable& aSetOfFrames,
+    nsIFrame* aCommonAncestor) {
+  for (nsIFrame* f = aChild; f && f != aCommonAncestor;
+       f = nsLayoutUtils::GetCrossDocParentFrameInProcess(f)) {
+    if (aSetOfFrames.Contains(f)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+class nsDisplayTextOverflowMarker final : public nsPaintedDisplayItem {
+ public:
+  nsDisplayTextOverflowMarker(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
+                              const nsRect& aRect, nscoord aAscent,
+                              const StyleTextOverflowSide& aStyle)
+      : nsPaintedDisplayItem(aBuilder, aFrame),
+        mRect(aRect),
+        mStyle(aStyle),
+        mAscent(aAscent) {
+    MOZ_COUNT_CTOR(nsDisplayTextOverflowMarker);
+  }
+
+  MOZ_COUNTED_DTOR_OVERRIDE(nsDisplayTextOverflowMarker)
+
+  virtual nsRect GetBounds(nsDisplayListBuilder* aBuilder,
+                           bool* aSnap) const override {
+    *aSnap = false;
+    nsRect shadowRect = nsLayoutUtils::GetTextShadowRectsUnion(mRect, mFrame);
+    return mRect.Union(shadowRect);
+  }
+
+  virtual nsRect GetComponentAlphaBounds(
+      nsDisplayListBuilder* aBuilder) const override {
+    if (gfxPlatform::GetPlatform()->RespectsFontStyleSmoothing()) {
+      // On OS X, web authors can turn off subpixel text rendering using the
+      // CSS property -moz-osx-font-smoothing. If they do that, we don't need
+      // to use component alpha layers for the affected text.
+      if (mFrame->StyleFont()->mFont.smoothing == NS_FONT_SMOOTHING_GRAYSCALE) {
+        return nsRect();
+      }
+    }
+    bool snap;
+    return GetBounds(aBuilder, &snap);
+  }
+
+  virtual void Paint(nsDisplayListBuilder* aBuilder, gfxContext* aCtx) override;
+
+  void PaintTextToContext(gfxContext* aCtx, nsPoint aOffsetFromRect);
+
+  virtual bool CreateWebRenderCommands(
+      mozilla::wr::DisplayListBuilder& aBuilder,
+      mozilla::wr::IpcResourceUpdateQueue& aResources,
+      const StackingContextHelper& aSc,
+      layers::RenderRootStateManager* aManager,
+      nsDisplayListBuilder* aDisplayListBuilder) override;
+
+  NS_DISPLAY_DECL_NAME("TextOverflow", TYPE_TEXT_OVERFLOW)
+ private:
+  nsRect mRect;  // in reference frame coordinates
+  const StyleTextOverflowSide mStyle;
+  nscoord mAscent;  // baseline for the marker text in mRect
+};
+
+static void PaintTextShadowCallback(gfxContext* aCtx, nsPoint aShadowOffset,
+                                    const nscolor& aShadowColor, void* aData) {
+  reinterpret_cast<nsDisplayTextOverflowMarker*>(aData)->PaintTextToContext(
+      aCtx, aShadowOffset);
+}
+
+void nsDisplayTextOverflowMarker::Paint(nsDisplayListBuilder* aBuilder,
+                                        gfxContext* aCtx) {
+  nscolor foregroundColor =
+      nsLayoutUtils::GetColor(mFrame, &nsStyleText::mWebkitTextFillColor);
+
+  // Paint the text-shadows for the overflow marker
+  nsLayoutUtils::PaintTextShadow(mFrame, aCtx, mRect,
+                                 GetPaintRect(aBuilder, aCtx), foregroundColor,
+                                 PaintTextShadowCallback, (void*)this);
+  aCtx->SetColor(gfx::sRGBColor::FromABGR(foregroundColor));
+  PaintTextToContext(aCtx, nsPoint(0, 0));
+}
+
+void nsDisplayTextOverflowMarker::PaintTextToContext(gfxContext* aCtx,
+                                                     nsPoint aOffsetFromRect) {
+  WritingMode wm = mFrame->GetWritingMode();
+  nsPoint pt(mRect.x, mRect.y);
+  if (wm.IsVertical()) {
+    if (wm.IsVerticalLR()) {
+      pt.x = NSToCoordFloor(
+          nsLayoutUtils::GetSnappedBaselineX(mFrame, aCtx, pt.x, mAscent));
+    } else {
+      pt.x = NSToCoordFloor(nsLayoutUtils::GetSnappedBaselineX(
+          mFrame, aCtx, pt.x + mRect.width, -mAscent));
+    }
+  } else {
+    pt.y = NSToCoordFloor(
+        nsLayoutUtils::GetSnappedBaselineY(mFrame, aCtx, pt.y, mAscent));
+  }
+  pt += aOffsetFromRect;
+
+  if (mStyle.IsEllipsis()) {
+    gfxTextRun* textRun = GetEllipsisTextRun(mFrame);
+    if (textRun) {
+      NS_ASSERTION(!textRun->IsRightToLeft(),
+                   "Ellipsis textruns should always be LTR!");
+      gfx::Point gfxPt(pt.x, pt.y);
+      auto& paletteCache = mFrame->PresContext()->FontPaletteCache();
+      textRun->Draw(gfxTextRun::Range(textRun), gfxPt,
+                    gfxTextRun::DrawParams(aCtx, paletteCache));
+    }
+  } else {
+    RefPtr<nsFontMetrics> fm =
+        nsLayoutUtils::GetInflatedFontMetricsForFrame(mFrame);
+    NS_ConvertUTF8toUTF16 str16{mStyle.AsString().AsString()};
+    nsLayoutUtils::DrawString(mFrame, *fm, aCtx, str16.get(), str16.Length(),
+                              pt);
+  }
+}
+
+bool nsDisplayTextOverflowMarker::CreateWebRenderCommands(
+    mozilla::wr::DisplayListBuilder& aBuilder,
+    mozilla::wr::IpcResourceUpdateQueue& aResources,
+    const StackingContextHelper& aSc, layers::RenderRootStateManager* aManager,
+    nsDisplayListBuilder* aDisplayListBuilder) {
+  bool snap;
+  nsRect bounds = GetBounds(aDisplayListBuilder, &snap);
+  if (bounds.IsEmpty()) {
+    return true;
+  }
+
+  // Run the rendering algorithm to capture the glyphs and shadows
+  RefPtr<TextDrawTarget> textDrawer =
+      new TextDrawTarget(aBuilder, aResources, aSc, aManager, this, bounds);
+  MOZ_ASSERT(textDrawer->IsValid());
+  if (!textDrawer->IsValid()) {
+    return false;
+  }
+  gfxContext captureCtx(textDrawer);
+  Paint(aDisplayListBuilder, &captureCtx);
+  textDrawer->TerminateShadows();
+
+  return textDrawer->Finish();
+}
+
+TextOverflow::TextOverflow(nsDisplayListBuilder* aBuilder,
+                           nsBlockFrame* aBlockFrame)
+    : mContentArea(aBlockFrame->GetWritingMode(),
+                   aBlockFrame->GetContentRectRelativeToSelf(),
+                   aBlockFrame->GetSize()),
+      mBuilder(aBuilder),
+      mBlock(aBlockFrame),
+      mScrollableFrame(nsLayoutUtils::GetScrollableFrameFor(aBlockFrame)),
+      mMarkerList(aBuilder),
+      mBlockSize(aBlockFrame->GetSize()),
+      mBlockWM(aBlockFrame->GetWritingMode()),
+      mCanHaveInlineAxisScrollbar(false),
+      mInLineClampContext(aBlockFrame->IsInLineClampContext()),
+      mAdjustForPixelSnapping(false) {
+  if (mScrollableFrame) {
+    auto scrollbarStyle = mBlockWM.IsVertical()
+                              ? mScrollableFrame->GetScrollStyles().mVertical
+                              : mScrollableFrame->GetScrollStyles().mHorizontal;
+    mCanHaveInlineAxisScrollbar = scrollbarStyle != StyleOverflow::Hidden;
+    if (!mAdjustForPixelSnapping) {
+      // Scrolling to the end position can leave some text still overflowing due
+      // to pixel snapping behaviour in our scrolling code.
+      mAdjustForPixelSnapping = mCanHaveInlineAxisScrollbar;
+    }
+    // Use a null containerSize to convert a vector from logical to physical.
+    const nsSize nullContainerSize;
+    mContentArea.MoveBy(
+        mBlockWM, LogicalPoint(mBlockWM, mScrollableFrame->GetScrollPosition(),
+                               nullContainerSize));
+  }
+  StyleDirection direction = aBlockFrame->StyleVisibility()->mDirection;
+  const nsStyleTextReset* style = aBlockFrame->StyleTextReset();
+
+  const auto& textOverflow = style->mTextOverflow;
+  bool shouldToggleDirection =
+      textOverflow.sides_are_logical && (direction == StyleDirection::Rtl);
+  const auto& leftSide =
+      shouldToggleDirection ? textOverflow.second : textOverflow.first;
+  const auto& rightSide =
+      shouldToggleDirection ? textOverflow.first : textOverflow.second;
+
+  if (mBlockWM.IsBidiLTR()) {
+    mIStart.Init(leftSide);
+    mIEnd.Init(rightSide);
+  } else {
+    mIStart.Init(rightSide);
+    mIEnd.Init(leftSide);
+  }
+  // The left/right marker string is setup in ExamineLineFrames when a line
+  // has overflow on that side.
+}
+
+/* static */
+Maybe<TextOverflow> TextOverflow::WillProcessLines(
+    nsDisplayListBuilder* aBuilder, nsBlockFrame* aBlockFrame) {
+  // Ignore text-overflow and -webkit-line-clamp for event and frame visibility
+  // processing.
+  if (aBuilder->IsForEventDelivery() || aBuilder->IsForFrameVisibility() ||
+      !CanHaveOverflowMarkers(aBlockFrame)) {
+    return Nothing();
+  }
+  nsIScrollableFrame* scrollableFrame =
+      nsLayoutUtils::GetScrollableFrameFor(aBlockFrame);
+  if (scrollableFrame && scrollableFrame->IsTransformingByAPZ()) {
+    // If the APZ is actively scrolling this, don't bother with markers.
+    return Nothing();
+  }
+  return Some(TextOverflow(aBuilder, aBlockFrame));
+}
+
+void TextOverflow::ExamineFrameSubtree(nsIFrame* aFrame,
+                                       const LogicalRect& aContentArea,
+                                       const LogicalRect& aInsideMarkersArea,
+                                       FrameHashtable* aFramesToHide,
+                                       AlignmentEdges* aAlignmentEdges,
+                                       bool* aFoundVisibleTextOrAtomic,
+                                       InnerClipEdges* aClippedMarkerEdges) {
+  const LayoutFrameType frameType = aFrame->Type();
+  if (frameType == LayoutFrameType::Br ||
+      frameType == LayoutFrameType::Placeholder) {
+    return;
+  }
+  const bool isAtomic = IsAtomicElement(aFrame, frameType);
+  if (aFrame->StyleVisibility()->IsVisible()) {
+    LogicalRect childRect =
+        GetLogicalScrollableOverflowRectRelativeToBlock(aFrame);
+    bool overflowIStart =
+        childRect.IStart(mBlockWM) < aContentArea.IStart(mBlockWM);
+    bool overflowIEnd = childRect.IEnd(mBlockWM) > aContentArea.IEnd(mBlockWM);
+    if (overflowIStart) {
+      mIStart.mHasOverflow = true;
+    }
+    if (overflowIEnd) {
+      mIEnd.mHasOverflow = true;
+    }
+    if (isAtomic && ((mIStart.mActive && overflowIStart) ||
+                     (mIEnd.mActive && overflowIEnd))) {
+      aFramesToHide->Insert(aFrame);
+    } else if (isAtomic || frameType == LayoutFrameType::Text) {
+      AnalyzeMarkerEdges(aFrame, frameType, aInsideMarkersArea, aFramesToHide,
+                         aAlignmentEdges, aFoundVisibleTextOrAtomic,
+                         aClippedMarkerEdges);
+    }
+  }
+  if (isAtomic) {
+    return;
+  }
+
+  for (nsIFrame* child : aFrame->PrincipalChildList()) {
+    ExamineFrameSubtree(child, aContentArea, aInsideMarkersArea, aFramesToHide,
+                        aAlignmentEdges, aFoundVisibleTextOrAtomic,
+                        aClippedMarkerEdges);
+  }
+}
+
+void TextOverflow::AnalyzeMarkerEdges(nsIFrame* aFrame,
+                                      LayoutFrameType aFrameType,
+                                      const LogicalRect& aInsideMarkersArea,
+                                      FrameHashtable* aFramesToHide,
+                                      AlignmentEdges* aAlignmentEdges,
+                                      bool* aFoundVisibleTextOrAtomic,
+                                      InnerClipEdges* aClippedMarkerEdges) {
+  MOZ_ASSERT(aFrameType == LayoutFrameType::Text ||
+             IsAtomicElement(aFrame, aFrameType));
+  LogicalRect borderRect(mBlockWM,
+                         nsRect(aFrame->GetOffsetTo(mBlock), aFrame->GetSize()),
+                         mBlockSize);
+  nscoord istartOverlap = std::max(
+      aInsideMarkersArea.IStart(mBlockWM) - borderRect.IStart(mBlockWM), 0);
+  nscoord iendOverlap = std::max(
+      borderRect.IEnd(mBlockWM) - aInsideMarkersArea.IEnd(mBlockWM), 0);
+  bool insideIStartEdge =
+      aInsideMarkersArea.IStart(mBlockWM) <= borderRect.IEnd(mBlockWM);
+  bool insideIEndEdge =
+      borderRect.IStart(mBlockWM) <= aInsideMarkersArea.IEnd(mBlockWM);
+
+  if (istartOverlap > 0) {
+    aClippedMarkerEdges->AccumulateIStart(mBlockWM, borderRect);
+    if (!mIStart.mActive) {
+      istartOverlap = 0;
+    }
+  }
+  if (iendOverlap > 0) {
+    aClippedMarkerEdges->AccumulateIEnd(mBlockWM, borderRect);
+    if (!mIEnd.mActive) {
+      iendOverlap = 0;
+    }
+  }
+
+  if ((istartOverlap > 0 && insideIStartEdge) ||
+      (iendOverlap > 0 && insideIEndEdge)) {
+    if (aFrameType == LayoutFrameType::Text) {
+      auto textFrame = static_cast<nsTextFrame*>(aFrame);
+      if ((aInsideMarkersArea.IStart(mBlockWM) <
+           aInsideMarkersArea.IEnd(mBlockWM)) &&
+          textFrame->HasNonSuppressedText()) {
+        // a clipped text frame and there is some room between the markers
+        nscoord snappedIStart, snappedIEnd;
+        bool isFullyClipped =
+            mBlockWM.IsBidiLTR()
+                ? IsFullyClipped(textFrame, istartOverlap, iendOverlap,
+                                 &snappedIStart, &snappedIEnd)
+                : IsFullyClipped(textFrame, iendOverlap, istartOverlap,
+                                 &snappedIEnd, &snappedIStart);
+        if (!isFullyClipped) {
+          LogicalRect snappedRect = borderRect;
+          if (istartOverlap > 0) {
+            snappedRect.IStart(mBlockWM) += snappedIStart;
+            snappedRect.ISize(mBlockWM) -= snappedIStart;
+          }
+          if (iendOverlap > 0) {
+            snappedRect.ISize(mBlockWM) -= snappedIEnd;
+          }
+          aAlignmentEdges->AccumulateInner(mBlockWM, snappedRect);
+          *aFoundVisibleTextOrAtomic = true;
+        }
+      }
+    } else {
+      aFramesToHide->Insert(aFrame);
+    }
+  } else if (!insideIStartEdge || !insideIEndEdge) {
+    // frame is outside
+    if (!insideIStartEdge) {
+      aAlignmentEdges->AccumulateOuter(mBlockWM, borderRect);
+    }
+    if (IsAtomicElement(aFrame, aFrameType)) {
+      aFramesToHide->Insert(aFrame);
+    }
+  } else {
+    // frame is inside
+    aAlignmentEdges->AccumulateInner(mBlockWM, borderRect);
+    if (aFrameType == LayoutFrameType::Text) {
+      auto textFrame = static_cast<nsTextFrame*>(aFrame);
+      if (textFrame->HasNonSuppressedText()) {
+        *aFoundVisibleTextOrAtomic = true;
+      }
+    } else {
+      *aFoundVisibleTextOrAtomic = true;
+    }
+  }
+}
+
+LogicalRect TextOverflow::ExamineLineFrames(nsLineBox* aLine,
+                                            FrameHashtable* aFramesToHide,
+                                            AlignmentEdges* aAlignmentEdges) {
+  // No ellipsing for 'clip' style.
+  bool suppressIStart = mIStart.IsSuppressed(mInLineClampContext);
+  bool suppressIEnd = mIEnd.IsSuppressed(mInLineClampContext);
+  if (mCanHaveInlineAxisScrollbar) {
+    LogicalPoint pos(mBlockWM, mScrollableFrame->GetScrollPosition(),
+                     mBlockSize);
+    LogicalRect scrollRange(mBlockWM, mScrollableFrame->GetScrollRange(),
+                            mBlockSize);
+    // No ellipsing when nothing to scroll to on that side (this includes
+    // overflow:auto that doesn't trigger a horizontal scrollbar).
+    if (pos.I(mBlockWM) <= scrollRange.IStart(mBlockWM)) {
+      suppressIStart = true;
+    }
+    if (pos.I(mBlockWM) >= scrollRange.IEnd(mBlockWM)) {
+      // Except that we always want to display a -webkit-line-clamp ellipsis.
+      if (!mIEnd.mHasBlockEllipsis) {
+        suppressIEnd = true;
+      }
+    }
+  }
+
+  LogicalRect contentArea = mContentArea;
+  bool snapStart = true, snapEnd = true;
+  nscoord startEdge, endEdge;
+  if (aLine->GetFloatEdges(&startEdge, &endEdge)) {
+    // Narrow the |contentArea| to account for any floats on this line, and
+    // don't bother with the snapping quirk on whichever side(s) we narrow.
+    nscoord delta = endEdge - contentArea.IEnd(mBlockWM);
+    if (delta < 0) {
+      nscoord newSize = contentArea.ISize(mBlockWM) + delta;
+      contentArea.ISize(mBlockWM) = std::max(nscoord(0), newSize);
+      snapEnd = false;
+    }
+    delta = startEdge - contentArea.IStart(mBlockWM);
+    if (delta > 0) {
+      contentArea.IStart(mBlockWM) = startEdge;
+      nscoord newSize = contentArea.ISize(mBlockWM) - delta;
+      contentArea.ISize(mBlockWM) = std::max(nscoord(0), newSize);
+      snapStart = false;
+    }
+  }
+  // Save the non-snapped area since that's what we want to use when placing
+  // the markers (our return value).  The snapped area is only for analysis.
+  LogicalRect nonSnappedContentArea = contentArea;
+  if (mAdjustForPixelSnapping) {
+    const nscoord scrollAdjust = mBlock->PresContext()->AppUnitsPerDevPixel();
+    if (snapStart) {
+      InflateIStart(mBlockWM, &contentArea, scrollAdjust);
+    }
+    if (snapEnd) {
+      InflateIEnd(mBlockWM, &contentArea, scrollAdjust);
+    }
+  }
+
+  LogicalRect lineRect(mBlockWM, aLine->ScrollableOverflowRect(), mBlockSize);
+  const bool istartWantsMarker =
+      !suppressIStart &&
+      lineRect.IStart(mBlockWM) < contentArea.IStart(mBlockWM);
+  const bool iendWantsTextOverflowMarker =
+      !suppressIEnd && lineRect.IEnd(mBlockWM) > contentArea.IEnd(mBlockWM);
+  const bool iendWantsBlockEllipsisMarker =
+      !suppressIEnd && mIEnd.mHasBlockEllipsis;
+  const bool iendWantsMarker =
+      iendWantsTextOverflowMarker || iendWantsBlockEllipsisMarker;
+  if (!istartWantsMarker && !iendWantsMarker) {
+    // We don't need any markers on this line.
+    return nonSnappedContentArea;
+  }
+
+  int pass = 0;
+  bool retryEmptyLine = true;
+  bool guessIStart = istartWantsMarker;
+  bool guessIEnd = iendWantsMarker;
+  mIStart.mActive = istartWantsMarker;
+  mIEnd.mActive = iendWantsMarker;
+  mIStart.mEdgeAligned = mCanHaveInlineAxisScrollbar && istartWantsMarker;
+  mIEnd.mEdgeAligned =
+      mCanHaveInlineAxisScrollbar && iendWantsTextOverflowMarker;
+  bool clippedIStartMarker = false;
+  bool clippedIEndMarker = false;
+  do {
+    // Setup marker strings as needed.
+    if (guessIStart) {
+      mIStart.SetupString(mBlock);
+    }
+    if (guessIEnd) {
+      mIEnd.SetupString(mBlock);
+    }
+
+    // If there is insufficient space for both markers then keep the one on the
+    // end side per the block's 'direction'.
+    nscoord istartMarkerISize = mIStart.mActive ? mIStart.mISize : 0;
+    nscoord iendMarkerISize = mIEnd.mActive ? mIEnd.mISize : 0;
+    if (istartMarkerISize && iendMarkerISize &&
+        istartMarkerISize + iendMarkerISize > contentArea.ISize(mBlockWM)) {
+      istartMarkerISize = 0;
+    }
+
+    // Calculate the area between the potential markers aligned at the
+    // block's edge.
+    LogicalRect insideMarkersArea = nonSnappedContentArea;
+    if (guessIStart) {
+      InflateIStart(mBlockWM, &insideMarkersArea, -istartMarkerISize);
+    }
+    if (guessIEnd) {
+      InflateIEnd(mBlockWM, &insideMarkersArea, -iendMarkerISize);
+    }
+
+    // Analyze the frames on aLine for the overflow situation at the content
+    // edges and at the edges of the area between the markers.
+    bool foundVisibleTextOrAtomic = false;
+    int32_t n = aLine->GetChildCount();
+    nsIFrame* child = aLine->mFirstChild;
+    InnerClipEdges clippedMarkerEdges;
+    for (; n-- > 0; child = child->GetNextSibling()) {
+      ExamineFrameSubtree(child, contentArea, insideMarkersArea, aFramesToHide,
+                          aAlignmentEdges, &foundVisibleTextOrAtomic,
+                          &clippedMarkerEdges);
+    }
+    if (!foundVisibleTextOrAtomic && retryEmptyLine) {
+      aAlignmentEdges->mAssignedInner = false;
+      aAlignmentEdges->mIEndOuter = 0;
+      aFramesToHide->Clear();
+      pass = -1;
+      if (mIStart.IsNeeded() && mIStart.mActive && !clippedIStartMarker) {
+        if (clippedMarkerEdges.mAssignedIStart &&
+            clippedMarkerEdges.mIStart >
+                nonSnappedContentArea.IStart(mBlockWM)) {
+          mIStart.mISize = clippedMarkerEdges.mIStart -
+                           nonSnappedContentArea.IStart(mBlockWM);
+          NS_ASSERTION(mIStart.mISize < mIStart.mIntrinsicISize,
+                       "clipping a marker should make it strictly smaller");
+          clippedIStartMarker = true;
+        } else {
+          mIStart.mActive = guessIStart = false;
+        }
+        continue;
+      }
+      if (mIEnd.IsNeeded() && mIEnd.mActive && !clippedIEndMarker) {
+        if (clippedMarkerEdges.mAssignedIEnd &&
+            nonSnappedContentArea.IEnd(mBlockWM) > clippedMarkerEdges.mIEnd) {
+          mIEnd.mISize =
+              nonSnappedContentArea.IEnd(mBlockWM) - clippedMarkerEdges.mIEnd;
+          NS_ASSERTION(mIEnd.mISize < mIEnd.mIntrinsicISize,
+                       "clipping a marker should make it strictly smaller");
+          clippedIEndMarker = true;
+        } else {
+          mIEnd.mActive = guessIEnd = false;
+        }
+        continue;
+      }
+      // The line simply has no visible content even without markers,
+      // so examine the line again without suppressing markers.
+      retryEmptyLine = false;
+      mIStart.mISize = mIStart.mIntrinsicISize;
+      mIStart.mActive = guessIStart = istartWantsMarker;
+      mIEnd.mISize = mIEnd.mIntrinsicISize;
+      mIEnd.mActive = guessIEnd = iendWantsMarker;
+      // If we wanted to place a block ellipsis but didn't, due to not having
+      // any visible content to align to or the line's content being scrolled
+      // out of view, then clip the ellipsis so that it looks like it is aligned
+      // with the out of view content.
+      if (mIEnd.IsNeeded() && mIEnd.mActive && mIEnd.mHasBlockEllipsis) {
+        NS_ASSERTION(nonSnappedContentArea.IStart(mBlockWM) >
+                         aAlignmentEdges->mIEndOuter,
+                     "Expected the alignment edge for the out of view content "
+                     "to be before the start of the content area");
+        mIEnd.mISize = std::max(
+            mIEnd.mIntrinsicISize - (nonSnappedContentArea.IStart(mBlockWM) -
+                                     aAlignmentEdges->mIEndOuter),
+            0);
+      }
+      continue;
+    }
+    if (guessIStart == (mIStart.mActive && mIStart.IsNeeded()) &&
+        guessIEnd == (mIEnd.mActive && mIEnd.IsNeeded())) {
+      break;
+    } else {
+      guessIStart = mIStart.mActive && mIStart.IsNeeded();
+      guessIEnd = mIEnd.mActive && mIEnd.IsNeeded();
+      mIStart.Reset();
+      mIEnd.Reset();
+      aFramesToHide->Clear();
+    }
+    NS_ASSERTION(pass == 0, "2nd pass should never guess wrong");
+  } while (++pass != 2);
+  if (!istartWantsMarker || !mIStart.mActive) {
+    mIStart.Reset();
+  }
+  if (!iendWantsMarker || !mIEnd.mActive) {
+    mIEnd.Reset();
+  }
+  return nonSnappedContentArea;
+}
+
+void TextOverflow::ProcessLine(const nsDisplayListSet& aLists, nsLineBox* aLine,
+                               uint32_t aLineNumber) {
+  if (mIStart.mStyle->IsClip() && mIEnd.mStyle->IsClip() &&
+      !aLine->HasLineClampEllipsis()) {
+    return;
+  }
+
+  mIStart.Reset();
+  mIStart.mActive = !mIStart.mStyle->IsClip();
+  mIEnd.Reset();
+  mIEnd.mHasBlockEllipsis = aLine->HasLineClampEllipsis();
+  mIEnd.mActive = !mIEnd.IsSuppressed(mInLineClampContext);
+
+  FrameHashtable framesToHide(64);
+  AlignmentEdges alignmentEdges;
+  const LogicalRect contentArea =
+      ExamineLineFrames(aLine, &framesToHide, &alignmentEdges);
+  bool needIStart = mIStart.IsNeeded();
+  bool needIEnd = mIEnd.IsNeeded();
+  if (!needIStart && !needIEnd) {
+    return;
+  }
+  NS_ASSERTION(!mIStart.IsSuppressed(mInLineClampContext) || !needIStart,
+               "left marker when not needed");
+  NS_ASSERTION(!mIEnd.IsSuppressed(mInLineClampContext) || !needIEnd,
+               "right marker when not needed");
+
+  // If there is insufficient space for both markers then keep the one on the
+  // end side per the block's 'direction'.
+  if (needIStart && needIEnd &&
+      mIStart.mISize + mIEnd.mISize > contentArea.ISize(mBlockWM)) {
+    needIStart = false;
+  }
+  LogicalRect insideMarkersArea = contentArea;
+  if (needIStart) {
+    InflateIStart(mBlockWM, &insideMarkersArea, -mIStart.mISize);
+  }
+  if (needIEnd) {
+    InflateIEnd(mBlockWM, &insideMarkersArea, -mIEnd.mISize);
+  }
+
+  if (alignmentEdges.mAssignedInner) {
+    if (mIStart.mEdgeAligned) {
+      alignmentEdges.mIStart = insideMarkersArea.IStart(mBlockWM);
+    }
+    if (mIEnd.mEdgeAligned) {
+      alignmentEdges.mIEnd = insideMarkersArea.IEnd(mBlockWM);
+    }
+    LogicalRect alignmentRect(mBlockWM, alignmentEdges.mIStart,
+                              insideMarkersArea.BStart(mBlockWM),
+                              alignmentEdges.ISize(), 1);
+    insideMarkersArea.IntersectRect(insideMarkersArea, alignmentRect);
+  } else {
+    // There was no content on the line that was visible at the current scolled
+    // position.  If we wanted to place a block ellipsis but failed due to
+    // having no visible content to align it to, we still need to ensure it
+    // is displayed.  It goes at the start of the line, even though it's an
+    // IEnd marker, since that is the side of the line that the content has
+    // been scrolled past.  We set the insideMarkersArea to a zero-sized
+    // rectangle placed next to the scrolled-out-of-view content.
+    if (mIEnd.mHasBlockEllipsis) {
+      insideMarkersArea = LogicalRect(mBlockWM, alignmentEdges.mIEndOuter,
+                                      insideMarkersArea.BStart(mBlockWM), 0, 1);
+    }
+  }
+
+  // Clip and remove display items as needed at the final marker edges.
+  nsDisplayList* lists[] = {aLists.Content(), aLists.PositionedDescendants()};
+  for (uint32_t i = 0; i < ArrayLength(lists); ++i) {
+    PruneDisplayListContents(lists[i], framesToHide, insideMarkersArea);
+  }
+  CreateMarkers(aLine, needIStart, needIEnd, insideMarkersArea, contentArea,
+                aLineNumber);
+}
+
+void TextOverflow::PruneDisplayListContents(
+    nsDisplayList* aList, const FrameHashtable& aFramesToHide,
+    const LogicalRect& aInsideMarkersArea) {
+  for (nsDisplayItem* item : aList->TakeItems()) {
+    nsIFrame* itemFrame = item->Frame();
+    if (IsFrameDescendantOfAny(itemFrame, aFramesToHide, mBlock)) {
+      item->Destroy(mBuilder);
+      continue;
+    }
+
+    nsDisplayList* wrapper = item->GetSameCoordinateSystemChildren();
+    if (wrapper) {
+      if (!itemFrame || GetSelfOrNearestBlock(itemFrame) == mBlock) {
+        PruneDisplayListContents(wrapper, aFramesToHide, aInsideMarkersArea);
+      }
+    }
+
+    nsDisplayText* textItem =
+        itemFrame ? nsDisplayText::CheckCast(item) : nullptr;
+    if (textItem && GetSelfOrNearestBlock(itemFrame) == mBlock) {
+      LogicalRect rect =
+          GetLogicalScrollableOverflowRectRelativeToBlock(itemFrame);
+      if (mIStart.IsNeeded()) {
+        nscoord istart =
+            aInsideMarkersArea.IStart(mBlockWM) - rect.IStart(mBlockWM);
+        if (istart > 0) {
+          (mBlockWM.IsBidiLTR() ? textItem->VisIStartEdge()
+                                : textItem->VisIEndEdge()) = istart;
+        }
+      }
+      if (mIEnd.IsNeeded()) {
+        nscoord iend = rect.IEnd(mBlockWM) - aInsideMarkersArea.IEnd(mBlockWM);
+        if (iend > 0) {
+          (mBlockWM.IsBidiLTR() ? textItem->VisIEndEdge()
+                                : textItem->VisIStartEdge()) = iend;
+        }
+      }
+    }
+
+    aList->AppendToTop(item);
+  }
+}
+
+/* static */
+bool TextOverflow::HasClippedTextOverflow(nsIFrame* aBlockFrame) {
+  const nsStyleTextReset* style = aBlockFrame->StyleTextReset();
+  return style->mTextOverflow.first.IsClip() &&
+         style->mTextOverflow.second.IsClip();
+}
+
+/* static */
+bool TextOverflow::HasBlockEllipsis(nsIFrame* aBlockFrame) {
+  nsBlockFrame* f = do_QueryFrame(aBlockFrame);
+  return f && f->HasAnyStateBits(NS_BLOCK_HAS_LINE_CLAMP_ELLIPSIS);
+}
+
+static bool BlockCanHaveLineClampEllipsis(nsBlockFrame* aBlockFrame,
+                                          bool aBeforeReflow) {
+  if (aBeforeReflow) {
+    return aBlockFrame->IsInLineClampContext();
+  }
+  return aBlockFrame->HasAnyStateBits(NS_BLOCK_HAS_LINE_CLAMP_ELLIPSIS);
+}
+
+/* static */
+bool TextOverflow::CanHaveOverflowMarkers(nsBlockFrame* aBlockFrame,
+                                          BeforeReflow aBeforeReflow) {
+  if (BlockCanHaveLineClampEllipsis(aBlockFrame,
+                                    aBeforeReflow == BeforeReflow::Yes)) {
+    return true;
+  }
+
+  // Nothing to do for text-overflow:clip or if 'overflow-x/y:visible'.
+  if (HasClippedTextOverflow(aBlockFrame) ||
+      IsInlineAxisOverflowVisible(aBlockFrame)) {
+    return false;
+  }
+
+  // Skip ComboboxControlFrame because it would clip the drop-down arrow.
+  // Its anon block inherits 'text-overflow' and does what is expected.
+  if (aBlockFrame->IsComboboxControlFrame()) {
+    return false;
+  }
+
+  // Inhibit the markers if a descendant content owns the caret.
+  RefPtr<nsCaret> caret = aBlockFrame->PresShell()->GetCaret();
+  if (caret && caret->IsVisible()) {
+    RefPtr<dom::Selection> domSelection = caret->GetSelection();
+    if (domSelection) {
+      nsCOMPtr<nsIContent> content =
+          nsIContent::FromNodeOrNull(domSelection->GetFocusNode());
+      if (content &&
+          content->IsInclusiveDescendantOf(aBlockFrame->GetContent())) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+void TextOverflow::CreateMarkers(const nsLineBox* aLine, bool aCreateIStart,
+                                 bool aCreateIEnd,
+                                 const LogicalRect& aInsideMarkersArea,
+                                 const LogicalRect& aContentArea,
+                                 uint32_t aLineNumber) {
+  if (!mBlock->IsVisibleForPainting()) {
+    return;
+  }
+
+  if (aCreateIStart) {
+    DisplayListClipState::AutoSaveRestore clipState(mBuilder);
+
+    LogicalRect markerLogicalRect(
+        mBlockWM, aInsideMarkersArea.IStart(mBlockWM) - mIStart.mIntrinsicISize,
+        aLine->BStart(), mIStart.mIntrinsicISize, aLine->BSize());
+    nsPoint offset = mBuilder->ToReferenceFrame(mBlock);
+    nsRect markerRect =
+        markerLogicalRect.GetPhysicalRect(mBlockWM, mBlockSize) + offset;
+    ClipMarker(aContentArea.GetPhysicalRect(mBlockWM, mBlockSize) + offset,
+               markerRect, clipState);
+
+    mMarkerList.AppendNewToTopWithIndex<nsDisplayTextOverflowMarker>(
+        mBuilder, mBlock, /* aIndex = */ (aLineNumber << 1) + 0, markerRect,
+        aLine->GetLogicalAscent(), *mIStart.mStyle);
+  }
+
+  if (aCreateIEnd) {
+    DisplayListClipState::AutoSaveRestore clipState(mBuilder);
+
+    LogicalRect markerLogicalRect(mBlockWM, aInsideMarkersArea.IEnd(mBlockWM),
+                                  aLine->BStart(), mIEnd.mIntrinsicISize,
+                                  aLine->BSize());
+    nsPoint offset = mBuilder->ToReferenceFrame(mBlock);
+    nsRect markerRect =
+        markerLogicalRect.GetPhysicalRect(mBlockWM, mBlockSize) + offset;
+    ClipMarker(aContentArea.GetPhysicalRect(mBlockWM, mBlockSize) + offset,
+               markerRect, clipState);
+
+    mMarkerList.AppendNewToTopWithIndex<nsDisplayTextOverflowMarker>(
+        mBuilder, mBlock, /* aIndex = */ (aLineNumber << 1) + 1, markerRect,
+        aLine->GetLogicalAscent(),
+        mIEnd.mHasBlockEllipsis ? StyleTextOverflowSide::Ellipsis()
+                                : *mIEnd.mStyle);
+  }
+}
+
+void TextOverflow::Marker::SetupString(nsIFrame* aFrame) {
+  if (mInitialized) {
+    return;
+  }
+
+  // A limitation here is that at the IEnd of a line, we only ever render one of
+  // a text-overflow marker and a -webkit-line-clamp block ellipsis.  Since we
+  // don't track the block ellipsis string and the text-overflow marker string
+  // separately, if both apply to the element, we will always use "…" as the
+  // string for text-overflow.
+  if (HasBlockEllipsis(aFrame) || mStyle->IsEllipsis()) {
+    gfxTextRun* textRun = GetEllipsisTextRun(aFrame);
+    if (textRun) {
+      mISize = textRun->GetAdvanceWidth();
+    } else {
+      mISize = 0;
+    }
+  } else {
+    UniquePtr<gfxContext> rc =
+        aFrame->PresShell()->CreateReferenceRenderingContext();
+    RefPtr<nsFontMetrics> fm =
+        nsLayoutUtils::GetInflatedFontMetricsForFrame(aFrame);
+    mISize = nsLayoutUtils::AppUnitWidthOfStringBidi(
+        NS_ConvertUTF8toUTF16(mStyle->AsString().AsString()), aFrame, *fm, *rc);
+  }
+  mIntrinsicISize = mISize;
+  mInitialized = true;
+}
+
+}  // namespace css
+}  // namespace mozilla