1 files changed, 315 insertions, 0 deletions
diff --git a/layout/generic/ColumnSetWrapperFrame.cpp b/layout/generic/ColumnSetWrapperFrame.cpp
new file mode 100644
index 0000000000..0f142ef4f3
--- /dev/null
+++ b/layout/generic/ColumnSetWrapperFrame.cpp
@@ -0,0 +1,315 @@
+/* -*- 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 https://mozilla.org/MPL/2.0/. */
+
+#include "ColumnSetWrapperFrame.h"
+
+#include "mozilla/ColumnUtils.h"
+#include "mozilla/PresShell.h"
+#include "nsContentUtils.h"
+#include "nsIFrame.h"
+#include "nsIFrameInlines.h"
+
+using namespace mozilla;
+
+nsBlockFrame* NS_NewColumnSetWrapperFrame(PresShell* aPresShell,
+                                          ComputedStyle* aStyle,
+                                          nsFrameState aStateFlags) {
+  ColumnSetWrapperFrame* frame = new (aPresShell)
+      ColumnSetWrapperFrame(aStyle, aPresShell->GetPresContext());
+
+  // CSS Multi-column level 1 section 2: A multi-column container
+  // establishes a new block formatting context, as per CSS 2.1 section
+  // 9.4.1.
+  frame->AddStateBits(aStateFlags | NS_BLOCK_FORMATTING_CONTEXT_STATE_BITS);
+  return frame;
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(ColumnSetWrapperFrame)
+
+NS_QUERYFRAME_HEAD(ColumnSetWrapperFrame)
+  NS_QUERYFRAME_ENTRY(ColumnSetWrapperFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsBlockFrame)
+
+ColumnSetWrapperFrame::ColumnSetWrapperFrame(ComputedStyle* aStyle,
+                                             nsPresContext* aPresContext)
+    : nsBlockFrame(aStyle, aPresContext, kClassID) {}
+
+void ColumnSetWrapperFrame::Init(nsIContent* aContent,
+                                 nsContainerFrame* aParent,
+                                 nsIFrame* aPrevInFlow) {
+  nsBlockFrame::Init(aContent, aParent, aPrevInFlow);
+
+  // ColumnSetWrapperFrame doesn't need to call ResolveBidi().
+  RemoveStateBits(NS_BLOCK_NEEDS_BIDI_RESOLUTION);
+}
+
+nsContainerFrame* ColumnSetWrapperFrame::GetContentInsertionFrame() {
+  nsIFrame* columnSet = PrincipalChildList().OnlyChild();
+  if (columnSet) {
+    // We have only one child, which means we don't have any column-span
+    // descendants. Thus we can safely return our only ColumnSet child's
+    // insertion frame as ours.
+    MOZ_ASSERT(columnSet->IsColumnSetFrame());
+    return columnSet->GetContentInsertionFrame();
+  }
+
+  // We have column-span descendants. Return ourselves as the insertion
+  // frame to let nsCSSFrameConstructor::WipeContainingBlock() figure out
+  // what to do.
+  return this;
+}
+
+void ColumnSetWrapperFrame::AppendDirectlyOwnedAnonBoxes(
+    nsTArray<OwnedAnonBox>& aResult) {
+  MOZ_ASSERT(!GetPrevContinuation(),
+             "Who set NS_FRAME_OWNS_ANON_BOXES on our continuations?");
+
+  // It's sufficient to append the first ColumnSet child, which is the first
+  // continuation of all the other ColumnSets.
+  //
+  // We don't need to append -moz-column-span-wrapper children because
+  // they're non-inheriting anon boxes, and they cannot have any directly
+  // owned anon boxes nor generate any native anonymous content themselves.
+  // Thus, no need to restyle them. AssertColumnSpanWrapperSubtreeIsSane()
+  // asserts all the conditions above which allow us to skip appending
+  // -moz-column-span-wrappers.
+  auto FindFirstChildInChildLists = [this]() -> nsIFrame* {
+    const ChildListID listIDs[] = {FrameChildListID::Principal,
+                                   FrameChildListID::Overflow};
+    for (nsIFrame* frag = this; frag; frag = frag->GetNextInFlow()) {
+      for (ChildListID id : listIDs) {
+        const nsFrameList& list = frag->GetChildList(id);
+        if (nsIFrame* firstChild = list.FirstChild()) {
+          return firstChild;
+        }
+      }
+    }
+    return nullptr;
+  };
+
+  nsIFrame* columnSet = FindFirstChildInChildLists();
+  MOZ_ASSERT(columnSet && columnSet->IsColumnSetFrame(),
+             "The first child should always be ColumnSet!");
+  aResult.AppendElement(OwnedAnonBox(columnSet));
+}
+
+#ifdef DEBUG_FRAME_DUMP
+nsresult ColumnSetWrapperFrame::GetFrameName(nsAString& aResult) const {
+  return MakeFrameName(u"ColumnSetWrapper"_ns, aResult);
+}
+#endif
+
+// Disallow any append, insert, or remove operations after building the
+// column hierarchy since any change to the column hierarchy in the column
+// sub-tree need to be re-created.
+void ColumnSetWrapperFrame::AppendFrames(ChildListID aListID,
+                                         nsFrameList&& aFrameList) {
+#ifdef DEBUG
+  MOZ_ASSERT(!mFinishedBuildingColumns, "Should only call once!");
+  mFinishedBuildingColumns = true;
+#endif
+
+  nsBlockFrame::AppendFrames(aListID, std::move(aFrameList));
+
+#ifdef DEBUG
+  nsIFrame* firstColumnSet = PrincipalChildList().FirstChild();
+  for (nsIFrame* child : PrincipalChildList()) {
+    if (child->IsColumnSpan()) {
+      AssertColumnSpanWrapperSubtreeIsSane(child);
+    } else if (child != firstColumnSet) {
+      // All the other ColumnSets are the continuation of the first ColumnSet.
+      MOZ_ASSERT(child->IsColumnSetFrame() && child->GetPrevContinuation(),
+                 "ColumnSet's prev-continuation is not set properly?");
+    }
+  }
+#endif
+}
+
+void ColumnSetWrapperFrame::InsertFrames(
+    ChildListID aListID, nsIFrame* aPrevFrame,
+    const nsLineList::iterator* aPrevFrameLine, nsFrameList&& aFrameList) {
+  MOZ_ASSERT_UNREACHABLE("Unsupported operation!");
+  nsBlockFrame::InsertFrames(aListID, aPrevFrame, aPrevFrameLine,
+                             std::move(aFrameList));
+}
+
+void ColumnSetWrapperFrame::RemoveFrame(DestroyContext& aContext,
+                                        ChildListID aListID,
+                                        nsIFrame* aOldFrame) {
+  MOZ_ASSERT_UNREACHABLE("Unsupported operation!");
+  nsBlockFrame::RemoveFrame(aContext, aListID, aOldFrame);
+}
+
+void ColumnSetWrapperFrame::MarkIntrinsicISizesDirty() {
+  nsBlockFrame::MarkIntrinsicISizesDirty();
+
+  // The parent's method adds NS_BLOCK_NEEDS_BIDI_RESOLUTION to all our
+  // continuations. Clear the bit because we don't want to call ResolveBidi().
+  for (nsIFrame* f = FirstContinuation(); f; f = f->GetNextContinuation()) {
+    f->RemoveStateBits(NS_BLOCK_NEEDS_BIDI_RESOLUTION);
+  }
+}
+
+nscoord ColumnSetWrapperFrame::GetMinISize(gfxContext* aRenderingContext) {
+  nscoord iSize = 0;
+  DISPLAY_MIN_INLINE_SIZE(this, iSize);
+
+  if (Maybe<nscoord> containISize =
+          ContainIntrinsicISize(NS_UNCONSTRAINEDSIZE)) {
+    // If we're size-contained in inline axis and contain-intrinsic-inline-size
+    // is not 'none', then use that size.
+    if (*containISize != NS_UNCONSTRAINEDSIZE) {
+      return *containISize;
+    }
+
+    // In the 'none' case, we determine our minimum intrinsic size purely from
+    // our column styling, as if we had no descendants. This should match what
+    // happens in nsColumnSetFrame::GetMinISize in an actual no-descendants
+    // scenario.
+    const nsStyleColumn* colStyle = StyleColumn();
+    if (colStyle->mColumnWidth.IsLength()) {
+      // As available inline size reduces to zero, our number of columns reduces
+      // to one, so no column gaps contribute to our minimum intrinsic size.
+      // Also, column-width doesn't set a lower bound on our minimum intrinsic
+      // size, either. Just use 0 because we're size-contained.
+      iSize = 0;
+    } else {
+      MOZ_ASSERT(colStyle->mColumnCount != nsStyleColumn::kColumnCountAuto,
+                 "column-count and column-width can't both be auto!");
+      // As available inline size reduces to zero, we still have mColumnCount
+      // columns, so compute our minimum intrinsic size based on N zero-width
+      // columns, with specified gap size between them.
+      const nscoord colGap =
+          ColumnUtils::GetColumnGap(this, NS_UNCONSTRAINEDSIZE);
+      iSize = ColumnUtils::IntrinsicISize(colStyle->mColumnCount, colGap, 0);
+    }
+  } else {
+    for (nsIFrame* f : PrincipalChildList()) {
+      iSize = std::max(iSize, f->GetMinISize(aRenderingContext));
+    }
+  }
+
+  return iSize;
+}
+
+nscoord ColumnSetWrapperFrame::GetPrefISize(gfxContext* aRenderingContext) {
+  nscoord iSize = 0;
+  DISPLAY_PREF_INLINE_SIZE(this, iSize);
+
+  if (Maybe<nscoord> containISize =
+          ContainIntrinsicISize(NS_UNCONSTRAINEDSIZE)) {
+    if (*containISize != NS_UNCONSTRAINEDSIZE) {
+      return *containISize;
+    }
+
+    const nsStyleColumn* colStyle = StyleColumn();
+    nscoord colISize;
+    if (colStyle->mColumnWidth.IsLength()) {
+      colISize =
+          ColumnUtils::ClampUsedColumnWidth(colStyle->mColumnWidth.AsLength());
+    } else {
+      MOZ_ASSERT(colStyle->mColumnCount != nsStyleColumn::kColumnCountAuto,
+                 "column-count and column-width can't both be auto!");
+      colISize = 0;
+    }
+
+    // If column-count is auto, assume one column.
+    const uint32_t numColumns =
+        colStyle->mColumnCount == nsStyleColumn::kColumnCountAuto
+            ? 1
+            : colStyle->mColumnCount;
+    const nscoord colGap =
+        ColumnUtils::GetColumnGap(this, NS_UNCONSTRAINEDSIZE);
+    iSize = ColumnUtils::IntrinsicISize(numColumns, colGap, colISize);
+  } else {
+    for (nsIFrame* f : PrincipalChildList()) {
+      iSize = std::max(iSize, f->GetPrefISize(aRenderingContext));
+    }
+  }
+
+  return iSize;
+}
+
+template <typename Iterator>
+Maybe<nscoord> ColumnSetWrapperFrame::GetBaselineBOffset(
+    Iterator aStart, Iterator aEnd, WritingMode aWM,
+    BaselineSharingGroup aBaselineGroup,
+    BaselineExportContext aExportContext) const {
+  // Either forward iterator + first baseline, or reverse iterator + last
+  // baseline
+  MOZ_ASSERT((*aStart == PrincipalChildList().FirstChild() &&
+              aBaselineGroup == BaselineSharingGroup::First) ||
+                 (*aStart == PrincipalChildList().LastChild() &&
+                  aBaselineGroup == BaselineSharingGroup::Last),
+             "Iterator direction must match baseline sharing group.");
+  if (StyleDisplay()->IsContainLayout()) {
+    return Nothing{};
+  }
+
+  // Start from start/end of principal child list, and use the first valid
+  // baseline.
+  for (auto itr = aStart; itr != aEnd; ++itr) {
+    const nsIFrame* kid = *itr;
+    auto kidBaseline =
+        kid->GetNaturalBaselineBOffset(aWM, aBaselineGroup, aExportContext);
+    if (!kidBaseline) {
+      continue;
+    }
+    // Baseline is offset from the kid's rectangle, so find the offset to the
+    // kid's rectangle.
+    LogicalRect kidRect{aWM, kid->GetLogicalNormalPosition(aWM, GetSize()),
+                        kid->GetLogicalSize(aWM)};
+    if (aBaselineGroup == BaselineSharingGroup::First) {
+      *kidBaseline += kidRect.BStart(aWM);
+    } else {
+      *kidBaseline += (GetLogicalSize().BSize(aWM) - kidRect.BEnd(aWM));
+    }
+    return kidBaseline;
+  }
+  return Nothing{};
+}
+
+Maybe<nscoord> ColumnSetWrapperFrame::GetNaturalBaselineBOffset(
+    WritingMode aWM, BaselineSharingGroup aBaselineGroup,
+    BaselineExportContext aExportContext) const {
+  if (aBaselineGroup == BaselineSharingGroup::First) {
+    return GetBaselineBOffset(PrincipalChildList().cbegin(),
+                              PrincipalChildList().cend(), aWM, aBaselineGroup,
+                              aExportContext);
+  }
+  return GetBaselineBOffset(PrincipalChildList().crbegin(),
+                            PrincipalChildList().crend(), aWM, aBaselineGroup,
+                            aExportContext);
+}
+
+#ifdef DEBUG
+
+/* static */
+void ColumnSetWrapperFrame::AssertColumnSpanWrapperSubtreeIsSane(
+    const nsIFrame* aFrame) {
+  MOZ_ASSERT(aFrame->IsColumnSpan(), "aFrame is not column-span?");
+
+  if (!nsLayoutUtils::GetStyleFrame(const_cast<nsIFrame*>(aFrame))
+           ->Style()
+           ->IsAnonBox()) {
+    // aFrame's style frame has "column-span: all". Traverse no further.
+    return;
+  }
+
+  MOZ_ASSERT(
+      aFrame->Style()->GetPseudoType() == PseudoStyleType::columnSpanWrapper,
+      "aFrame should be ::-moz-column-span-wrapper");
+
+  MOZ_ASSERT(!aFrame->HasAnyStateBits(NS_FRAME_OWNS_ANON_BOXES),
+             "::-moz-column-span-wrapper anonymous blocks cannot own "
+             "other types of anonymous blocks!");
+
+  for (const nsIFrame* child : aFrame->PrincipalChildList()) {
+    AssertColumnSpanWrapperSubtreeIsSane(child);
+  }
+}
+
+#endif