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/* -*- 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 */
#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.
return frame;
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().
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.
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) {
"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[] = {kPrincipalList, kOverflowList};
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!");
nsresult ColumnSetWrapperFrame::GetFrameName(nsAString& aResult) const {
return MakeFrameName(u"ColumnSetWrapper"_ns, aResult);
// 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;
nsBlockFrame::AppendFrames(aListID, aFrameList);
#ifdef DEBUG
nsIFrame* firstColumnSet = PrincipalChildList().FirstChild();
for (nsIFrame* child : PrincipalChildList()) {
if (child->IsColumnSpan()) {
} 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?");
void ColumnSetWrapperFrame::InsertFrames(
ChildListID aListID, nsIFrame* aPrevFrame,
const nsLineList::iterator* aPrevFrameLine, nsFrameList& aFrameList) {
MOZ_ASSERT_UNREACHABLE("Unsupported operation!");
nsBlockFrame::InsertFrames(aListID, aPrevFrame, aPrevFrameLine, aFrameList);
void ColumnSetWrapperFrame::RemoveFrame(ChildListID aListID,
nsIFrame* aOldFrame) {
MOZ_ASSERT_UNREACHABLE("Unsupported operation!");
nsBlockFrame::RemoveFrame(aListID, aOldFrame);
void ColumnSetWrapperFrame::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()) {
nscoord ColumnSetWrapperFrame::GetMinISize(gfxContext* aRenderingContext) {
nscoord iSize = 0;
if (StyleDisplay()->IsContainSize()) {
// If we're size-contained, 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;
if (StyleDisplay()->IsContainSize()) {
const nsStyleColumn* colStyle = StyleColumn();
nscoord colISize;
if (colStyle->mColumnWidth.IsLength()) {
colISize =
} 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;
#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))
->IsAnonBox()) {
// aFrame's style frame has "column-span: all". Traverse no further.
aFrame->Style()->GetPseudoType() == PseudoStyleType::columnSpanWrapper,
"aFrame should be ::-moz-column-span-wrapper");
"::-moz-column-span-wrapper anonymous blocks cannot own "
"other types of anonymous blocks!");
for (const nsIFrame* child : aFrame->PrincipalChildList()) {