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-rw-r--r--layout/generic/nsColumnSetFrame.cpp1353
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diff --git a/layout/generic/nsColumnSetFrame.cpp b/layout/generic/nsColumnSetFrame.cpp
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+++ b/layout/generic/nsColumnSetFrame.cpp
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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 http://mozilla.org/MPL/2.0/. */
+
+/* rendering object for css3 multi-column layout */
+
+#include "nsColumnSetFrame.h"
+
+#include "mozilla/ColumnUtils.h"
+#include "mozilla/Logging.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/StaticPrefs_layout.h"
+#include "mozilla/ToString.h"
+#include "nsCSSRendering.h"
+#include "nsDisplayList.h"
+#include "nsIFrameInlines.h"
+#include "nsLayoutUtils.h"
+
+using namespace mozilla;
+using namespace mozilla::layout;
+
+// To see this log, use $ MOZ_LOG=ColumnSet:4 ./mach run
+static LazyLogModule sColumnSetLog("ColumnSet");
+#define COLUMN_SET_LOG(msg, ...) \
+ MOZ_LOG(sColumnSetLog, LogLevel::Debug, (msg, ##__VA_ARGS__))
+
+class nsDisplayColumnRule : public nsPaintedDisplayItem {
+ public:
+ nsDisplayColumnRule(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame)
+ : nsPaintedDisplayItem(aBuilder, aFrame) {
+ MOZ_COUNT_CTOR(nsDisplayColumnRule);
+ }
+ MOZ_COUNTED_DTOR_OVERRIDE(nsDisplayColumnRule)
+
+ nsRect GetBounds(nsDisplayListBuilder* aBuilder, bool* aSnap) const override {
+ *aSnap = false;
+ // We just return the frame's ink-overflow rect, which is guaranteed to
+ // contain all the column-rule areas. It's not worth calculating the exact
+ // union of those areas since it would only lead to performance improvements
+ // during painting in rare edge cases.
+ return mFrame->InkOverflowRect() + ToReferenceFrame();
+ }
+
+ bool CreateWebRenderCommands(
+ mozilla::wr::DisplayListBuilder& aBuilder,
+ mozilla::wr::IpcResourceUpdateQueue& aResources,
+ const StackingContextHelper& aSc,
+ mozilla::layers::RenderRootStateManager* aManager,
+ nsDisplayListBuilder* aDisplayListBuilder) override;
+ void Paint(nsDisplayListBuilder* aBuilder, gfxContext* aCtx) override;
+
+ NS_DISPLAY_DECL_NAME("ColumnRule", TYPE_COLUMN_RULE);
+
+ private:
+ nsTArray<nsCSSBorderRenderer> mBorderRenderers;
+};
+
+void nsDisplayColumnRule::Paint(nsDisplayListBuilder* aBuilder,
+ gfxContext* aCtx) {
+ static_cast<nsColumnSetFrame*>(mFrame)->CreateBorderRenderers(
+ mBorderRenderers, aCtx, GetPaintRect(aBuilder, aCtx), ToReferenceFrame());
+
+ for (auto iter = mBorderRenderers.begin(); iter != mBorderRenderers.end();
+ iter++) {
+ iter->DrawBorders();
+ }
+}
+
+bool nsDisplayColumnRule::CreateWebRenderCommands(
+ mozilla::wr::DisplayListBuilder& aBuilder,
+ mozilla::wr::IpcResourceUpdateQueue& aResources,
+ const StackingContextHelper& aSc,
+ mozilla::layers::RenderRootStateManager* aManager,
+ nsDisplayListBuilder* aDisplayListBuilder) {
+ RefPtr dt = gfxPlatform::GetPlatform()->ScreenReferenceDrawTarget();
+ if (!dt || !dt->IsValid()) {
+ return false;
+ }
+ gfxContext screenRefCtx(dt);
+
+ bool dummy;
+ static_cast<nsColumnSetFrame*>(mFrame)->CreateBorderRenderers(
+ mBorderRenderers, &screenRefCtx, GetBounds(aDisplayListBuilder, &dummy),
+ ToReferenceFrame());
+
+ if (mBorderRenderers.IsEmpty()) {
+ return true;
+ }
+
+ for (auto& renderer : mBorderRenderers) {
+ renderer.CreateWebRenderCommands(this, aBuilder, aResources, aSc);
+ }
+
+ return true;
+}
+
+/**
+ * Tracking issues:
+ *
+ * XXX cursor movement around the top and bottom of colums seems to make the
+ * editor lose the caret.
+ *
+ * XXX should we support CSS columns applied to table elements?
+ */
+nsContainerFrame* NS_NewColumnSetFrame(PresShell* aPresShell,
+ ComputedStyle* aStyle,
+ nsFrameState aStateFlags) {
+ nsColumnSetFrame* it =
+ new (aPresShell) nsColumnSetFrame(aStyle, aPresShell->GetPresContext());
+ it->AddStateBits(aStateFlags);
+ return it;
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsColumnSetFrame)
+
+nsColumnSetFrame::nsColumnSetFrame(ComputedStyle* aStyle,
+ nsPresContext* aPresContext)
+ : nsContainerFrame(aStyle, aPresContext, kClassID),
+ mLastBalanceBSize(NS_UNCONSTRAINEDSIZE) {}
+
+void nsColumnSetFrame::ForEachColumnRule(
+ const std::function<void(const nsRect& lineRect)>& aSetLineRect,
+ const nsPoint& aPt) const {
+ nsIFrame* child = mFrames.FirstChild();
+ if (!child) return; // no columns
+
+ nsIFrame* nextSibling = child->GetNextSibling();
+ if (!nextSibling) return; // 1 column only - this means no gap to draw on
+
+ const nsStyleColumn* colStyle = StyleColumn();
+ nscoord ruleWidth = colStyle->GetColumnRuleWidth();
+ if (!ruleWidth) return;
+
+ WritingMode wm = GetWritingMode();
+ bool isVertical = wm.IsVertical();
+ bool isRTL = wm.IsBidiRTL();
+
+ nsRect contentRect = GetContentRectRelativeToSelf() + aPt;
+ nsSize ruleSize = isVertical ? nsSize(contentRect.width, ruleWidth)
+ : nsSize(ruleWidth, contentRect.height);
+
+ while (nextSibling) {
+ // The frame tree goes RTL in RTL.
+ // The |prevFrame| and |nextFrame| frames here are the visually preceding
+ // (left/above) and following (right/below) frames, not in logical writing-
+ // mode direction.
+ nsIFrame* prevFrame = isRTL ? nextSibling : child;
+ nsIFrame* nextFrame = isRTL ? child : nextSibling;
+
+ // Each child frame's position coordinates is actually relative to this
+ // nsColumnSetFrame.
+ // linePt will be at the top-left edge to paint the line.
+ nsPoint linePt;
+ if (isVertical) {
+ nscoord edgeOfPrev = prevFrame->GetRect().YMost() + aPt.y;
+ nscoord edgeOfNext = nextFrame->GetRect().Y() + aPt.y;
+ linePt = nsPoint(contentRect.x,
+ (edgeOfPrev + edgeOfNext - ruleSize.height) / 2);
+ } else {
+ nscoord edgeOfPrev = prevFrame->GetRect().XMost() + aPt.x;
+ nscoord edgeOfNext = nextFrame->GetRect().X() + aPt.x;
+ linePt = nsPoint((edgeOfPrev + edgeOfNext - ruleSize.width) / 2,
+ contentRect.y);
+ }
+
+ aSetLineRect(nsRect(linePt, ruleSize));
+
+ child = nextSibling;
+ nextSibling = nextSibling->GetNextSibling();
+ }
+}
+
+void nsColumnSetFrame::CreateBorderRenderers(
+ nsTArray<nsCSSBorderRenderer>& aBorderRenderers, gfxContext* aCtx,
+ const nsRect& aDirtyRect, const nsPoint& aPt) {
+ WritingMode wm = GetWritingMode();
+ bool isVertical = wm.IsVertical();
+ const nsStyleColumn* colStyle = StyleColumn();
+ StyleBorderStyle ruleStyle;
+
+ // Per spec, inset => ridge and outset => groove
+ if (colStyle->mColumnRuleStyle == StyleBorderStyle::Inset) {
+ ruleStyle = StyleBorderStyle::Ridge;
+ } else if (colStyle->mColumnRuleStyle == StyleBorderStyle::Outset) {
+ ruleStyle = StyleBorderStyle::Groove;
+ } else {
+ ruleStyle = colStyle->mColumnRuleStyle;
+ }
+
+ nscoord ruleWidth = colStyle->GetColumnRuleWidth();
+ if (!ruleWidth) {
+ return;
+ }
+
+ aBorderRenderers.Clear();
+ nscolor ruleColor =
+ GetVisitedDependentColor(&nsStyleColumn::mColumnRuleColor);
+
+ nsPresContext* pc = PresContext();
+ // In order to re-use a large amount of code, we treat the column rule as a
+ // border. We create a new border style object and fill in all the details of
+ // the column rule as the left border. PaintBorder() does all the rendering
+ // for us, so we not only save an enormous amount of code but we'll support
+ // all the line styles that we support on borders!
+ nsStyleBorder border(*pc->Document());
+ Sides skipSides;
+ if (isVertical) {
+ border.SetBorderWidth(eSideTop, ruleWidth, pc->AppUnitsPerDevPixel());
+ border.SetBorderStyle(eSideTop, ruleStyle);
+ border.mBorderTopColor = StyleColor::FromColor(ruleColor);
+ skipSides |= mozilla::SideBits::eLeftRight;
+ skipSides |= mozilla::SideBits::eBottom;
+ } else {
+ border.SetBorderWidth(eSideLeft, ruleWidth, pc->AppUnitsPerDevPixel());
+ border.SetBorderStyle(eSideLeft, ruleStyle);
+ border.mBorderLeftColor = StyleColor::FromColor(ruleColor);
+ skipSides |= mozilla::SideBits::eTopBottom;
+ skipSides |= mozilla::SideBits::eRight;
+ }
+ // If we use box-decoration-break: slice (the default), the border
+ // renderers will require clipping if we have continuations (see the
+ // aNeedsClip parameter to ConstructBorderRenderer in nsCSSRendering).
+ //
+ // Since it doesn't matter which box-decoration-break we use since
+ // we're only drawing borders (and not border-images), use 'clone'.
+ border.mBoxDecorationBreak = StyleBoxDecorationBreak::Clone;
+
+ ForEachColumnRule(
+ [&](const nsRect& aLineRect) {
+ // Assert that we're not drawing a border-image here; if we were, we
+ // couldn't ignore the ImgDrawResult that PaintBorderWithStyleBorder
+ // returns.
+ MOZ_ASSERT(border.mBorderImageSource.IsNone());
+
+ gfx::DrawTarget* dt = aCtx ? aCtx->GetDrawTarget() : nullptr;
+ bool borderIsEmpty = false;
+ Maybe<nsCSSBorderRenderer> br =
+ nsCSSRendering::CreateBorderRendererWithStyleBorder(
+ pc, dt, this, aDirtyRect, aLineRect, border, Style(),
+ &borderIsEmpty, skipSides);
+ if (br.isSome()) {
+ MOZ_ASSERT(!borderIsEmpty);
+ aBorderRenderers.AppendElement(br.value());
+ }
+ },
+ aPt);
+}
+
+static uint32_t ColumnBalancingDepth(const ReflowInput& aReflowInput,
+ uint32_t aMaxDepth) {
+ uint32_t depth = 0;
+ for (const ReflowInput* ri = aReflowInput.mParentReflowInput;
+ ri && depth < aMaxDepth; ri = ri->mParentReflowInput) {
+ if (ri->mFlags.mIsColumnBalancing) {
+ ++depth;
+ }
+ }
+ return depth;
+}
+
+nsColumnSetFrame::ReflowConfig nsColumnSetFrame::ChooseColumnStrategy(
+ const ReflowInput& aReflowInput, bool aForceAuto = false) const {
+ const nsStyleColumn* colStyle = StyleColumn();
+ nscoord availContentISize = aReflowInput.AvailableISize();
+ if (aReflowInput.ComputedISize() != NS_UNCONSTRAINEDSIZE) {
+ availContentISize = aReflowInput.ComputedISize();
+ }
+
+ nscoord colBSize = aReflowInput.AvailableBSize();
+ nscoord colGap =
+ ColumnUtils::GetColumnGap(this, aReflowInput.ComputedISize());
+ int32_t numColumns = colStyle->mColumnCount;
+
+ // If column-fill is set to 'balance' or we have a column-span sibling, then
+ // we want to balance the columns.
+ bool isBalancing = (colStyle->mColumnFill == StyleColumnFill::Balance ||
+ HasColumnSpanSiblings()) &&
+ !aForceAuto;
+ if (isBalancing) {
+ const uint32_t kMaxNestedColumnBalancingDepth = 2;
+ const uint32_t balancingDepth =
+ ColumnBalancingDepth(aReflowInput, kMaxNestedColumnBalancingDepth);
+ if (balancingDepth == kMaxNestedColumnBalancingDepth) {
+ isBalancing = false;
+ numColumns = 1;
+ }
+ }
+
+ nscoord colISize;
+ // In vertical writing-mode, "column-width" (inline size) will actually be
+ // physical height, but its CSS name is still column-width.
+ if (colStyle->mColumnWidth.IsLength()) {
+ colISize =
+ ColumnUtils::ClampUsedColumnWidth(colStyle->mColumnWidth.AsLength());
+ NS_ASSERTION(colISize >= 0, "negative column width");
+ // Reduce column count if necessary to make columns fit in the
+ // available width. Compute max number of columns that fit in
+ // availContentISize, satisfying colGap*(maxColumns - 1) +
+ // colISize*maxColumns <= availContentISize
+ if (availContentISize != NS_UNCONSTRAINEDSIZE && colGap + colISize > 0 &&
+ numColumns > 0) {
+ // This expression uses truncated rounding, which is what we
+ // want
+ int32_t maxColumns =
+ std::min(nscoord(nsStyleColumn::kMaxColumnCount),
+ (availContentISize + colGap) / (colGap + colISize));
+ numColumns = std::max(1, std::min(numColumns, maxColumns));
+ }
+ } else if (numColumns > 0 && availContentISize != NS_UNCONSTRAINEDSIZE) {
+ nscoord iSizeMinusGaps = availContentISize - colGap * (numColumns - 1);
+ colISize = iSizeMinusGaps / numColumns;
+ } else {
+ colISize = NS_UNCONSTRAINEDSIZE;
+ }
+ // Take care of the situation where there's only one column but it's
+ // still too wide
+ colISize = std::max(1, std::min(colISize, availContentISize));
+
+ nscoord expectedISizeLeftOver = 0;
+
+ if (colISize != NS_UNCONSTRAINEDSIZE &&
+ availContentISize != NS_UNCONSTRAINEDSIZE) {
+ // distribute leftover space
+
+ // First, determine how many columns will be showing if the column
+ // count is auto
+ if (numColumns <= 0) {
+ // choose so that colGap*(nominalColumnCount - 1) +
+ // colISize*nominalColumnCount is nearly availContentISize
+ // make sure to round down
+ if (colGap + colISize > 0) {
+ numColumns = (availContentISize + colGap) / (colGap + colISize);
+ // The number of columns should never exceed kMaxColumnCount.
+ numColumns =
+ std::min(nscoord(nsStyleColumn::kMaxColumnCount), numColumns);
+ }
+ if (numColumns <= 0) {
+ numColumns = 1;
+ }
+ }
+
+ // Compute extra space and divide it among the columns
+ nscoord extraSpace =
+ std::max(0, availContentISize -
+ (colISize * numColumns + colGap * (numColumns - 1)));
+ nscoord extraToColumns = extraSpace / numColumns;
+ colISize += extraToColumns;
+ expectedISizeLeftOver = extraSpace - (extraToColumns * numColumns);
+ }
+
+ if (isBalancing) {
+ if (numColumns <= 0) {
+ // Hmm, auto column count, column width or available width is unknown,
+ // and balancing is required. Let's just use one column then.
+ numColumns = 1;
+ }
+ colBSize = std::min(mLastBalanceBSize, colBSize);
+ } else {
+ // CSS Fragmentation spec says, "To guarantee progress, fragmentainers are
+ // assumed to have a minimum block size of 1px regardless of their used
+ // size." https://drafts.csswg.org/css-break/#breaking-rules
+ //
+ // Note: we don't enforce the minimum block-size during balancing because
+ // this affects the result. If a balancing column container or its
+ // next-in-flows has zero block-size, it eventually gives up balancing, and
+ // ends up here.
+ colBSize = std::max(colBSize, nsPresContext::CSSPixelsToAppUnits(1));
+ }
+
+ ReflowConfig config;
+ config.mUsedColCount = numColumns;
+ config.mColISize = colISize;
+ config.mExpectedISizeLeftOver = expectedISizeLeftOver;
+ config.mColGap = colGap;
+ config.mColBSize = colBSize;
+ config.mIsBalancing = isBalancing;
+ config.mForceAuto = aForceAuto;
+ config.mKnownFeasibleBSize = NS_UNCONSTRAINEDSIZE;
+ config.mKnownInfeasibleBSize = 0;
+
+ COLUMN_SET_LOG(
+ "%s: this=%p, mUsedColCount=%d, mColISize=%d, "
+ "mExpectedISizeLeftOver=%d, mColGap=%d, mColBSize=%d, mIsBalancing=%d",
+ __func__, this, config.mUsedColCount, config.mColISize,
+ config.mExpectedISizeLeftOver, config.mColGap, config.mColBSize,
+ config.mIsBalancing);
+
+ return config;
+}
+
+static void MarkPrincipalChildrenDirty(nsIFrame* aFrame) {
+ for (nsIFrame* childFrame : aFrame->PrincipalChildList()) {
+ childFrame->MarkSubtreeDirty();
+ }
+}
+
+static void MoveChildTo(nsIFrame* aChild, LogicalPoint aOrigin, WritingMode aWM,
+ const nsSize& aContainerSize) {
+ if (aChild->GetLogicalPosition(aWM, aContainerSize) == aOrigin) {
+ return;
+ }
+
+ aChild->SetPosition(aWM, aOrigin, aContainerSize);
+ nsContainerFrame::PlaceFrameView(aChild);
+}
+
+nscoord nsColumnSetFrame::GetMinISize(gfxContext* aRenderingContext) {
+ nscoord iSize = 0;
+ DISPLAY_MIN_INLINE_SIZE(this, iSize);
+
+ if (mFrames.FirstChild()) {
+ // We want to ignore this in the case that we're size contained
+ // because our children should not contribute to our
+ // intrinsic size.
+ iSize = mFrames.FirstChild()->GetMinISize(aRenderingContext);
+ }
+ const nsStyleColumn* colStyle = StyleColumn();
+ if (colStyle->mColumnWidth.IsLength()) {
+ nscoord colISize =
+ ColumnUtils::ClampUsedColumnWidth(colStyle->mColumnWidth.AsLength());
+ // As available width reduces to zero, we reduce our number of columns
+ // to one, and don't enforce the column width, so just return the min
+ // of the child's min-width with any specified column width.
+ iSize = std::min(iSize, colISize);
+ } else {
+ NS_ASSERTION(colStyle->mColumnCount > 0,
+ "column-count and column-width can't both be auto");
+ // As available width reduces to zero, we still have mColumnCount columns,
+ // so compute our minimum size based on the number of columns and their gaps
+ // and minimum per-column size.
+ nscoord colGap = ColumnUtils::GetColumnGap(this, NS_UNCONSTRAINEDSIZE);
+ iSize = ColumnUtils::IntrinsicISize(colStyle->mColumnCount, colGap, iSize);
+ }
+ // XXX count forced column breaks here? Maybe we should return the child's
+ // min-width times the minimum number of columns.
+ return iSize;
+}
+
+nscoord nsColumnSetFrame::GetPrefISize(gfxContext* aRenderingContext) {
+ // Our preferred width is our desired column width, if specified, otherwise
+ // the child's preferred width, times the number of columns, plus the width
+ // of any required column gaps
+ // XXX what about forced column breaks here?
+ nscoord result = 0;
+ DISPLAY_PREF_INLINE_SIZE(this, result);
+ const nsStyleColumn* colStyle = StyleColumn();
+
+ nscoord colISize;
+ if (colStyle->mColumnWidth.IsLength()) {
+ colISize =
+ ColumnUtils::ClampUsedColumnWidth(colStyle->mColumnWidth.AsLength());
+ } else if (mFrames.FirstChild()) {
+ // We want to ignore this in the case that we're size contained
+ // because our children should not contribute to our
+ // intrinsic size.
+ colISize = mFrames.FirstChild()->GetPrefISize(aRenderingContext);
+ } else {
+ colISize = 0;
+ }
+
+ // If column-count is auto, assume one column.
+ uint32_t numColumns =
+ colStyle->mColumnCount == nsStyleColumn::kColumnCountAuto
+ ? 1
+ : colStyle->mColumnCount;
+ nscoord colGap = ColumnUtils::GetColumnGap(this, NS_UNCONSTRAINEDSIZE);
+ result = ColumnUtils::IntrinsicISize(numColumns, colGap, colISize);
+ return result;
+}
+
+nsColumnSetFrame::ColumnBalanceData nsColumnSetFrame::ReflowColumns(
+ ReflowOutput& aDesiredSize, const ReflowInput& aReflowInput,
+ nsReflowStatus& aStatus, const ReflowConfig& aConfig,
+ bool aUnboundedLastColumn) {
+ ColumnBalanceData colData;
+ bool allFit = true;
+ WritingMode wm = GetWritingMode();
+ const bool isRTL = wm.IsBidiRTL();
+ const bool shrinkingBSize = mLastBalanceBSize > aConfig.mColBSize;
+ const bool changingBSize = mLastBalanceBSize != aConfig.mColBSize;
+
+ COLUMN_SET_LOG(
+ "%s: Doing column reflow pass: mLastBalanceBSize=%d,"
+ " mColBSize=%d, RTL=%d, mUsedColCount=%d,"
+ " mColISize=%d, mColGap=%d",
+ __func__, mLastBalanceBSize, aConfig.mColBSize, isRTL,
+ aConfig.mUsedColCount, aConfig.mColISize, aConfig.mColGap);
+
+ DrainOverflowColumns();
+
+ if (changingBSize) {
+ mLastBalanceBSize = aConfig.mColBSize;
+ // XXX Seems like this could fire if incremental reflow pushed the column
+ // set down so we reflow incrementally with a different available height.
+ // We need a way to do an incremental reflow and be sure availableHeight
+ // changes are taken account of! Right now I think block frames with
+ // absolute children might exit early.
+ /*
+ NS_ASSERTION(
+ aKidReason != eReflowReason_Incremental,
+ "incremental reflow should not have changed the balance height");
+ */
+ }
+
+ nsRect contentRect(0, 0, 0, 0);
+ OverflowAreas overflowRects;
+
+ nsIFrame* child = mFrames.FirstChild();
+ LogicalPoint childOrigin(wm, 0, 0);
+
+ // In vertical-rl mode, columns will not be correctly placed if the
+ // reflowInput's ComputedWidth() is UNCONSTRAINED (in which case we'll get
+ // a containerSize.width of zero here). In that case, the column positions
+ // will be adjusted later, after our correct contentSize is known.
+ //
+ // When column-span is enabled, containerSize.width is always constrained.
+ // However, for RTL, we need to adjust the column positions as well after our
+ // correct containerSize is known.
+ nsSize containerSize = aReflowInput.ComputedSizeAsContainerIfConstrained();
+
+ const nscoord computedBSize =
+ aReflowInput.mParentReflowInput->ComputedBSize();
+ nscoord contentBEnd = 0;
+ bool reflowNext = false;
+
+ while (child) {
+ const bool reflowLastColumnWithUnconstrainedAvailBSize =
+ aUnboundedLastColumn && colData.mColCount == aConfig.mUsedColCount &&
+ aConfig.mIsBalancing;
+
+ // We need to reflow the child (column) ...
+ bool reflowChild =
+ // if we are told to do so;
+ aReflowInput.ShouldReflowAllKids() ||
+ // if the child is dirty;
+ child->IsSubtreeDirty() ||
+ // if it's the last child because we need to obtain the block-end
+ // margin;
+ !child->GetNextSibling() ||
+ // if the next column is dirty, because the next column's first line(s)
+ // might be pullable back to this column;
+ child->GetNextSibling()->IsSubtreeDirty() ||
+ // if this is the last column and we are supposed to assign unbounded
+ // block-size to it, because that could change the available block-size
+ // from the last time we reflowed it and we should try to pull all the
+ // content from its next sibling (Note that it might be the last column,
+ // but not be the last child because the desired number of columns has
+ // changed.)
+ reflowLastColumnWithUnconstrainedAvailBSize;
+
+ // If column-fill is auto (not the default), then we might need to
+ // move content between columns for any change in column block-size.
+ //
+ // The same is true if we have a non-'auto' computed block-size.
+ //
+ // FIXME: It's not clear to me why it's *ever* valid to have
+ // reflowChild be false when changingBSize is true, since it
+ // seems like a child broken over multiple columns might need to
+ // change the size of the fragment in each column.
+ if (!reflowChild && changingBSize &&
+ (StyleColumn()->mColumnFill == StyleColumnFill::Auto ||
+ computedBSize != NS_UNCONSTRAINEDSIZE)) {
+ reflowChild = true;
+ }
+ // If we need to pull up content from the prev-in-flow then this is not just
+ // a block-size shrink. The prev in flow will have set the dirty bit.
+ // Check the overflow rect YMost instead of just the child's content
+ // block-size. The child may have overflowing content that cares about the
+ // available block-size boundary. (It may also have overflowing content that
+ // doesn't care about the available block-size boundary, but if so, too bad,
+ // this optimization is defeated.) We want scrollable overflow here since
+ // this is a calculation that affects layout.
+ if (!reflowChild && shrinkingBSize) {
+ switch (wm.GetBlockDir()) {
+ case WritingMode::eBlockTB:
+ if (child->ScrollableOverflowRect().YMost() > aConfig.mColBSize) {
+ reflowChild = true;
+ }
+ break;
+ case WritingMode::eBlockLR:
+ if (child->ScrollableOverflowRect().XMost() > aConfig.mColBSize) {
+ reflowChild = true;
+ }
+ break;
+ case WritingMode::eBlockRL:
+ // XXX not sure how to handle this, so for now just don't attempt
+ // the optimization
+ reflowChild = true;
+ break;
+ default:
+ MOZ_ASSERT_UNREACHABLE("unknown block direction");
+ break;
+ }
+ }
+
+ nscoord childContentBEnd = 0;
+ if (!reflowNext && !reflowChild) {
+ // This child does not need to be reflowed, but we may need to move it
+ MoveChildTo(child, childOrigin, wm, containerSize);
+
+ // If this is the last frame then make sure we get the right status
+ nsIFrame* kidNext = child->GetNextSibling();
+ if (kidNext) {
+ aStatus.Reset();
+ if (kidNext->HasAnyStateBits(NS_FRAME_IS_OVERFLOW_CONTAINER)) {
+ aStatus.SetOverflowIncomplete();
+ } else {
+ aStatus.SetIncomplete();
+ }
+ } else {
+ aStatus = mLastFrameStatus;
+ }
+ childContentBEnd = nsLayoutUtils::CalculateContentBEnd(wm, child);
+
+ COLUMN_SET_LOG("%s: Skipping child #%d %p: status=%s", __func__,
+ colData.mColCount, child, ToString(aStatus).c_str());
+ } else {
+ LogicalSize availSize(wm, aConfig.mColISize, aConfig.mColBSize);
+ if (reflowLastColumnWithUnconstrainedAvailBSize) {
+ availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE;
+
+ COLUMN_SET_LOG(
+ "%s: Reflowing last column with unconstrained block-size. Change "
+ "available block-size from %d to %d",
+ __func__, aConfig.mColBSize, availSize.BSize(wm));
+ }
+
+ if (reflowNext) {
+ child->MarkSubtreeDirty();
+ }
+
+ LogicalSize kidCBSize(wm, availSize.ISize(wm), computedBSize);
+ ReflowInput kidReflowInput(PresContext(), aReflowInput, child, availSize,
+ Some(kidCBSize));
+ kidReflowInput.mFlags.mIsTopOfPage = [&]() {
+ const bool isNestedMulticolOrPaginated =
+ aReflowInput.mParentReflowInput->mFrame->HasAnyStateBits(
+ NS_FRAME_HAS_MULTI_COLUMN_ANCESTOR) ||
+ PresContext()->IsPaginated();
+ if (isNestedMulticolOrPaginated) {
+ if (aConfig.mForceAuto) {
+ // If we are forced to fill columns sequentially, force fit the
+ // content whether we are at top of page or not.
+ return true;
+ }
+ if (aReflowInput.mFlags.mIsTopOfPage) {
+ // If this is the last balancing reflow, we want to force fit
+ // content to avoid infinite loops.
+ return !aConfig.mIsBalancing || aConfig.mIsLastBalancingReflow;
+ }
+ // If we are a not at the top of page, we shouldn't force fit content.
+ // This is because our ColumnSetWrapperFrame can be pushed to the next
+ // column or page and reflowed again with a potentially larger
+ // available block-size.
+ return false;
+ }
+ // We are a top-level multicol in non-paginated context. Force fit the
+ // content only if we are not balancing columns.
+ return !aConfig.mIsBalancing;
+ }();
+ kidReflowInput.mFlags.mTableIsSplittable = false;
+ kidReflowInput.mFlags.mIsColumnBalancing = aConfig.mIsBalancing;
+ kidReflowInput.mBreakType = ReflowInput::BreakType::Column;
+
+ // We need to reflow any float placeholders, even if our column block-size
+ // hasn't changed.
+ kidReflowInput.mFlags.mMustReflowPlaceholders = !changingBSize;
+
+ COLUMN_SET_LOG(
+ "%s: Reflowing child #%d %p: availSize=(%d,%d), kidCBSize=(%d,%d), "
+ "child's mIsTopOfPage=%d",
+ __func__, colData.mColCount, child, availSize.ISize(wm),
+ availSize.BSize(wm), kidCBSize.ISize(wm), kidCBSize.BSize(wm),
+ kidReflowInput.mFlags.mIsTopOfPage);
+
+ // Note if the column's next in flow is not being changed by this
+ // incremental reflow. This may allow the current column to avoid trying
+ // to pull lines from the next column.
+ if (child->GetNextSibling() && !HasAnyStateBits(NS_FRAME_IS_DIRTY) &&
+ !child->GetNextSibling()->HasAnyStateBits(NS_FRAME_IS_DIRTY)) {
+ kidReflowInput.mFlags.mNextInFlowUntouched = true;
+ }
+
+ ReflowOutput kidDesiredSize(wm);
+
+ // XXX it would be cool to consult the float manager for the
+ // previous block to figure out the region of floats from the
+ // previous column that extend into this column, and subtract
+ // that region from the new float manager. So you could stick a
+ // really big float in the first column and text in following
+ // columns would flow around it.
+
+ MOZ_ASSERT(kidReflowInput.ComputedLogicalMargin(wm).IsAllZero(),
+ "-moz-column-content has no margin!");
+ aStatus.Reset();
+ ReflowChild(child, PresContext(), kidDesiredSize, kidReflowInput, wm,
+ childOrigin, containerSize, ReflowChildFlags::Default,
+ aStatus);
+
+ if (colData.mColCount == 1 && aStatus.IsInlineBreakBefore()) {
+ COLUMN_SET_LOG("%s: Content in the first column reports break-before!",
+ __func__);
+ allFit = false;
+ break;
+ }
+
+ reflowNext = aStatus.NextInFlowNeedsReflow();
+
+ // The carried-out block-end margin of column content might be non-zero
+ // when we try to find the best column balancing block size, but it should
+ // never affect the size column set nor be further carried out. Set it to
+ // zero.
+ //
+ // FIXME: For some types of fragmentation, we should carry the margin into
+ // the next column. Also see
+ // https://drafts.csswg.org/css-break-4/#break-margins
+ //
+ // FIXME: This should never happen for the last column, since it should be
+ // a margin root; see nsBlockFrame::IsMarginRoot(). However, sometimes the
+ // last column has an empty continuation while searching for the best
+ // column balancing bsize, which prevents the last column from being a
+ // margin root.
+ kidDesiredSize.mCarriedOutBEndMargin.Zero();
+
+ NS_FRAME_TRACE_REFLOW_OUT("Column::Reflow", aStatus);
+
+ FinishReflowChild(child, PresContext(), kidDesiredSize, &kidReflowInput,
+ wm, childOrigin, containerSize,
+ ReflowChildFlags::Default);
+
+ childContentBEnd = nsLayoutUtils::CalculateContentBEnd(wm, child);
+ if (childContentBEnd > aConfig.mColBSize) {
+ allFit = false;
+ }
+ if (childContentBEnd > availSize.BSize(wm)) {
+ colData.mMaxOverflowingBSize =
+ std::max(childContentBEnd, colData.mMaxOverflowingBSize);
+ }
+
+ COLUMN_SET_LOG(
+ "%s: Reflowed child #%d %p: status=%s, desiredSize=(%d,%d), "
+ "childContentBEnd=%d, CarriedOutBEndMargin=%d (ignored)",
+ __func__, colData.mColCount, child, ToString(aStatus).c_str(),
+ kidDesiredSize.ISize(wm), kidDesiredSize.BSize(wm), childContentBEnd,
+ kidDesiredSize.mCarriedOutBEndMargin.get());
+ }
+
+ contentRect.UnionRect(contentRect, child->GetRect());
+
+ ConsiderChildOverflow(overflowRects, child);
+ contentBEnd = std::max(contentBEnd, childContentBEnd);
+ colData.mLastBSize = childContentBEnd;
+ colData.mSumBSize += childContentBEnd;
+
+ // Build a continuation column if necessary
+ nsIFrame* kidNextInFlow = child->GetNextInFlow();
+
+ if (aStatus.IsFullyComplete()) {
+ NS_ASSERTION(!kidNextInFlow, "next in flow should have been deleted");
+ child = nullptr;
+ break;
+ }
+
+ // Make sure that the column has a next-in-flow. If not, we must
+ // create one to hold the overflowing stuff, even if we're just
+ // going to put it on our overflow list and let *our*
+ // next in flow handle it.
+ if (!kidNextInFlow) {
+ NS_ASSERTION(aStatus.NextInFlowNeedsReflow(),
+ "We have to create a continuation, but the block doesn't "
+ "want us to reflow it?");
+
+ // We need to create a continuing column
+ kidNextInFlow = CreateNextInFlow(child);
+ }
+
+ // Make sure we reflow a next-in-flow when it switches between being
+ // normal or overflow container
+ if (aStatus.IsOverflowIncomplete()) {
+ if (!kidNextInFlow->HasAnyStateBits(NS_FRAME_IS_OVERFLOW_CONTAINER)) {
+ aStatus.SetNextInFlowNeedsReflow();
+ reflowNext = true;
+ kidNextInFlow->AddStateBits(NS_FRAME_IS_OVERFLOW_CONTAINER);
+ }
+ } else if (kidNextInFlow->HasAnyStateBits(NS_FRAME_IS_OVERFLOW_CONTAINER)) {
+ aStatus.SetNextInFlowNeedsReflow();
+ reflowNext = true;
+ kidNextInFlow->RemoveStateBits(NS_FRAME_IS_OVERFLOW_CONTAINER);
+ }
+
+ // We have reached the maximum number of columns. If we are balancing, stop
+ // this reflow and continue finding the optimal balancing block-size.
+ //
+ // Otherwise, i.e. we are not balancing, stop this reflow and let the parent
+ // of our multicol container create a next-in-flow if all of the following
+ // conditions are met.
+ //
+ // 1) We fill columns sequentially by the request of the style, not by our
+ // internal needs, i.e. aConfig.mForceAuto is false.
+ //
+ // We don't want to stop this reflow when we force fill the columns
+ // sequentially. We usually go into this mode when giving up balancing, and
+ // this is the last resort to fit all our children by creating overflow
+ // columns.
+ //
+ // 2) In a fragmented context, our multicol container still has block-size
+ // left for its next-in-flow, i.e.
+ // aReflowInput.mFlags.mColumnSetWrapperHasNoBSizeLeft is false.
+ //
+ // Note that in a continuous context, i.e. our multicol container's
+ // available block-size is unconstrained, if it has a fixed block-size
+ // mColumnSetWrapperHasNoBSizeLeft is always true because nothing stops it
+ // from applying all its block-size in the first-in-flow. Otherwise, i.e.
+ // our multicol container has an unconstrained block-size, we shouldn't be
+ // here because all our children should fit in the very first column even if
+ // mColumnSetWrapperHasNoBSizeLeft is false.
+ //
+ // According to the definition of mColumnSetWrapperHasNoBSizeLeft, if the
+ // bit is *not* set, either our multicol container has unconstrained
+ // block-size, or it has a constrained block-size and has block-size left
+ // for its next-in-flow. In either cases, the parent of our multicol
+ // container can create a next-in-flow for the container that guaranteed to
+ // have non-zero block-size for the container's children.
+ //
+ // Put simply, if either one of the above conditions is not met, we are
+ // going to create more overflow columns until all our children are fit.
+ if (colData.mColCount >= aConfig.mUsedColCount &&
+ (aConfig.mIsBalancing ||
+ (!aConfig.mForceAuto &&
+ !aReflowInput.mFlags.mColumnSetWrapperHasNoBSizeLeft))) {
+ NS_ASSERTION(aConfig.mIsBalancing ||
+ aReflowInput.AvailableBSize() != NS_UNCONSTRAINEDSIZE,
+ "Why are we here if we have unlimited block-size to fill "
+ "columns sequentially.");
+
+ // No more columns allowed here. Stop.
+ aStatus.SetNextInFlowNeedsReflow();
+ kidNextInFlow->MarkSubtreeDirty();
+ // Move any of our leftover columns to our overflow list. Our
+ // next-in-flow will eventually pick them up.
+ nsFrameList continuationColumns = mFrames.TakeFramesAfter(child);
+ if (continuationColumns.NotEmpty()) {
+ SetOverflowFrames(std::move(continuationColumns));
+ }
+ child = nullptr;
+
+ COLUMN_SET_LOG("%s: We are not going to create overflow columns.",
+ __func__);
+ break;
+ }
+
+ if (PresContext()->HasPendingInterrupt()) {
+ // Stop the loop now while |child| still points to the frame that bailed
+ // out. We could keep going here and condition a bunch of the code in
+ // this loop on whether there's an interrupt, or even just keep going and
+ // trying to reflow the blocks (even though we know they'll interrupt
+ // right after their first line), but stopping now is conceptually the
+ // simplest (and probably fastest) thing.
+ break;
+ }
+
+ // Advance to the next column
+ child = child->GetNextSibling();
+ ++colData.mColCount;
+
+ if (child) {
+ childOrigin.I(wm) += aConfig.mColISize + aConfig.mColGap;
+
+ COLUMN_SET_LOG("%s: Next childOrigin.iCoord=%d", __func__,
+ childOrigin.I(wm));
+ }
+ }
+
+ if (PresContext()->CheckForInterrupt(this) &&
+ HasAnyStateBits(NS_FRAME_IS_DIRTY)) {
+ // Mark all our kids starting with |child| dirty
+
+ // Note that this is a CheckForInterrupt call, not a HasPendingInterrupt,
+ // because we might have interrupted while reflowing |child|, and since
+ // we're about to add a dirty bit to |child| we need to make sure that
+ // |this| is scheduled to have dirty bits marked on it and its ancestors.
+ // Otherwise, when we go to mark dirty bits on |child|'s ancestors we'll
+ // bail out immediately, since it'll already have a dirty bit.
+ for (; child; child = child->GetNextSibling()) {
+ child->MarkSubtreeDirty();
+ }
+ }
+
+ colData.mMaxBSize = contentBEnd;
+ LogicalSize contentSize = LogicalSize(wm, contentRect.Size());
+ contentSize.BSize(wm) = std::max(contentSize.BSize(wm), contentBEnd);
+ mLastFrameStatus = aStatus;
+
+ if (computedBSize != NS_UNCONSTRAINEDSIZE && !HasColumnSpanSiblings()) {
+ NS_ASSERTION(aReflowInput.AvailableBSize() != NS_UNCONSTRAINEDSIZE,
+ "Available block-size should be constrained because it's "
+ "restricted by the computed block-size when our reflow "
+ "input is created in nsBlockFrame::ReflowBlockFrame()!");
+
+ // If a) our parent ColumnSetWrapper has constrained block-size
+ // (nsBlockFrame::ReflowBlockFrame() applies the block-size constraint
+ // when creating a ReflowInput for ColumnSetFrame child); and b) we are the
+ // sole ColumnSet or the last ColumnSet continuation split by column-spans
+ // in a ColumnSetWrapper, extend our block-size to consume the available
+ // block-size so that the column-rules are drawn to the content block-end
+ // edge of the multicol container.
+ contentSize.BSize(wm) =
+ std::max(contentSize.BSize(wm), aReflowInput.AvailableBSize());
+ }
+
+ aDesiredSize.SetSize(wm, contentSize);
+ aDesiredSize.mOverflowAreas = overflowRects;
+ aDesiredSize.UnionOverflowAreasWithDesiredBounds();
+
+ // In vertical-rl mode, make a second pass if necessary to reposition the
+ // columns with the correct container width. (In other writing modes,
+ // correct containerSize was not required for column positioning so we don't
+ // need this fixup.)
+ //
+ // RTL column positions also depend on ColumnSet's actual contentSize. We need
+ // this fixup, too.
+ if ((wm.IsVerticalRL() || isRTL) &&
+ containerSize.width != contentSize.Width(wm)) {
+ const nsSize finalContainerSize = aDesiredSize.PhysicalSize();
+ OverflowAreas overflowRects;
+ for (nsIFrame* child : mFrames) {
+ // Get the logical position as set previously using a provisional or
+ // dummy containerSize, and reset with the correct container size.
+ child->SetPosition(wm, child->GetLogicalPosition(wm, containerSize),
+ finalContainerSize);
+ ConsiderChildOverflow(overflowRects, child);
+ }
+ aDesiredSize.mOverflowAreas = overflowRects;
+ aDesiredSize.UnionOverflowAreasWithDesiredBounds();
+ }
+
+ colData.mFeasible = allFit && aStatus.IsFullyComplete();
+
+ COLUMN_SET_LOG(
+ "%s: Done column reflow pass: %s, mMaxBSize=%d, mSumBSize=%d, "
+ "mLastBSize=%d, mMaxOverflowingBSize=%d",
+ __func__, colData.mFeasible ? "Feasible :)" : "Infeasible :(",
+ colData.mMaxBSize, colData.mSumBSize, colData.mLastBSize,
+ colData.mMaxOverflowingBSize);
+
+ return colData;
+}
+
+void nsColumnSetFrame::DrainOverflowColumns() {
+ // First grab the prev-in-flows overflows and reparent them to this
+ // frame.
+ nsPresContext* presContext = PresContext();
+ nsColumnSetFrame* prev = static_cast<nsColumnSetFrame*>(GetPrevInFlow());
+ if (prev) {
+ AutoFrameListPtr overflows(presContext, prev->StealOverflowFrames());
+ if (overflows) {
+ nsContainerFrame::ReparentFrameViewList(*overflows, prev, this);
+
+ mFrames.InsertFrames(this, nullptr, std::move(*overflows));
+ }
+ }
+
+ // Now pull back our own overflows and append them to our children.
+ // We don't need to reparent them since we're already their parent.
+ AutoFrameListPtr overflows(presContext, StealOverflowFrames());
+ if (overflows) {
+ // We're already the parent for these frames, so no need to set
+ // their parent again.
+ mFrames.AppendFrames(nullptr, std::move(*overflows));
+ }
+}
+
+void nsColumnSetFrame::FindBestBalanceBSize(const ReflowInput& aReflowInput,
+ nsPresContext* aPresContext,
+ ReflowConfig& aConfig,
+ ColumnBalanceData aColData,
+ ReflowOutput& aDesiredSize,
+ bool aUnboundedLastColumn,
+ nsReflowStatus& aStatus) {
+ MOZ_ASSERT(aConfig.mIsBalancing,
+ "Why are we here if we are not balancing columns?");
+
+ const nscoord availableContentBSize = aReflowInput.AvailableBSize();
+
+ // Termination of the algorithm below is guaranteed because
+ // aConfig.knownFeasibleBSize - aConfig.knownInfeasibleBSize decreases in
+ // every iteration.
+ int32_t iterationCount = 1;
+
+ // We set this flag when we detect that we may contain a frame
+ // that can break anywhere (thus foiling the linear decrease-by-one
+ // search)
+ bool maybeContinuousBreakingDetected = false;
+ bool possibleOptimalBSizeDetected = false;
+
+ // This is the extra block-size added to the optimal column block-size
+ // estimation which is calculated in the while-loop by dividing
+ // aColData.mSumBSize into N columns.
+ //
+ // The constant is arbitrary. We use a half of line-height first. In case a
+ // column container uses *zero* (or a very small) line-height, use a half of
+ // default line-height 1140/2 = 570 app units as the minimum value. Otherwise
+ // we might take more than necessary iterations before finding a feasible
+ // block-size.
+ nscoord extraBlockSize = std::max(570, aReflowInput.GetLineHeight() / 2);
+
+ // We use divide-by-N to estimate the optimal column block-size only if the
+ // last column's available block-size is unbounded.
+ bool foundFeasibleBSizeCloserToBest = !aUnboundedLastColumn;
+
+ // Stop the binary search when the difference of the feasible and infeasible
+ // block-size is within this gap. Here we use one device pixel.
+ const int32_t gapToStop = aPresContext->DevPixelsToAppUnits(1);
+
+ while (!aPresContext->HasPendingInterrupt()) {
+ nscoord lastKnownFeasibleBSize = aConfig.mKnownFeasibleBSize;
+
+ // Record what we learned from the last reflow
+ if (aColData.mFeasible) {
+ // mMaxBSize is feasible. Also, mLastBalanceBSize is feasible.
+ aConfig.mKnownFeasibleBSize =
+ std::min(aConfig.mKnownFeasibleBSize, aColData.mMaxBSize);
+ aConfig.mKnownFeasibleBSize =
+ std::min(aConfig.mKnownFeasibleBSize, mLastBalanceBSize);
+
+ // Furthermore, no block-size less than the block-size of the last
+ // column can ever be feasible. (We might be able to reduce the
+ // block-size of a non-last column by moving content to a later column,
+ // but we can't do that with the last column.)
+ if (aColData.mColCount == aConfig.mUsedColCount) {
+ aConfig.mKnownInfeasibleBSize =
+ std::max(aConfig.mKnownInfeasibleBSize, aColData.mLastBSize - 1);
+ }
+ } else {
+ aConfig.mKnownInfeasibleBSize =
+ std::max(aConfig.mKnownInfeasibleBSize, mLastBalanceBSize);
+
+ // If a column didn't fit in its available block-size, then its current
+ // block-size must be the minimum block-size for unbreakable content in
+ // the column, and therefore no smaller block-size can be feasible.
+ aConfig.mKnownInfeasibleBSize = std::max(
+ aConfig.mKnownInfeasibleBSize, aColData.mMaxOverflowingBSize - 1);
+
+ if (aUnboundedLastColumn) {
+ // The last column is unbounded, so all content got reflowed, so the
+ // mMaxBSize is feasible.
+ aConfig.mKnownFeasibleBSize =
+ std::min(aConfig.mKnownFeasibleBSize, aColData.mMaxBSize);
+
+ NS_ASSERTION(mLastFrameStatus.IsComplete(),
+ "Last column should be complete if the available "
+ "block-size is unconstrained!");
+ }
+ }
+
+ COLUMN_SET_LOG(
+ "%s: this=%p, mKnownInfeasibleBSize=%d, mKnownFeasibleBSize=%d",
+ __func__, this, aConfig.mKnownInfeasibleBSize,
+ aConfig.mKnownFeasibleBSize);
+
+ if (aConfig.mKnownInfeasibleBSize >= aConfig.mKnownFeasibleBSize - 1) {
+ // aConfig.mKnownFeasibleBSize is where we want to be. This can happen in
+ // the very first iteration when a column container solely has a tall
+ // unbreakable child that overflows the container.
+ break;
+ }
+
+ if (aConfig.mKnownInfeasibleBSize >= availableContentBSize) {
+ // There's no feasible block-size to fit our contents. We may need to
+ // reflow one more time after this loop.
+ break;
+ }
+
+ const nscoord gap =
+ aConfig.mKnownFeasibleBSize - aConfig.mKnownInfeasibleBSize;
+ if (gap <= gapToStop && possibleOptimalBSizeDetected) {
+ // We detected a possible optimal block-size in the last iteration. If it
+ // is infeasible, we may need to reflow one more time after this loop.
+ break;
+ }
+
+ if (lastKnownFeasibleBSize - aConfig.mKnownFeasibleBSize == 1) {
+ // We decreased the feasible block-size by one twip only. This could
+ // indicate that there is a continuously breakable child frame
+ // that we are crawling through.
+ maybeContinuousBreakingDetected = true;
+ }
+
+ nscoord nextGuess = aConfig.mKnownInfeasibleBSize + gap / 2;
+ if (aConfig.mKnownFeasibleBSize - nextGuess < extraBlockSize &&
+ !maybeContinuousBreakingDetected) {
+ // We're close to our target, so just try shrinking just the
+ // minimum amount that will cause one of our columns to break
+ // differently.
+ nextGuess = aConfig.mKnownFeasibleBSize - 1;
+ } else if (!foundFeasibleBSizeCloserToBest) {
+ // Make a guess by dividing mSumBSize into N columns and adding
+ // extraBlockSize to try to make it on the feasible side.
+ nextGuess = aColData.mSumBSize / aConfig.mUsedColCount + extraBlockSize;
+ // Sanitize it
+ nextGuess = clamped(nextGuess, aConfig.mKnownInfeasibleBSize + 1,
+ aConfig.mKnownFeasibleBSize - 1);
+ // We keep doubling extraBlockSize in every iteration until we find a
+ // feasible guess.
+ extraBlockSize *= 2;
+ } else if (aConfig.mKnownFeasibleBSize == NS_UNCONSTRAINEDSIZE) {
+ // This can happen when we had a next-in-flow so we didn't
+ // want to do an unbounded block-size measuring step. Let's just increase
+ // from the infeasible block-size by some reasonable amount.
+ nextGuess = aConfig.mKnownInfeasibleBSize * 2 + extraBlockSize;
+ } else if (gap <= gapToStop) {
+ // Floor nextGuess to the greatest multiple of gapToStop below or equal to
+ // mKnownFeasibleBSize.
+ nextGuess = aConfig.mKnownFeasibleBSize / gapToStop * gapToStop;
+ possibleOptimalBSizeDetected = true;
+ }
+
+ // Don't bother guessing more than our block-size constraint.
+ nextGuess = std::min(availableContentBSize, nextGuess);
+
+ COLUMN_SET_LOG("%s: Choosing next guess=%d, iteration=%d", __func__,
+ nextGuess, iterationCount);
+ ++iterationCount;
+
+ aConfig.mColBSize = nextGuess;
+
+ aUnboundedLastColumn = false;
+ MarkPrincipalChildrenDirty(this);
+ aColData =
+ ReflowColumns(aDesiredSize, aReflowInput, aStatus, aConfig, false);
+
+ if (!foundFeasibleBSizeCloserToBest && aColData.mFeasible) {
+ foundFeasibleBSizeCloserToBest = true;
+ }
+ }
+
+ if (!aColData.mFeasible && !aPresContext->HasPendingInterrupt()) {
+ // We need to reflow one more time at the feasible block-size to
+ // get a valid layout.
+ if (aConfig.mKnownInfeasibleBSize >= availableContentBSize) {
+ aConfig.mColBSize = availableContentBSize;
+ if (mLastBalanceBSize == availableContentBSize) {
+ // If we end up here, we have a constrained available content
+ // block-size, and our last column's block-size exceeds it. Also, if
+ // this is the first balancing iteration, the last column is given
+ // unconstrained available block-size, so it has a fully complete
+ // reflow status. Therefore, we always want to reflow again at the
+ // available content block-size to get a valid layout and a correct
+ // reflow status (likely an *incomplete* status) so that our column
+ // container can be fragmented if needed.
+
+ if (aReflowInput.mFlags.mColumnSetWrapperHasNoBSizeLeft) {
+ // If our column container has a constrained block-size (either in a
+ // paginated context or in a nested column container), and is going
+ // to consume all its computed block-size in this fragment, then our
+ // column container has no block-size left to contain our
+ // next-in-flows. We have to give up balancing, and create our
+ // own overflow columns.
+ //
+ // We don't want to create overflow columns immediately when our
+ // content doesn't fit since this changes our reflow status from
+ // incomplete to complete. Valid reasons include 1) the outer column
+ // container might do column balancing, and it can enlarge the
+ // available content block-size so that the nested one could fit its
+ // content in next balancing iteration; or 2) the outer column
+ // container is filling columns sequentially, and may have more
+ // inline-size to create more column boxes for the nested column
+ // container's next-in-flows.
+ aConfig = ChooseColumnStrategy(aReflowInput, true);
+ }
+ }
+ } else {
+ aConfig.mColBSize = aConfig.mKnownFeasibleBSize;
+ }
+
+ // This is our last attempt to reflow. If our column container's available
+ // block-size is unconstrained, make sure that the last column is
+ // allowed to have arbitrary block-size here, even though we were
+ // balancing. Otherwise we'd have to split, and it's not clear what we'd
+ // do with that.
+ COLUMN_SET_LOG("%s: Last attempt to call ReflowColumns", __func__);
+ aConfig.mIsLastBalancingReflow = true;
+ const bool forceUnboundedLastColumn =
+ aReflowInput.mParentReflowInput->AvailableBSize() ==
+ NS_UNCONSTRAINEDSIZE;
+ MarkPrincipalChildrenDirty(this);
+ ReflowColumns(aDesiredSize, aReflowInput, aStatus, aConfig,
+ forceUnboundedLastColumn);
+ }
+}
+
+void nsColumnSetFrame::Reflow(nsPresContext* aPresContext,
+ ReflowOutput& aDesiredSize,
+ const ReflowInput& aReflowInput,
+ nsReflowStatus& aStatus) {
+ MarkInReflow();
+ // Don't support interruption in columns
+ nsPresContext::InterruptPreventer noInterrupts(aPresContext);
+
+ DO_GLOBAL_REFLOW_COUNT("nsColumnSetFrame");
+ DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
+ MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
+
+ MOZ_ASSERT(aReflowInput.mCBReflowInput->mFrame->StyleColumn()
+ ->IsColumnContainerStyle(),
+ "The column container should have relevant column styles!");
+ MOZ_ASSERT(aReflowInput.mParentReflowInput->mFrame->IsColumnSetWrapperFrame(),
+ "The column container should be ColumnSetWrapperFrame!");
+ MOZ_ASSERT(
+ aReflowInput.ComputedLogicalBorderPadding(aReflowInput.GetWritingMode())
+ .IsAllZero(),
+ "Only the column container can have border and padding!");
+ MOZ_ASSERT(
+ GetChildList(FrameChildListID::OverflowContainers).IsEmpty() &&
+ GetChildList(FrameChildListID::ExcessOverflowContainers).IsEmpty(),
+ "ColumnSetFrame should store overflow containers in principal "
+ "child list!");
+
+ //------------ Handle Incremental Reflow -----------------
+
+ COLUMN_SET_LOG("%s: Begin Reflow: this=%p, is nested multicol=%d", __func__,
+ this,
+ aReflowInput.mParentReflowInput->mFrame->HasAnyStateBits(
+ NS_FRAME_HAS_MULTI_COLUMN_ANCESTOR));
+
+ // If inline size is unconstrained, set aForceAuto to true to allow
+ // the columns to expand in the inline direction. (This typically
+ // happens in orthogonal flows where the inline direction is the
+ // container's block direction).
+ ReflowConfig config = ChooseColumnStrategy(
+ aReflowInput, aReflowInput.ComputedISize() == NS_UNCONSTRAINEDSIZE);
+
+ // If balancing, then we allow the last column to grow to unbounded
+ // block-size during the first reflow. This gives us a way to estimate
+ // what the average column block-size should be, because we can measure
+ // the block-size of all the columns and sum them up. But don't do this
+ // if we have a next in flow because we don't want to suck all its
+ // content back here and then have to push it out again!
+ nsIFrame* nextInFlow = GetNextInFlow();
+ bool unboundedLastColumn = config.mIsBalancing && !nextInFlow;
+ const ColumnBalanceData colData = ReflowColumns(
+ aDesiredSize, aReflowInput, aStatus, config, unboundedLastColumn);
+
+ // If we're not balancing, then we're already done, since we should have
+ // reflown all of our children, and there is no need for a binary search to
+ // determine proper column block-size.
+ if (config.mIsBalancing && !aPresContext->HasPendingInterrupt()) {
+ FindBestBalanceBSize(aReflowInput, aPresContext, config, colData,
+ aDesiredSize, unboundedLastColumn, aStatus);
+ }
+
+ if (aPresContext->HasPendingInterrupt() &&
+ aReflowInput.AvailableBSize() == NS_UNCONSTRAINEDSIZE) {
+ // In this situation, we might be lying about our reflow status, because
+ // our last kid (the one that got interrupted) was incomplete. Fix that.
+ aStatus.Reset();
+ }
+
+ NS_ASSERTION(aStatus.IsFullyComplete() ||
+ aReflowInput.AvailableBSize() != NS_UNCONSTRAINEDSIZE,
+ "Column set should be complete if the available block-size is "
+ "unconstrained");
+
+ MOZ_ASSERT(!HasAbsolutelyPositionedChildren(),
+ "ColumnSetWrapperFrame should be the abs.pos container!");
+ FinishAndStoreOverflow(&aDesiredSize, aReflowInput.mStyleDisplay);
+
+ COLUMN_SET_LOG("%s: End Reflow: this=%p", __func__, this);
+}
+
+void nsColumnSetFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
+ const nsDisplayListSet& aLists) {
+ DisplayBorderBackgroundOutline(aBuilder, aLists);
+
+ if (IsVisibleForPainting()) {
+ aLists.BorderBackground()->AppendNewToTop<nsDisplayColumnRule>(aBuilder,
+ this);
+ }
+
+ // Our children won't have backgrounds so it doesn't matter where we put them.
+ for (nsIFrame* f : mFrames) {
+ BuildDisplayListForChild(aBuilder, f, aLists);
+ }
+}
+
+void nsColumnSetFrame::AppendDirectlyOwnedAnonBoxes(
+ nsTArray<OwnedAnonBox>& aResult) {
+ // Everything in mFrames is continuations of the first thing in mFrames.
+ nsIFrame* column = mFrames.FirstChild();
+
+ // We might not have any columns, apparently?
+ if (!column) {
+ return;
+ }
+
+ MOZ_ASSERT(column->Style()->GetPseudoType() == PseudoStyleType::columnContent,
+ "What sort of child is this?");
+ aResult.AppendElement(OwnedAnonBox(column));
+}
+
+Maybe<nscoord> nsColumnSetFrame::GetNaturalBaselineBOffset(
+ WritingMode aWM, BaselineSharingGroup aBaselineGroup,
+ BaselineExportContext aExportContext) const {
+ Maybe<nscoord> result;
+ for (const auto* kid : mFrames) {
+ auto kidBaseline =
+ kid->GetNaturalBaselineBOffset(aWM, aBaselineGroup, aExportContext);
+ if (!kidBaseline) {
+ continue;
+ }
+ // The kid frame may not necessarily be aligned with the columnset frame.
+ 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));
+ }
+ // Take the smallest of the baselines (i.e. Closest to border-block-start
+ // for `BaselineSharingGroup::First`, border-block-end for
+ // `BaselineSharingGroup::Last`)
+ if (!result || *kidBaseline < *result) {
+ result = kidBaseline;
+ }
+ }
+ return result;
+}
+
+#ifdef DEBUG
+void nsColumnSetFrame::SetInitialChildList(ChildListID aListID,
+ nsFrameList&& aChildList) {
+ MOZ_ASSERT(aListID != FrameChildListID::Principal || aChildList.OnlyChild(),
+ "initial principal child list must have exactly one child");
+ nsContainerFrame::SetInitialChildList(aListID, std::move(aChildList));
+}
+
+void nsColumnSetFrame::AppendFrames(ChildListID aListID,
+ nsFrameList&& aFrameList) {
+ MOZ_CRASH("unsupported operation");
+}
+
+void nsColumnSetFrame::InsertFrames(ChildListID aListID, nsIFrame* aPrevFrame,
+ const nsLineList::iterator* aPrevFrameLine,
+ nsFrameList&& aFrameList) {
+ MOZ_CRASH("unsupported operation");
+}
+
+void nsColumnSetFrame::RemoveFrame(DestroyContext&, ChildListID, nsIFrame*) {
+ MOZ_CRASH("unsupported operation");
+}
+#endif