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nsColumnSetFrame.cpp
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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 "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<gfxContext> screenRefCtx = gfxContext::CreateOrNull(
gfxPlatform::GetPlatform()->ScreenReferenceDrawTarget().get());
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->GetComputedColumnRuleWidth();
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->GetComputedColumnRuleWidth();
if (!ruleWidth) return;
aBorderRenderers.Clear();
nscolor ruleColor =
GetVisitedDependentColor(&nsStyleColumn::mColumnRuleColor);
nsPresContext* presContext = 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(*presContext->Document());
Sides skipSides;
if (isVertical) {
border.SetBorderWidth(eSideTop, ruleWidth);
border.SetBorderStyle(eSideTop, ruleStyle);
border.mBorderTopColor = StyleColor::FromColor(ruleColor);
skipSides |= mozilla::SideBits::eLeftRight;
skipSides |= mozilla::SideBits::eBottom;
} else {
border.SetBorderWidth(eSideLeft, ruleWidth);
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(
presContext, 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();
}
}
nsColumnSetFrame::ColumnBalanceData nsColumnSetFrame::ReflowColumns(
ReflowOutput& aDesiredSize, const ReflowInput& aReflowInput,
nsReflowStatus& aReflowStatus, ReflowConfig& aConfig,
bool aUnboundedLastColumn) {
const ColumnBalanceData colData = ReflowChildren(
aDesiredSize, aReflowInput, aReflowStatus, aConfig, aUnboundedLastColumn);
if (!colData.mHasExcessBSize) {
return colData;
}
aConfig = ChooseColumnStrategy(aReflowInput, true);
// We need to reflow our children again one last time, otherwise we might
// end up with a stale column block-size for some of our columns, since we
// bailed out of balancing.
return ReflowChildren(aDesiredSize, aReflowInput, aReflowStatus, aConfig,
aUnboundedLastColumn);
}
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::ReflowChildren(
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 isMeasuringFeasibleContentBSize =
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.)
isMeasuringFeasibleContentBSize;
// 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 (isMeasuringFeasibleContentBSize) {
availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE;
COLUMN_SET_LOG(
"%s: Measuring content 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 = true;
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)",
__func__, colData.mColCount, child, availSize.ISize(wm),
availSize.BSize(wm), kidCBSize.ISize(wm), kidCBSize.BSize(wm));
// 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.
// Reflow the frame
const auto childMargin = kidReflowInput.ComputedLogicalMargin(wm);
const LogicalPoint origin(wm, childOrigin.I(wm) + childMargin.IStart(wm),
childOrigin.B(wm) + childMargin.BStart(wm));
aStatus.Reset();
ReflowChild(child, PresContext(), kidDesiredSize, kidReflowInput, wm,
origin, containerSize, ReflowChildFlags::Default, aStatus);
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() && !aStatus.IsTruncated()) {
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);
}
if (contentBEnd > aReflowInput.mCBReflowInput->ComputedMaxBSize() &&
aConfig.mIsBalancing) {
// We overflowed vertically, but have not exceeded the number of
// columns. We're going to go into overflow columns now, so balancing
// no longer applies.
colData.mHasExcessBSize = true;
}
// 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.RemoveFramesAfter(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 BlockReflowInput for ColumnSetFrame); 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() && !aStatus.IsTruncated();
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, *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, *overflows);
}
}
void nsColumnSetFrame::FindBestBalanceBSize(const ReflowInput& aReflowInput,
nsPresContext* aPresContext,
ReflowConfig& aConfig,
ColumnBalanceData aColData,
ReflowOutput& aDesiredSize,
bool aUnboundedLastColumn,
nsReflowStatus& aStatus) {
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.