bool MultiColumnFragmentainerGroup::recalculateColumnHeight(BalancedColumnHeightCalculation calculationMode)
{
LayoutUnit oldColumnHeight = m_columnHeight;
m_maxColumnHeight = calculateMaxColumnHeight();
if (heightIsAuto()) {
if (calculationMode == GuessFromFlowThreadPortion) {
// Post-process the content runs and find out where the implicit breaks will occur.
distributeImplicitBreaks();
}
LayoutUnit newColumnHeight = calculateColumnHeight(calculationMode);
setAndConstrainColumnHeight(newColumnHeight);
// After having calculated an initial column height, the multicol container typically needs at
// least one more layout pass with a new column height, but if a height was specified, we only
// need to do this if we think that we need less space than specified. Conversely, if we
// determined that the columns need to be as tall as the specified height of the container, we
// have already laid it out correctly, and there's no need for another pass.
} else {
// The position of the column set may have changed, in which case height available for
// columns may have changed as well.
setAndConstrainColumnHeight(m_columnHeight);
}
// We can get rid of the content runs now, if we haven't already done so. They are only needed
// to calculate the initial balanced column height. In fact, we have to get rid of them before
// the next layout pass, since each pass will rebuild this.
m_contentRuns.clear();
if (m_columnHeight == oldColumnHeight)
return false; // No change. We're done.
m_minSpaceShortage = LayoutUnit::max();
return true; // Need another pass.
}
bool MultiColumnFragmentainerGroup::recalculateColumnHeight(BalancedColumnHeightCalculation calculationMode)
{
LayoutUnit oldColumnHeight = m_columnHeight;
m_maxColumnHeight = calculateMaxColumnHeight();
if (heightIsAuto()) {
LayoutUnit newColumnHeight = calculateColumnHeight(calculationMode);
setAndConstrainColumnHeight(newColumnHeight);
// After having calculated an initial column height, the multicol container typically needs at
// least one more layout pass with a new column height, but if a height was specified, we only
// need to do this if we think that we need less space than specified. Conversely, if we
// determined that the columns need to be as tall as the specified height of the container, we
// have already laid it out correctly, and there's no need for another pass.
} else {
// The position of the column set may have changed, in which case height available for
// columns may have changed as well.
setAndConstrainColumnHeight(m_columnHeight);
}
if (m_columnHeight == oldColumnHeight)
return false; // No change. We're done.
return true; // Need another pass.
}
void MultiColumnFragmentainerGroup::resetColumnHeight()
{
// Nuke previously stored minimum column height. Contents may have changed for all we know.
m_minimumColumnHeight = 0;
m_maxColumnHeight = calculateMaxColumnHeight();
LayoutMultiColumnFlowThread* flowThread = m_columnSet.multiColumnFlowThread();
LayoutMultiColumnFlowThread* enclosingFlowThread = flowThread->enclosingFlowThread();
if (enclosingFlowThread && enclosingFlowThread->isPageLogicalHeightKnown()) {
// TODO(mstensho): Do this better. If height is auto here, we shouldn't set a
// height, or forced breaks and pagination struts might mess up column balancing.
LayoutUnit columnHeight = heightIsAuto() ? m_maxColumnHeight : heightAdjustedForRowOffset(flowThread->columnHeightAvailable());
setAndConstrainColumnHeight(columnHeight);
} else if (heightIsAuto()) {
m_columnHeight = LayoutUnit();
} else {
setAndConstrainColumnHeight(heightAdjustedForRowOffset(flowThread->columnHeightAvailable()));
}
}
void MultiColumnFragmentainerGroup::resetColumnHeight()
{
// Nuke previously stored minimum column height. Contents may have changed for all we know.
m_minimumColumnHeight = 0;
m_maxColumnHeight = calculateMaxColumnHeight();
LayoutUnit oldColumnHeight = m_columnHeight;
if (heightIsAuto())
m_columnHeight = LayoutUnit();
else
setAndConstrainColumnHeight(heightAdjustedForRowOffset(m_columnSet.multiColumnFlowThread()->columnHeightAvailable()));
if (m_columnHeight != oldColumnHeight)
m_columnSet.setChildNeedsLayout(MarkOnlyThis);
// Content runs are only needed in the initial layout pass, in order to find an initial column
// height, and should have been deleted afterwards. We're about to rebuild the content runs, so
// the list needs to be empty.
ASSERT(m_contentRuns.isEmpty());
}
void LayoutMultiColumnSet::addContentRun(LayoutUnit endOffsetFromFirstPage)
{
if (!heightIsAuto())
return;
fragmentainerGroupAtFlowThreadOffset(endOffsetFromFirstPage).addContentRun(endOffsetFromFirstPage);
}