void RenderMultiColumnSet::prepareForLayout()
{
RenderBlockFlow* multicolBlock = toRenderBlockFlow(parent());
const RenderStyle& multicolStyle = multicolBlock->style();
// Set box logical top.
ASSERT(!previousSiblingBox() || !previousSiblingBox()->isRenderMultiColumnSet()); // FIXME: multiple set not implemented; need to examine previous set to calculate the correct logical top.
setLogicalTop(multicolBlock->borderAndPaddingBefore());
// Set box width.
updateLogicalWidth();
if (multicolBlock->multiColumnFlowThread()->requiresBalancing()) {
// Set maximum column height. We will not stretch beyond this.
m_maxColumnHeight = RenderFlowThread::maxLogicalHeight();
if (!multicolStyle.logicalHeight().isAuto()) {
m_maxColumnHeight = multicolBlock->computeContentLogicalHeight(multicolStyle.logicalHeight());
if (m_maxColumnHeight == -1)
m_maxColumnHeight = RenderFlowThread::maxLogicalHeight();
}
if (!multicolStyle.logicalMaxHeight().isUndefined()) {
LayoutUnit logicalMaxHeight = multicolBlock->computeContentLogicalHeight(multicolStyle.logicalMaxHeight());
if (logicalMaxHeight != -1 && m_maxColumnHeight > logicalMaxHeight)
m_maxColumnHeight = logicalMaxHeight;
}
m_maxColumnHeight = heightAdjustedForSetOffset(m_maxColumnHeight);
m_computedColumnHeight = 0; // Restart balancing.
} else
setAndConstrainColumnHeight(heightAdjustedForSetOffset(multicolBlock->multiColumnFlowThread()->columnHeightAvailable()));
clearForcedBreaks();
// Nuke previously stored minimum column height. Contents may have changed for all we know.
m_minimumColumnHeight = 0;
}
bool RenderMultiColumnSet::recalculateBalancedHeight(bool initial)
{
ASSERT(multiColumnFlowThread()->requiresBalancing());
LayoutUnit oldColumnHeight = m_computedColumnHeight;
if (initial)
distributeImplicitBreaks();
LayoutUnit newColumnHeight = calculateBalancedHeight(initial);
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.
if (m_computedColumnHeight == oldColumnHeight)
return false; // No change. We're done.
m_minSpaceShortage = RenderFlowThread::maxLogicalHeight();
clearForcedBreaks();
return true; // Need another pass.
}
