LayoutRect MultiColumnFragmentainerGroup::fragmentsBoundingBox(const LayoutRect& boundingBoxInFlowThread) const
{
// Find the start and end column intersected by the bounding box.
LayoutRect flippedBoundingBoxInFlowThread(boundingBoxInFlowThread);
LayoutFlowThread* flowThread = m_columnSet.flowThread();
flowThread->flipForWritingMode(flippedBoundingBoxInFlowThread);
bool isHorizontalWritingMode = m_columnSet.isHorizontalWritingMode();
LayoutUnit boundingBoxLogicalTop = isHorizontalWritingMode ? flippedBoundingBoxInFlowThread.y() : flippedBoundingBoxInFlowThread.x();
LayoutUnit boundingBoxLogicalBottom = isHorizontalWritingMode ? flippedBoundingBoxInFlowThread.maxY() : flippedBoundingBoxInFlowThread.maxX();
if (boundingBoxLogicalBottom <= logicalTopInFlowThread() || boundingBoxLogicalTop >= logicalBottomInFlowThread())
return LayoutRect(); // The bounding box doesn't intersect this fragmentainer group.
unsigned startColumn;
unsigned endColumn;
columnIntervalForBlockRangeInFlowThread(boundingBoxLogicalTop, boundingBoxLogicalBottom, startColumn, endColumn);
LayoutRect startColumnFlowThreadOverflowPortion = flowThreadPortionOverflowRectAt(startColumn);
flowThread->flipForWritingMode(startColumnFlowThreadOverflowPortion);
LayoutRect startColumnRect(boundingBoxInFlowThread);
startColumnRect.intersect(startColumnFlowThreadOverflowPortion);
startColumnRect.move(flowThreadTranslationAtOffset(logicalTopInFlowThreadAt(startColumn)));
if (startColumn == endColumn)
return startColumnRect; // It all takes place in one column. We're done.
LayoutRect endColumnFlowThreadOverflowPortion = flowThreadPortionOverflowRectAt(endColumn);
flowThread->flipForWritingMode(endColumnFlowThreadOverflowPortion);
LayoutRect endColumnRect(boundingBoxInFlowThread);
endColumnRect.intersect(endColumnFlowThreadOverflowPortion);
endColumnRect.move(flowThreadTranslationAtOffset(logicalTopInFlowThreadAt(endColumn)));
return unionRect(startColumnRect, endColumnRect);
}
LayoutSize LayoutMultiColumnFlowThread::columnOffset(const LayoutPoint& point) const
{
if (!hasValidColumnSetInfo())
return LayoutSize(0, 0);
LayoutPoint flowThreadPoint = flipForWritingMode(point);
LayoutUnit blockOffset = isHorizontalWritingMode() ? flowThreadPoint.y() : flowThreadPoint.x();
return flowThreadTranslationAtOffset(blockOffset);
}
void MultiColumnFragmentainerGroup::collectLayerFragments(PaintLayerFragments& fragments, const LayoutRect& layerBoundingBox, const LayoutRect& dirtyRect) const
{
// |layerBoundingBox| is in the flow thread coordinate space, relative to the top/left edge of
// the flow thread, but note that it has been converted with respect to writing mode (so that
// it's visual/physical in that sense).
//
// |dirtyRect| is visual, relative to the multicol container.
//
// Then there's the output from this method - the stuff we put into the list of fragments. The
// fragment.paginationOffset point is the actual visual translation required to get from a
// location in the flow thread to a location in a given column. The fragment.paginationClip
// rectangle, on the other hand, is in flow thread coordinates, but otherwise completely
// physical in terms of writing mode.
LayoutMultiColumnFlowThread* flowThread = m_columnSet.multiColumnFlowThread();
bool isHorizontalWritingMode = m_columnSet.isHorizontalWritingMode();
// Put the layer bounds into flow thread-local coordinates by flipping it first. Since we're in
// a layoutObject, most rectangles are represented this way.
LayoutRect layerBoundsInFlowThread(layerBoundingBox);
flowThread->flipForWritingMode(layerBoundsInFlowThread);
// Now we can compare with the flow thread portions owned by each column. First let's
// see if the rect intersects our flow thread portion at all.
LayoutRect clippedRect(layerBoundsInFlowThread);
clippedRect.intersect(m_columnSet.flowThreadPortionOverflowRect());
if (clippedRect.isEmpty())
return;
// Now we know we intersect at least one column. Let's figure out the logical top and logical
// bottom of the area we're checking.
LayoutUnit layerLogicalTop = isHorizontalWritingMode ? layerBoundsInFlowThread.y() : layerBoundsInFlowThread.x();
LayoutUnit layerLogicalBottom = (isHorizontalWritingMode ? layerBoundsInFlowThread.maxY() : layerBoundsInFlowThread.maxX());
// Figure out the start and end columns for the layer and only check within that range so that
// we don't walk the entire column row.
unsigned startColumn;
unsigned endColumn;
columnIntervalForBlockRangeInFlowThread(layerLogicalTop, layerLogicalBottom, startColumn, endColumn);
// Now intersect with the columns actually occupied by the dirty rect, to narrow it down even further.
unsigned firstColumnInDirtyRect, lastColumnInDirtyRect;
columnIntervalForVisualRect(dirtyRect, firstColumnInDirtyRect, lastColumnInDirtyRect);
if (firstColumnInDirtyRect > endColumn || lastColumnInDirtyRect < startColumn)
return; // The two column intervals are disjoint. There's nothing to collect.
if (startColumn < firstColumnInDirtyRect)
startColumn = firstColumnInDirtyRect;
if (endColumn > lastColumnInDirtyRect)
endColumn = lastColumnInDirtyRect;
ASSERT(endColumn >= startColumn);
for (unsigned i = startColumn; i <= endColumn; i++) {
PaintLayerFragment fragment;
// Set the physical translation offset.
fragment.paginationOffset = toLayoutPoint(flowThreadTranslationAtOffset(logicalTopInFlowThreadAt(i)));
// Set the overflow clip rect that corresponds to the column.
fragment.paginationClip = flowThreadPortionOverflowRectAt(i);
// Flip it into more a physical (PaintLayer-style) rectangle.
flowThread->flipForWritingMode(fragment.paginationClip);
fragments.append(fragment);
}
}
