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/*
* Copyright (C) 2017-2020 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "LayoutIntegrationPagination.h"
#include "BlockLayoutState.h"
#include "FontCascade.h"
#include "InlineIteratorLineBox.h"
#include "PlacedFloats.h"
#include "RenderBlockFlow.h"
#include "RenderStyleInlines.h"
#include "RenderTableCell.h"
namespace WebCore {
namespace LayoutIntegration {
static LayoutUnit computeFirstLineSnapAdjustment(const InlineDisplay::Line& line, const Layout::BlockLayoutState::LineGrid& lineGrid)
{
auto gridLineHeight = lineGrid.rowHeight;
auto& gridFontMetrics = lineGrid.primaryFont->fontMetrics();
auto lineGridFontAscent = gridFontMetrics.intAscent(line.baselineType());
auto lineGridFontHeight = gridFontMetrics.intHeight();
auto lineGridHalfLeading = (gridLineHeight - lineGridFontHeight) / 2;
auto firstLineTop = lineGrid.topRowOffset;
auto firstTextTop = firstLineTop + lineGridHalfLeading;
auto firstBaselinePosition = firstTextTop + lineGridFontAscent;
auto baseline = LayoutUnit { line.baseline() };
return lineGrid.paginationOrigin.value_or(LayoutSize { }).height() + firstBaselinePosition - baseline;
}
std::pair<Vector<LineAdjustment>, std::optional<LayoutRestartLine>> computeAdjustmentsForPagination(const InlineContent& inlineContent, const Layout::PlacedFloats& placedFloats, bool allowLayoutRestart, const Layout::BlockLayoutState& blockLayoutState, RenderBlockFlow& flow)
{
auto lineCount = inlineContent.displayContent().lines.size();
Vector<LineAdjustment> adjustments { lineCount };
UncheckedKeyHashMap<size_t, LayoutUnit, DefaultHash<size_t>, WTF::UnsignedWithZeroKeyHashTraits<size_t>> lineFloatBottomMap;
for (auto& floatBox : placedFloats.list()) {
if (!floatBox.layoutBox())
continue;
auto& renderer = downcast<RenderBox>(*floatBox.layoutBox()->rendererForIntegration());
bool isUsplittable = renderer.isUnsplittableForPagination() || renderer.style().breakInside() == BreakInside::Avoid;
auto placedByLine = floatBox.placedByLine();
if (!placedByLine) {
if (isUsplittable) {
auto rect = floatBox.absoluteRectWithMargin();
flow.updateMinimumPageHeight(rect.top(), rect.height());
}
continue;
}
auto floatMinimumBottom = [&] {
if (isUsplittable)
return floatBox.absoluteRectWithMargin().bottom();
if (auto* block = dynamicDowncast<RenderBlockFlow>(renderer)) {
if (auto firstLine = InlineIterator::firstLineBoxFor(*block))
return LayoutUnit { firstLine->logicalBottom() };
}
return 0_lu;
}();
auto result = lineFloatBottomMap.add(*placedByLine, floatMinimumBottom);
if (!result.isNewEntry)
result.iterator->value = std::max(floatMinimumBottom, result.iterator->value);
}
std::optional<size_t> previousPageBreakIndex;
std::optional<LayoutRestartLine> layoutRestartLine;
size_t widows = flow.style().hasAutoWidows() ? 0 : flow.style().widows();
size_t orphans = flow.style().orphans();
auto accumulatedOffset = 0_lu;
for (size_t lineIndex = 0; lineIndex < lineCount;) {
auto line = InlineIterator::lineBoxFor(inlineContent, lineIndex);
auto floatMinimumBottom = lineFloatBottomMap.getOptional(lineIndex).value_or(0_lu);
auto adjustment = flow.computeLineAdjustmentForPagination(line, accumulatedOffset, floatMinimumBottom);
if (layoutRestartLine && layoutRestartLine->index == lineIndex) {
ASSERT(!layoutRestartLine->offset);
layoutRestartLine->offset = adjustment.strut;
}
if (adjustment.isFirstAfterPageBreak) {
auto remainingLines = lineCount - lineIndex;
// Ignore the last line if it is completely empty.
if (inlineContent.displayContent().lines.last().lineBoxRect().isEmpty())
remainingLines--;
// See if there are enough lines left to meet the widow requirement.
if (remainingLines < widows && allowLayoutRestart && !layoutRestartLine) {
auto previousPageLineCount = lineIndex - previousPageBreakIndex.value_or(0);
auto neededLines = widows - remainingLines;
auto availableLines = previousPageLineCount > orphans ? previousPageLineCount - orphans : 0;
auto linesToMove = std::min(neededLines, availableLines);
if (linesToMove) {
auto breakIndex = lineIndex - linesToMove;
// Set the widow break and recompute the adjustments starting from that line.
flow.setBreakAtLineToAvoidWidow(breakIndex + 1);
lineIndex = breakIndex;
// We need to redo the layout starting from the break for things like intrusive floats.
layoutRestartLine = { breakIndex, { } };
continue;
}
}
previousPageBreakIndex = lineIndex;
}
accumulatedOffset += adjustment.strut;
if (adjustment.isFirstAfterPageBreak) {
if (!lineIndex)
accumulatedOffset += inlineContent.clearGapBeforeFirstLine();
if (flow.style().lineSnap() != LineSnap::None && blockLayoutState.lineGrid())
accumulatedOffset += computeFirstLineSnapAdjustment(inlineContent.displayContent().lines[lineIndex], *blockLayoutState.lineGrid());
}
adjustments[lineIndex] = LineAdjustment { accumulatedOffset, adjustment.isFirstAfterPageBreak };
++lineIndex;
}
flow.clearDidBreakAtLineToAvoidWidow();
if (!previousPageBreakIndex)
return { };
return { adjustments, layoutRestartLine };
}
void adjustLinePositionsForPagination(InlineContent& inlineContent, const Vector<LineAdjustment>& adjustments)
{
if (adjustments.isEmpty())
return;
auto writingMode = inlineContent.formattingContextRoot().style().writingMode();
bool isHorizontalWritingMode = writingMode.isHorizontal();
auto& displayContent = inlineContent.displayContent();
for (size_t lineIndex = 0; lineIndex < displayContent.lines.size(); ++lineIndex) {
auto& line = displayContent.lines[lineIndex];
auto& adjustment = adjustments[lineIndex];
line.moveInBlockDirection(adjustment.offset, isHorizontalWritingMode);
if (adjustment.isFirstAfterPageBreak)
line.setIsFirstAfterPageBreak();
}
for (auto& box : displayContent.boxes) {
auto offset = adjustments[box.lineIndex()].offset;
if (isHorizontalWritingMode)
box.moveVertically(offset);
else
box.moveHorizontally(offset);
}
}
}
}
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