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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"
#if ENABLE(LAYOUT_FORMATTING_CONTEXT)
#include "FontCascade.h"
#include "RenderBlockFlow.h"
#include "RenderTableCell.h"
namespace WebCore {
namespace LayoutIntegration {
struct Strut {
unsigned lineBreak;
float offset;
};
struct PaginatedLine {
LayoutUnit top;
LayoutUnit height;
};
using PaginatedLines = Vector<PaginatedLine, 20>;
static PaginatedLine computeLineTopAndBottomWithOverflow(const RenderBlockFlow&, const InlineContent::Lines& lines, unsigned lineIndex, Vector<Strut>& struts)
{
LayoutUnit offset = 0;
for (auto& strut : struts) {
if (strut.lineBreak > lineIndex)
break;
offset += strut.offset;
}
auto overflowRect = LayoutRect(lines[lineIndex].inkOverflow());
return { overflowRect.y() + offset, overflowRect.height() };
}
static unsigned computeLineBreakIndex(unsigned breakCandidate, unsigned lineCount, int orphansNeeded, int widowsNeeded,
const Vector<Strut>& struts)
{
// First line does not fit the current page.
if (!breakCandidate)
return breakCandidate;
int widowsOnTheNextPage = lineCount - breakCandidate;
if (widowsNeeded <= widowsOnTheNextPage)
return breakCandidate;
// Only break after the first line with widows.
auto lineBreak = std::max<int>(lineCount - widowsNeeded, 1);
if (orphansNeeded > lineBreak)
return breakCandidate;
// Break on current page only.
if (struts.isEmpty())
return lineBreak;
ASSERT(struts.last().lineBreak + 1 < lineCount);
return std::max<unsigned>(struts.last().lineBreak + 1, lineBreak);
}
static LayoutUnit computeOffsetAfterLineBreak(LayoutUnit lineBreakPosition, bool isFirstLine, bool atTheTopOfColumnOrPage, const RenderBlockFlow& flow)
{
// No offset for top of the page lines unless widows pushed the line break.
LayoutUnit offset = isFirstLine ? flow.borderAndPaddingBefore() : 0_lu;
if (atTheTopOfColumnOrPage)
return offset;
return offset + flow.pageRemainingLogicalHeightForOffset(lineBreakPosition, RenderBlockFlow::ExcludePageBoundary);
}
static void setPageBreakForLine(unsigned lineBreakIndex, PaginatedLines& lines, RenderBlockFlow& flow, Vector<Strut>& struts, bool atTheTopOfColumnOrPage, bool lineDoesNotFit, bool& isPageBreakWithLineStrut)
{
auto line = lines.at(lineBreakIndex);
auto remainingLogicalHeight = flow.pageRemainingLogicalHeightForOffset(line.top, RenderBlockFlow::ExcludePageBoundary);
if (atTheTopOfColumnOrPage)
flow.setPageBreak(line.top, line.height);
else
flow.setPageBreak(line.top, line.height - remainingLogicalHeight);
auto& style = flow.style();
auto firstLineDoesNotFit = !lineBreakIndex && line.height < flow.pageLogicalHeightForOffset(line.top);
auto moveOrphanToNextColumn = lineDoesNotFit && !style.hasAutoOrphans() && style.orphans() > (short)lineBreakIndex;
// Special table cell handling. See RenderBlockFlow::adjustLinePositionForPagination for details.
if ((firstLineDoesNotFit || moveOrphanToNextColumn) && !is<RenderTableCell>(flow)) {
auto firstLine = lines.first();
auto firstLineUpperOverhang = std::max(LayoutUnit(-firstLine.top), 0_lu);
flow.setPaginationStrut(line.top + remainingLogicalHeight + firstLineUpperOverhang);
isPageBreakWithLineStrut = false;
return;
}
isPageBreakWithLineStrut = true;
struts.append({ lineBreakIndex, computeOffsetAfterLineBreak(lines[lineBreakIndex].top, !lineBreakIndex, atTheTopOfColumnOrPage, flow) });
}
static void updateMinimumPageHeight(RenderBlockFlow& flow, const InlineContent& inlineContent, unsigned lineCount)
{
auto& style = flow.style();
auto widows = style.hasAutoWidows() ? 1 : std::max<int>(style.widows(), 1);
auto orphans = style.hasAutoOrphans() ? 1 : std::max<int>(style.orphans(), 1);
auto minimumLineCount = std::min<unsigned>(std::max(widows, orphans), lineCount);
flow.updateMinimumPageHeight(0, LayoutUnit(inlineContent.lines[minimumLineCount - 1].lineBoxBottom()));
}
static std::unique_ptr<InlineContent> makeAdjustedContent(const InlineContent& inlineContent, Vector<float> adjustments, Vector<bool> isFirstLineAfterPageBreakList)
{
auto moveVertically = [](FloatRect rect, float offset) {
rect.move(FloatSize(0, offset));
return rect;
};
auto adjustedLine = [&] (auto& line, auto offset, auto isFirstAfterPageBreak) {
return Line {
line.firstBoxIndex(),
line.boxCount(),
moveVertically({ FloatPoint { line.lineBoxLeft(), line.lineBoxTop() }, FloatPoint { line.lineBoxRight(), line.lineBoxBottom() } }, offset),
line.enclosingContentTop() + offset,
line.enclosingContentBottom() + offset,
moveVertically(line.scrollableOverflow(), offset),
moveVertically(line.inkOverflow(), offset),
line.baseline(),
line.baselineType(),
line.contentLogicalOffset(),
line.contentLogicalWidth(),
line.isHorizontal(),
isFirstAfterPageBreak
};
};
auto adjustedBox = [&](auto& box, auto offset) {
auto adjustedBox = box;
adjustedBox.moveVertically(offset);
return adjustedBox;
};
auto adjustedContent = makeUnique<InlineContent>(inlineContent.lineLayout());
for (size_t lineIndex = 0; lineIndex < inlineContent.lines.size(); ++lineIndex)
adjustedContent->lines.append(adjustedLine(inlineContent.lines[lineIndex], adjustments[lineIndex], isFirstLineAfterPageBreakList[lineIndex]));
for (auto& box : inlineContent.boxes)
adjustedContent->boxes.append(adjustedBox(box, adjustments[box.lineIndex()]));
return adjustedContent;
}
std::unique_ptr<InlineContent> adjustLinePositionsForPagination(const InlineContent& inlineContent, RenderBlockFlow& flow)
{
Vector<Strut> struts;
auto lineCount = inlineContent.lines.size();
updateMinimumPageHeight(flow, inlineContent, lineCount);
// First pass with no pagination offset?
if (!flow.pageLogicalHeightForOffset(0))
return nullptr;
auto widows = flow.style().hasAutoWidows() ? 1 : std::max<int>(flow.style().widows(), 1);
auto orphans = flow.style().hasAutoOrphans() ? 1 : std::max<int>(flow.style().orphans(), 1);
PaginatedLines lines;
auto isFirstLineAfterPageBreakList = Vector<bool>(lineCount, false);
for (size_t lineIndex = 0; lineIndex < lineCount; ++lineIndex) {
auto line = computeLineTopAndBottomWithOverflow(flow, inlineContent.lines, lineIndex, struts);
lines.append(line);
auto remainingHeight = flow.pageRemainingLogicalHeightForOffset(line.top, RenderBlockFlow::ExcludePageBoundary);
auto atTheTopOfColumnOrPage = flow.pageLogicalHeightForOffset(line.top) == remainingHeight;
auto lineDoesNotFit = line.height > remainingHeight;
if (lineDoesNotFit || (atTheTopOfColumnOrPage && lineIndex)) {
auto lineBreakIndex = computeLineBreakIndex(lineIndex, lineCount, orphans, widows, struts);
// Are we still at the top of the column/page?
atTheTopOfColumnOrPage = atTheTopOfColumnOrPage ? lineIndex == lineBreakIndex : false;
auto isPageBreakWithLineStrut = false;
setPageBreakForLine(lineBreakIndex, lines, flow, struts, atTheTopOfColumnOrPage, lineDoesNotFit, isPageBreakWithLineStrut);
isFirstLineAfterPageBreakList[lineBreakIndex] = isPageBreakWithLineStrut;
// Recompute line positions that we already visited but widow break pushed them to a new page.
for (auto i = lineBreakIndex; i < lines.size(); ++i)
lines.at(i) = computeLineTopAndBottomWithOverflow(flow, inlineContent.lines, i, struts);
}
}
if (struts.isEmpty())
return nullptr;
auto adjustments = Vector<float>(lineCount, 0);
for (auto& strut : struts) {
for (auto lineIndex = strut.lineBreak; lineIndex < lineCount; ++lineIndex)
adjustments[lineIndex] += strut.offset;
}
return makeAdjustedContent(inlineContent, adjustments, isFirstLineAfterPageBreakList);
}
}
}
#endif
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