Source/WebCore/layout/formattingContexts/inline/InlineLineBoxBuilder.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 2021 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 "InlineLineBoxBuilder.h"

 #include "InlineLineBoxVerticalAligner.h"
 #include "InlineLineBuilder.h"
 #include "LayoutBoxGeometry.h"
 #include "LayoutReplacedBox.h"

 #if ENABLE(LAYOUT_FORMATTING_CONTEXT)

 namespace WebCore {
 namespace Layout {

 static std::optional<InlineLayoutUnit> horizontalAlignmentOffset(TextAlignMode textAlign, const LineBuilder::LineContent& lineContent)
 {
     // Depending on the line’s alignment/justification, the hanging glyph can be placed outside the line box.
     auto& runs = lineContent.runs;
     auto contentLogicalWidth = lineContent.contentLogicalWidth;
     if (lineContent.hangingWhitespaceWidth) {
         ASSERT(!runs.isEmpty());
         // If white-space is set to pre-wrap, the UA must (unconditionally) hang this sequence, unless the sequence is followed
         // by a forced line break, in which case it must conditionally hang the sequence is instead.
         // Note that end of last line in a paragraph is considered a forced break.
         auto isConditionalHanging = runs.last().isLineBreak() || lineContent.isLastLineWithInlineContent;
         // In some cases, a glyph at the end of a line can conditionally hang: it hangs only if it does not otherwise fit in the line prior to justification.
         // FIXME: Only the overflowing glyphs should be considered for hanging.
         if (isConditionalHanging)
             contentLogicalWidth = std::min(contentLogicalWidth, lineContent.lineLogicalWidth);
         else
             contentLogicalWidth -= lineContent.hangingWhitespaceWidth;
     }
     auto extraHorizontalSpace = lineContent.lineLogicalWidth - contentLogicalWidth;
     if (extraHorizontalSpace <= 0)
         return { };

     auto computedHorizontalAlignment = [&] {
         if (textAlign != TextAlignMode::Justify)
             return textAlign;
         // Text is justified according to the method specified by the text-justify property,
         // in order to exactly fill the line box. Unless otherwise specified by text-align-last,
         // the last line before a forced break or the end of the block is start-aligned.
         if (lineContent.isLastLineWithInlineContent || (!runs.isEmpty() && runs.last().isLineBreak()))
             return TextAlignMode::Start;
         return TextAlignMode::Justify;
     };

     switch (computedHorizontalAlignment()) {
     case TextAlignMode::Left:
     case TextAlignMode::WebKitLeft:
     case TextAlignMode::Start:
         return { };
     case TextAlignMode::Right:
     case TextAlignMode::WebKitRight:
     case TextAlignMode::End:
         return extraHorizontalSpace;
     case TextAlignMode::Center:
     case TextAlignMode::WebKitCenter:
         return extraHorizontalSpace / 2;
     case TextAlignMode::Justify:
         // TextAlignMode::Justify is a run alignment (and we only do inline box alignment here)
         return { };
     default:
         ASSERT_NOT_IMPLEMENTED_YET();
         return { };
     }
     ASSERT_NOT_REACHED();
     return { };
 }

 LineBoxBuilder::LineBoxBuilder(const InlineFormattingContext& inlineFormattingContext)
     : m_inlineFormattingContext(inlineFormattingContext)
 {
 }

 LineBoxBuilder::LineAndLineBox LineBoxBuilder::build(const LineBuilder::LineContent& lineContent, size_t lineIndex)
 {
     auto textAlign = !lineIndex ? rootBox().firstLineStyle().textAlign() : rootBox().style().textAlign();
     auto contentLogicalLeft = Layout::horizontalAlignmentOffset(textAlign, lineContent).value_or(InlineLayoutUnit { });
     auto lineBox = LineBox { rootBox(), contentLogicalLeft, lineContent.contentLogicalWidth, lineIndex, lineContent.nonSpanningInlineLevelBoxCount };

     auto lineBoxLogicalHeight = constructAndAlignInlineLevelBoxes(lineBox, lineContent.runs, lineIndex);

     auto line = [&] {
         auto lineBoxLogicalRect = InlineRect { lineContent.logicalTopLeft, lineContent.lineLogicalWidth, lineBoxLogicalHeight };
         auto scrollableOverflowRect = lineBoxLogicalRect;
         auto& rootInlineBox = lineBox.rootInlineBox();
         auto enclosingTopAndBottom = InlineDisplay::Line::EnclosingTopAndBottom { lineBoxLogicalRect.top() + rootInlineBox.logicalTop(), lineBoxLogicalRect.top() + rootInlineBox.logicalBottom() };

         for (auto& inlineLevelBox : lineBox.nonRootInlineLevelBoxes()) {
             if (!inlineLevelBox.isAtomicInlineLevelBox() && !inlineLevelBox.isInlineBox())
                 continue;

             auto& layoutBox = inlineLevelBox.layoutBox();
             auto borderBox = InlineRect { };

             if (inlineLevelBox.isAtomicInlineLevelBox()) {
                 borderBox = lineBox.logicalBorderBoxForAtomicInlineLevelBox(layoutBox, formattingContext().geometryForBox(layoutBox));
                 borderBox.moveBy(lineBoxLogicalRect.topLeft());
             } else if (inlineLevelBox.isInlineBox()) {
                 auto& boxGeometry = formattingContext().geometryForBox(layoutBox);
                 borderBox = lineBox.logicalBorderBoxForInlineBox(layoutBox, boxGeometry);
                 borderBox.moveBy(lineBoxLogicalRect.topLeft());
                 // Collect scrollable overflow from inline boxes. All other inline level boxes (e.g atomic inline level boxes) stretch the line.
                 auto hasScrollableContent = [&] {
                     // In standards mode, inline boxes always start with an imaginary strut.
                     return layoutState().inStandardsMode() || inlineLevelBox.hasContent() || boxGeometry.horizontalBorder() || (boxGeometry.horizontalPadding() && boxGeometry.horizontalPadding().value());
                 };
                 if (lineBox.hasContent() && hasScrollableContent()) {
                     // Empty lines (e.g. continuation pre/post blocks) don't expect scrollbar overflow.
                     scrollableOverflowRect.expandToContain(borderBox);
                 }
             } else
                 ASSERT_NOT_REACHED();

             enclosingTopAndBottom.top = std::min(enclosingTopAndBottom.top, borderBox.top());
             enclosingTopAndBottom.bottom = std::max(enclosingTopAndBottom.bottom, borderBox.bottom());
         }
         return InlineDisplay::Line { lineBoxLogicalRect, scrollableOverflowRect, enclosingTopAndBottom, rootInlineBox.logicalTop() + rootInlineBox.baseline(), rootInlineBox.logicalLeft(), rootInlineBox.logicalWidth() };
     };
     return { line(), lineBox };
 }

 void LineBoxBuilder::adjustVerticalGeometryForInlineBoxWithFallbackFonts(InlineLevelBox& inlineBox, const TextUtil::FallbackFontList& fallbackFontsForContent) const
 {
     ASSERT(!fallbackFontsForContent.isEmpty());
     ASSERT(inlineBox.isInlineBox());
     if (!inlineBox.isPreferredLineHeightFontMetricsBased())
         return;

     // https://www.w3.org/TR/css-inline-3/#inline-height
     // When the computed line-height is normal, the layout bounds of an inline box encloses all its glyphs, going from the highest A to the deepest D.
     auto maxAscent = InlineLayoutUnit { };
     auto maxDescent = InlineLayoutUnit { };
     // If line-height computes to normal and either text-edge is leading or this is the root inline box,
     // the font's line gap metric may also be incorporated into A and D by adding half to each side as half-leading.
     // FIXME: We don't support the text-edge property yet, but its initial value is 'leading' which makes the line-gap adjustment always on.
     auto isTextEdgeLeading = true;
     auto shouldUseLineGapToAdjustAscentDescent = inlineBox.isRootInlineBox() || isTextEdgeLeading;
     for (auto* font : fallbackFontsForContent) {
         auto& fontMetrics = font->fontMetrics();
         InlineLayoutUnit ascent = fontMetrics.ascent();
         InlineLayoutUnit descent = fontMetrics.descent();
         if (shouldUseLineGapToAdjustAscentDescent) {
             auto logicalHeight = ascent + descent;
             auto halfLineGap = (fontMetrics.lineSpacing() - logicalHeight) / 2;
             ascent = ascent + halfLineGap;
             descent = descent + halfLineGap;
         }
         maxAscent = std::max(maxAscent, ascent);
         maxDescent = std::max(maxDescent, descent);
     }

     // We need floor/ceil to match legacy layout integral positioning.
     auto layoutBounds = inlineBox.layoutBounds();
     inlineBox.setLayoutBounds({ std::max(layoutBounds.ascent, floorf(maxAscent)), std::max(layoutBounds.descent, ceilf(maxDescent)) });
 }

 struct HeightAndLayoutBounds {
     InlineLayoutUnit ascent { 0 };
     InlineLayoutUnit descent { 0 };
     InlineLevelBox::LayoutBounds layoutBounds { };
 };
 static auto computedHeightAndLayoutBounds(const FontMetrics& fontMetrics, std::optional<InlineLayoutUnit> preferredLineHeight)
 {
     InlineLayoutUnit ascent = fontMetrics.ascent();
     InlineLayoutUnit descent = fontMetrics.descent();
     auto logicalHeight = ascent + descent;

     if (preferredLineHeight) {
         // If line-height computes to normal and either text-edge is leading or this is the root inline box,
         // the font’s line gap metric may also be incorporated into A and D by adding half to each side as half-leading.
         // https://www.w3.org/TR/css-inline-3/#inline-height
         // Since text-edge is not supported yet and the initial value is leading, we should just apply it to
         // all inline boxes.
         auto halfLeading = (*preferredLineHeight - logicalHeight) / 2;
         return HeightAndLayoutBounds { ascent, descent, { ascent + halfLeading, descent + halfLeading } };
     }
     // Preferred line height is purely font metrics based (i.e glyphs stretch the line).
     auto halfLineGap = (fontMetrics.lineSpacing() - logicalHeight) / 2;
     return HeightAndLayoutBounds { ascent, descent, { ascent + halfLineGap, descent + halfLineGap } };
 }

 void LineBoxBuilder::setVerticalGeometryForLineBreakBox(InlineLevelBox& lineBreakBox, const InlineLevelBox& parentInlineBox) const
 {
     // We need floor/ceil to match legacy layout integral positioning.
     ASSERT(lineBreakBox.isLineBreakBox());
     ASSERT(parentInlineBox.isInlineBox());

     auto& fontMetrics = parentInlineBox.primaryFontMetrics();
     auto preferredLineHeight = parentInlineBox.isPreferredLineHeightFontMetricsBased() ? std::nullopt : std::make_optional(parentInlineBox.preferredLineHeight());
     auto heightAndLayoutBounds = computedHeightAndLayoutBounds(fontMetrics, preferredLineHeight);

     lineBreakBox.setBaseline(floorf(heightAndLayoutBounds.ascent));
     lineBreakBox.setDescent(ceilf(heightAndLayoutBounds.descent));
     lineBreakBox.setLogicalHeight(heightAndLayoutBounds.ascent + heightAndLayoutBounds.descent);
     lineBreakBox.setLayoutBounds({ floorf(heightAndLayoutBounds.layoutBounds.ascent), ceilf(heightAndLayoutBounds.layoutBounds.descent) });
 }

 void LineBoxBuilder::setInitialVerticalGeometryForInlineBox(InlineLevelBox& inlineBox) const
 {
     // We need floor/ceil to match legacy layout integral positioning.
     ASSERT(inlineBox.isInlineBox());

     auto& fontMetrics = inlineBox.primaryFontMetrics();
     auto preferredLineHeight = inlineBox.isPreferredLineHeightFontMetricsBased() ? std::nullopt : std::make_optional(inlineBox.preferredLineHeight());
     auto heightAndLayoutBounds = computedHeightAndLayoutBounds(fontMetrics, preferredLineHeight);

     inlineBox.setBaseline(floorf(heightAndLayoutBounds.ascent));
     inlineBox.setDescent(ceilf(heightAndLayoutBounds.descent));
     inlineBox.setLogicalHeight(heightAndLayoutBounds.ascent + heightAndLayoutBounds.descent);
     inlineBox.setLayoutBounds({ floorf(heightAndLayoutBounds.layoutBounds.ascent), ceilf(heightAndLayoutBounds.layoutBounds.descent) });
 }

 InlineLayoutUnit LineBoxBuilder::constructAndAlignInlineLevelBoxes(LineBox& lineBox, const Line::RunList& runs, size_t lineIndex)
 {
     auto& rootInlineBox = lineBox.rootInlineBox();
     setInitialVerticalGeometryForInlineBox(rootInlineBox);

     // FIXME: Add fast path support for line-height content.
     // FIXME: We should always be able to exercise the fast path when the line has no content at all, even in non-standards mode or with line-height set.
     auto canUseSimplifiedAlignment = layoutState().inStandardsMode() && rootInlineBox.isPreferredLineHeightFontMetricsBased();
     auto updateCanUseSimplifiedAlignment = [&](auto& inlineLevelBox, std::optional<const BoxGeometry> boxGeometry = std::nullopt) {
         if (!canUseSimplifiedAlignment)
             return;
         canUseSimplifiedAlignment = LineBoxVerticalAligner::canUseSimplifiedAlignmentForInlineLevelBox(rootInlineBox, inlineLevelBox, boxGeometry);
     };

     auto styleToUse = [&] (const auto& layoutBox) -> const RenderStyle& {
         return !lineIndex ? layoutBox.firstLineStyle() : layoutBox.style();
     };

     auto lineHasContent = false;
     for (auto& run : runs) {
         auto& layoutBox = run.layoutBox();
         auto& style = styleToUse(layoutBox);
         auto runHasContent = [&] () -> bool {
             ASSERT(!lineHasContent);
             if (run.isText() || run.isBox() || run.isSoftLineBreak() || run.isHardLineBreak())
                 return true;
             if (run.isLineSpanningInlineBoxStart())
                 return false;
             if (run.isWordBreakOpportunity())
                 return false;
             auto& inlineBoxGeometry = formattingContext().geometryForBox(layoutBox);
             // Even negative horizontal margin makes the line "contentful".
             if (run.isInlineBoxStart())
                 return inlineBoxGeometry.marginStart() || inlineBoxGeometry.borderLeft() || inlineBoxGeometry.paddingLeft().value_or(0_lu);
             if (run.isInlineBoxEnd())
                 return inlineBoxGeometry.marginEnd() || inlineBoxGeometry.borderRight() || inlineBoxGeometry.paddingRight().value_or(0_lu);
             ASSERT_NOT_REACHED();
             return true;
         };
         lineHasContent = lineHasContent || runHasContent();
         auto logicalLeft = rootInlineBox.logicalLeft() + run.logicalLeft();
         if (run.isBox()) {
             auto& inlineLevelBoxGeometry = formattingContext().geometryForBox(layoutBox);
             auto marginBoxHeight = inlineLevelBoxGeometry.marginBoxHeight();
             auto ascent = InlineLayoutUnit { };
             if (layoutState().shouldNotSynthesizeInlineBlockBaseline()) {
                 // Integration codepath constructs replaced boxes for inline-block content.
                 ASSERT(layoutBox.isReplacedBox());
                 ascent = *downcast<ReplacedBox>(layoutBox).baseline();
             } else if (layoutBox.isInlineBlockBox()) {
                 // The baseline of an 'inline-block' is the baseline of its last line box in the normal flow, unless it has either no in-flow line boxes or
                 // if its 'overflow' property has a computed value other than 'visible', in which case the baseline is the bottom margin edge.
                 auto synthesizeBaseline = !layoutBox.establishesInlineFormattingContext() || !style.isOverflowVisible();
                 if (synthesizeBaseline)
                     ascent = marginBoxHeight;
                 else {
                     auto& formattingState = layoutState().formattingStateForInlineFormattingContext(downcast<ContainerBox>(layoutBox));
                     auto& lastLine = formattingState.lines().last();
                     auto inlineBlockBaseline = lastLine.lineBoxLogicalRect().top() + lastLine.baseline();
                     ascent = inlineLevelBoxGeometry.marginBefore() + inlineLevelBoxGeometry.borderTop() + inlineLevelBoxGeometry.paddingTop().value_or(0) + inlineBlockBaseline;
                 }
             } else if (layoutBox.isReplacedBox())
                 ascent = downcast<ReplacedBox>(layoutBox).baseline().value_or(marginBoxHeight);
             else
                 ascent = marginBoxHeight;
             logicalLeft += std::max(0_lu, inlineLevelBoxGeometry.marginStart());
             auto atomicInlineLevelBox = InlineLevelBox::createAtomicInlineLevelBox(layoutBox, style, logicalLeft, { inlineLevelBoxGeometry.borderBoxWidth(), marginBoxHeight });
             atomicInlineLevelBox.setBaseline(ascent);
             atomicInlineLevelBox.setLayoutBounds(InlineLevelBox::LayoutBounds { ascent, marginBoxHeight - ascent });
             updateCanUseSimplifiedAlignment(atomicInlineLevelBox, inlineLevelBoxGeometry);
             lineBox.addInlineLevelBox(WTFMove(atomicInlineLevelBox));
             continue;
         }
         if (run.isLineSpanningInlineBoxStart()) {
             auto marginStart = InlineLayoutUnit { };
 #if ENABLE(CSS_BOX_DECORATION_BREAK)
             if (style.boxDecorationBreak() == BoxDecorationBreak::Clone)
                 marginStart = formattingContext().geometryForBox(layoutBox).marginStart();
 #endif
             auto adjustedLogicalStart = logicalLeft + marginStart;
             auto logicalWidth = rootInlineBox.logicalWidth() - adjustedLogicalStart;
             auto inlineBox = InlineLevelBox::createInlineBox(layoutBox, style, adjustedLogicalStart, logicalWidth, InlineLevelBox::LineSpanningInlineBox::Yes);
             setInitialVerticalGeometryForInlineBox(inlineBox);
             updateCanUseSimplifiedAlignment(inlineBox);
             lineBox.addInlineLevelBox(WTFMove(inlineBox));
             continue;
         }
         if (run.isInlineBoxStart()) {
             // At this point we don't know yet how wide this inline box is. Let's assume it's as long as the line is
             // and adjust it later if we come across an inlineBoxEnd run (see below).
             // Inline box run is based on margin box. Let's convert it to border box.
             auto marginStart = formattingContext().geometryForBox(layoutBox).marginStart();
             auto initialLogicalWidth = rootInlineBox.logicalWidth() - (run.logicalLeft() + marginStart);
             ASSERT(initialLogicalWidth >= 0);
             auto inlineBox = InlineLevelBox::createInlineBox(layoutBox, style, logicalLeft + marginStart, initialLogicalWidth);
             inlineBox.setIsFirstBox();
             setInitialVerticalGeometryForInlineBox(inlineBox);
             updateCanUseSimplifiedAlignment(inlineBox);
             lineBox.addInlineLevelBox(WTFMove(inlineBox));
             continue;
         }
         if (run.isInlineBoxEnd()) {
             // Adjust the logical width when the inline box closes on this line.
             // Note that margin end does not affect the logical width (e.g. positive margin right does not make the run wider).
             auto& inlineBox = lineBox.inlineLevelBoxForLayoutBox(layoutBox);
             ASSERT(inlineBox.isInlineBox());
             // Inline box run is based on margin box. Let's convert it to border box.
             // Negative margin end makes the run have negative width.
             auto marginEndAdjustemnt = -formattingContext().geometryForBox(layoutBox).marginEnd();
             auto logicalWidth = run.logicalWidth() + marginEndAdjustemnt;
             auto inlineBoxLogicalRight = logicalLeft + logicalWidth;
             // When the content pulls the </span> to the logical left direction (e.g. negative letter space)
             // make sure we don't end up with negative logical width on the inline box.
             inlineBox.setLogicalWidth(std::max(0.f, inlineBoxLogicalRight - inlineBox.logicalLeft()));
             inlineBox.setIsLastBox();
             updateCanUseSimplifiedAlignment(inlineBox);
             continue;
         }
         if (run.isText()) {
             auto& parentInlineBox = lineBox.inlineLevelBoxForLayoutBox(layoutBox.parent());
             parentInlineBox.setHasContent();
             auto fallbackFonts = TextUtil::fallbackFontsForRun(run, style);
             if (!fallbackFonts.isEmpty()) {
                 // Adjust non-empty inline box height when glyphs from the non-primary font stretch the box.
                 adjustVerticalGeometryForInlineBoxWithFallbackFonts(parentInlineBox, fallbackFonts);
                 updateCanUseSimplifiedAlignment(parentInlineBox);
             }
             continue;
         }
         if (run.isSoftLineBreak()) {
             lineBox.inlineLevelBoxForLayoutBox(layoutBox.parent()).setHasContent();
             continue;
         }
         if (run.isHardLineBreak()) {
             auto lineBreakBox = InlineLevelBox::createLineBreakBox(layoutBox, style, logicalLeft);
             auto& parentInlineBox = lineBox.inlineLevelBoxForLayoutBox(layoutBox.parent());
             setVerticalGeometryForLineBreakBox(lineBreakBox, parentInlineBox);
             updateCanUseSimplifiedAlignment(lineBreakBox);
             lineBox.addInlineLevelBox(WTFMove(lineBreakBox));
             continue;
         }
         if (run.isWordBreakOpportunity()) {
             lineBox.addInlineLevelBox(InlineLevelBox::createGenericInlineLevelBox(layoutBox, style, logicalLeft));
             continue;
         }
         ASSERT_NOT_REACHED();
     }

     lineBox.setHasContent(lineHasContent);

     auto verticalAligner = LineBoxVerticalAligner { formattingContext() };
     canUseSimplifiedAlignment = canUseSimplifiedAlignment || !lineHasContent;
     return verticalAligner.computeLogicalHeightAndAlign(lineBox, canUseSimplifiedAlignment);
 }

 }
 }

 #endif
	/*
	* Copyright (C) 2021 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 "InlineLineBoxBuilder.h"

	#include "InlineLineBoxVerticalAligner.h"
	#include "InlineLineBuilder.h"
	#include "LayoutBoxGeometry.h"
	#include "LayoutReplacedBox.h"

	#if ENABLE(LAYOUT_FORMATTING_CONTEXT)

	namespace WebCore {
	namespace Layout {

	static std::optional<InlineLayoutUnit> horizontalAlignmentOffset(TextAlignMode textAlign, const LineBuilder::LineContent& lineContent)
	{
	// Depending on the line’s alignment/justification, the hanging glyph can be placed outside the line box.
	auto& runs = lineContent.runs;
	auto contentLogicalWidth = lineContent.contentLogicalWidth;
	if (lineContent.hangingWhitespaceWidth) {
	ASSERT(!runs.isEmpty());
	// If white-space is set to pre-wrap, the UA must (unconditionally) hang this sequence, unless the sequence is followed
	// by a forced line break, in which case it must conditionally hang the sequence is instead.
	// Note that end of last line in a paragraph is considered a forced break.
	auto isConditionalHanging = runs.last().isLineBreak() \|\| lineContent.isLastLineWithInlineContent;
	// In some cases, a glyph at the end of a line can conditionally hang: it hangs only if it does not otherwise fit in the line prior to justification.
	// FIXME: Only the overflowing glyphs should be considered for hanging.
	if (isConditionalHanging)
	contentLogicalWidth = std::min(contentLogicalWidth, lineContent.lineLogicalWidth);
	else
	contentLogicalWidth -= lineContent.hangingWhitespaceWidth;
	}
	auto extraHorizontalSpace = lineContent.lineLogicalWidth - contentLogicalWidth;
	if (extraHorizontalSpace <= 0)
	return { };

	auto computedHorizontalAlignment = [&] {
	if (textAlign != TextAlignMode::Justify)
	return textAlign;
	// Text is justified according to the method specified by the text-justify property,
	// in order to exactly fill the line box. Unless otherwise specified by text-align-last,
	// the last line before a forced break or the end of the block is start-aligned.
	if (lineContent.isLastLineWithInlineContent \|\| (!runs.isEmpty() && runs.last().isLineBreak()))
	return TextAlignMode::Start;
	return TextAlignMode::Justify;
	};

	switch (computedHorizontalAlignment()) {
	case TextAlignMode::Left:
	case TextAlignMode::WebKitLeft:
	case TextAlignMode::Start:
	return { };
	case TextAlignMode::Right:
	case TextAlignMode::WebKitRight:
	case TextAlignMode::End:
	return extraHorizontalSpace;
	case TextAlignMode::Center:
	case TextAlignMode::WebKitCenter:
	return extraHorizontalSpace / 2;
	case TextAlignMode::Justify:
	// TextAlignMode::Justify is a run alignment (and we only do inline box alignment here)
	return { };
	default:
	ASSERT_NOT_IMPLEMENTED_YET();
	return { };
	}
	ASSERT_NOT_REACHED();
	return { };
	}

	LineBoxBuilder::LineBoxBuilder(const InlineFormattingContext& inlineFormattingContext)
	: m_inlineFormattingContext(inlineFormattingContext)
	{
	}

	LineBoxBuilder::LineAndLineBox LineBoxBuilder::build(const LineBuilder::LineContent& lineContent, size_t lineIndex)
	{
	auto textAlign = !lineIndex ? rootBox().firstLineStyle().textAlign() : rootBox().style().textAlign();
	auto contentLogicalLeft = Layout::horizontalAlignmentOffset(textAlign, lineContent).value_or(InlineLayoutUnit { });
	auto lineBox = LineBox { rootBox(), contentLogicalLeft, lineContent.contentLogicalWidth, lineIndex, lineContent.nonSpanningInlineLevelBoxCount };

	auto lineBoxLogicalHeight = constructAndAlignInlineLevelBoxes(lineBox, lineContent.runs, lineIndex);

	auto line = [&] {
	auto lineBoxLogicalRect = InlineRect { lineContent.logicalTopLeft, lineContent.lineLogicalWidth, lineBoxLogicalHeight };
	auto scrollableOverflowRect = lineBoxLogicalRect;
	auto& rootInlineBox = lineBox.rootInlineBox();
	auto enclosingTopAndBottom = InlineDisplay::Line::EnclosingTopAndBottom { lineBoxLogicalRect.top() + rootInlineBox.logicalTop(), lineBoxLogicalRect.top() + rootInlineBox.logicalBottom() };

	for (auto& inlineLevelBox : lineBox.nonRootInlineLevelBoxes()) {
	if (!inlineLevelBox.isAtomicInlineLevelBox() && !inlineLevelBox.isInlineBox())
	continue;

	auto& layoutBox = inlineLevelBox.layoutBox();
	auto borderBox = InlineRect { };

	if (inlineLevelBox.isAtomicInlineLevelBox()) {
	borderBox = lineBox.logicalBorderBoxForAtomicInlineLevelBox(layoutBox, formattingContext().geometryForBox(layoutBox));
	borderBox.moveBy(lineBoxLogicalRect.topLeft());
	} else if (inlineLevelBox.isInlineBox()) {
	auto& boxGeometry = formattingContext().geometryForBox(layoutBox);
	borderBox = lineBox.logicalBorderBoxForInlineBox(layoutBox, boxGeometry);
	borderBox.moveBy(lineBoxLogicalRect.topLeft());
	// Collect scrollable overflow from inline boxes. All other inline level boxes (e.g atomic inline level boxes) stretch the line.
	auto hasScrollableContent = [&] {
	// In standards mode, inline boxes always start with an imaginary strut.
	return layoutState().inStandardsMode() \|\| inlineLevelBox.hasContent() \|\| boxGeometry.horizontalBorder() \|\| (boxGeometry.horizontalPadding() && boxGeometry.horizontalPadding().value());
	};
	if (lineBox.hasContent() && hasScrollableContent()) {
	// Empty lines (e.g. continuation pre/post blocks) don't expect scrollbar overflow.
	scrollableOverflowRect.expandToContain(borderBox);
	}
	} else
	ASSERT_NOT_REACHED();

	enclosingTopAndBottom.top = std::min(enclosingTopAndBottom.top, borderBox.top());
	enclosingTopAndBottom.bottom = std::max(enclosingTopAndBottom.bottom, borderBox.bottom());
	}
	return InlineDisplay::Line { lineBoxLogicalRect, scrollableOverflowRect, enclosingTopAndBottom, rootInlineBox.logicalTop() + rootInlineBox.baseline(), rootInlineBox.logicalLeft(), rootInlineBox.logicalWidth() };
	};
	return { line(), lineBox };
	}

	void LineBoxBuilder::adjustVerticalGeometryForInlineBoxWithFallbackFonts(InlineLevelBox& inlineBox, const TextUtil::FallbackFontList& fallbackFontsForContent) const
	{
	ASSERT(!fallbackFontsForContent.isEmpty());
	ASSERT(inlineBox.isInlineBox());
	if (!inlineBox.isPreferredLineHeightFontMetricsBased())
	return;

	// https://www.w3.org/TR/css-inline-3/#inline-height
	// When the computed line-height is normal, the layout bounds of an inline box encloses all its glyphs, going from the highest A to the deepest D.
	auto maxAscent = InlineLayoutUnit { };
	auto maxDescent = InlineLayoutUnit { };
	// If line-height computes to normal and either text-edge is leading or this is the root inline box,
	// the font's line gap metric may also be incorporated into A and D by adding half to each side as half-leading.
	// FIXME: We don't support the text-edge property yet, but its initial value is 'leading' which makes the line-gap adjustment always on.
	auto isTextEdgeLeading = true;
	auto shouldUseLineGapToAdjustAscentDescent = inlineBox.isRootInlineBox() \|\| isTextEdgeLeading;
	for (auto* font : fallbackFontsForContent) {
	auto& fontMetrics = font->fontMetrics();
	InlineLayoutUnit ascent = fontMetrics.ascent();
	InlineLayoutUnit descent = fontMetrics.descent();
	if (shouldUseLineGapToAdjustAscentDescent) {
	auto logicalHeight = ascent + descent;
	auto halfLineGap = (fontMetrics.lineSpacing() - logicalHeight) / 2;
	ascent = ascent + halfLineGap;
	descent = descent + halfLineGap;
	}
	maxAscent = std::max(maxAscent, ascent);
	maxDescent = std::max(maxDescent, descent);
	}

	// We need floor/ceil to match legacy layout integral positioning.
	auto layoutBounds = inlineBox.layoutBounds();
	inlineBox.setLayoutBounds({ std::max(layoutBounds.ascent, floorf(maxAscent)), std::max(layoutBounds.descent, ceilf(maxDescent)) });
	}

	struct HeightAndLayoutBounds {
	InlineLayoutUnit ascent { 0 };
	InlineLayoutUnit descent { 0 };
	InlineLevelBox::LayoutBounds layoutBounds { };
	};
	static auto computedHeightAndLayoutBounds(const FontMetrics& fontMetrics, std::optional<InlineLayoutUnit> preferredLineHeight)
	{
	InlineLayoutUnit ascent = fontMetrics.ascent();
	InlineLayoutUnit descent = fontMetrics.descent();
	auto logicalHeight = ascent + descent;

	if (preferredLineHeight) {
	// If line-height computes to normal and either text-edge is leading or this is the root inline box,
	// the font’s line gap metric may also be incorporated into A and D by adding half to each side as half-leading.
	// https://www.w3.org/TR/css-inline-3/#inline-height
	// Since text-edge is not supported yet and the initial value is leading, we should just apply it to
	// all inline boxes.
	auto halfLeading = (*preferredLineHeight - logicalHeight) / 2;
	return HeightAndLayoutBounds { ascent, descent, { ascent + halfLeading, descent + halfLeading } };
	}
	// Preferred line height is purely font metrics based (i.e glyphs stretch the line).
	auto halfLineGap = (fontMetrics.lineSpacing() - logicalHeight) / 2;
	return HeightAndLayoutBounds { ascent, descent, { ascent + halfLineGap, descent + halfLineGap } };
	}

	void LineBoxBuilder::setVerticalGeometryForLineBreakBox(InlineLevelBox& lineBreakBox, const InlineLevelBox& parentInlineBox) const
	{
	// We need floor/ceil to match legacy layout integral positioning.
	ASSERT(lineBreakBox.isLineBreakBox());
	ASSERT(parentInlineBox.isInlineBox());

	auto& fontMetrics = parentInlineBox.primaryFontMetrics();
	auto preferredLineHeight = parentInlineBox.isPreferredLineHeightFontMetricsBased() ? std::nullopt : std::make_optional(parentInlineBox.preferredLineHeight());
	auto heightAndLayoutBounds = computedHeightAndLayoutBounds(fontMetrics, preferredLineHeight);

	lineBreakBox.setBaseline(floorf(heightAndLayoutBounds.ascent));
	lineBreakBox.setDescent(ceilf(heightAndLayoutBounds.descent));
	lineBreakBox.setLogicalHeight(heightAndLayoutBounds.ascent + heightAndLayoutBounds.descent);
	lineBreakBox.setLayoutBounds({ floorf(heightAndLayoutBounds.layoutBounds.ascent), ceilf(heightAndLayoutBounds.layoutBounds.descent) });
	}

	void LineBoxBuilder::setInitialVerticalGeometryForInlineBox(InlineLevelBox& inlineBox) const
	{
	// We need floor/ceil to match legacy layout integral positioning.
	ASSERT(inlineBox.isInlineBox());

	auto& fontMetrics = inlineBox.primaryFontMetrics();
	auto preferredLineHeight = inlineBox.isPreferredLineHeightFontMetricsBased() ? std::nullopt : std::make_optional(inlineBox.preferredLineHeight());
	auto heightAndLayoutBounds = computedHeightAndLayoutBounds(fontMetrics, preferredLineHeight);

	inlineBox.setBaseline(floorf(heightAndLayoutBounds.ascent));
	inlineBox.setDescent(ceilf(heightAndLayoutBounds.descent));
	inlineBox.setLogicalHeight(heightAndLayoutBounds.ascent + heightAndLayoutBounds.descent);
	inlineBox.setLayoutBounds({ floorf(heightAndLayoutBounds.layoutBounds.ascent), ceilf(heightAndLayoutBounds.layoutBounds.descent) });
	}

	InlineLayoutUnit LineBoxBuilder::constructAndAlignInlineLevelBoxes(LineBox& lineBox, const Line::RunList& runs, size_t lineIndex)
	{
	auto& rootInlineBox = lineBox.rootInlineBox();
	setInitialVerticalGeometryForInlineBox(rootInlineBox);

	// FIXME: Add fast path support for line-height content.
	// FIXME: We should always be able to exercise the fast path when the line has no content at all, even in non-standards mode or with line-height set.
	auto canUseSimplifiedAlignment = layoutState().inStandardsMode() && rootInlineBox.isPreferredLineHeightFontMetricsBased();
	auto updateCanUseSimplifiedAlignment = [&](auto& inlineLevelBox, std::optional<const BoxGeometry> boxGeometry = std::nullopt) {
	if (!canUseSimplifiedAlignment)
	return;
	canUseSimplifiedAlignment = LineBoxVerticalAligner::canUseSimplifiedAlignmentForInlineLevelBox(rootInlineBox, inlineLevelBox, boxGeometry);
	};

	auto styleToUse = [&] (const auto& layoutBox) -> const RenderStyle& {
	return !lineIndex ? layoutBox.firstLineStyle() : layoutBox.style();
	};

	auto lineHasContent = false;
	for (auto& run : runs) {
	auto& layoutBox = run.layoutBox();
	auto& style = styleToUse(layoutBox);
	auto runHasContent = [&] () -> bool {
	ASSERT(!lineHasContent);
	if (run.isText() \|\| run.isBox() \|\| run.isSoftLineBreak() \|\| run.isHardLineBreak())
	return true;
	if (run.isLineSpanningInlineBoxStart())
	return false;
	if (run.isWordBreakOpportunity())
	return false;
	auto& inlineBoxGeometry = formattingContext().geometryForBox(layoutBox);
	// Even negative horizontal margin makes the line "contentful".
	if (run.isInlineBoxStart())
	return inlineBoxGeometry.marginStart() \|\| inlineBoxGeometry.borderLeft() \|\| inlineBoxGeometry.paddingLeft().value_or(0_lu);
	if (run.isInlineBoxEnd())
	return inlineBoxGeometry.marginEnd() \|\| inlineBoxGeometry.borderRight() \|\| inlineBoxGeometry.paddingRight().value_or(0_lu);
	ASSERT_NOT_REACHED();
	return true;
	};
	lineHasContent = lineHasContent \|\| runHasContent();
	auto logicalLeft = rootInlineBox.logicalLeft() + run.logicalLeft();
	if (run.isBox()) {
	auto& inlineLevelBoxGeometry = formattingContext().geometryForBox(layoutBox);
	auto marginBoxHeight = inlineLevelBoxGeometry.marginBoxHeight();
	auto ascent = InlineLayoutUnit { };
	if (layoutState().shouldNotSynthesizeInlineBlockBaseline()) {
	// Integration codepath constructs replaced boxes for inline-block content.
	ASSERT(layoutBox.isReplacedBox());
	ascent = *downcast<ReplacedBox>(layoutBox).baseline();
	} else if (layoutBox.isInlineBlockBox()) {
	// The baseline of an 'inline-block' is the baseline of its last line box in the normal flow, unless it has either no in-flow line boxes or
	// if its 'overflow' property has a computed value other than 'visible', in which case the baseline is the bottom margin edge.
	auto synthesizeBaseline = !layoutBox.establishesInlineFormattingContext() \|\| !style.isOverflowVisible();
	if (synthesizeBaseline)
	ascent = marginBoxHeight;
	else {
	auto& formattingState = layoutState().formattingStateForInlineFormattingContext(downcast<ContainerBox>(layoutBox));
	auto& lastLine = formattingState.lines().last();
	auto inlineBlockBaseline = lastLine.lineBoxLogicalRect().top() + lastLine.baseline();
	ascent = inlineLevelBoxGeometry.marginBefore() + inlineLevelBoxGeometry.borderTop() + inlineLevelBoxGeometry.paddingTop().value_or(0) + inlineBlockBaseline;
	}
	} else if (layoutBox.isReplacedBox())
	ascent = downcast<ReplacedBox>(layoutBox).baseline().value_or(marginBoxHeight);
	else
	ascent = marginBoxHeight;
	logicalLeft += std::max(0_lu, inlineLevelBoxGeometry.marginStart());
	auto atomicInlineLevelBox = InlineLevelBox::createAtomicInlineLevelBox(layoutBox, style, logicalLeft, { inlineLevelBoxGeometry.borderBoxWidth(), marginBoxHeight });
	atomicInlineLevelBox.setBaseline(ascent);
	atomicInlineLevelBox.setLayoutBounds(InlineLevelBox::LayoutBounds { ascent, marginBoxHeight - ascent });
	updateCanUseSimplifiedAlignment(atomicInlineLevelBox, inlineLevelBoxGeometry);
	lineBox.addInlineLevelBox(WTFMove(atomicInlineLevelBox));
	continue;
	}
	if (run.isLineSpanningInlineBoxStart()) {
	auto marginStart = InlineLayoutUnit { };
	#if ENABLE(CSS_BOX_DECORATION_BREAK)
	if (style.boxDecorationBreak() == BoxDecorationBreak::Clone)
	marginStart = formattingContext().geometryForBox(layoutBox).marginStart();
	#endif
	auto adjustedLogicalStart = logicalLeft + marginStart;
	auto logicalWidth = rootInlineBox.logicalWidth() - adjustedLogicalStart;
	auto inlineBox = InlineLevelBox::createInlineBox(layoutBox, style, adjustedLogicalStart, logicalWidth, InlineLevelBox::LineSpanningInlineBox::Yes);
	setInitialVerticalGeometryForInlineBox(inlineBox);
	updateCanUseSimplifiedAlignment(inlineBox);
	lineBox.addInlineLevelBox(WTFMove(inlineBox));
	continue;
	}
	if (run.isInlineBoxStart()) {
	// At this point we don't know yet how wide this inline box is. Let's assume it's as long as the line is
	// and adjust it later if we come across an inlineBoxEnd run (see below).
	// Inline box run is based on margin box. Let's convert it to border box.
	auto marginStart = formattingContext().geometryForBox(layoutBox).marginStart();
	auto initialLogicalWidth = rootInlineBox.logicalWidth() - (run.logicalLeft() + marginStart);
	ASSERT(initialLogicalWidth >= 0);
	auto inlineBox = InlineLevelBox::createInlineBox(layoutBox, style, logicalLeft + marginStart, initialLogicalWidth);
	inlineBox.setIsFirstBox();
	setInitialVerticalGeometryForInlineBox(inlineBox);
	updateCanUseSimplifiedAlignment(inlineBox);
	lineBox.addInlineLevelBox(WTFMove(inlineBox));
	continue;
	}
	if (run.isInlineBoxEnd()) {
	// Adjust the logical width when the inline box closes on this line.
	// Note that margin end does not affect the logical width (e.g. positive margin right does not make the run wider).
	auto& inlineBox = lineBox.inlineLevelBoxForLayoutBox(layoutBox);
	ASSERT(inlineBox.isInlineBox());
	// Inline box run is based on margin box. Let's convert it to border box.
	// Negative margin end makes the run have negative width.
	auto marginEndAdjustemnt = -formattingContext().geometryForBox(layoutBox).marginEnd();
	auto logicalWidth = run.logicalWidth() + marginEndAdjustemnt;
	auto inlineBoxLogicalRight = logicalLeft + logicalWidth;
	// When the content pulls the </span> to the logical left direction (e.g. negative letter space)
	// make sure we don't end up with negative logical width on the inline box.
	inlineBox.setLogicalWidth(std::max(0.f, inlineBoxLogicalRight - inlineBox.logicalLeft()));
	inlineBox.setIsLastBox();
	updateCanUseSimplifiedAlignment(inlineBox);
	continue;
	}
	if (run.isText()) {
	auto& parentInlineBox = lineBox.inlineLevelBoxForLayoutBox(layoutBox.parent());
	parentInlineBox.setHasContent();
	auto fallbackFonts = TextUtil::fallbackFontsForRun(run, style);
	if (!fallbackFonts.isEmpty()) {
	// Adjust non-empty inline box height when glyphs from the non-primary font stretch the box.
	adjustVerticalGeometryForInlineBoxWithFallbackFonts(parentInlineBox, fallbackFonts);
	updateCanUseSimplifiedAlignment(parentInlineBox);
	}
	continue;
	}
	if (run.isSoftLineBreak()) {
	lineBox.inlineLevelBoxForLayoutBox(layoutBox.parent()).setHasContent();
	continue;
	}
	if (run.isHardLineBreak()) {
	auto lineBreakBox = InlineLevelBox::createLineBreakBox(layoutBox, style, logicalLeft);
	auto& parentInlineBox = lineBox.inlineLevelBoxForLayoutBox(layoutBox.parent());
	setVerticalGeometryForLineBreakBox(lineBreakBox, parentInlineBox);
	updateCanUseSimplifiedAlignment(lineBreakBox);
	lineBox.addInlineLevelBox(WTFMove(lineBreakBox));
	continue;
	}
	if (run.isWordBreakOpportunity()) {
	lineBox.addInlineLevelBox(InlineLevelBox::createGenericInlineLevelBox(layoutBox, style, logicalLeft));
	continue;
	}
	ASSERT_NOT_REACHED();
	}

	lineBox.setHasContent(lineHasContent);

	auto verticalAligner = LineBoxVerticalAligner { formattingContext() };
	canUseSimplifiedAlignment = canUseSimplifiedAlignment \|\| !lineHasContent;
	return verticalAligner.computeLogicalHeightAndAlign(lineBox, canUseSimplifiedAlignment);
	}

	}
	}

	#endif