FloatingObjects::FloatingObjects(const RenderBlockFlow& renderer)
: m_leftObjectsCount(0)
, m_rightObjectsCount(0)
, m_horizontalWritingMode(renderer.isHorizontalWritingMode())
, m_renderer(renderer)
{
}
RootInlineBox::RootInlineBox(RenderBlockFlow& block)
: InlineFlowBox(block)
, m_lineBreakPos(0)
, m_lineBreakObj(nullptr)
{
setIsHorizontal(block.isHorizontalWritingMode());
}
bool canUseFor(const RenderBlockFlow& flow)
{
if (!flow.frame().settings().simpleLineLayoutEnabled())
return false;
if (!flow.firstChild())
return false;
// This currently covers <blockflow>#text</blockflow> case.
// The <blockflow><inline>#text</inline></blockflow> case is also popular and should be relatively easy to cover.
if (flow.firstChild() != flow.lastChild())
return false;
if (!flow.firstChild()->isText())
return false;
if (!flow.isHorizontalWritingMode())
return false;
if (flow.flowThreadState() != RenderObject::NotInsideFlowThread)
return false;
if (flow.hasOutline())
return false;
if (flow.isRubyText() || flow.isRubyBase())
return false;
if (flow.parent()->isDeprecatedFlexibleBox())
return false;
// FIXME: Implementation of wrap=hard looks into lineboxes.
if (flow.parent()->isTextArea() && flow.parent()->element()->fastHasAttribute(HTMLNames::wrapAttr))
return false;
// FIXME: Placeholders do something strange.
if (flow.parent()->isTextControl() && toRenderTextControl(*flow.parent()).textFormControlElement().placeholderElement())
return false;
const RenderStyle& style = flow.style();
if (style.textDecorationsInEffect() != TextDecorationNone)
return false;
if (style.textAlign() == JUSTIFY)
return false;
// Non-visible overflow should be pretty easy to support.
if (style.overflowX() != OVISIBLE || style.overflowY() != OVISIBLE)
return false;
if (!style.textIndent().isZero())
return false;
if (!style.wordSpacing().isZero() || style.letterSpacing())
return false;
if (style.textTransform() != TTNONE)
return false;
if (!style.isLeftToRightDirection())
return false;
if (style.lineBoxContain() != RenderStyle::initialLineBoxContain())
return false;
if (style.writingMode() != TopToBottomWritingMode)
return false;
if (style.lineBreak() != LineBreakAuto)
return false;
if (style.wordBreak() != NormalWordBreak)
return false;
if (style.unicodeBidi() != UBNormal || style.rtlOrdering() != LogicalOrder)
return false;
if (style.lineAlign() != LineAlignNone || style.lineSnap() != LineSnapNone)
return false;
if (style.hyphens() == HyphensAuto)
return false;
if (style.textEmphasisFill() != TextEmphasisFillFilled || style.textEmphasisMark() != TextEmphasisMarkNone)
return false;
if (style.textShadow())
return false;
if (style.textOverflow() || (flow.isAnonymousBlock() && flow.parent()->style().textOverflow()))
return false;
if (style.hasPseudoStyle(FIRST_LINE) || style.hasPseudoStyle(FIRST_LETTER))
return false;
if (style.hasTextCombine())
return false;
if (style.backgroundClip() == TextFillBox)
return false;
if (style.borderFit() == BorderFitLines)
return false;
const RenderText& textRenderer = toRenderText(*flow.firstChild());
if (flow.containsFloats()) {
// We can't use the code path if any lines would need to be shifted below floats. This is because we don't keep per-line y coordinates.
float minimumWidthNeeded = textRenderer.minLogicalWidth();
for (auto& floatRenderer : *flow.floatingObjectSet()) {
ASSERT(floatRenderer);
float availableWidth = flow.availableLogicalWidthForLine(floatRenderer->y(), false);
if (availableWidth < minimumWidthNeeded)
return false;
}
}
if (textRenderer.isCombineText() || textRenderer.isCounter() || textRenderer.isQuote() || textRenderer.isTextFragment()
|| textRenderer.isSVGInlineText())
return false;
if (style.font().codePath(TextRun(textRenderer.text())) != Font::Simple)
return false;
if (style.font().isSVGFont())
return false;
// We assume that all lines have metrics based purely on the primary font.
auto& primaryFontData = *style.font().primaryFont();
if (primaryFontData.isLoading())
return false;
if (!canUseForText(textRenderer, primaryFontData))
return false;
return true;
}
static AvoidanceReasonFlags canUseForWithReason(const RenderBlockFlow& flow, FallThrough fallthrough)
{
#ifndef NDEBUG
static std::once_flag onceFlag;
std::call_once(onceFlag, [] {
registerNotifyCallback("com.apple.WebKit.showSimpleLineLayoutCoverage", printSimpleLineLayoutCoverage);
registerNotifyCallback("com.apple.WebKit.showSimpleLineLayoutReasons", printSimpleLineLayoutBlockList);
});
#endif
AvoidanceReasonFlags reasons = NoReason;
if (!flow.frame().settings().simpleLineLayoutEnabled())
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FeatureIsDisabled, fallthrough);
if (!flow.parent())
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowHasNoParent, fallthrough);
if (!flow.firstChild())
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowHasNoChild, fallthrough);
if (flow.flowThreadState() != RenderObject::NotInsideFlowThread)
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowIsInsideRegion, fallthrough);
if (!flow.isHorizontalWritingMode())
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowHasHorizonalWritingMode, fallthrough);
if (flow.hasOutline())
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowHasOutline, fallthrough);
if (flow.isRubyText() || flow.isRubyBase())
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowIsRuby, fallthrough);
// Printing does pagination without a flow thread.
if (flow.document().paginated())
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowIsPaginated, fallthrough);
if (flow.isAnonymous() && flow.firstLineBlock())
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowHasPseudoFirstLine, fallthrough);
if (flow.isAnonymousBlock() && flow.parent()->style().textOverflow())
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowHasTextOverflow, fallthrough);
if (flow.parent()->isDeprecatedFlexibleBox())
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowIsDepricatedFlexBox, fallthrough);
// FIXME: Placeholders do something strange.
if (is<RenderTextControl>(*flow.parent()) && downcast<RenderTextControl>(*flow.parent()).textFormControlElement().placeholderElement())
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowParentIsPlaceholderElement, fallthrough);
// FIXME: Implementation of wrap=hard looks into lineboxes.
if (flow.parent()->isTextArea() && flow.parent()->element()->fastHasAttribute(HTMLNames::wrapAttr))
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowParentIsTextAreaWithWrapping, fallthrough);
// This currently covers <blockflow>#text</blockflow>, <blockflow>#text<br></blockflow> and mutiple (sibling) RenderText cases.
// The <blockflow><inline>#text</inline></blockflow> case is also popular and should be relatively easy to cover.
for (const auto* child = flow.firstChild(); child;) {
if (is<RenderText>(*child)) {
child = child->nextSibling();
continue;
}
if (is<RenderLineBreak>(child) && !downcast<RenderLineBreak>(*child).isWBR() && child->style().clear() == CNONE) {
child = child->nextSibling();
continue;
}
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowHasNonSupportedChild, fallthrough);
break;
}
auto styleReasons = canUseForStyle(flow.style(), fallthrough);
if (styleReasons != NoReason)
SET_REASON_AND_RETURN_IF_NEEDED(reasons, styleReasons, fallthrough);
// We can't use the code path if any lines would need to be shifted below floats. This is because we don't keep per-line y coordinates.
if (flow.containsFloats()) {
float minimumWidthNeeded = std::numeric_limits<float>::max();
for (const auto& textRenderer : childrenOfType<RenderText>(flow)) {
minimumWidthNeeded = std::min(minimumWidthNeeded, textRenderer.minLogicalWidth());
for (auto& floatingObject : *flow.floatingObjectSet()) {
ASSERT(floatingObject);
#if ENABLE(CSS_SHAPES)
// if a float has a shape, we cannot tell if content will need to be shifted until after we lay it out,
// since the amount of space is not uniform for the height of the float.
if (floatingObject->renderer().shapeOutsideInfo())
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowHasUnsupportedFloat, fallthrough);
#endif
float availableWidth = flow.availableLogicalWidthForLine(floatingObject->y(), false);
if (availableWidth < minimumWidthNeeded)
SET_REASON_AND_RETURN_IF_NEEDED(reasons, FlowHasUnsupportedFloat, fallthrough);
}
}
}
auto fontAndTextReasons = canUseForFontAndText(flow, fallthrough);
if (fontAndTextReasons != NoReason)
SET_REASON_AND_RETURN_IF_NEEDED(reasons, fontAndTextReasons, fallthrough);
return reasons;
}
bool canUseFor(const RenderBlockFlow& flow)
{
#if !PLATFORM(MAC) && !PLATFORM(GTK) && !PLATFORM(EFL)
// FIXME: Non-mac platforms are hitting ASSERT(run.charactersLength() >= run.length())
// https://bugs.webkit.org/show_bug.cgi?id=123338
return false;
#else
if (!flow.frame().settings().simpleLineLayoutEnabled())
return false;
if (!flow.firstChild())
return false;
// This currently covers <blockflow>#text</blockflow> case.
// The <blockflow><inline>#text</inline></blockflow> case is also popular and should be relatively easy to cover.
if (flow.firstChild() != flow.lastChild())
return false;
if (!flow.firstChild()->isText())
return false;
if (!flow.isHorizontalWritingMode())
return false;
if (flow.flowThreadState() != RenderObject::NotInsideFlowThread)
return false;
if (flow.hasOutline())
return false;
if (flow.isRubyText() || flow.isRubyBase())
return false;
if (flow.parent()->isDeprecatedFlexibleBox())
return false;
// FIXME: Implementation of wrap=hard looks into lineboxes.
if (flow.parent()->isTextArea() && flow.parent()->element()->fastHasAttribute(HTMLNames::wrapAttr))
return false;
// FIXME: Placeholders do something strange.
if (flow.parent()->isTextControl() && toRenderTextControl(*flow.parent()).textFormControlElement().placeholderElement())
return false;
// These tests only works during layout. Outside layout this function may give false positives.
if (flow.view().layoutState()) {
#if ENABLE(CSS_SHAPES)
if (flow.view().layoutState()->shapeInsideInfo())
return false;
#endif
if (flow.view().layoutState()->m_columnInfo)
return false;
}
const RenderStyle& style = flow.style();
if (style.textDecorationsInEffect() != TextDecorationNone)
return false;
if (style.textAlign() == JUSTIFY)
return false;
// Non-visible overflow should be pretty easy to support.
if (style.overflowX() != OVISIBLE || style.overflowY() != OVISIBLE)
return false;
if (!style.textIndent().isZero())
return false;
if (style.wordSpacing() || style.letterSpacing())
return false;
if (style.textTransform() != TTNONE)
return false;
if (!style.isLeftToRightDirection())
return false;
if (style.lineBoxContain() != RenderStyle::initialLineBoxContain())
return false;
if (style.writingMode() != TopToBottomWritingMode)
return false;
if (style.lineBreak() != LineBreakAuto)
return false;
if (style.wordBreak() != NormalWordBreak)
return false;
if (style.unicodeBidi() != UBNormal || style.rtlOrdering() != LogicalOrder)
return false;
if (style.lineAlign() != LineAlignNone || style.lineSnap() != LineSnapNone)
return false;
if (style.hyphens() == HyphensAuto)
return false;
if (style.textEmphasisFill() != TextEmphasisFillFilled || style.textEmphasisMark() != TextEmphasisMarkNone)
return false;
if (style.textShadow())
return false;
#if ENABLE(CSS_SHAPES)
if (style.resolvedShapeInside())
return true;
#endif
if (style.textOverflow() || (flow.isAnonymousBlock() && flow.parent()->style().textOverflow()))
return false;
if (style.hasPseudoStyle(FIRST_LINE) || style.hasPseudoStyle(FIRST_LETTER))
return false;
if (style.hasTextCombine())
return false;
if (style.backgroundClip() == TextFillBox)
return false;
if (style.borderFit() == BorderFitLines)
return false;
const RenderText& textRenderer = toRenderText(*flow.firstChild());
if (flow.containsFloats()) {
// We can't use the code path if any lines would need to be shifted below floats. This is because we don't keep per-line y coordinates.
// It is enough to test the first line width only as currently all floats must be overhanging.
if (textRenderer.minLogicalWidth() > LineWidth(const_cast<RenderBlockFlow&>(flow), false, DoNotIndentText).availableWidth())
return false;
}
if (textRenderer.isCombineText() || textRenderer.isCounter() || textRenderer.isQuote() || textRenderer.isTextFragment()
#if ENABLE(SVG)
|| textRenderer.isSVGInlineText()
#endif
)
return false;
if (style.font().codePath(TextRun(textRenderer.text())) != Font::Simple)
return false;
if (style.font().isSVGFont())
return false;
// We assume that all lines have metrics based purely on the primary font.
auto& primaryFontData = *style.font().primaryFont();
if (primaryFontData.isLoading())
return false;
if (!canUseForText(textRenderer, primaryFontData))
return false;
return true;
#endif
}
bool canUseFor(const RenderBlockFlow& flow)
{
#if !PLATFORM(MAC)
// FIXME: Non-mac platforms are hitting ASSERT(run.charactersLength() >= run.length())
// https://bugs.webkit.org/show_bug.cgi?id=123338
return false;
#endif
if (!flow.firstChild())
return false;
// This currently covers <blockflow>#text</blockflow> case.
// The <blockflow><inline>#text</inline></blockflow> case is also popular and should be relatively easy to cover.
if (flow.firstChild() != flow.lastChild())
return false;
if (!flow.firstChild()->isText())
return false;
// Supporting floats would be very beneficial.
if (flow.containsFloats())
return false;
if (!flow.isHorizontalWritingMode())
return false;
if (flow.flowThreadState() != RenderObject::NotInsideFlowThread)
return false;
if (flow.hasOutline())
return false;
if (flow.isRubyText() || flow.isRubyBase())
return false;
// These tests only works during layout. Outside layout this function may give false positives.
if (flow.view().layoutState()) {
#if ENABLE(CSS_SHAPES)
if (flow.view().layoutState()->shapeInsideInfo())
return false;
#endif
if (flow.view().layoutState()->m_columnInfo)
return false;
}
const RenderStyle& style = *flow.style();
// It shoudn't be hard to support other alignments.
if (style.textAlign() != LEFT && style.textAlign() != WEBKIT_LEFT && style.textAlign() != TASTART)
return false;
// Non-visible overflow should be pretty easy to support.
if (style.overflowX() != OVISIBLE || style.overflowY() != OVISIBLE)
return false;
// Pre/no-wrap would be very helpful to support.
if (style.whiteSpace() != NORMAL)
return false;
if (!style.textIndent().isZero())
return false;
if (style.wordSpacing() || style.letterSpacing())
return false;
if (style.textTransform() != TTNONE)
return false;
if (!style.isLeftToRightDirection())
return false;
if (style.lineBoxContain() != RenderStyle::initialLineBoxContain())
return false;
if (style.writingMode() != TopToBottomWritingMode)
return false;
if (style.lineBreak() != LineBreakAuto)
return false;
if (style.wordBreak() != NormalWordBreak)
return false;
if (style.unicodeBidi() != UBNormal || style.rtlOrdering() != LogicalOrder)
return false;
if (style.lineAlign() != LineAlignNone || style.lineSnap() != LineSnapNone)
return false;
if (style.hyphens() == HyphensAuto)
return false;
if (style.textEmphasisFill() != TextEmphasisFillFilled || style.textEmphasisMark() != TextEmphasisMarkNone)
return false;
if (style.textShadow())
return false;
#if ENABLE(CSS_SHAPES)
if (style.resolvedShapeInside())
return true;
#endif
if (style.textOverflow() || (flow.isAnonymousBlock() && flow.parent()->style()->textOverflow()))
return false;
if (style.hasPseudoStyle(FIRST_LINE) || style.hasPseudoStyle(FIRST_LETTER))
return false;
if (style.hasTextCombine())
return false;
if (style.overflowWrap() != NormalOverflowWrap)
return false;
if (style.backgroundClip() == TextFillBox)
return false;
if (style.borderFit() == BorderFitLines)
return false;
const RenderText& textRenderer = toRenderText(*flow.firstChild());
if (textRenderer.isCombineText() || textRenderer.isCounter() || textRenderer.isQuote() || textRenderer.isTextFragment()
#if ENABLE(SVG)
|| textRenderer.isSVGInlineText()
#endif
)
return false;
if (style.font().codePath(TextRun(textRenderer.text())) != Font::Simple)
return false;
auto primaryFontData = style.font().primaryFont();
unsigned length = textRenderer.textLength();
unsigned consecutiveSpaceCount = 0;
for (unsigned i = 0; i < length; ++i) {
// This rejects anything with more than one consecutive whitespace, except at the beginning or end.
// This is because we don't currently do subruns within lines. Fixing this would improve coverage significantly.
UChar character = textRenderer.characterAt(i);
if (isWhitespace(character))
++consecutiveSpaceCount;
else {
if (consecutiveSpaceCount != i && consecutiveSpaceCount > 1)
return false;
consecutiveSpaceCount = 0;
}
// These would be easy to support.
if (character == noBreakSpace)
return false;
if (character == softHyphen)
return false;
static const UChar lowestRTLCharacter = 0x590;
if (character >= lowestRTLCharacter) {
UCharDirection direction = u_charDirection(character);
if (direction == U_RIGHT_TO_LEFT || direction == U_RIGHT_TO_LEFT_ARABIC
|| direction == U_RIGHT_TO_LEFT_EMBEDDING || direction == U_RIGHT_TO_LEFT_OVERRIDE
|| direction == U_LEFT_TO_RIGHT_EMBEDDING || direction == U_LEFT_TO_RIGHT_OVERRIDE)
return false;
}
if (!primaryFontData->glyphForCharacter(character))
return false;
}
return true;
}
bool canUseFor(const RenderBlockFlow& flow)
{
#if !PLATFORM(MAC) && !PLATFORM(GTK) && !PLATFORM(EFL)
// FIXME: Non-mac platforms are hitting ASSERT(run.charactersLength() >= run.length())
// https://bugs.webkit.org/show_bug.cgi?id=123338
return false;
#endif
if (!flow.frame().settings().simpleLineLayoutEnabled())
return false;
if (!flow.firstChild())
return false;
// This currently covers <blockflow>#text</blockflow> case.
// The <blockflow><inline>#text</inline></blockflow> case is also popular and should be relatively easy to cover.
if (flow.firstChild() != flow.lastChild())
return false;
if (!flow.firstChild()->isText())
return false;
// Supporting floats would be very beneficial.
if (flow.containsFloats())
return false;
if (!flow.isHorizontalWritingMode())
return false;
if (flow.flowThreadState() != RenderObject::NotInsideFlowThread)
return false;
if (flow.hasOutline())
return false;
if (flow.isRubyText() || flow.isRubyBase())
return false;
if (flow.parent()->isDeprecatedFlexibleBox())
return false;
// These tests only works during layout. Outside layout this function may give false positives.
if (flow.view().layoutState()) {
#if ENABLE(CSS_SHAPES)
if (flow.view().layoutState()->shapeInsideInfo())
return false;
#endif
if (flow.view().layoutState()->m_columnInfo)
return false;
}
const RenderStyle& style = flow.style();
if (style.textDecorationsInEffect() != TextDecorationNone)
return false;
if (style.textAlign() == JUSTIFY)
return false;
// Non-visible overflow should be pretty easy to support.
if (style.overflowX() != OVISIBLE || style.overflowY() != OVISIBLE)
return false;
// Pre/no-wrap would be very helpful to support.
if (style.whiteSpace() != NORMAL)
return false;
if (!style.textIndent().isZero())
return false;
if (style.wordSpacing() || style.letterSpacing())
return false;
if (style.textTransform() != TTNONE)
return false;
if (!style.isLeftToRightDirection())
return false;
if (style.lineBoxContain() != RenderStyle::initialLineBoxContain())
return false;
if (style.writingMode() != TopToBottomWritingMode)
return false;
if (style.lineBreak() != LineBreakAuto)
return false;
if (style.wordBreak() != NormalWordBreak)
return false;
if (style.unicodeBidi() != UBNormal || style.rtlOrdering() != LogicalOrder)
return false;
if (style.lineAlign() != LineAlignNone || style.lineSnap() != LineSnapNone)
return false;
if (style.hyphens() == HyphensAuto)
return false;
if (style.textEmphasisFill() != TextEmphasisFillFilled || style.textEmphasisMark() != TextEmphasisMarkNone)
return false;
if (style.textShadow())
return false;
#if ENABLE(CSS_SHAPES)
if (style.resolvedShapeInside())
return true;
#endif
if (style.textOverflow() || (flow.isAnonymousBlock() && flow.parent()->style().textOverflow()))
return false;
if (style.hasPseudoStyle(FIRST_LINE) || style.hasPseudoStyle(FIRST_LETTER))
return false;
if (style.hasTextCombine())
return false;
if (style.overflowWrap() != NormalOverflowWrap)
return false;
if (style.backgroundClip() == TextFillBox)
return false;
if (style.borderFit() == BorderFitLines)
return false;
const RenderText& textRenderer = toRenderText(*flow.firstChild());
if (textRenderer.isCombineText() || textRenderer.isCounter() || textRenderer.isQuote() || textRenderer.isTextFragment()
#if ENABLE(SVG)
|| textRenderer.isSVGInlineText()
#endif
)
return false;
if (style.font().codePath(TextRun(textRenderer.text())) != Font::Simple)
return false;
// We assume that all lines have metrics based purely on the primary font.
auto& primaryFontData = *style.font().primaryFont();
if (primaryFontData.isLoading())
return false;
unsigned length = textRenderer.textLength();
for (unsigned i = 0; i < length; ++i) {
UChar character = textRenderer.characterAt(i);
if (character == ' ')
continue;
// These would be easy to support.
if (character == noBreakSpace)
return false;
if (character == softHyphen)
return false;
UCharDirection direction = u_charDirection(character);
if (direction == U_RIGHT_TO_LEFT || direction == U_RIGHT_TO_LEFT_ARABIC
|| direction == U_RIGHT_TO_LEFT_EMBEDDING || direction == U_RIGHT_TO_LEFT_OVERRIDE
|| direction == U_LEFT_TO_RIGHT_EMBEDDING || direction == U_LEFT_TO_RIGHT_OVERRIDE
|| direction == U_POP_DIRECTIONAL_FORMAT || direction == U_BOUNDARY_NEUTRAL)
return false;
if (!primaryFontData.glyphForCharacter(character))
return false;
}
return true;
}
LayoutUnit RootInlineBox::lineSnapAdjustment(LayoutUnit delta) const
{
// If our block doesn't have snapping turned on, do nothing.
// FIXME: Implement bounds snapping.
if (blockFlow().style().lineSnap() == LineSnapNone)
return 0;
// Get the current line grid and offset.
LayoutState* layoutState = blockFlow().view().layoutState();
RenderBlockFlow* lineGrid = layoutState->lineGrid();
LayoutSize lineGridOffset = layoutState->lineGridOffset();
if (!lineGrid || lineGrid->style().writingMode() != blockFlow().style().writingMode())
return 0;
// Get the hypothetical line box used to establish the grid.
RootInlineBox* lineGridBox = lineGrid->lineGridBox();
if (!lineGridBox)
return 0;
LayoutUnit lineGridBlockOffset = lineGrid->isHorizontalWritingMode() ? lineGridOffset.height() : lineGridOffset.width();
LayoutUnit blockOffset = blockFlow().isHorizontalWritingMode() ? layoutState->layoutOffset().height() : layoutState->layoutOffset().width();
// Now determine our position on the grid. Our baseline needs to be adjusted to the nearest baseline multiple
// as established by the line box.
// FIXME: Need to handle crazy line-box-contain values that cause the root line box to not be considered. I assume
// the grid should honor line-box-contain.
LayoutUnit gridLineHeight = lineGridBox->lineBottomWithLeading() - lineGridBox->lineTopWithLeading();
if (!gridLineHeight)
return 0;
LayoutUnit lineGridFontAscent = lineGrid->style().fontMetrics().ascent(baselineType());
LayoutUnit lineGridFontHeight = lineGridBox->logicalHeight();
LayoutUnit firstTextTop = lineGridBlockOffset + lineGridBox->logicalTop();
LayoutUnit firstLineTopWithLeading = lineGridBlockOffset + lineGridBox->lineTopWithLeading();
LayoutUnit firstBaselinePosition = firstTextTop + lineGridFontAscent;
LayoutUnit currentTextTop = blockOffset + logicalTop() + delta;
LayoutUnit currentFontAscent = blockFlow().style().fontMetrics().ascent(baselineType());
LayoutUnit currentBaselinePosition = currentTextTop + currentFontAscent;
LayoutUnit lineGridPaginationOrigin = isHorizontal() ? layoutState->lineGridPaginationOrigin().height() : layoutState->lineGridPaginationOrigin().width();
// If we're paginated, see if we're on a page after the first one. If so, the grid resets on subsequent pages.
// FIXME: If the grid is an ancestor of the pagination establisher, then this is incorrect.
LayoutUnit pageLogicalTop = 0;
if (layoutState->isPaginated() && layoutState->pageLogicalHeight()) {
pageLogicalTop = blockFlow().pageLogicalTopForOffset(lineTopWithLeading() + delta);
if (pageLogicalTop > firstLineTopWithLeading)
firstTextTop = pageLogicalTop + lineGridBox->logicalTop() - lineGrid->borderAndPaddingBefore() + lineGridPaginationOrigin;
}
if (blockFlow().style().lineSnap() == LineSnapContain) {
// Compute the desired offset from the text-top of a grid line.
// Look at our height (logicalHeight()).
// Look at the total available height. It's going to be (textBottom - textTop) + (n-1)*(multiple with leading)
// where n is number of grid lines required to enclose us.
if (logicalHeight() <= lineGridFontHeight)
firstTextTop += (lineGridFontHeight - logicalHeight()) / 2;
else {
LayoutUnit numberOfLinesWithLeading = ceilf(static_cast<float>(logicalHeight() - lineGridFontHeight) / gridLineHeight);
LayoutUnit totalHeight = lineGridFontHeight + numberOfLinesWithLeading * gridLineHeight;
firstTextTop += (totalHeight - logicalHeight()) / 2;
}
firstBaselinePosition = firstTextTop + currentFontAscent;
} else
firstBaselinePosition = firstTextTop + lineGridFontAscent;
// If we're above the first line, just push to the first line.
if (currentBaselinePosition < firstBaselinePosition)
return delta + firstBaselinePosition - currentBaselinePosition;
// Otherwise we're in the middle of the grid somewhere. Just push to the next line.
LayoutUnit baselineOffset = currentBaselinePosition - firstBaselinePosition;
LayoutUnit remainder = roundToInt(baselineOffset) % roundToInt(gridLineHeight);
LayoutUnit result = delta;
if (remainder)
result += gridLineHeight - remainder;
// If we aren't paginated we can return the result.
if (!layoutState->isPaginated() || !layoutState->pageLogicalHeight() || result == delta)
return result;
// We may end up shifted to a new page. We need to do a re-snap when that happens.
LayoutUnit newPageLogicalTop = blockFlow().pageLogicalTopForOffset(lineBottomWithLeading() + result);
if (newPageLogicalTop == pageLogicalTop)
return result;
// Put ourselves at the top of the next page to force a snap onto the new grid established by that page.
return lineSnapAdjustment(newPageLogicalTop - (blockOffset + lineTopWithLeading()));
}