Changeset 246634 in webkit

Timestamp:

Jun 20, 2019 8:18:27 AM (5 years ago)

Author:

Alan Bujtas

Message:

[LFC][IFC] Make the initial strut explicit
​https://bugs.webkit.org/show_bug.cgi?id=199057
<rdar://problem/51927864>

Reviewed by Antti Koivisto.

The strut always sets the initial vertical constraints on the new line in strict mode. However in quirks mode
we can ignore it as long as there's no baseline type content on the line.

• layout/inlineformatting/InlineFormattingContext.h:
• layout/inlineformatting/InlineFormattingContextLineLayout.cpp:

(WebCore::Layout::InlineFormattingContext::LineLayout::placeInlineItems const):

• layout/inlineformatting/InlineFormattingContextQuirks.cpp:

(WebCore::Layout::InlineFormattingContext::Quirks::lineHeightConstraints):

• layout/inlineformatting/InlineLine.cpp:

(WebCore::Layout::Line::appendTextContent):
(WebCore::Layout::Line::appendHardLineBreak):
(WebCore::Layout::Line::adjustBaselineAndLineHeight):

• layout/inlineformatting/InlineLine.h:

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• layout/inlineformatting/InlineFormattingContext.h (modified) (1 diff)
• layout/inlineformatting/InlineFormattingContextLineLayout.cpp (modified) (1 diff)
• layout/inlineformatting/InlineFormattingContextQuirks.cpp (modified) (1 diff)
• layout/inlineformatting/InlineLine.cpp (modified) (5 diffs)
• layout/inlineformatting/InlineLine.h (modified) (2 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2019-06-20  Zalan Bujtas  <zalan@apple.com>
+
+        [LFC][IFC] Make the initial strut explicit
+        https://bugs.webkit.org/show_bug.cgi?id=199057
+        <rdar://problem/51927864>
+
+        Reviewed by Antti Koivisto.
+
+        The strut always sets the initial vertical constraints on the new line in strict mode. However in quirks mode
+        we can ignore it as long as there's no baseline type content on the line.  
+
+        * layout/inlineformatting/InlineFormattingContext.h:
+        * layout/inlineformatting/InlineFormattingContextLineLayout.cpp:
+        (WebCore::Layout::InlineFormattingContext::LineLayout::placeInlineItems const):
+        * layout/inlineformatting/InlineFormattingContextQuirks.cpp:
+        (WebCore::Layout::InlineFormattingContext::Quirks::lineHeightConstraints):
+        * layout/inlineformatting/InlineLine.cpp:
+        (WebCore::Layout::Line::appendTextContent):
+        (WebCore::Layout::Line::appendHardLineBreak):
+        (WebCore::Layout::Line::adjustBaselineAndLineHeight):
+        * layout/inlineformatting/InlineLine.h:
+
 2019-06-20  Zalan Bujtas  <zalan@apple.com>
 

trunk/Source/WebCore/layout/inlineformatting/InlineFormattingContext.h

@@ -98 +98 @@
     public:
         static bool lineDescentNeedsCollapsing(const LayoutState&, const Line::Content&);
+        static Line::InitialConstraints::HeightAndBaseline lineHeightConstraints(const LayoutState&, const Box& formattingRoot);
     };
 

trunk/Source/WebCore/layout/inlineformatting/InlineFormattingContextLineLayout.cpp

@@ -128 +128 @@
 InlineFormattingContext::LineLayout::LineContent InlineFormattingContext::LineLayout::placeInlineItems(const LineInput& lineInput) const
 {
-    auto mimimumLineHeight = m_formattingRoot.style().computedLineHeight();
-    auto initialBaselineOffset = Line::halfLeadingMetrics(m_formattingRoot.style().fontMetrics(), mimimumLineHeight).ascent;
     auto initialLineConstraints = Line::InitialConstraints {
         lineInput.horizontalConstraint.logicalTopLeft,
         lineInput.horizontalConstraint.availableLogicalWidth,
-        mimimumLineHeight,
-        initialBaselineOffset
+        Quirks::lineHeightConstraints(layoutState(), m_formattingRoot)
     };
     auto line = Line { layoutState(), initialLineConstraints, lineInput.skipVerticalAligment };

trunk/Source/WebCore/layout/inlineformatting/InlineFormattingContextQuirks.cpp

@@ -83 +83 @@
 }
 
+Line::InitialConstraints::HeightAndBaseline InlineFormattingContext::Quirks::lineHeightConstraints(const LayoutState& layoutState, const Box& formattingRoot)
+{
+    // computedLineHeight takes font-size into account when line-height is not set.
+    // Strut is the imaginary box that we put on every line. It sets the initial vertical constraints for each new line.
+    auto strutHeight = formattingRoot.style().computedLineHeight();
+    auto strutBaselineOffset = Line::halfLeadingMetrics(formattingRoot.style().fontMetrics(), strutHeight).ascent;
+    if (layoutState.inNoQuirksMode())
+        return { strutHeight, strutBaselineOffset, { } };
+
+    auto lineHeight = formattingRoot.style().lineHeight();
+    if (lineHeight.isPercentOrCalculated()) {
+        auto initialBaselineOffset = Line::halfLeadingMetrics(formattingRoot.style().fontMetrics(), { }).ascent;
+        return { initialBaselineOffset, initialBaselineOffset, LineBox::Baseline { strutBaselineOffset, strutHeight - strutBaselineOffset } };
+    }
+    // FIXME: The only reason why we use intValue() here is to match current inline tree (integral)behavior.
+    auto initialLineHeight = LayoutUnit { lineHeight.intValue() };
+    auto initialBaselineOffset = Line::halfLeadingMetrics(formattingRoot.style().fontMetrics(), initialLineHeight).ascent;
+    return { initialLineHeight, initialBaselineOffset, LineBox::Baseline { strutBaselineOffset, strutHeight - strutBaselineOffset } };
+}
+
 }
 }

trunk/Source/WebCore/layout/inlineformatting/InlineLine.cpp

@@ -49 +49 @@
     , m_content(std::make_unique<Line::Content>())
     , m_logicalTopLeft(initialConstraints.topLeft)
-    , m_baseline({ initialConstraints.baselineOffset, initialConstraints.height - initialConstraints.baselineOffset })
-    , m_contentLogicalHeight(initialConstraints.height)
+    , m_baseline({ initialConstraints.heightAndBaseline.baselineOffset, initialConstraints.heightAndBaseline.height - initialConstraints.heightAndBaseline.baselineOffset })
+    , m_initialStrut(initialConstraints.heightAndBaseline.strut)
+    , m_contentLogicalHeight(initialConstraints.heightAndBaseline.height)
     , m_lineLogicalWidth(initialConstraints.availableWidth)
     , m_skipVerticalAligment(skipVerticalAligment == SkipVerticalAligment::Yes)
@@ -255 +256 @@
     logicalRect.setLeft(contentLogicalRight());
     logicalRect.setWidth(logicalWidth);
-    if (!m_skipVerticalAligment)
-        logicalRect.setHeight(inlineItemContentHeight(inlineItem));
+    if (!m_skipVerticalAligment) {
+        auto runHeight = inlineItemContentHeight(inlineItem);
+        logicalRect.setHeight(runHeight);
+        adjustBaselineAndLineHeight(inlineItem, runHeight);
+    }
 
     auto textContext = Content::Run::TextContext { inlineItem.start(), inlineItem.isCollapsed() ? 1 : inlineItem.length() };
@@ -296 +300 @@
     logicalRect.setLeft(contentLogicalRight());
     logicalRect.setWidth({ });
-    if (!m_skipVerticalAligment)
+    if (!m_skipVerticalAligment) {
+        adjustBaselineAndLineHeight(inlineItem, { });
         logicalRect.setHeight(logicalHeight());
+    }
     m_content->runs().append(std::make_unique<Content::Run>(inlineItem, logicalRect, Content::Run::TextContext { }, false, false));
 }
@@ -303 +309 @@
 void Line::adjustBaselineAndLineHeight(const InlineItem& inlineItem, LayoutUnit runHeight)
 {
-    ASSERT(!inlineItem.isContainerEnd() && !inlineItem.isText());
+    ASSERT(!inlineItem.isContainerEnd());
     auto& layoutBox = inlineItem.layoutBox();
     auto& style = layoutBox.style();
@@ -315 +321 @@
             m_baseline.ascent = std::max(m_baseline.ascent, halfLeading.ascent);
         m_contentLogicalHeight = std::max(m_contentLogicalHeight, baselineAlignedContentHeight());
+        return;
+    }
+    // Apply initial strut if needed.
+    if (inlineItem.isText() || inlineItem.isHardLineBreak()) {
+        if (!m_initialStrut)
+            return;
+        m_baseline.ascent = std::max(m_initialStrut->ascent, m_baseline.ascent);
+        m_baseline.descent = std::max(m_initialStrut->descent, m_baseline.descent);
+        m_contentLogicalHeight = std::max(m_contentLogicalHeight, baselineAlignedContentHeight());
+        m_initialStrut = { };
         return;
     }

trunk/Source/WebCore/layout/inlineformatting/InlineLine.h

@@ -42 +42 @@
         LayoutPoint topLeft;
         LayoutUnit availableWidth;
-        LayoutUnit height;
-        LayoutUnit baselineOffset;
+        struct HeightAndBaseline {
+            LayoutUnit height;
+            LayoutUnit baselineOffset;
+            Optional<LineBox::Baseline> strut;
+        };
+        HeightAndBaseline heightAndBaseline;
     };
     enum class SkipVerticalAligment { No, Yes };
@@ -142 +146 @@
     LayoutUnit m_baselineTop;
 
+    Optional<LineBox::Baseline> m_initialStrut;
     LayoutUnit m_contentLogicalHeight;
     LayoutUnit m_lineLogicalWidth;