Changeset 268825 in webkit

Timestamp:

Oct 21, 2020, 2:24:06 PM (6 years ago)

Author:

Alan Bujtas

Message:

[LFC][Integration] Add content dependent vertical line snapping
​https://bugs.webkit.org/show_bug.cgi?id=218034

Reviewed by Antti Koivisto.

This patch ensures that IFC integration line snapping matches the legacy line layout snapping behavior (e.g. images prevent line snapping).

• layout/inlineformatting/InlineLineBox.h:

(WebCore::Layout::LineBox::InlineLevelBox::isAtomicInlineLevelBox const):

• layout/integration/LayoutIntegrationLineLayout.cpp:

(WebCore::LayoutIntegration::LineLayout::constructContent):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• layout/inlineformatting/InlineLineBox.h (modified) (1 diff)
• layout/integration/LayoutIntegrationLineLayout.cpp (modified) (3 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2020-10-21  Zalan Bujtas  <zalan@apple.com>
+
+        [LFC][Integration] Add content dependent vertical line snapping
+        https://bugs.webkit.org/show_bug.cgi?id=218034
+
+        Reviewed by Antti Koivisto.
+
+        This patch ensures that IFC integration line snapping matches the legacy line layout snapping behavior (e.g. images prevent line snapping).
+
+        * layout/inlineformatting/InlineLineBox.h:
+        (WebCore::Layout::LineBox::InlineLevelBox::isAtomicInlineLevelBox const):
+        * layout/integration/LayoutIntegrationLineLayout.cpp:
+        (WebCore::LayoutIntegration::LineLayout::constructContent):
+
 2020-10-21  Zalan Bujtas  <zalan@apple.com>
 

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

@@ -84 +84 @@
 
         bool isInlineBox() const { return m_type == Type::InlineBox || m_type == Type::RootInlineBox; }
+        bool isAtomicInlineLevelBox() const { return m_type == Type::AtomicInlineLevelBox; }
         bool isLineBreakBox() const { return m_type == Type::LineBreakBox; }
         bool hasLineBoxRelativeAlignment() const;

trunk/Source/WebCore/layout/integration/LayoutIntegrationLineLayout.cpp

@@ -139 +139 @@
     auto& displayInlineContent = ensureInlineContent();
 
+    auto lineNeedsLegacyIntegralVerticalPosition = [&](size_t lineIndex) {
+        RELEASE_ASSERT(m_inlineFormattingState.lineBoxes().size() > lineIndex);
+        // InlineTree rounds y position to integral value for certain content (see InlineFlowBox::placeBoxesInBlockDirection).
+        auto inlineLevelBoxList = m_inlineFormattingState.lineBoxes()[lineIndex].inlineLevelBoxList();
+        if (inlineLevelBoxList.size() == 1) {
+            // This is text content only with root inline box.
+            return true;
+        }
+        // Text + <br> (or just <br> or text<span></span><br>) behaves like text.
+        for (auto& inlineLevelBox : inlineLevelBoxList) {
+            if (inlineLevelBox->isAtomicInlineLevelBox()) {
+                // Content like text<img> prevents legacy snapping.
+                return false;
+            }
+        }
+        return true;
+    };
+
     auto constructDisplayLineRuns = [&] {
         auto initialContaingBlockSize = m_layoutState.viewportSize();
+        struct LineLegacyVerticalPositionPolicy {
+            size_t lineIndex { 0 };
+            bool needsIntegralPosition { true }; 
+        };
+        auto lineLegacyVerticalPositionPolicy = LineLegacyVerticalPositionPolicy { 0, lineNeedsLegacyIntegralVerticalPosition(0) };
         for (auto& lineRun : m_inlineFormattingState.lineRuns()) {
             auto& layoutBox = lineRun.layoutBox();
@@ -165 +188 @@
             auto lineBoxLogicalRect = m_inlineFormattingState.lines()[lineIndex].lineBoxLogicalRect();
             runRect.moveBy({ lineBoxLogicalRect.left(), lineBoxLogicalRect.top() });
-            // InlineTree rounds y position to integral value, see InlineFlowBox::placeBoxesInBlockDirection.
-            auto needsLegacyIntegralPosition = !layoutBox.isReplacedBox();
-            if (needsLegacyIntegralPosition)
+            if (lineIndex != lineLegacyVerticalPositionPolicy.lineIndex)
+                lineLegacyVerticalPositionPolicy = LineLegacyVerticalPositionPolicy { lineIndex, lineNeedsLegacyIntegralVerticalPosition(lineIndex) };
+            if (lineLegacyVerticalPositionPolicy.needsIntegralPosition)
                 runRect.setY(roundToInt(runRect.y()));
 
@@ -216 +239 @@
             // Painting code (specifically TextRun's xPos) needs the line box offset to be able to compute tab positions.
             lineRect.setX(lineBoxLogicalRect.left());
-            // InlineTree rounds y position to integral value, see InlineFlowBox::placeBoxesInBlockDirection.
-            lineRect.setY(roundToInt(lineRect.y()));
+            if (lineNeedsLegacyIntegralVerticalPosition(lineIndex))
+                lineRect.setY(roundToInt(lineRect.y()));
             displayInlineContent.lines.append({ firstRunIndex, runCount, lineRect, scrollableOverflowRect, lineInkOverflowRect, line.baseline(), line.horizontalAlignmentOffset() });
         }