[LFC][IFC] Add right to left direction support for text-overflow: ell…

…ipsis

https://bugs.webkit.org/show_bug.cgi?id=244251

Reviewed by Antti Koivisto.

Compute the ellipsis start position using the display boxes in the reversed direction when the inline content has right to left flow.

* Source/WebCore/layout/formattingContexts/inline/display/InlineDisplayContentBuilder.cpp:
(WebCore::Layout::InlineDisplayContentBuilder::build):
(WebCore::Layout::InlineDisplayContentBuilder::processOverflownRunsForEllipsis):
* Source/WebCore/layout/formattingContexts/inline/display/InlineDisplayContentBuilder.h:

Canonical link: https://commits.webkit.org/253689@main

Source/WebCore/layout/formattingContexts/inline/display/InlineDisplayContentBuilder.cpp

@@ -104,7 +104,7 @@ DisplayBoxes InlineDisplayContentBuilder::build(const LineBuilder::LineContent&
         processBidiContent(lineContent, lineBox, displayLine, boxes);
     else
         processNonBidiContent(lineContent, lineBox, displayLine, boxes);
-    processOverflownRunsForEllipsis(lineContent, boxes, displayLine.right());
+    processOverflownRunsForEllipsis(lineContent, boxes, displayLine);
     collectInkOverflowForTextDecorations(boxes, displayLine);
     collectInkOverflowForInlineBoxes(boxes);
     return boxes;
@@ -756,15 +756,15 @@ void InlineDisplayContentBuilder::processBidiContent(const LineBuilder::LineCont
     handleTrailingOpenInlineBoxes();
 }
 
-void InlineDisplayContentBuilder::processOverflownRunsForEllipsis(const LineBuilder::LineContent& lineContent, DisplayBoxes& boxes, InlineLayoutUnit lineBoxRight)
+void InlineDisplayContentBuilder::processOverflownRunsForEllipsis(const LineBuilder::LineContent& lineContent, DisplayBoxes& boxes, const InlineDisplay::Line& displayLine)
 {
     if (root().style().textOverflow() != TextOverflow::Ellipsis)
         return;
     auto& rootInlineBox = boxes[0];
+    auto isLeftToRightDirection = rootInlineBox.style().isLeftToRightDirection();
     ASSERT(rootInlineBox.isRootInlineBox());
 
-    if (rootInlineBox.right() <= lineBoxRight) {
-        ASSERT(boxes.last().right() <= lineBoxRight);
+    if (displayLine.contentLogicalWidth() <= displayLine.lineBoxRect().width()) {
         ASSERT(lineContent.runs.isEmpty() || !lineContent.runs[lineContent.runs.size() - 1].isTruncated());
         return;
     }
@@ -774,31 +774,34 @@ void InlineDisplayContentBuilder::processOverflownRunsForEllipsis(const LineBuil
     auto ellipsisWidth = !m_lineIndex ? root().firstLineStyle().fontCascade().width(ellipsisRun) : root().style().fontCascade().width(ellipsisRun);
 
     auto ellipsisVisualLeft = [&] {
-        auto truncatedWidth = [&] () -> float {
+        auto ellipsedContentWidth = [&] () -> float {
             for (auto& lineRun : lineContent.runs) {
                 if (lineRun.isTruncated())
                     return lineRun.isText() ? lineRun.textContent()->partiallyVisibleContent->width : 0.f;
             }
             return { };
         };
-        auto left = 0.f;
-        for (auto& box : boxes) {
+        auto ellipsisStart = isLeftToRightDirection ? 0.f : displayLine.right();
+        for (size_t i = 0; i < boxes.size(); ++i) {
+            auto& box = isLeftToRightDirection ? boxes[i] : boxes[boxes.size() - 1 - i];
             if (box.isInlineBox())
                 continue;
             switch (box.isVisuallyHidden()) {
             case InlineDisplay::Box::IsVisuallyHidden::No:
-                left = std::max(left, box.right());
+                ellipsisStart = isLeftToRightDirection ? std::max(ellipsisStart, box.right()) : std::min(ellipsisStart, box.left());
                 break;
             case InlineDisplay::Box::IsVisuallyHidden::Partially:
-                return std::max(left, box.left() + truncatedWidth());
+                ellipsisStart = isLeftToRightDirection ? std::max(ellipsisStart, box.left() + ellipsedContentWidth()) : std::min(ellipsisStart, box.right() - ellipsedContentWidth());
+                FALLTHROUGH;
             case InlineDisplay::Box::IsVisuallyHidden::Yes:
-                return left;
+                return isLeftToRightDirection ? ellipsisStart : ellipsisStart - ellipsisWidth;
             default:
                 ASSERT_NOT_REACHED();
                 break;
             }
         }
-        return left;
+        ASSERT_NOT_REACHED();
+        return ellipsisStart;
     }();
     auto ellispisBoxRect = InlineRect { rootInlineBox.top(), ellipsisVisualLeft, ellipsisWidth, rootInlineBox.height() };
 

Source/WebCore/layout/formattingContexts/inline/display/InlineDisplayContentBuilder.h

@@ -54,7 +54,7 @@ class InlineDisplayContentBuilder {
 private:
     void processNonBidiContent(const LineBuilder::LineContent&, const LineBox&, const InlineDisplay::Line&, DisplayBoxes&);
     void processBidiContent(const LineBuilder::LineContent&, const LineBox&, const InlineDisplay::Line&, DisplayBoxes&);
-    void processOverflownRunsForEllipsis(const LineBuilder::LineContent&, DisplayBoxes&, InlineLayoutUnit lineBoxRight);
+    void processOverflownRunsForEllipsis(const LineBuilder::LineContent&, DisplayBoxes&, const InlineDisplay::Line&);
     void collectInkOverflowForInlineBoxes(DisplayBoxes&);
     void collectInkOverflowForTextDecorations(DisplayBoxes&, const InlineDisplay::Line&);