Changeset 286000 in webkit

Timestamp:

Nov 18, 2021, 6:43:13 AM (5 years ago)

Author:

Alan Bujtas

Message:

[LFC][IFC] Inline boxes with unbreakable decoration can produce a breaking position with no trailing run
​https://bugs.webkit.org/show_bug.cgi?id=233302

Reviewed by Antti Koivisto.

Source/WebCore:

This is a rare case when the overflowing run is the first inline box start with unbreakable decoration while its content is breakable.
e.g.
<div style="width: 0xp"><span style="border: solid; word-break: break-word;">breakable</span></div>

While the overflowing run (inline box start) is unbreakable (border), we find the first breaking position right between
the <span> (inline box start) and its content (inline text item).
However we also don't want to separate the content from its parent inline box (i.e. should not be breaking between these 2 inline items)
so we start searching for a trailing run candidate by looking at the previous set of runs.
Now if this <span> is the first run in this set we won't find a trailing run and we should just return the breaking position with no trailing content.

Test: fast/inline/inline-box-with-unbreakable-decoration-and-word-break.html

• layout/formattingContexts/inline/InlineContentBreaker.cpp:

(WebCore::Layout::InlineContentBreaker::tryBreakingNextOverflowingRuns const):

LayoutTests:

• fast/inline/inline-box-with-unbreakable-decoration-and-word-break-expected.html: Added.
• fast/inline/inline-box-with-unbreakable-decoration-and-word-break.html: Added.

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/fast/inline/inline-box-with-unbreakable-decoration-and-word-break-expected.html (added)
• LayoutTests/fast/inline/inline-box-with-unbreakable-decoration-and-word-break.html (added)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/layout/formattingContexts/inline/InlineContentBreaker.cpp (modified) (1 diff)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2021-11-18  Alan Bujtas  <zalan@apple.com>
+
+        [LFC][IFC] Inline boxes with unbreakable decoration can produce a breaking position with no trailing run
+        https://bugs.webkit.org/show_bug.cgi?id=233302
+
+        Reviewed by Antti Koivisto.
+
+        * fast/inline/inline-box-with-unbreakable-decoration-and-word-break-expected.html: Added.
+        * fast/inline/inline-box-with-unbreakable-decoration-and-word-break.html: Added.
+
 2021-11-18  Ziran Sun  <zsun@igalia.com>
 

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2021-11-18  Alan Bujtas  <zalan@apple.com>
+
+        [LFC][IFC] Inline boxes with unbreakable decoration can produce a breaking position with no trailing run
+        https://bugs.webkit.org/show_bug.cgi?id=233302
+
+        Reviewed by Antti Koivisto.
+
+        This is a rare case when the overflowing run is the first inline box start with unbreakable decoration while its content is breakable.
+        e.g.
+        <div style="width: 0xp"><span style="border: solid; word-break: break-word;">breakable</span></div>
+
+          While the overflowing run (inline box start) is unbreakable (border), we find the first breaking position right between
+          the <span> (inline box start) and its content (inline text item).
+          However we also don't want to separate the content from its parent inline box (i.e. should not be breaking between these 2 inline items)
+          so we start searching for a trailing run candidate by looking at the previous set of runs.
+          Now if this <span> is the first run in this set we won't find a trailing run and we should just return the breaking position with no trailing content.
+
+        Test: fast/inline/inline-box-with-unbreakable-decoration-and-word-break.html
+
+        * layout/formattingContexts/inline/InlineContentBreaker.cpp:
+        (WebCore::Layout::InlineContentBreaker::tryBreakingNextOverflowingRuns const):
+
 2021-11-18  Alan Bujtas  <zalan@apple.com>
 

trunk/Source/WebCore/layout/formattingContexts/inline/InlineContentBreaker.cpp

@@ -578 +578 @@
                 return OverflowingTextContent::BreakingPosition { index, OverflowingTextContent::BreakingPosition::TrailingContent { true, partialRun } };
             }
-            auto trailingRunIndex = *findTrailingRunIndex(runs, index);
-            // At worst we are back to the overflowing run, like in the example above.
-            ASSERT(trailingRunIndex >= overflowingRunIndex);
-            return OverflowingTextContent::BreakingPosition { trailingRunIndex, OverflowingTextContent::BreakingPosition::TrailingContent { true } };
+            if (auto trailingRunIndex = findTrailingRunIndex(runs, index)) {
+                // At worst we are back to the overflowing run, like in the example above.
+                ASSERT(*trailingRunIndex >= overflowingRunIndex);
+                return OverflowingTextContent::BreakingPosition { *trailingRunIndex, OverflowingTextContent::BreakingPosition::TrailingContent { true } };
+            }
+            // This happens when the overflowing run is also the first run in this set, no trailing run.
+            return OverflowingTextContent::BreakingPosition { overflowingRunIndex, { } };
         }
         nextContentWidth += run.logicalWidth;