Merge r222539 - Fall back to normal line layout position, when simple…

… line layout fails to find one.

https://bugs.webkit.org/show_bug.cgi?id=176220
<rdar://problem/34205774>

Reviewed by Brent Fulgham.

Source/WebCore:

In case of empty content, let's just fall back to normal line layout and try to
find the visually correct one.

Test: fast/text/invalid-positionForPoint-offset.html

* rendering/RenderText.cpp:
(WebCore::RenderText::positionForPoint):
* rendering/SimpleLineLayoutResolver.cpp:
(WebCore::SimpleLineLayout::RunResolver::runForPoint const):

LayoutTests:

* fast/text/invalid-positionForPoint-offset-expected.txt: Added.
* fast/text/invalid-positionForPoint-offset.html: Added.

LayoutTests/ChangeLog

@@ -1,3 +1,14 @@
+2017-09-26  Zalan Bujtas  <zalan@apple.com>
+
+        Fall back to normal line layout position, when simple line layout fails to find one.
+        https://bugs.webkit.org/show_bug.cgi?id=176220
+        <rdar://problem/34205774>
+
+        Reviewed by Brent Fulgham.
+
+        * fast/text/invalid-positionForPoint-offset-expected.txt: Added.
+        * fast/text/invalid-positionForPoint-offset.html: Added.
+
 2017-09-26  Joanmarie Diggs  <jdiggs@igalia.com>
 
         AX: ARIA grids claim to be multiselectable even with aria-multiselectable is set to false

LayoutTests/fast/text/invalid-positionForPoint-offset-expected.txt

@@ -0,0 +1 @@
+

LayoutTests/fast/text/invalid-positionForPoint-offset.html

@@ -0,0 +1,25 @@
+<style>
+* { 
+    border-bottom: green solid; 
+    margin: 0px; 
+}
+</style>
+<script>
+if (window.testRunner) {
+    testRunner.dumpAsText();
+    testRunner.waitUntilDone();
+}
+function eventhandler() {
+    dd.before(a);
+    document.caretRangeFromPoint(0,0);
+    if (window.testRunner)
+        testRunner.notifyDone();
+}
+</script>
+<h6>
+<a id="a"></a>
+</h6>
+<dd id="dd"></dd>
+<svg>
+PASS if no crash.
+<set attributeName="dominant-baseline" onbegin="eventhandler()" />

Source/WebCore/ChangeLog

@@ -1,3 +1,21 @@
+2017-09-26  Zalan Bujtas  <zalan@apple.com>
+
+        Fall back to normal line layout position, when simple line layout fails to find one.
+        https://bugs.webkit.org/show_bug.cgi?id=176220
+        <rdar://problem/34205774>
+
+        Reviewed by Brent Fulgham.
+
+        In case of empty content, let's just fall back to normal line layout and try to
+        find the visually correct one.
+
+        Test: fast/text/invalid-positionForPoint-offset.html
+
+        * rendering/RenderText.cpp:
+        (WebCore::RenderText::positionForPoint):
+        * rendering/SimpleLineLayoutResolver.cpp:
+        (WebCore::SimpleLineLayout::RunResolver::runForPoint const):
+
 2017-09-26  Joanmarie Diggs  <jdiggs@igalia.com>
 
         AX: ARIA grids claim to be multiselectable even with aria-multiselectable is set to false

Source/WebCore/rendering/RenderText.cpp

@@ -447,7 +447,11 @@ Vector<FloatQuad> RenderText::absoluteQuadsForRange(unsigned start, unsigned end
 Position RenderText::positionForPoint(const LayoutPoint& point)
 {
     if (simpleLineLayout() && parent()->firstChild() == parent()->lastChild()) {
-        auto position = Position(textNode(), SimpleLineLayout::textOffsetForPoint(point, *this, *simpleLineLayout()));
+        auto offset = SimpleLineLayout::textOffsetForPoint(point, *this, *simpleLineLayout());
+        // Did not find a valid offset. Fall back to the normal line layout based Position.
+        if (offset == textLength())
+            return positionForPoint(point, nullptr).deepEquivalent();
+        auto position = Position(textNode(), offset);
         ASSERT(position == positionForPoint(point, nullptr).deepEquivalent());
         return position;
     }

Source/WebCore/rendering/SimpleLineLayoutResolver.cpp

@@ -239,6 +239,8 @@ RunResolver::Iterator RunResolver::runForPoint(const LayoutPoint& point) const
 {
     if (!m_lineHeight)
         return end();
+    if (begin() == end())
+        return end();
     unsigned lineIndex = lineIndexForHeight(point.y(), IndexType::Last);
     auto x = point.x() - m_borderAndPaddingBefore;
     auto it = begin();