Bug 455826. Look into overflow-lists of inlines to find text when we're building textruns. r=smontagu

layout/generic/nsTextFrameThebes.cpp

@@ -784,10 +784,32 @@ TextContainsLineBreakerWhiteSpace(const void* aText, PRUint32 aLength,
 }
 
 struct FrameTextTraversal {
-  nsIFrame*    mFrameToDescendInto;
-  PRPackedBool mDescendIntoFrameSiblings;
+  // These fields identify which frames should be recursively scanned
+  // The first normal frame to scan (or null, if no such frame should be scanned)
+  nsIFrame*    mFrameToScan;
+  // The first overflow frame to scan (or null, if no such frame should be scanned)
+  nsIFrame*    mOverflowFrameToScan;
+  // Whether to scan the siblings of mFrameToDescendInto/mOverflowFrameToDescendInto
+  PRPackedBool mScanSiblings;
+
+  // These identify the boundaries of the context required for
+  // line breaking or textrun construction
   PRPackedBool mLineBreakerCanCrossFrameBoundary;
   PRPackedBool mTextRunCanCrossFrameBoundary;
+
+  nsIFrame* NextFrameToScan() {
+    nsIFrame* f;
+    if (mFrameToScan) {
+      f = mFrameToScan;
+      mFrameToScan = mScanSiblings ? f->GetNextSibling() : nsnull;
+    } else if (mOverflowFrameToScan) {
+      f = mOverflowFrameToScan;
+      mOverflowFrameToScan = mScanSiblings ? f->GetNextSibling() : nsnull;
+    } else {
+      f = nsnull;
+    }
+    return f;
+  }
 };
 
 static FrameTextTraversal
@@ -802,28 +824,33 @@ CanTextCrossFrameBoundary(nsIFrame* aFrame, nsIAtom* aType)
     // placeholders are "invisible", so a text run should be able to span
     // across one. But don't descend into the out-of-flow.
     result.mLineBreakerCanCrossFrameBoundary = PR_TRUE;
+    result.mOverflowFrameToScan = nsnull;
     if (continuesTextRun) {
       // ... Except for first-letter floats, which are really in-flow
       // from the point of view of capitalization etc, so we'd better
       // descend into them. But we actually need to break the textrun for
       // first-letter floats since things look bad if, say, we try to make a
       // ligature across the float boundary.
-      result.mFrameToDescendInto =
+      result.mFrameToScan =
         (static_cast<nsPlaceholderFrame*>(aFrame))->GetOutOfFlowFrame();
-      result.mDescendIntoFrameSiblings = PR_FALSE;
+      result.mScanSiblings = PR_FALSE;
       result.mTextRunCanCrossFrameBoundary = PR_FALSE;
     } else {
-      result.mFrameToDescendInto = nsnull;
+      result.mFrameToScan = nsnull;
       result.mTextRunCanCrossFrameBoundary = PR_TRUE;
     }
   } else {
     if (continuesTextRun) {
-      result.mFrameToDescendInto = aFrame->GetFirstChild(nsnull);
-      result.mDescendIntoFrameSiblings = PR_TRUE;
+      result.mFrameToScan = aFrame->GetFirstChild(nsnull);
+      result.mOverflowFrameToScan = aFrame->GetFirstChild(nsGkAtoms::overflowList);
+      NS_WARN_IF_FALSE(!result.mOverflowFrameToScan,
+                       "Scanning overflow inline frames is something we should avoid");
+      result.mScanSiblings = PR_TRUE;
       result.mTextRunCanCrossFrameBoundary = PR_TRUE;
       result.mLineBreakerCanCrossFrameBoundary = PR_TRUE;
     } else {
-      result.mFrameToDescendInto = nsnull;
+      result.mFrameToScan = nsnull;
+      result.mOverflowFrameToScan = nsnull;
       result.mTextRunCanCrossFrameBoundary = PR_FALSE;
       result.mLineBreakerCanCrossFrameBoundary = PR_FALSE;
     }
@@ -879,13 +906,11 @@ BuildTextRunsScanner::FindBoundaries(nsIFrame* aFrame, FindBoundaryState* aState
       return FB_FOUND_VALID_TEXTRUN_BOUNDARY;
   }
   
-  for (nsIFrame* f = traversal.mFrameToDescendInto; f;
-       f = f->GetNextSibling()) {
+  for (nsIFrame* f = traversal.NextFrameToScan(); f;
+       f = traversal.NextFrameToScan()) {
     FindBoundaryResult result = FindBoundaries(f, aState);
     if (result != FB_CONTINUE)
       return result;
-    if (!traversal.mDescendIntoFrameSiblings)
-      break;
   }
 
   if (!traversal.mTextRunCanCrossFrameBoundary) {
@@ -1294,11 +1319,9 @@ void BuildTextRunsScanner::ScanFrame(nsIFrame* aFrame)
     FlushFrames(PR_FALSE, PR_FALSE);
   }
 
-  for (nsIFrame* f = traversal.mFrameToDescendInto; f;
-       f = f->GetNextSibling()) {
+  for (nsIFrame* f = traversal.NextFrameToScan(); f;
+       f = traversal.NextFrameToScan()) {
     ScanFrame(f);
-    if (!traversal.mDescendIntoFrameSiblings)
-      break;
   }
 
   if (!traversal.mLineBreakerCanCrossFrameBoundary) {

layout/reftests/bugs/455826-1-ref.html

@@ -0,0 +1,6 @@
+<!DOCTYPE html>
+<html>
+<body style="font-family: monospace; white-space:pre;">aa
+aa
+a<b>a a</b></body>
+</html>

layout/reftests/bugs/455826-1.html

@@ -0,0 +1,4 @@
+<!DOCTYPE html>
+<html>
+<body style="font-family: monospace; width: 4.1ch;">aa aa a<b>a a</b></body>
+</html>

layout/reftests/bugs/reftest.list

@@ -945,6 +945,7 @@ fails == 441259-2.html 441259-2-ref.html # bug 441400
 == 455105-2.html 455105-ref.html
 == 455171-5.html 455171-5-ref.html
 == 455280-1.xhtml 455280-1-ref.xhtml
+== 455826-1.html 455826-1-ref.html
 fails-if(MOZ_WIDGET_TOOLKIT=="cocoa") == 456147.xul 456147-ref.html # bug 456147, but not caused by it
 == 456330-1.gif 456330-1-ref.png
 == 456484-1.html 456484-1-ref.html