Fix textarea font autosizing oscillation when the number of lines exceeds 4. The proposed fix is no…

Source/core/rendering/TextAutosizer.cpp

Index: Source/core/rendering/TextAutosizer.cpp
diff --git a/Source/core/rendering/TextAutosizer.cpp b/Source/core/rendering/TextAutosizer.cpp
index 6fd64b6f333e69ad97f40c075fee6f03a8277bd6..3c5abae998930dabaf28d2c36e5bd21acf758f96 100644
--- a/Source/core/rendering/TextAutosizer.cpp
+++ b/Source/core/rendering/TextAutosizer.cpp
@@ -364,7 +364,8 @@ bool TextAutosizer::isAutosizingCluster(const RenderBlock* renderer, TextAutosiz
 
     return isNarrowDescendant(renderer, parentClusterInfo)
         || isWiderDescendant(renderer, parentClusterInfo)
-        || isIndependentDescendant(renderer);
+        || isIndependentDescendant(renderer)
+        || containerIsTextArea(renderer);

[johnme, 2013/04/29 11:11:26]

Please add this as a condition in isIndependentDescendant instead of here. This
is just a convenience method; isIndependentDescendant has all the logic for
determining what is a cluster, except for the width-based checks which are done
in the other two methods.

[timvolodine, 2013/04/29 17:59:13]

Done.

 }
 
 bool TextAutosizer::containerShouldBeAutosized(const RenderBlock* container)
@@ -438,6 +439,11 @@ bool TextAutosizer::containerIsRowOfLinks(const RenderObject* container)
     return (linkCount >= 3);
 }
 
+bool TextAutosizer::containerIsTextArea(const RenderBlock* container)

[johnme, 2013/04/29 11:11:26]

Nit: This method is so simple, that you might as well just inline it in the two
places it gets used.

[timvolodine, 2013/04/29 17:59:13]

Done.

+{
+    return container->isTextArea();
+}
+
 bool TextAutosizer::contentHeightIsConstrained(const RenderBlock* container)
 {
     // FIXME: Propagate constrainedness down the tree, to avoid inefficiently walking back up from each box.
@@ -476,6 +482,11 @@ bool TextAutosizer::compositeClusterShouldBeAutosized(Vector<TextAutosizingClust
     // if a cluster contains very few lines of text then it's ok to have to zoom
     // in and pan from side to side to read each line, since if there are very
     // few lines of text you'll only need to pan across once or twice.
+    //
+    // An exception to the 4 lines of text are the textarea clusters, which are
+    // always autosized by default (i.e. threated as if they contain more than 4
+    // lines of text). This is to ensure that the text does not suddenly gets

[johnme, 2013/04/29 11:11:26]

Nit: s/gets/get/

[timvolodine, 2013/04/29 17:59:13]

Done.

+    // autosized when the user enters more than 4 lines of text.
     float totalTextWidth = 0;
     const float minLinesOfText = 4;
     float minTextWidth = blockWidth * minLinesOfText;
@@ -483,6 +494,8 @@ bool TextAutosizer::compositeClusterShouldBeAutosized(Vector<TextAutosizingClust
         measureDescendantTextWidth(clusterInfos[i].blockContainingAllText, clusterInfos[i], minTextWidth, totalTextWidth);
         if (totalTextWidth >= minTextWidth)
             return true;
+        if (containerIsTextArea(clusterInfos[i].root))

[johnme, 2013/04/29 11:11:26]

Nit: would be nice to move this check to the start of the for loop, so that when
it is a textarea we early-out rather than doing the expensive call to
measureDescendantTextWidth.

[timvolodine, 2013/04/29 17:59:13]

Done.

+            return true;
     }
     return false;
 }