Consolidate Font::codePath kerning & ligatures exceptions

Source/platform/fonts/Font.cpp

Index: Source/platform/fonts/Font.cpp
diff --git a/Source/platform/fonts/Font.cpp b/Source/platform/fonts/Font.cpp
index e2ccfba1a003a2602ba31caaea166e73ec7850db..8252dc9fdb79bea43179a155871fdad641b04656 100644
--- a/Source/platform/fonts/Font.cpp
+++ b/Source/platform/fonts/Font.cpp
@@ -110,12 +110,7 @@ float Font::drawText(GraphicsContext* context, const TextRunPaintInfo& runInfo,
     if (shouldSkipDrawing() && customFontNotReadyAction == DoNotPaintIfFontNotReady)
         return 0;
 
-    CodePath codePathToUse = codePath(runInfo.run);
-    // FIXME: Use the fast code path once it handles partial runs with kerning and ligatures. See http://webkit.org/b/100050
-    if (codePathToUse != ComplexPath && fontDescription().typesettingFeatures() && (runInfo.from || runInfo.to != runInfo.run.length()))
-        codePathToUse = ComplexPath;
-
-    if (codePathToUse != ComplexPath)
+    if (codePath(runInfo.run, runInfo.from, runInfo.to) != ComplexPath)
         return drawSimpleText(context, runInfo, point);
 
     return drawComplexText(context, runInfo, point);
@@ -126,12 +121,7 @@ void Font::drawEmphasisMarks(GraphicsContext* context, const TextRunPaintInfo& r
     if (shouldSkipDrawing())
         return;
 
-    CodePath codePathToUse = codePath(runInfo.run);
-    // FIXME: Use the fast code path once it handles partial runs with kerning and ligatures. See http://webkit.org/b/100050
-    if (codePathToUse != ComplexPath && fontDescription().typesettingFeatures() && (runInfo.from || runInfo.to != runInfo.run.length()))
-        codePathToUse = ComplexPath;
-
-    if (codePathToUse != ComplexPath)
+    if (codePath(runInfo.run, runInfo.from, runInfo.to) != ComplexPath)
         drawEmphasisMarksForSimpleText(context, runInfo, mark, point);
     else
         drawEmphasisMarksForComplexText(context, runInfo, mark, point);
@@ -211,12 +201,7 @@ PassTextBlobPtr Font::buildTextBlob(const TextRunPaintInfo& runInfo, const Float
     if (shouldSkipDrawing() && customFontNotReadyAction == DoNotPaintIfFontNotReady)
         return nullptr;
 
-    CodePath codePathToUse = codePath(runInfo.run);
-    // FIXME: Use the fast code path once it handles partial runs with kerning and ligatures. See http://webkit.org/b/100050
-    if (codePathToUse != ComplexPath && fontDescription().typesettingFeatures() && (runInfo.from || runInfo.to != runInfo.run.length()))
-        codePathToUse = ComplexPath;
-
-    if (codePathToUse != ComplexPath)
+    if (codePath(runInfo.run, runInfo.from, runInfo.to) != ComplexPath)
         return buildTextBlobForSimpleText(runInfo, textOrigin, couldUseLCDRenderedText);
 
     return nullptr;
@@ -297,12 +282,7 @@ FloatRect Font::selectionRectForText(const TextRun& run, const FloatPoint& point
 {
     to = (to == -1 ? run.length() : to);
 
-    CodePath codePathToUse = codePath(run);
-    // FIXME: Use the fast code path once it handles partial runs with kerning and ligatures. See http://webkit.org/b/100050
-    if (codePathToUse != ComplexPath && fontDescription().typesettingFeatures() && (from || to != run.length()))
-        codePathToUse = ComplexPath;
-
-    if (codePathToUse != ComplexPath)
+    if (codePath(run, from, to) != ComplexPath)
         return selectionRectForSimpleText(run, point, h, from, to, accountForGlyphBounds);
 
     return selectionRectForComplexText(run, point, h, from, to);
@@ -322,13 +302,15 @@ void Font::setCodePath(CodePath p)
     s_codePath = p;
 }
 
-CodePath Font::codePath()
+CodePath Font::codePath(const TextRun& run, int from, int to) const

[Dominik Röttsches, 2014/10/10 13:37:53]

I would make the argument a TextRunPaintInfo - which has the from, to parameters
and then just pass the existing runInfo that exists in the first 3 of the 4 call
sites, and create one for the 4th.

[f(malita), 2014/10/10 14:09:12]

Done.

 {
-    return s_codePath;
-}
+    // FIXME: Do we really want to override s_codePath?

[Dominik Röttsches, 2014/10/10 13:37:54]

Can you elaborate on the question? What do we need s_codePath for?

[f(malita), 2014/10/10 14:09:12]

Per comments, I assumed it is a way to force a particular code path for
debugging/layout test purposes - in which case it seems it should take
precedence over kerning/ligatures heuristics.

But a quick search reveals that it's not actually being used/set at all!
Removed.

+    // FIXME: Use the fast code path once it handles partial runs with kerning and ligatures.

[Dominik Röttsches, 2014/10/10 13:37:54]

The second FIXME is obsolete. We plan to remove the fast/simple code path.

[f(malita), 2014/10/10 14:09:12]

Do you mean SimpleShaper & friends are going away?

+    //        See http://webkit.org/b/100050
+    //        (Is that still feasible?)
+    if (fontDescription().typesettingFeatures() && (from || to != run.length()))
+        return ComplexPath;
 
-CodePath Font::codePath(const TextRun& run) const
-{
     if (s_codePath != AutoPath)
         return s_codePath;