Add fallback code for TextContexts that don't support all features

include/gpu/GrTextContext.h

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrTextContext_DEFINED
 #define GrTextContext_DEFINED
 
@@ skipping 11 matching lines @@
 /*
  * This class wraps the state for a single text render
  */
 class GrTextContext {
 public:
     virtual ~GrTextContext() {}
     virtual void drawText(const char text[], size_t byteLength, SkScalar x, SkScalar y) = 0;
     virtual void drawPosText(const char text[], size_t byteLength,
                              const SkScalar pos[], SkScalar constY,
                              int scalarsPerPosition) = 0;
-
+    
 protected:
     GrTextContext(GrContext*, const GrPaint&, const SkPaint&, const SkDeviceProperties&);
 
     static GrFontScaler* GetGrFontScaler(SkGlyphCache* cache);
     static void MeasureText(SkGlyphCache* cache, SkDrawCacheProc glyphCacheProc,
                             const char text[], size_t byteLength, SkVector* stopVector);
 
     GrContext*         fContext;
     GrPaint            fPaint;
     SkPaint            fSkPaint;
     SkDeviceProperties fDeviceProperties;
     GrDrawTarget*      fDrawTarget;
 
     SkIRect            fClipRect;
 };
 
 /*
  * These classes wrap the creation of a single text context for a given GPU device. The
  * assumption is that we'll only be using one text context at a time for that device.
  */
 class GrTextContextManager {
 public:
     virtual ~GrTextContextManager() {}
     virtual GrTextContext* create(GrContext* grContext, const GrPaint& grPaint,
                                   const SkPaint& skPaint, const SkDeviceProperties& props) = 0;
+    virtual bool canDraw(const SkPaint& paint, const SkMatrix& ctm) = 0;
 };
 
 template <class TextContextClass>
 class GrTTextContextManager : public GrTextContextManager {
 private:
     class ManagedTextContext : public TextContextClass {
     public:
         virtual ~ManagedTextContext() {}
 
         ManagedTextContext(GrContext* grContext,
@@ skipping 35 matching lines @@
                                  SK_OVERRIDE {
         // add check for usePath here?
         SkASSERT(!fUsed);
         ManagedTextContext* obj = SkNEW_PLACEMENT_ARGS(fAllocation, ManagedTextContext,
                                                        (grContext, grPaint, skPaint, properties,
                                                         this));
         fUsed = true;
         return obj;
     }
 
+    virtual bool canDraw(const SkPaint& paint, const SkMatrix& ctm) SK_OVERRIDE {
+        return TextContextClass::CanDraw(paint, ctm);
+    }
+
 private:
     void recycle(GrTextContext* textContext) {
         SkASSERT((void*)textContext == fAllocation);
         SkASSERT(fUsed);
         fUsed = false;
     }
 
     void* fAllocation;
     bool  fUsed;
 };
 
 #endif