try texture-maker to generalize stretching for npot and min-tex-size

src/gpu/SkGrPriv.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkGrPriv_DEFINED
 #define SkGrPriv_DEFINED
 
 #include "GrTypes.h"
 #include "SkImageInfo.h"
 #include "SkXfermode.h"
 
 class GrCaps;
 class GrContext;
 class GrFragmentProcessor;
 class GrPaint;
 class GrUniqueKey;
 class SkPaint;
 class SkMatrix;
 struct SkIRect;
 
+struct SkGrStretch {
+    enum Type {
+        kNone_Type,
+        kBilerp_Type,
+        kNearest_Type
+    } fType;
+    int fWidth;
+    int fHeight;
+};
+
 /**
  *  Our key includes the offset, width, and height so that bitmaps created by extractSubset()
  *  are unique.
  *
  *  The imageID is in the shared namespace (see SkNextID::ImageID()
  *      - SkBitmap/SkPixelRef
  *      - SkImage
  *      - SkImageGenerator
  *
  *  Note: width/height must fit in 16bits for this impl.
@@ skipping 26 matching lines @@
     drawVertices and drawAtlas.
  */
 bool SkPaintToGrPaintWithXfermode(GrContext* context,
                                   const SkPaint& skPaint,
                                   const SkMatrix& viewM,
                                   SkXfermode::Mode primColorMode,
                                   bool primitiveIsSrc,
                                   GrPaint* grPaint);
 
 #endif