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

src/gpu/GrTextureMaker.h

Index: src/gpu/GrTextureMaker.h
diff --git a/src/gpu/GrTextureMaker.h b/src/gpu/GrTextureMaker.h
new file mode 100644
index 0000000000000000000000000000000000000000..669a7eeb08e24ae4d83c21e53558d5c2c7cef75f
--- /dev/null
+++ b/src/gpu/GrTextureMaker.h
@@ -0,0 +1,76 @@
+/*
+ * 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 GrTextureMaker_DEFINED
+#define GrTextureMaker_DEFINED
+
+#include "SkGrPriv.h"
+
+class GrContext;
+class GrTexture;
+class GrTextureParams;
+class GrUniqueKey;
+class SkBitmap;
+
+class GrTextureMaker {
+public:
+    GrTextureMaker(int width, int height) : fWidth(width), fHeight(height) {}
+    virtual ~GrTextureMaker() {}
+
+    int width() const { return fWidth; }
+    int height() const { return fHeight; }
+
+    GrTexture* refCachedTexture(GrContext*, const GrTextureParams*);
+
+protected:
+    /**
+     *  Return the maker's "original" unstretched texture. It is the responsibility of the maker
+     *  to make this efficient ... if the texture is being generated, the maker must handle
+     *  caching it.
+     */
+    virtual GrTexture* onRefUnstretchedTexture(GrContext*) = 0;
+
+    /**
+     *  If we need to stretch the maker's original texture, the maker is asked to return a key
+     *  that identifies its origianl + the stretch parameter. If the maker does not want to cache
+     *  the stretched version (e.g. the maker is volatile), this should ignore the key parameter
+     *  and return false.
+     */
+    virtual bool onMakeStretchedKey(const SkGrStretch&, GrUniqueKey* stretchedKey) = 0;
+
+    /**
+     *  Return a new (uncached) texture that is the stretch of the maker's original.
+     *
+     *  The base-class handles general logic for this, and only needs access to the following
+     *  methods:
+     *  - onRefUnstretchedTexture()
+     *  - onGetROBitmap()
+     *
+     *  Subclass may override this if they can handle stretching more efficiently.
+     */
+    virtual GrTexture* onGenerateStretchedTexture(GrContext*, const SkGrStretch&);
+
+    /**
+     *  If a stretched version of the texture is generated, it may be cached (assuming that
+     *  onMakeStretchedKey() returns true). In that case, the maker is notified in case it
+     *  wants to note that for when the maker is destroyed.
+     */
+    virtual void onNotifyStretchCached(const GrUniqueKey& stretchedKey) = 0;
+
+    /**
+     *  Some GPUs are unreliable w/ very small texture sizes. If we run into that case, this
+     *  method will be called (in service of onGenerateStretchedTexture) to return a raster version
+     *  of the original texture.
+     */
+    virtual bool onGetROBitmap(SkBitmap*) = 0;
+
+private:
+    const int fWidth;
+    const int fHeight;
+};
+
+#endif