refactor bitmapshader to use a controller

src/core/SkBitmapController.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 SkBitmapController_DEFINED
+#define SkBitmapController_DEFINED
+
+#include "SkFilterQuality.h"
+
+class SkBitmap;
+class SkMatrix;
+
+/**
+ *  Handles request to scale, filter, and lock a bitmap to be rasterized.
+ */
+class SkBitmapController {
+public:
+    bool requestBitmap(const SkBitmap& inBM, const SkMatrix& inverse, SkFilterQuality inQuality,
+                       SkBitmap* outBM, SkMatrix* outInv, SkFilterQuality* outQuality);

[scroggo, 2015/06/02 13:24:54]

Maybe add a comment - it looks like all of these must be non-NULL?

[reed1, 2015/06/02 14:07:46]

New version is simpler/clearer.

+
+protected:
+    virtual bool onRequestBitmap(const SkBitmap& inBM, const SkMatrix& inverse, SkFilterQuality inQ,
+                                 SkBitmap* outBM, SkMatrix* outInv, SkFilterQuality* outQ) = 0;
+};
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+class SkDefaultBitmapController : public SkBitmapController {
+public:
+    SkDefaultBitmapController() {}
+    
+protected:
+    bool onRequestBitmap(const SkBitmap&, const SkMatrix&, SkFilterQuality,
+                         SkBitmap*, SkMatrix*, SkFilterQuality*) override;
+};
+
+#endif