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 "SkBitmap.h"
+#include "SkFilterQuality.h"
+#include "SkMatrix.h"
+
+/**
+ *  Handles request to scale, filter, and lock a bitmap to be rasterized.
+ */
+class SkBitmapController : ::SkNoncopyable {
+public:
+    class State : ::SkNoncopyable {
+    public:
+        virtual ~State() {}
+
+        const SkBitmap& lockedBitmap() const { return fLockedBitmap; }
+        const SkMatrix& invMatrix() const { return fInvMatrix; }
+        SkFilterQuality quality() const { return fQuality; }
+    
+    protected:
+        SkBitmap        fLockedBitmap;
+        SkMatrix        fInvMatrix;
+        SkFilterQuality fQuality;
+    
+    private:
+        friend class SkBitmapController;
+    };
+
+    virtual ~SkBitmapController() {}
+
+    State* requestBitmap(const SkBitmap&, const SkMatrix& inverse, SkFilterQuality,
+                         void* storage, size_t storageSize);
+
+    State* requestBitmap(const SkBitmap& bm, const SkMatrix& inverse, SkFilterQuality quality) {
+        return this->requestBitmap(bm, inverse, quality, NULL, 0);
+    }
+
+protected:
+    virtual State* onRequestBitmap(const SkBitmap&, const SkMatrix& inverse, SkFilterQuality,
+                                   void* storage, size_t storageSize) = 0;
+};
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+class SkDefaultBitmapController : public SkBitmapController {
+public:
+    SkDefaultBitmapController() {}
+    
+protected:
+    State* onRequestBitmap(const SkBitmap&, const SkMatrix& inverse, SkFilterQuality,
+                           void* storage, size_t storageSize) override;
+};
+
+#endif