refactor bitmapshader to use a controller

src/core/SkInPlace.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 SkInPlace_DEFINED
+#define SkInPlace_DEFINED
+
+#include "SkTypes.h"
+
+class SkInPlace {

[scroggo, 2015/06/02 21:17:34]

Can we merge this with SkSmallAllocator? It looks like SkSmallAllocator sets a
hard limit on the number of objects it will create, so that we could limit the
space we reserve for pointers. It looks like this class only allows 1 object, so
maybe it is a special case of SkSmallAllocator?

[reed2, 2015/06/03 02:33:35]

SmallAllocator is templated on size, meaning the public signature would have to
know how big the preallocated storage was, which seems odd. Also SA just fails
if the request is too big, whereas InPlace succeeds (by calling new) which seems
correct given that I don't know the size of the client's sublass.

+public:
+    SkInPlace(void* storage, size_t size) : fStorage(storage), fSize(size) {}
+    
+    template <typename T> T* create() {
+        if (sizeof(T) <= fSize) {
+            fSize = 0;
+            return new (fStorage) T;

[scroggo, 2015/06/02 21:17:34]

SkNEW_PLACEMENT?

+        } else {
+            return SkNEW(T);
+        }
+    }
+    
+    template <typename T, typename A1> T* create(const A1& a1) {
+        if (sizeof(T) <= fSize) {
+            fSize = 0;
+            return new (fStorage) T(a1);

[scroggo, 2015/06/02 21:17:34]

SkNEW_PLACEMENT_ARGS?

+        } else {
+            return SkNEW_ARGS(T, (a1));
+        }
+    }
+    
+    template <typename T, typename A1, typename A2> T* create(const A1& a1, const A2& a2) {
+        if (sizeof(T) <= fSize) {
+            fSize = 0;
+            return new (fStorage) T(a1, a1);
+        } else {
+            return SkNEW_ARGS(T, (a1, a2));
+        }
+    }
+    
+    template <typename T, typename A1, typename A2, typename A3> T* create(const A1& a1, const A2& a2, const A3& a3) {

[scroggo, 2015/06/02 21:17:34]

nit: line length

+        if (sizeof(T) <= fSize) {
+            fSize = 0;
+            return new (fStorage) T(a1, a2, a3);
+        } else {
+            return SkNEW_ARGS(T, (a1, a2, a3));
+        }
+    }
+    
+    template <typename T> void destroy(T* obj) {
+        if (obj) {
+            if ((T*)fStorage == obj) {
+                obj->~T();
+            } else {
+                delete obj;
+            }
+        }
+    }
+    
+private:
+    void*   fStorage;
+    size_t  fSize;
+};
+
+template <size_t SIZE> class SkSInPlace : public SkInPlace {
+public:
+    SkSInPlace() : SkInPlace(fStorage, SIZE) {
+        SkASSERT(SIZE <= sizeof(fStorage));
+    }
+
+private:
+    intptr_t fStorage[(SIZE + (sizeof(intptr_t) - 1)) / sizeof(intptr_t)];
+};
+
+#endif