1 files changed, 135 insertions, 0 deletions
diff --git a/skia/include/SkRefCnt.h b/skia/include/SkRefCnt.h
new file mode 100644
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+++ b/skia/include/SkRefCnt.h
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+/* include/graphics/SkRefCnt.h
+**
+** Copyright 2006, Google Inc.
+**
+** Licensed under the Apache License, Version 2.0 (the "License"); 
+** you may not use this file except in compliance with the License. 
+** You may obtain a copy of the License at 
+**
+**     http://www.apache.org/licenses/LICENSE-2.0 
+**
+** Unless required by applicable law or agreed to in writing, software 
+** distributed under the License is distributed on an "AS IS" BASIS, 
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
+** See the License for the specific language governing permissions and 
+** limitations under the License.
+*/
+
+#ifndef SkRefCnt_DEFINED
+#define SkRefCnt_DEFINED
+
+#include "SkThread.h"
+
+/** \class SkRefCnt
+
+    SkRefCnt is the base class for objects that may be shared by multiple
+    objects. When a new owner wants a reference, it calls ref(). When an owner
+    wants to release its reference, it calls unref(). When the shared object's
+    reference count goes to zero as the result of an unref() call, its (virtual)
+    destructor is called. It is an error for the destructor to be called
+    explicitly (or via the object going out of scope on the stack or calling
+    delete) if getRefCnt() > 1.
+*/
+class SkRefCnt : SkNoncopyable {
+public:
+    /** Default construct, initializing the reference count to 1.
+    */
+    SkRefCnt() : fRefCnt(1) {}
+
+    /**  Destruct, asserting that the reference count is 1.
+    */
+    virtual ~SkRefCnt() { SkASSERT(fRefCnt == 1); }
+
+    /** Return the reference count.
+    */
+    int32_t getRefCnt() const { return fRefCnt; }
+
+    /** Increment the reference count. Must be balanced by a call to unref().
+    */
+    void ref() const {
+        SkASSERT(fRefCnt > 0);
+        sk_atomic_inc(&fRefCnt);
+    }
+
+    /** Decrement the reference count. If the reference count is 1 before the
+        decrement, then call delete on the object. Note that if this is the
+        case, then the object needs to have been allocated via new, and not on
+        the stack.
+    */
+    void unref() const {
+        SkASSERT(fRefCnt > 0);
+        if (sk_atomic_dec(&fRefCnt) == 1) {
+            fRefCnt = 1;    // so our destructor won't complain
+            SkDELETE(this);
+        }
+    }
+    
+    /** Helper version of ref(), that first checks to see if this is not null.
+        If this is null, then do nothing.
+    */
+    void safeRef() const {
+        if (this) {
+            this->ref();
+        }
+    }
+
+    /** Helper version of unref(), that first checks to see if this is not null.
+        If this is null, then do nothing.
+    */
+    void safeUnref() const {
+        if (this) {
+            this->unref();
+        }
+    }
+
+private:
+    mutable int32_t fRefCnt;
+};
+
+/** \class SkAutoUnref
+
+    SkAutoUnref is a stack-helper class that will automatically call unref() on
+    the object it points to when the SkAutoUnref object goes out of scope.
+    If obj is null, do nothing.
+*/
+class SkAutoUnref : SkNoncopyable {
+public:
+    SkAutoUnref(SkRefCnt* obj) : fObj(obj) {}
+    ~SkAutoUnref();
+
+    SkRefCnt*   get() const { return fObj; }
+
+    /** If the hosted object is null, do nothing and return false, else call
+        ref() on it and return true
+    */
+    bool        ref();
+
+    /** If the hosted object is null, do nothing and return false, else call
+        unref() on it, set its reference to null, and return true
+    */
+    bool        unref();
+
+    /** If the hosted object is null, do nothing and return NULL, else call
+        unref() on it, set its reference to null, and return the object
+    */
+    SkRefCnt*   detach();
+
+private:
+    SkRefCnt*   fObj;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+/** Helper macro to safely assign one SkRefCnt[TS]* to another, checking for
+    null in on each side of the assignment, and ensuring that ref() is called
+    before unref(), in case the two pointers point to the same object.
+*/
+#define SkRefCnt_SafeAssign(dst, src)   \
+    do {                                \
+        if (src) src->ref();            \
+        if (dst) dst->unref();          \
+        dst = src;                      \
+    } while (0)
+
+#endif
+