1/*
2 * Copyright 2011 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef GrResource_DEFINED
9#define GrResource_DEFINED
10
11#include "SkRefCnt.h"
12#include "SkTInternalLList.h"
13
14class GrGpu;
15class GrContext;
16class GrResourceEntry;
17
18/**
19 * Base class for the GPU resources created by a GrContext.
20 */
21class GrResource : public SkRefCnt {
22public:
23    SK_DECLARE_INST_COUNT(GrResource)
24
25    /**
26     * Frees the resource in the underlying 3D API. It must be safe to call this
27     * when the resource has been previously abandoned.
28     */
29    void release();
30
31    /**
32     * Removes references to objects in the underlying 3D API without freeing
33     * them. Used when the API context has been torn down before the GrContext.
34     */
35    void abandon();
36
37    /**
38     * Tests whether a resource has been abandoned or released. All resources
39     * will be in this state after their creating GrContext is destroyed or has
40     * contextLost called. It's up to the client to test isValid() before
41     * attempting to use a resource if it holds refs on resources across
42     * ~GrContext, freeResources with the force flag, or contextLost.
43     *
44     * @return true if the resource has been released or abandoned,
45     *         false otherwise.
46     */
47    bool isValid() const { return NULL != fGpu; }
48
49    /**
50     * Retrieves the size of the object in GPU memory. This is approximate since
51     * we aren't aware of additional padding or copies made by the driver.
52     *
53     * @return the size of the buffer in bytes
54     */
55    virtual size_t sizeInBytes() const = 0;
56
57    /**
58     * Retrieves the context that owns the resource. Note that it is possible
59     * for this to return NULL. When resources have been release()ed or
60     * abandon()ed they no longer have an owning context. Destroying a
61     * GrContext automatically releases all its resources.
62     */
63    const GrContext* getContext() const;
64    GrContext* getContext();
65
66    void setCacheEntry(GrResourceEntry* cacheEntry) { fCacheEntry = cacheEntry; }
67    GrResourceEntry* getCacheEntry() { return fCacheEntry; }
68
69    void incDeferredRefCount() const {
70        SkASSERT(fDeferredRefCount >= 0);
71        ++fDeferredRefCount;
72    }
73
74    void decDeferredRefCount() const {
75        SkASSERT(fDeferredRefCount > 0);
76        --fDeferredRefCount;
77        if (0 == fDeferredRefCount && this->needsDeferredUnref()) {
78            SkASSERT(this->getRefCnt() > 1);
79            this->unref();
80        }
81    }
82
83    int getDeferredRefCount() const { return fDeferredRefCount; }
84
85    void setNeedsDeferredUnref() { fFlags |= kDeferredUnref_FlagBit; }
86
87protected:
88    /**
89     * isWrapped indicates we have wrapped a client-created backend resource in a GrResource. If it
90     * is true then the client is responsible for the lifetime of the underlying backend resource.
91     * Otherwise, our onRelease() should free the resource.
92     */
93    GrResource(GrGpu* gpu, bool isWrapped);
94    virtual ~GrResource();
95
96    GrGpu* getGpu() const { return fGpu; }
97
98    // Derived classes should always call their parent class' onRelease
99    // and onAbandon methods in their overrides.
100    virtual void onRelease() {};
101    virtual void onAbandon() {};
102
103    bool isInCache() const { return NULL != fCacheEntry; }
104    bool isWrapped() const { return kWrapped_FlagBit & fFlags; }
105    bool needsDeferredUnref() const { return SkToBool(kDeferredUnref_FlagBit & fFlags); }
106
107private:
108#ifdef SK_DEBUG
109    friend class GrGpu; // for assert in GrGpu to access getGpu
110#endif
111
112    // We're in an internal doubly linked list
113    SK_DECLARE_INTERNAL_LLIST_INTERFACE(GrResource);
114
115    GrGpu*              fGpu;               // not reffed. The GrGpu can be deleted while there
116                                            // are still live GrResources. It will call
117                                            // release() on all such resources in its
118                                            // destructor.
119    GrResourceEntry*    fCacheEntry;        // NULL if not in cache
120    mutable int         fDeferredRefCount;  // How many references in deferred drawing buffers.
121
122    enum Flags {
123        /**
124         * This resource wraps a GPU resource given to us by the user.
125         * Lifetime management is left up to the user (i.e., we will not
126         * free it).
127         */
128        kWrapped_FlagBit         = 0x1,
129
130        /**
131         * This texture should be de-refed when the deferred ref count goes
132         * to zero. A resource gets into this state when the resource cache
133         * is holding a ref-of-obligation (i.e., someone needs to own it but
134         * no one else wants to) but doesn't really want to keep it around.
135         */
136        kDeferredUnref_FlagBit  = 0x2,
137    };
138    uint32_t         fFlags;
139
140    typedef SkRefCnt INHERITED;
141};
142
143#endif
144