xref: /external/skia/include/gpu/GrGpuResourceRef.h

/*
 * Copyright 2014 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef GrProgramResource_DEFINED
#define GrProgramResource_DEFINED

#include "SkRefCnt.h"

class GrGpuResource;

/**
 * Class that wraps a resource referenced by a GrProgramElement or GrDrawState. It manages
 * converting refs to pending io operations. Like SkAutoTUnref, its constructor and setter adopt
 * a ref from their caller. This class is intended only for internal use in core Gr code.
 */
class GrProgramResource : SkNoncopyable {
public:
    enum IOType {
        kRead_IOType,
        kWrite_IOType,
        kRW_IOType,

        kNone_IOType, // For internal use only, don't specify to constructor or setResource().
    };

    SK_DECLARE_INST_COUNT_ROOT(GrProgramResource);
    GrProgramResource();

    /** Adopts a ref from the caller. ioType expresses what type of IO operations will be marked as
        pending on the resource when markPendingIO is called. */
    explicit GrProgramResource(GrGpuResource*, IOType ioType);

    ~GrProgramResource();

    GrGpuResource* getResource() const { return fResource; }

    /** Adopts a ref from the caller. ioType expresses what type of IO operations will be marked as
        pending on the resource when markPendingIO is called. */
    void setResource(GrGpuResource*, IOType ioType);

    /** Does this object own a pending read or write on the resource it is wrapping. */
    bool ownsPendingIO() const { return fPendingIO; }

    /** Shortcut for calling setResource() with NULL. It cannot be called after markingPendingIO
        is called. */
    void reset();

private:
    /** Called by owning GrProgramElement when the program element is first scheduled for
        execution. */
    void markPendingIO() const;

    /** Called when the program element/draw state is no longer owned by GrDrawTarget-client code.
        This lets the cache know that the drawing code will no longer schedule additional reads or
        writes to the resource using the program element or draw state. */
    void removeRef() const;

    friend class GrDrawState;
    friend class GrProgramElement;

    GrGpuResource*      fResource;
    mutable bool        fOwnRef;
    mutable bool        fPendingIO;
    IOType              fIOType;

    typedef SkNoncopyable INHERITED;
};

#endif