ImageRef.h

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// This may look like C code, but it is really -*- C++ -*-
//
// Copyright Bob Friesenhahn, 1999, 2000, 2001, 2002
// Copyright Dirk Lemstra 2014-2015
//
// Definition of an Image reference
//
// This is a private implementation class which should never be
// referenced by any user code.
//

#if !defined(Magick_ImageRef_header)
#define Magick_ImageRef_header

#include <string>
#include "Magick++/Include.h"
#include "Magick++/Thread.h"

namespace Magick
{
  class Options;

  //
  // Reference counted access to Image *
  //
  class MagickPPExport ImageRef
  {
  public:

    // Construct with null image and default options
    ImageRef(void);

    // Construct with an image pointer and default options
    ImageRef(MagickCore::Image *image_);

    // Destroy image and options
    ~ImageRef(void);

    // Decreases reference count and return the new count
    size_t decrease();

    // Retrieve image from reference
    MagickCore::Image *&image(void);

    // Increases reference count
    void increase();

    // Returns true if the reference count is more than one
    bool isShared();

    // Retrieve Options from reference
    void options(Options *options_);
    Options *options(void);

    // Tries to replaces the images with the specified image, returns
    // a new instance when the current image is shared.
    static ImageRef *replaceImage(ImageRef *imgRef,
      MagickCore::Image *replacement_);

    // Image signature. Set force_ to true in order to re-calculate
    // the signature regardless of whether the image data has been
    // modified.
    std::string signature(const bool force_=false);

  private:

    // Construct with an image pointer and options
    ImageRef(MagickCore::Image *image_,const Options *options_);

    // Copy constructor and assignment are not supported
    ImageRef(const ImageRef&);

    ImageRef& operator=(const ImageRef&);

    MagickCore::Image *_image;    // ImageMagick Image
    MutexLock         _mutexLock; // Mutex lock
    Options           *_options;  // User-specified options
    ::ssize_t         _refCount;  // Reference count
  };

} // end of namespace Magick

#endif // Magick_ImageRef_header