lyx_mirror/src/graphics/GraphicsCacheItem.h

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// -*- C++ -*-
/**
* \file GraphicsCacheItem.h
* This file is part of LyX, the document processor.
* Licence details can be found in the file COPYING.
*
* \author Baruch Even
* \author Angus Leeming
*
* Full author contact details are available in file CREDITS.
*
* The graphics cache is a container of graphics::CacheItems.
* Each graphics::CacheItem, defined here represents a separate image file.
*
* The routines here can be used to load the graphics file into memory at
* which point (status() == graphics::Loaded).
* The user is then free to access image() in order to copy it and to then
* transform the copy (rotate, scale, clip) and to generate the pixmap.
*
* The graphics cache supports fully asynchronous:
* file conversion to a loadable format;
* file loading.
*
* Whether you get that, of course, depends on graphics::Converter and
* on the graphics::Image-derived image class.
*/
#ifndef GRAPHICSCACHEITEM_H
#define GRAPHICSCACHEITEM_H
#include "GraphicsTypes.h"
#include <boost/signal.hpp>
namespace lyx {
namespace support { class FileName; }
namespace graphics {
class Image;
class Converter;
/// A graphics::Cache item holder.
class CacheItem {
public:
///
CacheItem(support::FileName const & file);
/// Needed for the pimpl
~CacheItem();
///
support::FileName const & filename() const;
/// It's in the cache. Now start the loading process.
void startLoading() const;
/** Monitor any changes to the file.
* There is no point monitoring the file before startLoading() is
* invoked.
*/
void startMonitoring() const;
///
bool monitoring() const;
/** Returns the check checksum of filename() so that, for example, you can
* ascertain whether to output a new PostScript version of the file
* for a LaTeX run.
*/
unsigned long checksum() const;
/** Get the image associated with filename().
* If the image is not yet loaded, returns 0.
* This routine returns a pointer to const; if you want to modify it,
* create a copy and modify that.
*/
Image const * image() const;
/// How far have we got in loading the image?
ImageStatus status() const;
/** Connect and you'll be informed when the loading status of the image
* changes.
*/
typedef boost::signal<void()> sig_type;
typedef sig_type::slot_type slot_type;
///
boost::signals::connection connect(slot_type const &) const;
private:
/// noncopyable
CacheItem(CacheItem const &);
void operator=(CacheItem const &);
/// Use the Pimpl idiom to hide the internals.
class Impl;
/// The pointer never changes although *pimpl_'s contents may.
Impl * const pimpl_;
};
} // namespace graphics
} // namespace lyx
#endif // GRAPHICSCACHEITEM_H