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 lyx::graphics::CacheItems.
* Each lyx::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() == lyx::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 lyx::graphics::Converter and
* on the lyx::graphics::Image-derived image class.
*/
#ifndef GRAPHICSCACHEITEM_H
#define GRAPHICSCACHEITEM_H
#include "GraphicsTypes.h"
#include <boost/utility.hpp>
#include <boost/scoped_ptr.hpp>
#include <boost/signals/signal0.hpp>
class InsetGraphics;
namespace lyx {
namespace graphics {
class Image;
class Converter;
/// A lyx::graphics::Cache item holder.
class CacheItem : boost::noncopyable {
public:
///
CacheItem(std::string const & file);
/// Define an empty d-tor out-of-line to keep boost::scoped_ptr happy.
~CacheItem();
///
std::string 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 sum 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::signal0<void>::slot_type slot_type;
///
boost::signals::connection connect(slot_type const &) const;
private:
/// Use the Pimpl idiom to hide the internals.
class Impl;
/// The pointer never changes although *pimpl_'s contents may.
boost::scoped_ptr<Impl> const pimpl_;
};
} // namespace graphics
} // namespace lyx
#endif // GRAPHICSCACHEITEM_H