3 * \file GraphicsCacheItem.h
4 * This file is part of LyX, the document processor.
5 * Licence details can be found in the file COPYING.
8 * \author Angus Leeming
10 * Full author contact details are available in file CREDITS.
12 * The graphics cache is a container of lyx::graphics::CacheItems.
13 * Each lyx::graphics::CacheItem, defined here represents a separate image file.
15 * The routines here can be used to load the graphics file into memory at
16 * which point (status() == lyx::graphics::Loaded).
17 * The user is then free to access image() in order to copy it and to then
18 * transform the copy (rotate, scale, clip) and to generate the pixmap.
20 * The graphics cache supports fully asynchronous:
21 * file conversion to a loadable format;
24 * Whether you get that, of course, depends on lyx::graphics::Converter and
25 * on the lyx::graphics::Image-derived image class.
28 #ifndef GRAPHICSCACHEITEM_H
29 #define GRAPHICSCACHEITEM_H
31 #include "GraphicsTypes.h"
33 #include <boost/utility.hpp>
34 #include <boost/scoped_ptr.hpp>
35 #include <boost/signal.hpp>
44 /// A lyx::graphics::Cache item holder.
45 class CacheItem : boost::noncopyable {
48 CacheItem(std::string const & file);
50 /// Define an empty d-tor out-of-line to keep boost::scoped_ptr happy.
54 std::string const & filename() const;
56 /// It's in the cache. Now start the loading process.
57 void startLoading() const;
59 /** Monitor any changes to the file.
60 * There is no point monitoring the file before startLoading() is
63 void startMonitoring() const;
65 bool monitoring() const;
66 /** Returns the check sum of filename() so that, for example, you can
67 * ascertain whether to output a new PostScript version of the file
70 unsigned long checksum() const;
72 /** Get the image associated with filename().
73 * If the image is not yet loaded, returns 0.
74 * This routine returns a pointer to const; if you want to modify it,
75 * create a copy and modify that.
77 Image const * image() const;
79 /// How far have we got in loading the image?
80 ImageStatus status() const;
82 /** Connect and you'll be informed when the loading status of the image
85 typedef boost::signal<void()> sig_type;
86 typedef sig_type::slot_type slot_type;
88 boost::signals::connection connect(slot_type const &) const;
91 /// Use the Pimpl idiom to hide the internals.
94 /// The pointer never changes although *pimpl_'s contents may.
95 boost::scoped_ptr<Impl> const pimpl_;
98 } // namespace graphics
101 #endif // GRAPHICSCACHEITEM_H