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>
40 namespace support { class FileName; }
47 /// A lyx::graphics::Cache item holder.
48 class CacheItem : boost::noncopyable {
51 CacheItem(support::FileName const & file);
53 /// Define an empty d-tor out-of-line to keep boost::scoped_ptr happy.
57 support::FileName const & filename() const;
59 /// It's in the cache. Now start the loading process.
60 void startLoading() const;
62 /** Monitor any changes to the file.
63 * There is no point monitoring the file before startLoading() is
66 void startMonitoring() const;
68 bool monitoring() const;
69 /** Returns the check sum of filename() so that, for example, you can
70 * ascertain whether to output a new PostScript version of the file
73 unsigned long checksum() const;
75 /** Get the image associated with filename().
76 * If the image is not yet loaded, returns 0.
77 * This routine returns a pointer to const; if you want to modify it,
78 * create a copy and modify that.
80 Image const * image() const;
82 /// How far have we got in loading the image?
83 ImageStatus status() const;
85 /** Connect and you'll be informed when the loading status of the image
88 typedef boost::signal<void()> sig_type;
89 typedef sig_type::slot_type slot_type;
91 boost::signals::connection connect(slot_type const &) const;
94 /// Use the Pimpl idiom to hide the internals.
97 /// The pointer never changes although *pimpl_'s contents may.
98 boost::scoped_ptr<Impl> const pimpl_;
101 } // namespace graphics
104 #endif // GRAPHICSCACHEITEM_H