1 // -*- C++ -*-
2 /**
3  * \file GraphicsCacheItem.h
4  * This file is part of LyX, the document processor.
5  * Licence details can be found in the file COPYING.
6  *
7  * \author Baruch Even
8  * \author Angus Leeming
9  *
10  * Full author contact details are available in file CREDITS.
11  *
12  * The graphics cache is a container of graphics::CacheItems.
13  * Each graphics::CacheItem, defined here represents a separate image file.
14  *
15  * The routines here can be used to load the graphics file into memory at
16  * which point (status() == 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.
19  *
20  * The graphics cache supports fully asynchronous:
21  * file conversion to a loadable format;
22  * file loading.
23  *
24  * Whether you get that, of course, depends on graphics::Converter and
25  * on the graphics::Image-derived image class.
26  */
27 
28 #ifndef GRAPHICSCACHEITEM_H
29 #define GRAPHICSCACHEITEM_H
30 
31 #include "GraphicsTypes.h"
32 
33 #include "support/signals.h"
34 
35 
36 namespace lyx {
37 
38 namespace support { class FileName; }
39 
40 namespace graphics {
41 
42 class Image;
43 class Converter;
44 
45 /// A graphics::Cache item holder.
46 class CacheItem {
47 public:
48 	///
49 	CacheItem(support::FileName const & file, support::FileName const & doc_file);
50 	/// Needed for the pimpl
51 	~CacheItem();
52 
53 	///
54 	support::FileName const & filename() const;
55 
56 	/// Try to load a display format.
57 	bool tryDisplayFormat() const;
58 
59 	/// It's in the cache. Now start the loading process.
60 	void startLoading() const;
61 
62 	/** Monitor any changes to the file.
63 	 *  There is no point monitoring the file before startLoading() is
64 	 *  invoked.
65 	 */
66 	void startMonitoring() const;
67 	///
68 	bool monitoring() const;
69 	/// perform a modification check asynchronously
70 	void checkModifiedAsync() const;
71 
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.
76 	 */
77 	Image const * image() const;
78 
79 	/// How far have we got in loading the image?
80 	ImageStatus status() const;
81 
82 	/** Connect and you'll be informed when the loading status of the image
83 	 *  changes.
84 	 */
85 	typedef signals2::signal<void()>::slot_type slot_type;
86 	///
87 	signals2::connection connect(slot_type const &) const;
88 
89 private:
90 	/// noncopyable
91 	CacheItem(CacheItem const &);
92 	void operator=(CacheItem const &);
93 
94 	/// Use the Pimpl idiom to hide the internals.
95 	class Impl;
96 	/// The pointer never changes although *pimpl_'s contents may.
97 	Impl * const pimpl_;
98 };
99 
100 } // namespace graphics
101 } // namespace lyx
102 
103 #endif // GRAPHICSCACHEITEM_H
104