src/graphics/GraphicsLoader.h

   1 // -*- C++ -*-
   2 /**
   3  * \file GraphicsLoader.h
   4  * This file is part of LyX, the document processor.
   5  * Licence details can be found in the file COPYING.
   6  *
   7  * \author Angus Leeming
   8  *
   9  * Full author contact details are available in file CREDITS.
  10  *
  11  * The public face of the graphics cache.
  12  *
  13  *  * The user supplies an image file and the display parameters.
  14  *  * He can change the file or the display parameters through a reset() method.
  15  *  * He must start the loading process explicitly with startLoading().
  16  *  * If he is connected through the connect() method, then he'll be informed
  17  *    when the loading status changes.
  18  *  * When (status() == Ready), he can use image() to access the loaded image
  19  *    and pass it to the Painter.
  20  *
  21  * What could be simpler?
  22  */
  23
  24 #ifndef GRAPHICSLOADER_H
  25 #define GRAPHICSLOADER_H
  26
  27 #include "GraphicsTypes.h"
  28
  29 #include <boost/signal.hpp>
  30
  31 namespace lyx {
  32
  33 namespace support { class FileName; }
  34
  35 namespace graphics {
  36
  37 class Image;
  38 class Params;
  39
  40 class Loader {
  41 public:
  42         /// Must use the reset methods to make this instance usable.
  43         Loader();
  44         /// The image is not transformed, just displayed as-is.
  45         Loader(support::FileName const & file_with_path, bool display = true);
  46         /// The image is transformed before display.
  47         Loader(support::FileName const & file_with_path, Params const &);
  48         ///
  49         Loader(Loader const &);
  50         /// Needed for the pimpl
  51         ~Loader();
  52
  53         Loader & operator=(Loader const &);
  54
  55         /// The file can be changed, or the display params, or both.
  56         void reset(support::FileName const & file_with_path, bool display = true) const;
  57         ///
  58         void reset(support::FileName const & file_with_path, Params const &) const;
  59         ///
  60         void reset(Params const &) const;
  61
  62         /// Returns the absolute path of the loaded (loading?) file.
  63         support::FileName const & filename() const;
  64         ///
  65
  66         /** starting loading of the image is done by a urgency-based
  67          *  decision. Here we only call LoaderQueue::touch to request it.
  68          */
  69         void startLoading() const;
  70
  71         /** Tries to reload the image.
  72          */
  73         void reload() const;
  74
  75         /** Monitor any changes to the file.
  76          *  There is no point monitoring the file before startLoading() is
  77          *  invoked.
  78          */
  79         void startMonitoring() const;
  80         ///
  81         bool monitoring() const;
  82         /** Returns the check checksum of filename() so that, for example, you can
  83          *  ascertain whether to output a new PostScript version of the file
  84          *  for a LaTeX run.
  85          */
  86         unsigned long checksum() const;
  87
  88         /// How far have we got in loading the image?
  89         ImageStatus status() const;
  90
  91         /** Connect and you'll be informed when the loading status of the image
  92          *  changes.
  93          */
  94         typedef boost::signal<void()> sig_type;
  95         typedef sig_type::slot_type slot_type;
  96         ///
  97         boost::signals::connection connect(slot_type const &) const;
  98
  99         /** The loaded image with Pixmap set.
 100          *  If the Pixmap is not yet set (see status() for why...), returns 0.
 101          */
 102         Image const * image() const;
 103
 104 private:
 105         /// Use the Pimpl idiom to hide the internals.
 106         class Impl;
 107         /// The pointer never changes although *pimpl_'s contents may.
 108         Impl * const pimpl_;
 109 };
 110
 111 } // namespace graphics
 112 } // namespace lyx
 113
 114 #endif // GRAPHICSLOADER_H