src/graphics/PreviewLoader.h

   1 // -*- C++ -*-
   2 /**
   3  * \file PreviewLoader.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  * graphics::PreviewLoader collects latex snippets together. Then, on a
  12  * startLoading() call, these are dumped to file and processed, converting
  13  * each snippet to a separate bitmap image file. Once a bitmap file is ready
  14  * to be loaded back into LyX, the PreviewLoader emits a signal to inform
  15  * the initiating process.
  16  */
  17
  18 #ifndef PREVIEWLOADER_H
  19 #define PREVIEWLOADER_H
  20
  21 #include <boost/signal.hpp>
  22
  23
  24 namespace lyx {
  25
  26 class Buffer;
  27
  28 namespace graphics {
  29
  30 class PreviewImage;
  31
  32 class PreviewLoader {
  33 public:
  34         /** We need buffer because we require the preamble to the
  35          *  LaTeX file.
  36          */
  37         PreviewLoader(Buffer const & buffer);
  38         ///
  39         ~PreviewLoader();
  40
  41         /** Is there an image already associated with this snippet of LaTeX?
  42          *  If so, returns a pointer to it, else returns 0.
  43          */
  44         PreviewImage const * preview(std::string const & latex_snippet) const;
  45
  46         ///
  47         enum Status {
  48                 ///
  49                 NotFound,
  50                 ///
  51                 InQueue,
  52                 ///
  53                 Processing,
  54                 ///
  55                 Ready
  56         };
  57
  58         /// How far have we got in loading the image?
  59         Status status(std::string const & latex_snippet) const;
  60
  61         /// Add a snippet of LaTeX to the queue for processing.
  62         void add(std::string const & latex_snippet) const;
  63
  64         /// Remove this snippet of LaTeX from the PreviewLoader.
  65         void remove(std::string const & latex_snippet) const;
  66
  67         /** We have accumulated several latex snippets with status "InQueue".
  68          *  Initiate their transformation into bitmap images.
  69          */
  70         void startLoading() const;
  71
  72         /** Connect and you'll be informed when the bitmap image file
  73          *  has been created and is ready for loading through
  74          *  lyx::graphics::PreviewImage::image().
  75          */
  76         typedef boost::signal<void(PreviewImage const &)> sig_type;
  77         typedef sig_type::slot_type slot_type;
  78         ///
  79         boost::signals::connection connect(slot_type const &) const;
  80
  81         /** When PreviewImage has finished loading the image file into memory,
  82          *  it tells the PreviewLoader to tell the outside world
  83          */
  84         void emitSignal(PreviewImage const &) const;
  85
  86         /// Which buffer owns this loader.
  87         Buffer const & buffer() const;
  88
  89 private:
  90         /// noncopyable
  91         PreviewLoader(PreviewLoader const &);
  92         void operator=(PreviewLoader 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 // PREVIEWLOADER_H