kio/kio/thumbcreator.h

   1 /*  This file is part of the KDE libraries
   2     Copyright (C) 2000 Malte Starostik <malte@kde.org>
   3
   4     This library is free software; you can redistribute it and/or
   5     modify it under the terms of the GNU Library General Public
   6     License as published by the Free Software Foundation; either
   7     version 2 of the License, or (at your option) any later version.
   8
   9     This library is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12     Library General Public License for more details.
  13
  14     You should have received a copy of the GNU Library General Public License
  15     along with this library; see the file COPYING.LIB.  If not, write to
  16     the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17     Boston, MA 02110-1301, USA.
  18 */
  19
  20 #ifndef _THUMBCREATOR_H_
  21 #define _THUMBCREATOR_H_
  22
  23 #include <kio/kio_export.h>
  24
  25 class QString;
  26 class QImage;
  27 /**
  28  * This is the baseclass for "thumbnail-plugins" in KDE. Using the class
  29  * KIO::PreviewJob allows you to generate small images (thumbnails)
  30  * for any kind of file, where a "ThumbCreator" is available. Have a look
  31  * at kdebase/kioslave/thumbnail/ for existing ThumbCreators.
  32  *
  33  * What you need to do to create and register a ThumbCreator:
  34  * @li Inherit from this class and reimplement the create() method to
  35  *     generate a thumbnail for the given file-path.
  36  * @li Provide a factory method in your implementation file to instantiate
  37  * your plugin, e.g.:
  38  * \code
  39  * extern "C"
  40  * {
  41  *   KDE_EXPORT ThumbCreator *new_creator()
  42  *   {
  43  *     return new YourThumbCreator();
  44  *   }
  45  * };
  46  * \endcode
  47  *
  48  * Compile your ThumbCreator as a module. The contents of CMakeLists.txt
  49  * should look something like this, with "filetype" replaced by the type of
  50  * file this plugin creates thumbnails for:
  51  * \code
  52  * project(filetypethumbcreator)
  53  *
  54  * find_package(KDE4 REQUIRED)
  55  * include (KDE4Defaults)
  56  * include(MacroOptionalAddSubdirectory)
  57  *
  58  * set(filetypethumbnail_SRCS filetypethumbnail.cpp)
  59  *
  60  *
  61  * kde4_add_ui_files(filetypethumbnail_SRCS config.ui )
  62  *
  63  * kde4_add_plugin(filetypethumbnail ${filetypethumbnail_SRCS})
  64  * target_link_libraries(filetypethumbnail ${KDE4_KIO_LIBS})
  65  *
  66  * install(TARGETS filetypethumbnail DESTINATION ${PLUGIN_INSTALL_DIR})
  67  * install(FILES filetypethumbcreator.desktop DESTINATION ${SERVICES_INSTALL_DIR})
  68  *
  69  * \endcode
  70  *
  71  * @li Create a file filetypethumbcreator.desktop with the following contents:
  72  * \code
  73  * [Desktop Entry]
  74  * Encoding=UTF-8
  75  * Type=Service
  76  * Name=Name of the type of files your ThumbCreator supports
  77  * ServiceTypes=ThumbCreator
  78  * MimeType=application/x-somemimetype;
  79  * CacheThumbnail=true
  80  * X-KDE-Library=yourthumbcreator
  81  * \endcode
  82  *
  83  * You can supply a comma-separated list of mimetypes to the MimeTypes entry,
  84  * naming all mimetypes your ThumbCreator supports. You can also use simple
  85  * wildcards, like (where you see [slash], put a /)
  86  * \code
  87  *              text[slash]* or image[slash]*.
  88  * \endcode
  89  *
  90  * If your plugin is rather inexpensive (e.g. like the text preview ThumbCreator),
  91  * you can set CacheThumbnail=false to prevent your thumbnails from being cached
  92  * on disk.
  93  *
  94  * @short Baseclass for thumbnail-generating plugins.
  95  */
  96 class KIO_EXPORT ThumbCreator
  97 {
  98 public:
  99   /**
 100    * The flags of this plugin.
 101    * @see flags()
 102    */
 103     enum Flags { None = 0, DrawFrame = 1, BlendIcon = 2 };
 104     virtual ~ThumbCreator();
 105
 106     /**
 107      * Creates a thumbnail
 108      * Note that the width and height parameters should not be used
 109      * for scaling. Only plugins that create an image "from scratch",
 110      * like the TextCreator should directly use the specified size.
 111      * If the resulting preview is larger than width x height, it will be
 112      * scaled down.
 113      *
 114      * @param path the (always local) file path to create a preview for
 115      * @param width maximum width for the preview
 116      * @param height maximum height for the preview
 117      * @param img this image will contain the preview on success
 118      *
 119      * @return true if preview generation succeeded
 120      */
 121     virtual bool create(const QString &path, int width, int height, QImage &img) = 0;
 122
 123     /**
 124      * The flags of this plugin:
 125      * @li None nothing special
 126      * @li DrawFrame a frame should be painted around the preview
 127      * @li BlendIcon the mimetype icon should be blended over the preview
 128      *
 129      * @return flags for this plugin
 130      */
 131     virtual Flags flags() const { return None; } //krazy:exclude=inline
 132 };
 133
 134 typedef ThumbCreator *(*newCreator)();
 135
 136 #endif