ThumbCreator Class Reference

#include <thumbcreator.h>

Inheritance diagram for ThumbCreator:

Public Types
enum	Flags { None = 0, DrawFrame = 1, BlendIcon = 2 }

Public Member Functions
virtual	~ThumbCreator ()
virtual bool	create (const QString &path, int width, int height, QImage &img)=0
virtual Flags	flags () const

Detailed Description

This is the baseclass for "thumbnail-plugins" in KDE.

Using the class KIO::PreviewJob allows you to generate small images (thumbnails) for any kind of file, where a "ThumbCreator" is available. Have a look at kdebase/kioslave/thumbnail/ for existing ThumbCreators. Use ThumbCreatorV2 if the thumbnail-plugin should be configurable by the user.

What you need to do to create and register a ThumbCreator:

• Inherit from this class and reimplement the create() method to generate a thumbnail for the given file-path.
• Provide a factory method in your implementation file to instantiate your plugin, e.g.:

  extern "C"
  {
    KDE_EXPORT ThumbCreator *new_creator()
    {
      return new YourThumbCreator();
    }
  };

Compile your ThumbCreator as a module. The contents of CMakeLists.txt should look something like this, with "filetype" replaced by the type of file this plugin creates thumbnails for:

project(filetypethumbcreator)

find_package(KDE4 REQUIRED)
include (KDE4Defaults)
include(MacroOptionalAddSubdirectory)

set(filetypethumbnail_SRCS filetypethumbnail.cpp)


kde4_add_ui_files(filetypethumbnail_SRCS config.ui )

kde4_add_plugin(filetypethumbnail ${filetypethumbnail_SRCS})
target_link_libraries(filetypethumbnail ${KDE4_KIO_LIBS})

install(TARGETS filetypethumbnail DESTINATION ${PLUGIN_INSTALL_DIR})
install(FILES filetypethumbcreator.desktop DESTINATION ${SERVICES_INSTALL_DIR})

• Create a file filetypethumbcreator.desktop with the following contents:

  [Desktop Entry]
  Encoding=UTF-8
  Type=Service
  Name=Name of the type of files your ThumbCreator supports
  ServiceTypes=ThumbCreator
  MimeType=application/x-somemimetype;
  CacheThumbnail=true
  X-KDE-Library=yourthumbcreator

You can supply a comma-separated list of mimetypes to the MimeTypes entry, naming all mimetypes your ThumbCreator supports. You can also use simple wildcards, like (where you see [slash], put a /)

text[slash]* or image[slash]*.

If your plugin is rather inexpensive (e.g. like the text preview ThumbCreator), you can set CacheThumbnail=false to prevent your thumbnails from being cached on disk.

The following optional property can also be added to the .desktop file:

ThumbnailerVersion=N

where N is some nonnegative integer. If a cached thumbnail has been created with a previous version of the thumbnailer, then the cached thumbnail will be discarded and a new one will be regenerated. Increase (or define) the version number if and only if old thumbnails need to be regenerated. If no version number is provided, then the version is assumed to be <0.

Baseclass for thumbnail-generating plugins.

Definition at line 109 of file thumbcreator.h.

Member Enumeration Documentation

enum ThumbCreator::Flags

The flags of this plugin.

See also

flags()

Enumerator
None
DrawFrame
BlendIcon

Definition at line 116 of file thumbcreator.h.

Constructor & Destructor Documentation

ThumbCreator::~ThumbCreator ( )

virtual

Definition at line 22 of file thumbcreator.cpp.

Member Function Documentation

virtual bool ThumbCreator::create ( const QString &  path, int  width, int  height, QImage &  img  )

pure virtual

Creates a thumbnail Note that the width and height parameters should not be used for scaling.

Only plugins that create an image "from scratch", like the TextCreator should directly use the specified size. If the resulting preview is larger than width x height, it will be scaled down.

Parameters

path	the (always local) file path to create a preview for
width	maximum width for the preview
height	maximum height for the preview
img	this image will contain the preview on success

Returns

true if preview generation succeeded

ThumbCreator::Flags ThumbCreator::flags ( ) const

virtual

The flags of this plugin:

• None nothing special
• DrawFrame a frame should be painted around the preview
• BlendIcon the mimetype icon should be blended over the preview

Returns

flags for this plugin

Definition at line 26 of file thumbcreator.cpp.

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The documentation for this class was generated from the following files:

• thumbcreator.h
• thumbcreator.cpp