Manual:Image administration/ru

Данная статья содержит сведения о том, как MediaWiki хранит файлы и о том, как настроить этот функционал.

Это относится к изображениям так же, как и к любым другим типам файлов, которые могут быть загружены (uploaded). Все файлы хранятся с соответствующей статьёй в пространстве имён "File:" ("Файл:"). MediaWiki до версии 1.14 использовали пространство имён "Image:" вместо "File:". "Image:" до сих пор поддерживается как псевдоним для обратной совместимости.

Загрузка и использование изображений
Смотрите: Help:Images

Включение функции загрузки файлов
Для загрузки файла должны совпасть три условия:


 * 1) Функция загрузки файлов в MediaWiki должна быть включена. Установите $wgEnableUploads в true.
 * 2) Тип файла должен быть разрешенным. Подробности: $wgFileExtensions.
 * 3) Пользователь должен входить в группу с правом "upload". По умолчанию это право дано всем авторизованным пользователям.

Загрузка файлов выполняется с помощью Special:Upload.

Смотрите Manual:Configuring file uploads, Manual:Mime type detection

Параметры, относящиеся к работе с файлами
Следующие параметры имеют отношения к функционалу работы с файлами:
 * Конфигурация изображений
 * Конфигурация путей
 * Конфигурация загрузок

Создание миниатюр изображений
Расширенный синтаксис изображений MediaWiki позволяет автоматически создавать миниатюры изображений (см. Manual:Configuring file uploads/ru по общей помощи по загрузке файлов).

функция создания миниатюр (Image thumbnailing) требует наличия ImageMagick или библиотеки GD. Рекомендуется использовать ImageMagick для получения миниатюр лучшего качества, загрузить его можно с imagemagick.org. Библиотека GD доступна для загрузки с libgd.org.

Ни один из этих компонентов не является частью mediawiki, хотя GD может идти как расширение PHP.

В старых версиях МедиаВики (до 1.10.0) для того, что бы включить создание миниатюр, требуется установить $wgUseImageResize в true. В новых версиях этого не требуется.

Если вы используете ImageMagick, установите $wgUseImageMagick в true в файле LocalSettings.php. Убедитесь что $wgImageMagickConvertCommand указывает на абсолютное положение команды конвертации и что команда выполнима для веб-сервера.

Для пересоздания старых файлов миниатюр, созданных до использования ImageMagic, используйте $wgThumbnailEpoch.

GIF
Для создания миниатюр для GIF-Анимаций под Windows требуется установить ImageMagick согласно описанию выше.

SVG
MediaWiki supports SVG image rendering: if enabled, SVG images can be used like other image files: they will automatically be rendered as a PNG file and thumbnailed as needed on the fly.

Для включения поддержки SVG необходимо:


 * 1) Allow upload of SVG files in the LocalSettings.php file: $wgFileExtensions[] = 'svg'; Note that MediaWiki will refuse SVG files containing JavaScript, for security reasons. To avoid some false positives, set $wgAllowTitlesInSVG = true;. If you get an error saying the file is corrupt, make sure mime type detection is  working properly.
 * 2) Set $wgSVGConverter to the renderer you want to use. Available options are ImageMagick, sodipodi, inkscape, batik, and rsvg.
 * 3) * If the converter program is not in the system path, you have to specify the directory that contains the program using $wgSVGConverterPath.


 * librsvg is fast but not very accurate. It has a ridiculously large chain of dependencies, so you may not want to bother unless you have a repository that includes it and resolves the dependencies for you. The Wikimedia projects use rsvg 2.14. Note: As of version 2.22.3, there is a bug in locale handling (see Wikimedia bug report and GNOME bug report). A patch is available for the   tool.
 * Batik is the most accurate SVG renderer available. It relies on Java. It is also much slower than rsvg, though this may not be a huge issue unless you're constantly adding SVG files. See SVG benchmarks.
 * Inkscape also does an accurate job of SVGs, half the speed of rsvg, but was designed for interactive graphical use - it requires a writable home directory for the user it's run as. Since it will be running as user www or something similar, it will try to create .inkscape/ and .gnome2/ directories in the corresponding home directory, and will fail silently if it is not able to. Inkscape is preferable to rsvg (a) on Windows (it comes as a standalone package) or (b) if you have important SVGs drawn in Inkscape that do not render correctly in rsvg. Inkscape has as complicated a dependency chain as librsvg &mdash; use only if it's in your distribution or available as a complete standalone package.
 * Sodipodi is the program Inkscape was forked from. The same considerations apply. Sodipod is no longer under active development.
 * ImageMagick renders SVGs, but very buggily. Also slow. This is the default, but avoid it if possible.
 * The GD library is not capable of converting SVG images to the PNG format, at least according to Joen Asmussen's June 2008 NoScope blog.
 * Most current web browsers except Internet Explorer can display SVGs directly, fast but inaccurately (about as well as ImageMagick). Using librsvg to render SVGs to a PNG will give much more accurate results. Direct SVG display is not supported in MediaWiki by default.

Удаление изображений
Файлы, вики страницы могут удаляться только пользователем с полномочиями sysop. Удаение вызывает так же удаление ассоциированной страницы описания.

Удаление отдельных ревизий файлов
If a file has been altered, there is a revision history of the files which is displayed on the file article page. Each revision has a "delete" link. If this is clicked, the revision and the file are permanently deleted.

file article (aka description page) revision and file revision are separate things.

Information about old revisions of files are stored in the oldimage table.

Восстановление файлов
Before MediaWiki version 1.8, deleted images/files can not be undeleted (only the associated description page can be restored).

From MediaWiki version 1.8 up to 1.10, archiving deleted images/files (and thus undeleting them) is disabled per default, but can be enabled by setting $wgSaveDeletedFiles = true.

Since MediaWiki version 1.11, this is enabled per default, and $wgSaveDeletedFiles is deprecated. Instead, the behavior is controlled by $wgFileStore.

Information about deleted images are stored in the filearchive table.

Хранение данных
Whenever an image is uploaded, several things are created:


 * 1) An article in the namespace image with the exact name of the file, e.g. Image:MyPicture.png. This article is stored and behaves like any other article.
 * 2) The file itself is stored in a folder of the hosting (unix) system.
 * 3) If the file is wider than 800px or higher than 600px, a thumb with either 800px width or 600px height will be created. The thumb is stored in the folder pathofwiki/images/thumb/x/xy/MyPicture.png/MyPicture.png. Each thumb gets its own folder by the name of the original picture. Any time you create a thumb or resized image within an article, another thumb is created and stored here, prefixed by its width in px, e.g. 800px-MyPicture.png.

MediaWiki creates several subfolders in the folder images: x/xy, where:
 * x: 0 to F
 * xy: with x equals the x of the upper folder and y: 0 to F.

This subfolders only appear if you have $wgHashedUploadDirectory = true (default). xy are the two first characters of the md5 hash of the final image filename.

Папки
Все изображения хранятся в отдельных папках. По умолчанию это pathofwiki/images/x/xy/MyPicture.png. Смотрите $wgUploadPath.

Note: If $wgHashedUploadDirectory = true, MediaWiki uses the /a/ab/foo.png directory structure. If set to false, these folders are not created and all pictures are stored in the image directory itself (this saves about 3 MB of space on disks).

Description of /image subfolders:


 * 0-f/x0-xf: This is the storage place for the original image files (most recent version).
 * archive/0-f/x0-xf: This is the storage place for the original image files, that have been replaced by newer versions.
 * temp/0-f/x0-xf: used for image uploading. Often old files remain here. They should be deleted regulary (for space reasons). (Bug description: When you upload a picture, it is first stored in temp and then moved. If the image already exists, the user gets a warning. If he then clicks on cancel, the upload process is halted, but the image remains in the folder temp.)
 * thumb/0-f/x0-xf: corresponds with 0-f: Thumbnails (automatically generated) for the pictures in 0-f. If these get lost, they are automatically regenerated. If you delete the whole folder thumb, it will build itself up. You may experience some cache problems.

Depending on the configuration, there may be additional /image subfolders:
 * math/0-f/x0-xf: Folder to store your rendered TeX input, see also Manual:Enable TeX or Math.
 * gnuplot: Used by Extension:Gnuplot to save your gnuplot graphs.

Таблицы базы данных

 * The article Image:MyPicture.png: is stored as any article in page, text, revision etc.
 * table image: Holds some meta data like the size of the image. It does not contain the link to the file. This is probably calculated by the name of the file and the reason why it is not possible to move articles in the namespace image.
 * table imagelinks: Holds the information in which article an image is used.
 * table oldimage: This is the archive for pictures that have been replaced with newer versions. Note: Deleted pictures are not stored here, they are permanently deleted (or, in newer MediaWiki versions, moved to the filearchive).
 * table filearchive: holds the information on the deleted images.

Использование дискового пространства
Pictures need considerably more space than articles. The following calculations assume a block size of 4KB with Linux/Unix servers.

Настройка по умолчанию выглядит как $wgHashedUploadDirectory = true.

Требуемое дисковое пространство для всех папок:


 * image directories: 0-f/x0-f: max. 16*16 = 256 directories = 256*4 KB = 1024 KB
 * archive directories: 0-f/x0-f: max. 16*16 = 256 directories = 256*4 KB = 1024 KB
 * thumb directories: 0-f/x0-f: max. 16*16 = 256 directories = 256*4 KB = 1024 KB
 * temp directories: 0-f/x0-f: max. 16*16 = 256 directories = 256*4 KB = 1024 KB

Therefore, the basic amount of space needed without any images uploaded is 4 MB in theory (although the directories are created only when needed).

Для каждого изображения необходимо:
 * size of the original image file + 2 KB average overhead

Для изображений высотой более 600 пикселей или шириной более 800 пикселей:
 * size of the created thumbnail(s) + 2 KB average overhead (each)
 * directory for thumbnail (4KB) (each image has its own thumbnail directory)

Примеры:
 * image 20778 Byte png (small size, no thumb): 24 KB for the image: Total 24 KB
 * image 123.000 Byte jpeg (big size, auto thumb): 124 KB for the image, 4KB for the thumb directory, 64 KB for the thumb: Total: 192 KB

Доступ к файлам
Uploaded files are generally served directly by the web server, not through MediaWiki. While there may be a minimal level of security through obscurity with path encryption (eg. /c/c4/...) if $wgHashedUploadDirectory is set, the path can be calculated easily from the file name and does not provide true protection.

For limiting access to authorized users, see Image Authorization

Лицензирование
A feature of MediaWiki allows the Special:Upload Page to streamline licensing of images. Wikipedia's Upload Page has a Licensing drop down box below image summary. This feature is turned off in default MediaWiki. To turn this feature on a sysop needs to edit Licenses in the MediaWiki namespace. Example: MediaWiki:Licenses

Licenses expects a certain format in a wiki list.

Line 1 will produce "License text" and substitute the license 1 template in the image page and transclude license 2.

Line 2 will show a greyed out header with text "Header 1:"

Line 3 will produce "Attribution ShareAlike 2.5" and transclude template cc-by-sa-2.5 on the image page.

For detailed real world example, see http://en.wikipedia.org/wiki/MediaWiki:Licenses

Внешние хранилища
It is possible to access files stored in foreign repositories, without needing to upload them to the wiki, by setting the $wgForeignFileRepos array. This feature offers several possibilities:
 * ForeignAPIRepo accesses files from a remote MediaWiki installation, such as Wikimedia Commons, through its API
 * ForeignDBRepo accesses files through a database, and is useful for creating wiki families
 * FSRepo accesses files from a local folder

In all cases, one would be able to embed files into a page using ordinary image syntax and specifying the name of the file in the foreign repository. Note that some of the above implementations are still experimental, and might not be suitable for high-traffic sites.

If one merely wants make a file accessible from one's site, an alternative to implementing all of the above is:
 * 1) Place the file in e.g., images/
 * 2) Link to it in wikitext via [/images/lawnmower.png My lawnmower]

Версии MediaWiki
Применимо к версиям:
 * MediaWiki 1.9.x и выше
 * другие версии не проверялись