Hilfe:Images: Unterschied zwischen den Versionen

Aktuelle Version vom 11. August 2010, 11:36 Uhr

This page explains the image syntax when editing the wiki. You or another user must usually upload an image before you can use it on a page.

Images that are stored on a MediaWiki server are usually rendered by using the File: namespace prefix (but the legacy Image: namespace prefix is still supported as a synonym) as the target of a MediaWiki link. The alternate Media: namespace prefix is also usable to reference the original media file content (for rendering or downloading it separately, out of any MediaWiki page).

Inhaltsverzeichnis

1 Supported media types for images
2 Rendering a single image
3 Rendering a gallery of images
- 3.1 Gallery syntax
- 3.2 Optional gallery attributes
4 Linking to an image without displaying it
5 Requisites
6 Files at other websites

Supported media types for images

The file name extension (remapped to lowercase) is used to determine the supported media type for images and to retrieve its internal preferred dimensions:

.svg : scalable image in the Standard Vector Graphics format (specified by the W3 Consortium).
.jpg or .jpeg : bitmap image compressed in the standard JPEG format (this lossy format is most suitable for photographs).
.png : bitmap image in the Portable Network Graphics format (specified by the W3 Consortium).
.gif : bitmap image in the legacy Graphics Interchange Format.
Note that animations of multiframed GIF images are currently supported only if the image is not rescaled into thumbnails; otherwise, only the first frame will be rendered.
.pdf : multipaged documents in the Portable Document Format (initially specified by Adobe).
.djvu : multipaged bitmap documents in the DejaVu format (most often, scans of books).
By default only the first page of .pdf and .djvu files will be rendered.

Other media types may be supported depending on your MediaWiki version (look at the installation requirements, the release notes and the documentation).

Rendering a single image

Syntax

The full syntax for displaying an image is:

[[File:file name.extension|options|caption]]

where options can be zero or more of the following, separated by pipes (|):

Format option: one of border and/or frameless, frame, thumb (or thumbnail);
Controls how the rendered image is formatted and embedded in the rest of the page.
Resizing option: one of
- {width}px — Resizes the image to fit within the given maximum width in pixels, without restricting its height;
- x{height}px — Resizes the image to fit within the given maximum height in pixels, without restricting its width;
- {width}x{height}px — Resizes the image to fit within the given width and height in pixels;
- upright — Resizes an image to fit within reasonable dimensions, according to user preferences (suitable for images whose height is larger than width).
Note that the image will always retain its aspect ratio, and can only be reduced (not increased) in size unless it's in a scalable media type (bitmap images cannot be scaled up).

The default maximum size depends on the format and the internal image dimensions (according to its media type).
Horizontal alignment option: one of left, right, center, none;
Controls the horizontal alignment (and inline/block or floating styles) of the image within a text (no default value).
Vertical alignment option: one of baseline, sub, super, top, text-top, middle, bottom, text-bottom;
Controls the vertical alignment of a non-floating inline image with the text before or after the image, and in the same block (the default vertical alignment is middle).
Link option: one of
- link={target} — Allows to change the target (to an arbitrary page title, or URL) of the generated link, activable on the rendered image surface;
- link= (with an empty value) — (Vorlage:Mediawiki) Displays an image without any activable link; e.g. [[File:Example.jpg|20px|link=]] renders as 20px.
Note that the link option cannot be used in conjunction with thumb or thumbnail, as thumb is always meant to link to the larger version of the image.

In addition, link cannot be used with frame.
Other specific options:
- alt={alternative text} — (Vorlage:Mediawiki) Defines the alternative text (maps to the HTML attribute alt="..." of the generated <image /> element) of an image that will be rendered if either the referenced image cannot be downloaded and embedded, or if the support media must use the alternative description text (e.g. when using a Braille reader or with accessibility options set by the user in its browser).
- page={number} — Renders the specified page number (currently only applicable when showing a .djvu or .pdf file).

The options can be given in any order. If the given options conflict each other, the latter is applied, except for the format options, where the options take the priority in the order of: frame; thumb (or thumbnail); frameless and/or border.

If a parameter does not match any of the other possibilities, it is assumed to be the caption text. Caption text shows below the image in thumb and frame formats, or as mouseover text in border, frameless formats or when the format is omitted. Caption text displayed in the thumb and frame formats may contain wiki links and other formatting. In the other options, wiki-formatting will not work though transclusion will.

If no caption text is supplied, a caption is automatically created showing the file name. To completely remove the caption, set it to . For example, [[File:Example.jpg|20px|]] renders as Datei:Example.jpg.

Format

The following table shows the effect of all available formats.

Description	You type	You get Hilfe:Images/frame Hilfe:Images/frame Hilfe:Images/frame Hilfe:Images/frame Hilfe:Images/frame Hilfe:Images/frame

When the height of an image in thumbnail is bigger than its width (i.e. in portrait orientation rather than lansdscape) and you find it too outstanding, you may try the option upright, which will try to adjust its size to more desirable size by reducing the height instead the width. The alternative is to specify the desired maximum height (in pixels) explicitly.

Note that by writing thumb={filename}, you can use a different image for the thumbnail.

Size and Frame

Among different formats, the effect of the size parameter may be different, as shown below.

For how it appears when its size is not specified, see Format section above.
When the format is not specified, or only bordered, the size can be both reduced and enlarged to any specified size.
In the examples below, the original size of the image is 400 × 267 pixels.
An image with frame always ignores the size specification, the original image will be reduced it it exceeds the maximum size defined in user preferences.
The size of an image with thumb and frameless can be reduced, but can not be enlarged beyond the original size of the image.

Format	Reduced	Enlarged Hilfe:Images/size Hilfe:Images/size Hilfe:Images/size Hilfe:Images/size Hilfe:Images/size

Horizontal alignment

Note that when using the frame or thumb[nail] formats, the default horizontal alignment will be right.

Description	You type	You get Hilfe:Images/frame Hilfe:Images/frame Hilfe:Images/frame Hilfe:Images/frame Hilfe:Images/frame

Vertical alignment

The vertical alignment options take effect only if the image is rendered as an inline element and is not floating. They alter the way the inlined image will be vertically aligned with the text present in the same block before and/or after this image on the same rendered row.

Note that the rendered line of text where inline images are inserted (and the lines of text rendered after the current one) may be moved down (this will increase the line-height conditionally by additional line spacing, just as it may occur with spans of text with variable font sizes, or with superscripts and subscripts) to allow the image height to be fully displayed with this alignment constraint.

<p style="border:1px solid #AAA;background:#FF0;padding:0;font-size:150%;line-height:2">
<span style="background:#FFF;color:#000;text-decoration:overline"><u><del>text</del>
'''top:''' [[File:Example.jpg|20px|top]] [[File:Example.jpg|40px|top]] [[File:Example.jpg|40px|border|top]]
<del>text</del></u></span></p>

<p style="border:1px solid #AAA;background:#FF0;padding:0;font-size:150%;line-height:2">
<span style="background:#FFF;color:#000;text-decoration:overline"><u><del>text</del>
'''text-top:''' [[File:Example.jpg|20px|text-top]] [[File:Example.jpg|40px|text-top]] [[File:Example.jpg|40px|border|text-top]]
<del>text</del></u></span></p>

<p style="border:1px solid #AAA;background:#FF0;padding:0;font-size:150%;line-height:2">
<span style="background:#FFF;color:#000;text-decoration:overline"><u><del>text</del>
<sup>super:</sup> [[File:Example.jpg|20px|super]] [[File:Example.jpg|40px|super]] [[File:Example.jpg|40px|border|super]]
<del>text</del></u></span></p>

<p style="border:1px solid #AAA;background:#FF0;padding:0;font-size:150%;line-height:2">
<span style="background:#FFF;color:#000;text-decoration:overline"><u><del>text</del>
'''baseline:''' [[File:Example.jpg|20px|baseline]] [[File:Example.jpg|40px|baseline]] [[File:Example.jpg|40px|border|baseline]]
<del>text</del></u></span></p>

<p style="border:1px solid #AAA;background:#FF0;padding:0;font-size:150%;line-height:2">
<span style="background:#FFF;color:#000;text-decoration:overline"><u><del>text</del>
<sub>'''sub:'''</sub> [[File:Example.jpg|20px|sub]] [[File:Example.jpg|40px|sub]] [[File:Example.jpg|40px|border|sub]]
<del>text</del></u></span></p>

<p style="border:1px solid #AAA;background:#FF0;padding:0;font-size:150%;line-height:2">
<span style="background:#FFF;color:#000;text-decoration:overline"><u><del>text</del>
'''default:''' [[File:Example.jpg|20px]][[File:Example.jpg|40px]] [[File:Example.jpg|40px|border]]
<del>text</del></u></span></p>

<p style="border:1px solid #AAA;background:#FF0;padding:0;font-size:150%;line-height:2">
<span style="background:#FFF;color:#000;text-decoration:overline"><u><del>text</del>
'''middle:''' [[File:Example.jpg|20px|middle]] [[File:Example.jpg|40px|middle]] [[File:Example.jpg|40px|border|middle]]
<del>text</del></u></span></p>

<p style="border:1px solid #AAA;background:#FF0;padding:0;font-size:150%;line-height:2">
<span style="background:#FFF;color:#000;text-decoration:overline"><u><del>text</del>
'''text-bottom:''' [[File:Example.jpg|20px|text-bottom]] [[File:Example.jpg|40px|text-bottom]] [[File:Example.jpg|40px|border|text-bottom]]
<del>text</del></u></span></p>

<p style="border:1px solid #AAA;background:#FF0;padding:0;font-size:150%;line-height:2">
<span style="background:#FFF;color:#000;text-decoration:overline"><u><del>text</del>
'''bottom:'' [[File:Example.jpg|20px|bottom]] [[File:Example.jpg|40px|bottom]] [[File:Example.jpg|40px|border|bottom]]
<del>text</del></u></span></p>

results in the following (to show the alignment result more clearly, the text spans are overlined and underlined, the line-height is increased to 200% of the font-height, the font-height is emphasized with a yellow background covering the line margins, and the full line-height is shown with a dark gray border; additionally images of different sizes are aligned, including one with an additional border that adds some pixels to its specified dimensions and slightly changes its vertical alignment):

~~text~~ top: 20px 40px 40px ~~text~~

~~text~~ text-top: 20px 40px 40px ~~text~~

~~text~~ ^super: 20px 40px 40px ~~text~~

~~text~~ baseline: 20px 40px 40px ~~text~~

~~text~~ _sub: 20px 40px 40px ~~text~~

~~text~~ default: 20px 40px 40px ~~text~~

~~text~~ middle: 20px 40px 40px ~~text~~

~~text~~ text-bottom: 20px 40px 40px ~~text~~

~~text~~ bottom: 20px 40px 40px ~~text~~

Notes:

The "middle" vertical alignment position of the image (which is also the default) usually refers to the middle between the x-height and the baseline of the text (on which the vertical middle of the image will be aligned, and on which usually the text may be overstroke), but not to the middle of the line-height of the font-height that refers to the space between the "text-top" and "text-bottom" positions ; the font-height excludes:
- the additional line separation spacing normally divided equally into two line-margins (here 0.5em, according to line-height set to 200%) above and below the font-height).
- the additional line spacing which may be added by superscripts and subscripts.
However, if the image height causes its top or bottom position to go above or below the normal full line-height of text, the middle position will be adjusted after the increasing the top and/or bottom line-margins so that the image can fit and align properly, and all images (including those with smaller heights) will be vertically centered on the adjusted middle position (for computing the effective line-height, the text of each rendered row with the larger font-height will be considered).
The "text-top" and "text-bottom" alignment positions also excludes the extra line spacing added by superscripts and subscripts, but not the additional line-spacing defined by the line-height.
The "top" and "bottom" alignment positions take into account all these extra line spacings (including superscripts and subscripts, if they are present in a rendered line span). When the image alignment constrains the image to grow above or below the normal line-spacing, and the image is not absolutely positioned, the image will cause the "top" and "bottom" positions to be adjusted (just like superscripts and subscripts), so the effective line-height between rendered lines of text will be higher.
The "underline", "overline" and "overstrike" text-decoration positions should be somewhere within these two limits and may depend on the type and height of fonts used (the superscript and subscript styles may be taken into account in some browsers, but usually these styles are ignored and the position of these decorations may not be adjusted); so these decorations normally don't affect the vertical position of images, relatively to the text.

Stopping the text flow

On occasion it is desirable to stop text (or other inline non-floating images) from flowing around a floating image. Depending on the web browser's screen resolution and such, text flow on the right side of an image may cause a section header (for instance, == My Header ==) to appear to the right of the image, instead of below it, as a user may expect. The text flow can be stopped by placing   before the text that should start below the floatting image.

All images rendered as blocks (including non-floating centered images, left- or right-floating images, as well as framed or thumbnailed floating images) are implicitly breaking the surrounding lines of text (terminating the current block of text before the image, and creating a new paragraph for the text after them). They will then stack vertically along their left or right alignment margin (or along the center line between these margins for centered images).

Altering the default link target

The following table shows how to alter the link target (whose default is the image description page) or how to remove it. Changing the link does not alter the format described in the previous sections.

Description	You type	You get Hilfe:Images/frame Hilfe:Images/frame Hilfe:Images/frame

Warning :

The licencing requirements on your wiki may not allow you to remove all links to the description page that displays the required authors attributions, the copyrights statements, the applicable licencing terms, or a more complete description of the rendered image (including its history of modifications).

If you change or remove the target link of an image, you will then have to provide somewhere else on your page an explicit link to this description page, or to display the copyright and author statement and a link to the applicable licence, if they are different from the elements applicable to the embedding page itself.

Your wiki policy may restrict the use of the alternate link parameter, or may even enforce a prohibition of alternate link parameters for embedded media files (in which case, the link parameter will be ignored), or may only accept to them after validation by authorized users or administrators.

Rendering a gallery of images

Gallery syntax

It's easy to make a gallery of thumbnails only, not other images, with the <gallery> tag. The syntax is:

<gallery>
Image:file_name.ext|caption
Image:file_name.ext|caption
{...}
</gallery>

Note that the image code is not enclosed in brackets when enclosed in gallery tags.

Captions are optional, and may contain wiki links or other formatting.

for example:

<gallery>
File:Example.jpg|Item 1
File:Example.jpg|a link to [[Help:Contents]]
File:Example.jpg
File:Example.jpg
File:Example.jpg| ''italic caption''
File:Example.jpg|on page "{{PAGENAME}}"
</gallery>

is formatted as:

Example.jpg

Item 1
Example.jpg

a link to Help:Contents
Example.jpg
Example.jpg
Example.jpg

italic caption
Example.jpg

on page "Images"

Optional gallery attributes

The gallery tag itself takes several additional parameters, specified as attribute name-value pairs:

<gallery {parameters}>
{images}
</gallery>

caption={caption}: sets a caption on the gallery.
widths={width}px: sets the widths of the images, default 120px. Note the plural, widths
heights={heights}px: sets the (max) heights of the images.
perrow={integer}: sets the number of images per row.

Example:

Coding:

<gallery widths=60px heights=60px perrow=7 caption="sunflowers are groovy">
File:Example.jpg
File:Example.jpg
File:Example.jpg
File:Example.jpg
File:Example.jpg
File:Example.jpg
File:Example.jpg
File:Example.jpg
File:Example.jpg
File:Example.jpg
</gallery>

Result:

sunflowers are groovy
Example.jpg
Example.jpg
Example.jpg
Example.jpg
Example.jpg
Example.jpg
Example.jpg
Example.jpg
Example.jpg
Example.jpg

Linking to an image without displaying it

Link to description page

If you put a colon (:) before Datei:, the image will not be embedded and the link will lead to the description page of the file.

[[:Datei:Beispiel.jpg]]
[[:Datei:Beispiel.jpg|Sunflowers]]

results in

Datei:Beispiel.jpg Sunflowers

Link to another page

This will make a 50px width picture with a link to the page MediaWiki:

[[File:Wiki.png|50px|link=MediaWiki]]

50px

Link directly to the media file

You can use the pseudo-namespace “Medium” to link directly to a file without rendering it, bypassing the description page.

[[Medium:Beispiel.jpg]]
[[Medium:Beispiel.jpg|Sunflowers]]

results in

Medium:Beispiel.jpg Sunflowers

You can also use:

[[Spezial:Dateipfad/Beispiel.jpg]]

which can be used to link to a potential file, even if it doesn't exist. You can also use:

{{FILEPATH:Beispiel.jpg}}

which generates an external URL to the file inline:

Requisites

Before using images in your page, the system administrator of your wiki must have Vorlage:Mediawiki and a user has to upload the file. System administrators may also set the wiki to accept files from Vorlage:Mediawiki, such as the Wikimedia Commons. For server side image resizing it is necessary to have a scaler configured (such as GD2, ImageMagick, etc.).

Files at other websites

You can link to an external file available online using the same syntax used for linking to an external web page. With these syntaxes, the image will not be rendered, but only the text of the link to this image will be displayed.

[http://url.for/some/image.png]

Or with a different displayed text:

[http://url.for/some/image.png link text here]

Additional MediaWiki markup or HTML/CSS formatting (for inline elements) is permitted in this displayed text (with the exception of embedded links that would break the surrounding link):

[http://www.example.com/some/image.png Example '''<del>rich</del>''' ''<ins>link text</ins>'' here.]

which renders as: Example ~~rich~~ link text<ins> here.

If it is enabled on your wiki (see Vorlage:Mediawiki), you can also embed external images. To do that, simply insert the image's url:

http://url.for/some/image.png

Currently, embedded images cannot be resized, but they may be formatted by surrounding MediaWiki markup or HTML/CSS code.

If this wiki option is not enabled, the image will not be embedded but rendered as a textual link to the external site, just like above.