[MediaWiki-l] Understanding the generation of thumbs ...

[kgh] mediawiki at kghoffmeyer.de
Wed Mar 1 22:17:17 UTC 2017

Heiya, it's me again about this. ;)

I found out that the default generation of thumbs is tied to the 
"$wgImageLimits" AND to the "$wgThumbLimits" configuration setting. If 
one for example sets the following for a minimum initial creation of thumbs:

$wgImageLimits = array( array( 320, 240 ) );
$wgThumbLimits = array( 320 );

Result: one gets in minimum five thumbs: 120 (default preview size on 
file pages), 180 (default preview size on "Special:ListFiles") as well 
as 320 (default size for thumbs), 480 (1.5x of default size for thumbs) 
and 640 (2x of default size for thumbs)

If one would change the setting for $wgImageLimits another three thumbs 
would be created. To be frank, thumb generation is indeed not 
controllable at all.

Cheers Karsten

Am 27.02.2017 um 17:54 schrieb Bartosz Dziewoński:
> Other funny sizes probably come from the thumbnails shown on the file 
> page itself. For example, for this random file:
> https://commons.wikimedia.org/wiki/File:Bruxelles_à_travers_les_âges_(1884)_(14740799976).jpg 
> The main big thumbnail is 796×600 pixels, and the small thumbnail 
> under "File history" is 120×90.
> Additionally, for every thumbnail, thumbnails with 1.5× and 2× sizes 
> are generated to be used on devices with high-resolution screens.
> And additionally, you can set an arbitrary size for any thumbnail used 
> in an article, and MediaWiki will dutifully generate a thumbnail of 
> that size.
> As far as I know there is currently no option to disallow generation 
> of thumbnails of arbitrary sizes, and limit it to some preset list.

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