[MediaWiki-l] Image thumbnailing in MediaWiki

Brian Wolff bawolff at gmail.com
Tue Aug 1 18:12:03 UTC 2017


It should be fine to switch over an existing wiki, and ive done it before.
I think its more likely something else was wrong, some config missing (if
you had custom wgLocalFileRepos the config changes. If you have custom
wgForeignFileRepos things may get more complicated. Older versions of
mediawiki had an issue with wgUseInstantCommons being incompatible with 404
rendering, but that should be fixed now) or some weird incompatibility with
something else.

I know you wouldnt have them anymore, but mediawiki can be configured to
generate logs that can be used to debug this sort of thing, and going
directly to the thumb file in 404 rendering mode can also give helpful
error messages.

--
bawolff

On Tuesday, August 1, 2017, [[kgh]] <mediawiki at kghoffmeyer.de> wrote:
> Building up on this information:
>
> I have once tried to switch from "regular thumb handling" to "404 thumb
> handling" on an existing wiki and found that this does not work since as
> a result no thumbs were rendered at all. Starting with "404 thumb
> handling" on a fresh wiki however works fine. I have not dug into this
> more but may it be that all existing thumbs have to be deleted to clear
> the way for the new handling mode when switching the mode on wiki
> already in use?
>
> Cheers Karsten
>
>
> Am 31.07.2017 um 15:52 schrieb Brian Wolff:
>> Thumbnails will generally not be deleted except if an image is deleted,
>> overwritten with another file or purged (ie appending ?action=purge to
the
>> file description page)
>>
>> --
>> bawolff
>>
>> On Monday, July 31, 2017, Krabina Bernhard <krabina at kdz.or.at> wrote:
>>> Dear all,
>>>
>>> thank you for your help, it is much appreciated.
>>>
>>> An additional question regarding thumbnailing: do thumbs ever get
deleted
>> by MediaWiki?
>>> They probably get deleted once the image gets deleted. But other than
>> that, do all generated thumbnails exist as long as the image exists?
>>> cheers,
>>> Bernhard
>>>
>>>
>>> ----- Am 29. Jul 2017 um 2:22 schrieb Brian Wolff bawolff at gmail.com:
>>>
>>>> Hi,
>>>>
>>>> MediaWiki will by default only create image thumbs for needed sizes at
>>>> time the size is used on a page. So for example when you add an image
>>>> to a page, MW will create the thumbnail sizes needed to display an
>>>> article. However, if the image is uploaded but never added to a normal
>>>> page, then thumbnails for the image won't be generated (except for
>>>> those needed on image description page, which are different sizes)
>>>>
>>>> There is a second mode mediawiki can operate in, where images are
>>>> rendered on demand when someone views the image (so-called "404 thumb
>>>> handling"). Wikimedia wikis use this mode. In this mode, thumbs are
>>>> created on first view. Additionally in this mode, $wgImageLimits
>>>> creates additional links on the image description page. This mode is
>>>> generally more efficient (especially on page saves), and also more
>>>> reliable in the event that there is a missing thumb.
>>>>
>>>> For information to set up 404-thumb rendering see
>>>> https://www.mediawiki.org/wiki/Manual:Thumb.php
>>>>
>>>> --
>>>> Brian
>>>>
>>>> On Fri, Jul 28, 2017 at 9:18 AM, Krabina Bernhard <krabina at kdz.or.at>
>> wrote:
>>>>> Dear MediaWiki experts,
>>>>>
>>>>> I cannot really figure out the behaviour of MediaWiki regarding
>> thumbnailing.
>>>>> What I want to achieve is that my MediaWiki installation produces
>> thumbnails in
>>>>> a specified size.
>>>>>
>>>>> What I did after reading through several help pages is this:
>>>>> ---------------------------
>>>>> # Images und Thumbnails
>>>>> $wgThumbLimits = array( 80, 250, 390 );
>>>>> $wgDefaultUserOptions['thumbsize'] = 1; // thumb size 250
>>>>>
>>>>> $wgImageLimits = array( array( 80, 90 ), array( 800, 600 ), array(
>> 1280, 1024 )
>>>>> );
>>>>> $wgDefaultUserOptions['imagesize'] = 2; // image size 800, 600
>>>>> ---------------------------
>>>>>
>>>>> In my opinion this should guarantee that for every image uploaded,
>> there is an
>>>>> 80, 250 and 390px sized thumbnail. In many cases this is true, but
>> there are
>>>>> some cases were I can find a 100px thumbnail, but no 80px thumbnail.
>>>>>
>>>>> If I understand it correctly, this can perfectly be the case if any
>> user sets
>>>>> his/her preference to 100px. I don't mind so much extra sizes to be
>> produced,
>>>>> but I want to make sure that a 80px thumbnail is there.
>>>>>
>>>>> Maybe in the cases where it is not present the images were uploaded
>> before the
>>>>> above mentioned setting was made? But how can I get the wiki to redo
>> thumbnails
>>>>> in my desired size?
>>>>>
>>>>> cheers,
>>>>> Bernhard
>>>>>
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