Author: gerardo.ballabio

Description:
Request:
let thumbnail size be specified as a percentage of the default size, as set in the user preference settings.

Example: [[Image:xxx.jpg|thumb|150%]]
If a user has set a default thumbnail size of 180px, he should see this image at 270px; if he has set 250px, he should see it at 375px; and so on.

Rationale:
currently one can set a default thumbnail size in the user preference settings, but if any thumbnail is set to a different size, the user setting is overridden. And you can only specify thumbnail size in absolute units (number of pixels). When you do that, somebody is going to dislike it -- some have a high screen resolution, some have it low; some like big images, some like them small. And rendering ALL thumbnails at the default size isn't an option: for example, images with an extreme height/width ratio don't really fit well.

There should be a way to specify thumbnail size in relative units. I initially thought one should be able to specify it as a percentage of screen estate, but was told it isn't possible because images are rescaled server-side to save bandwidth. So I thought that a percentage of the default thumbnail should be used instead. This can be computed server-side and also works for users who want a larger or smaller size for reasons not related to screen resolution (e.g., visually impaired users).

I suppose that this feature can be implemented quite easily. It basically just takes to parse for "%" as well as for "px" and multiply by the preference value.

Version: 1.14.x
Severity: enhancement