Enforce size/dimension limits for apps logos

[selfhoster1312]

The apps repos is way too big and app logos vary wildly... It's README currently mentions to keep the logo « as small as possible » and « almost square ».

However, it's not clear:

• what minimum/maximum pixel size is recommended
• what maximum byte size is recommended
• how UIs must deal with various width/height ratios
• whether the UI should support logos with different resolutions ; or, if the repo should keep links to upstream higher-resolution resources in case that ever changes
• whether the background should be dark, light, or transparent depending on what upstream logo supports
• whether it's recommended to edit the upstream logo to fit those criteria, and in that case, how to document the source materials and the transformations applied

Illustrating the problem

For example:

• bonfire.png is 48x48 pixels (really bad quality)
• pleroma.png has really bad quality with white pixels jumping out of the black background
• owncast-emojiwall.png is 311KiB ... just running pngquant owncast-emojiwall.png produces a file that's 106KiB and that's visually indistinguishable

Solutions

• enforce a minimum pixel size so apps can be displayed properly
• enforce a maximum pixel size so users don't have to load a big picture when the UI isn't designed for it
• ideally, the minimum pixel size is also the maximum pixel size and the CI will automatically downsize submitted images
• enforce a maximum byte size (10K? 20K? 50K?), have the CI deny the PR if running pngquant (or other) reduces size by more than 10%
• ensure logos are square and have CI deny non-square logos
• add a source URL for the logo in the apps.json for high-resolution PNG or SVG

I'm happy to help with this if given specific guidelines to enforce.

[Salamandar]

We shall also follow Android logo guidelines such as margins around logo :

[ericgaspar]

Most of my logo additions are set to 300px square. Following Android logo guidelines will involve a significant effort to gain 84px

[Salamandar]

I'm sorry, what I meant only was about the margins. See for example Immich vs Jellyfin, Immich is really not pretty here.

Android suggests that the actual icon makes up for 75% of the outer dimensions.

[ericgaspar]

I yes, my bad

[ericgaspar]

I also think that we shoul optimise the file size of PNGs (personally, I am using ImageOptim to shrink the file size)

[selfhoster1312]

Personal opinion: if we apply transformations on upstream logos, it's much better if these are done by a script so they can be edited/reproduced without graphics editing skills, either when the upstream logo changes, or when our logo guidelines change (for example, if we allow more sizes). Something like:

logo_source = "https://foo.bar/baz.png"
logo_transform = "convert -i \"$1\" .........."