File previews

[groenroos]

Uploaded files that are not images should also generate a sensible preview asset, such as a thumbnail of the first page of a PDF, type specimen for font files, etc.

[groenroos]

As a preview of every conceivable filetype would be impractical, need to define a list of the most used/useful files to have previews.

(Probably) easy and obvious ones:

• Images (jpg, png, gif, tiff, bmp, webp, svg)
• Videos (mp4, ogv, wmv, avi)
• Office documents (docx, xlsx, pptx, odt, ods, odp)
• Other documents (txt, rtf, pdf)

(Probably) harder ones that would depend on demand, and availability of an easy out-of-the-box thumbnail generation lib:

• Audio (wav, mp3, aiff, ogg)
• Fonts (ttf, otf, woff, woff2)

Don't know if I'm missing anything obvious.