[Clipart] getid3 svgz support

[Frederik Elwert]

Hi!

It's great to have svgz support for the OCAL. This could affect the
plans for thumbnails. In quite a lot of cases, the svgz files are
smaller than PNG thumbnails, while remaining scalable.

What are the general plans for thumbnails, though? I thought about it a
bit in the last couple of days, so I'd like to share my ideas and ask
for your comments.

1. PNG thumbnails

      * Don't depend on browser's rendering capabilities.
      * Are quite small in file size (when exported with thumbnail
        dimensions, we have a lot of full-sized PNGs).
      * Require server-side rendering:
              * Generate on upload.
              * Generate for the existing files: At once or one by one
                at request?
              * Optimizing might be needed in order to make them smaller
                (pngcrush).

2. SVG thumbnails

      * Require browser support.
      * Are often even smaller when gzipped.
      * Remain scalable (once thumbnails are in place, one might think
        of large versions on hover or click or the like).
      * Require server-side modifications:
              * Add viewBox (this might make a "thumbnail SVG" in
                addition to the original file necessary, since Inkscape
                still doesn't handle viewboxed files very good).
              * Modify height and width values (dito).
              * GZip for optimal size.
              * Or just gzip on the server side and adjust viewBox,
                width and height on the client side with JavaScript: No
                need for extra files on the server.


      * Do we want one or the other or both?
      * Let the users choose via preferences?

Cheers,
Frederik