Tiny low-resolution image previews #3030
Description
Problem
Currently, when someone posts an image to the chatroom, we include it as an attachment, which needs to be separately fetched. This could result in a delay before an image is shown. The same goes for all images we use (e.g., profile pictures).
Likewise, when someone sends a video, we show a blank box with an option to download. It'd be nice to display a video thumbnail, or something close to that.
Solution
We could use some techniques for improving UX by generating a tiny description of the image that could be displayed while resources are still loading. An example of such a technique is BlurHash. There are other ways of doing this too, such as, e.g., downsizing the image to ~20x20 and then showing a blurred version of that to users as a preview. The important point is including a tiny representation that doesn't need to be fetched separately as a file / attachment.