The idea of this feature is to allow optionally fetching any external images specified in posts, signatures, avatars and storing them.
Remote avatars would be auto-converted to local avatars. Linked images to attachments.
An alternative option (suggested by bantu) would be to merely cache these images and re-fetch them every now and then. But that brings a lot more issues (cron, dying images, etc...)
Why do this?
- Faster responses
- Less reliance on external servers
- Detect broken images
- Detect password protected images
- Images cannot die
- Requests to arbitrary site could be abused (already possible via remote avatar upload)
- Some people like / want / need direct links (for example signatures showing "your IP", images with dynamic statistics...)
Challenge / tricky
- How to store signature images
- How to store such images in MODs (API?)