Since I can link to forum photos from the VCBF map, so that the photos just show up on the map, and since on the forums, there is the facility to link to a forum photo URL and have it open, why can I not use the photo URL to upload a file from a forum posting to a new posting, under the Manage Attachments dialog where it says "Upload File from a URL"? Every couple of years, I try it thinking it should work.
The same mechanism that prevents other places for hotlinking images from these forums (and chewing up our server resources) prevents what you are suggesting.
No, I don't get it. Google Images links to your photos. Our map links to your photos. Or are those somehow not hotlinks? Wouldn't it be better use of resources to be able to hotlink within the system rather than upload the same maybe hi-res photo again and have the system reduce it? I wasn't even talking about hotlinking, I don't think. The dialog just says "Upload file from a URL", and that, within the system, also would be less use of resources because the file would already be reduced in size. I'm assuming you're saying the system is just set up that way and you don't control that.
The attachments (which are attached as jpgs) are wrapped in php code. I'm guessing this is a mechanism to 1) prevent hotlinking and 2) avoid duplication of filenames (I don't really know). Since vBulletin is so popular, maybe they know how to reverse engineer the php to extract the jpg for indexing. But, you're right -- it doesn't seem like the system knows how to pull out the jpgs from its own URLs. It doesn't appear to be anything I can manipulate (turn off/on) in the admin options.
This issue is solved now. Let's say I want to talk about Sue Wagner's photo, posted in a Neighbourhood Blog thread. I didn't used to be able to do this without uploading the photo again. In this case, I clicked the Image icon and pasted in the link location. It looks like it will come in the full width of my screen, but it will display as a thumbnail, like we want. Another win for the xenForo software (and the routine that doesn't allow photos to display full-size in the text area).