The same way you used to - by showing it at 100% size, with the browser handling scroll bars for navigation.
I think I like where that’s headed, but it sounds like it will still take the user away from the page/window/tab containing the topic. This nearly defeats the point of having the enlarged image show on that same page.
The new way of viewing images is a great “preview” option. However, for extra-large images, an additional “zoom in” would be preferable over having to download or open the image on a separate page/tab/window/program. The trick is to allow this full-size viewing while maintaining a readily available yet unobtrusive option to close it and return to the thread.
DeviantART handles this reasonably, I think. One click zooms the image into a fit-to-width size, another zooms it to full size, and a third returns to the regular view. All the while, you can use the browser’s scrolling functions to move around and see parts of the image that overflow the screen.
Something similar to this could probably work for Discourse.
- First click on the image opens it up similarly to how it is now - it fills nearly the whole browser window except for some room for a border that includes an easily-recognized close button.
- Second click:
- Clicking on the close button or on the border - anywhere except on the image itself - exits the image view and returns the user to the normal topic display.
- Clicking on the image itself zooms the image to 100% size if it wasn’t already there. The browser’s built-in scroll functions allow the user to move their view around.
- Third click returns to the fit-to-window view, from which the user may return to the regular topic view via clicking anywhere except on the image itself.
Additions to the fit-to-window view that show metadata and allow downloading of the image would also be very useful, and I’d like to see them added on top of this. But I also believe handling zoom functionality as suggested above would help to keep the focus on the discussion while still enabling users to easily see images in their full detail.