add viewing mode that keeps the image/screen ratio instead of image zoom percentage
Unfortunately, none of the zoom options in Preferences > Viewer suits my needs: let's say in the fullscreen viewer I have an 1000x1000 px image zoomed out so that it's 'framed' by about 10% of the screen height at the top and bottom. This is my favourite way of viewing images as they don't appear squeezd into the screen then.
Right now, switching to the next image (for example 500x300 px) with "Keep previous zoom" enabled would make it appear much smaller.
When switching to next/prev images, it would be nice if gthumb kept this 'frame' regardless of the image size:
- open an image, adjust zoom
- detect the smallest image/screen edge distance (top/bottom or left/right)
- apply this border to all four screen edges (viewing frame)
- zoom the new images so they fit in
This is not my use case, but maybe it also makes sense to keep the image/screen edge distance when the image is zoomed in further than the screen size, like a 'negative frame', or 'cut-off ratio'.