positioning.lua: add this script

[guidocella]

This script provides script messages and bindings to pan videos and images, making mpv a better image viewer out of the box.

I've had this script for 3 years in my image config so why not upstream it to view images better out of the box. Credits to occivink for the original ideas of the bindings.

I also have a mouse gesture and a oneshot double page mode in my script but those may not be worth upstreaming.

For the reasoning behind the suppress_osd naming, see #9051 (comment)

Touch input in cursor-centric-zoom is untested.

For negative zoom, I think we need a global option like --auto-recenter-video (implemented in vo_get_src_dst_rects()?) to reset video-align to 0 when the image is smaller than the OSD, so that it also applies when changing video-zoom/panscan/video-unscaled/video-aspect-override/video-scale/changing file. Then positioning.lua should do nothing when that option is true and the image is smaller than the OSD. In my config, I use

mp.observe_property('osd-dimensions', 'native', function (_, dims)
    if dims.ml + dims.mr > 0 then
        mp.set_property('video-align-x', 0)
    end
    if dims.mt + dims.mb > 0 then
        mp.set_property('video-align-y', 0)
    end
end)

[github-actions]

Download the artifacts for this pull request:

Windows

• mpv-i686-w64-mingw32
• mpv-x86_64-w64-mingw32
• mpv-x86_64-windows-msvc

macOS

• mpv-macos-13-intel
• mpv-macos-14-arm
• mpv-macos-15-arm