osc: add feature to bottombar to not cover the video

Normally I use the OSC like this: not at all, but have a key binding
that does "cycle osc" to show it. And in that case, I don't really want
it to overlap the damn video.

I could use the zoom/pan options to move the video out of the way, but
this is also sort of annoying. Likewise, you could write a script or so
which does this automatically if the OSC appears, but that's still
annoying, and computing values for these options such that the video is
moved correctly is tricky.

So I added a bunch of options that set explicit video borders (previous
commit), and a option for the OSC to use them (this commit).

Disabled by default, since I'm afraid this is too awkward and
unpolished, especially with OSC default settings.

I'm also using "osc-visibility=always". Effectively, making the OSC
appear will box the video, and making it disappear (by unloading
osc.lua) will restore the video back to normal.

DOCS/man/osc.rst

@@ -321,6 +321,26 @@ Configurable Options
     default is conservative to allow wide fonts to be used without overflow.
     However, with many common fonts a bigger number can be used. YMMV.
 
+``boxvideo``
+    Default: no
+
+    Whether to overlay the osc over the video (``no``), or to box the video
+    within the areas not covered by the osc (``yes``). If this option is set,
+    the osc may overwrite the ``--video-margin-ratio-*`` options, even if the
+    user has set them. (It will not overwrite them if all of them are set to
+    default values.)
+
+    Currently, this is supported for the ``bottombar`` layout only. The other
+    layouts do not change if this option is set.
+
+    The border is static and appears even if the OSC is configured to appear
+    only on mouse interaction. If the OSC is invisible, the border is simply
+    filled with the background color (black by default).
+
+    This currently still makes the OSC overlap with subtitles (if the
+    ``--sub-use-margins`` option is set to ``yes``, the default). This may be
+    fixed later.
+
 Script Commands
 ~~~~~~~~~~~~~~~
 

player/lua/osc.lua

@@ -44,6 +44,7 @@ local user_opts = {
     timems = false,             -- display timecodes with milliseconds?
     visibility = "auto",        -- only used at init to set visibility_mode(...)
     boxmaxchars = 80,           -- title crop threshold for box layout
+    boxvideo = false,           -- apply osc_param.video_margins to video
 }
 
 -- read_options may modify hidetimeout, so save the original default value in
@@ -62,6 +63,9 @@ local osc_param = { -- calculated by osc_init()
     display_aspect = 1,
     unscaled_y = 0,
     areas = {},
+    video_margins = {
+        l = 0, r = 0, t = 0, b = 0,         -- left/right/top/bottom
+    },
 }
 
 local osc_styles = {
@@ -108,6 +112,7 @@ local state = {
     input_enabled = true,
     showhide_enabled = false,
     dmx_cache = 0,
+    using_video_margins = false,
 }
 
 
@@ -117,6 +122,13 @@ local state = {
 -- Helperfunctions
 --
 
+local margins_opts = {
+    {"l", "video-margin-ratio-left"},
+    {"r", "video-margin-ratio-right"},
+    {"t", "video-margin-ratio-top"},
+    {"b", "video-margin-ratio-bottom"},
+}
+
 -- scale factor for translating between real and virtual ASS coordinates
 function get_virt_scale_factor()
     local w, h = mp.get_osd_size()
@@ -1408,6 +1420,8 @@ layouts["bottombar"] = function()
     lo.slider.tooltip_an = 5
     lo.slider.stype = user_opts["seekbarstyle"]
     lo.slider.rtype = user_opts["seekrangestyle"]
+
+    osc_param.video_margins.b = osc_geo.h / osc_param.playresy
 end
 
 layouts["topbar"] = function()
@@ -1998,9 +2012,40 @@ function osc_init()
     --do something with the elements
     prepare_elements()
 
+    if user_opts.boxvideo then
+        -- check whether any margin option has a non-default value
+        local margins_used = false
+
+        for _, opt in ipairs(margins_opts) do
+            if mp.get_property_number(opt[2], 0.0) ~= 0.0 then
+                margins_used = true
+            end
+        end
+
+        if not margins_used then
+            local margins = osc_param.video_margins
+            for _, opt in ipairs(margins_opts) do
+                local v = margins[opt[1]]
+                if v ~= 0 then
+                    mp.set_property_number(opt[2], v)
+                    state.using_video_margins = true
+                end
+            end
+        end
+    else
+        reset_margins()
+    end
+
 end
 
-
+function reset_margins()
+    if state.using_video_margins then
+        for _, opt in ipairs(margins_opts) do
+            mp.set_property_number(opt[2], 0.0)
+        end
+        state.using_video_margins = false
+    end
+end
 
 --
 -- Other important stuff
@@ -2386,6 +2431,7 @@ end
 
 validate_user_opts()
 
+mp.register_event("shutdown", reset_margins)
 mp.register_event("start-file", request_init)
 mp.register_event("tracks-changed", request_init)
 mp.observe_property("playlist", nil, request_init)