client API, lua: add new API for setting OSD overlays

Lua scripting has an undocumented mp.set_osd_ass() function, which is
used by osc.lua and console.lua. Apparently, 3rd party scripts also use
this. It's probably time to make this a public API.

The Lua implementation just bypassed the libmpv API. To make it usable
by any type of client, turn it into a command, "osd-overlay".

There's already a "overlay-add". Ignore it (although the manpage admits
guiltiness). I don't really want to deal with that old command. Its main
problem is that it uses global IDs, while I'd like to avoid that scripts
mess with each others overlays (whether that is accidentally or
intentionally). Maybe "overlay-add" can eventually be merged into
"osd-overlay", but I'm too lazy to do that now.

Scripting now uses the commands. There is a helper to manage OSD
overlays. The helper is very "thin"; I only want to force script authors
to use the ID allocation, which may help with putting multiple scripts
into a single .lua file without causing conflicts (basically, avoiding
singletons within a script's environment). The old set_osd_ass() is
emulated with the new API.

The JS scripting wrapper also provides a set_osd_ass() function, which
calls internal mpv API. Comment that part (to keep it compiling), but
I'm leaving it to @avih to finish the change.

1 files changed, 59 insertions, 0 deletions

diff --git a/player/lua/defaults.lua b/player/lua/defaults.lua
index ba59653828..22ffa086d1 100644
--- a/player/lua/defaults.lua
+++ b/player/lua/defaults.lua
@@ -589,6 +589,65 @@ function mp.abort_async_command(t)
     end
 end
 
+local overlay_mt = {}
+overlay_mt.__index = overlay_mt
+local overlay_new_id = 0
+
+function mp.create_osd_overlay(format)
+    overlay_new_id = overlay_new_id + 1
+    local overlay = {
+        format = format,
+        id = overlay_new_id,
+        data = "",
+        res_x = 0,
+        res_y = 720,
+    }
+    setmetatable(overlay, overlay_mt)
+    return overlay
+end
+
+function overlay_mt.update(ov)
+    local cmd = {}
+    for k, v in pairs(ov) do
+        cmd[k] = v
+    end
+    cmd.name = "osd-overlay"
+    mp.command_native(cmd)
+end
+
+function overlay_mt.remove(ov)
+    mp.command_native {
+        name = "osd-overlay",
+        id = ov.id,
+        format = "none",
+        data = "",
+    }
+end
+
+-- legacy API
+function mp.set_osd_ass(res_x, res_y, data)
+    if not mp._legacy_overlay then
+        mp._legacy_overlay = mp.create_osd_overlay("ass-events")
+    end
+    mp._legacy_overlay.res_x = res_x
+    mp._legacy_overlay.res_y = res_y
+    mp._legacy_overlay.data = data
+    mp._legacy_overlay:update()
+end
+
+function mp.get_osd_size()
+    local w = mp.get_property_number("osd-width", 0)
+    local h = mp.get_property_number("osd-height", 0)
+    local par = mp.get_property_number("osd-par", 0)
+    if par == 0 then
+        par = 1
+    end
+
+    local aspect = 1.0 * w / math.max(h) / par
+    return w, h, aspect
+end
+
+
 local mp_utils = package.loaded["mp.utils"]
 
 function mp_utils.format_table(t, set)