command: extend osd-overlay command with bounds reporting

This is more or less a minimal hack to make _some_ text measurement
functionality available to scripts. Since libass does not support such a
thing, this simply uses the bounding box of the rendered text.

This is far from ideal. Problems include:
- using a bitmap bounding box
- additional memory waste and/or flushing caches
- dependency on window size
- odd small deviations with different window sizes (run osd-test.lua and
  resize the window after each timer update; the bounding boxes aren't
  adjusted in an overly useful way)
- inability to query the size _after_ actual rendering

But I guess it's a start. Since I'm aware that it's crap, add a threat
to the manpage that this may be changed/removed again. For now, I'm
interested whether anyone will have use for it in its current form, as
it's an often requested feature.

2 files changed, 18 insertions, 1 deletions

diff --git a/player/command.c b/player/command.c
index 2ac6add009..334a25c087 100644
--- a/player/command.c
+++ b/player/command.c
@@ -4106,6 +4106,7 @@ static void cmd_osd_overlay(void *p)
 {
     struct mp_cmd_ctx *cmd = p;
     struct MPContext *mpctx = cmd->mpctx;
+    double rc[4] = {0};
 
     struct osd_external_ass ov = {
         .owner  = cmd->cmd->sender,
@@ -4115,9 +4116,23 @@ static void cmd_osd_overlay(void *p)
         .res_x  = cmd->args[3].v.i,
         .res_y  = cmd->args[4].v.i,
         .z      = cmd->args[5].v.i,
+        .hidden = cmd->args[6].v.i,
+        .out_rc = cmd->args[7].v.i ? rc : NULL,
     };
 
     osd_set_external(mpctx->osd, &ov);
+
+    struct mpv_node *res = &cmd->result;
+    node_init(res, MPV_FORMAT_NODE_MAP, NULL);
+
+    // (An empty rc uses INFINITY, avoid in JSON, just leave it unset.)
+    if (rc[0] < rc[2] && rc[1] < rc[3]) {
+        node_map_add_double(res, "x0", rc[0]);
+        node_map_add_double(res, "y0", rc[1]);
+        node_map_add_double(res, "x1", rc[2]);
+        node_map_add_double(res, "y1", rc[3]);
+    }
+
     mp_wakeup_core(mpctx);
 }
 
@@ -5927,6 +5942,8 @@ const struct mp_cmd_def mp_cmds[] = {
             OPT_INT("res_x", v.i, 0, OPTDEF_INT(0)),
             OPT_INT("res_y", v.i, 0, OPTDEF_INT(720)),
             OPT_INT("z", v.i, 0, OPTDEF_INT(0)),
+            OPT_FLAG("hidden", v.i, 0, OPTDEF_INT(0)),
+            OPT_FLAG("compute_bounds", v.i, 0, OPTDEF_INT(0)),
         },
         .is_noisy = true,
     },
diff --git a/player/lua/defaults.lua b/player/lua/defaults.lua
index 7681ca173e..395ca87e03 100644
--- a/player/lua/defaults.lua
+++ b/player/lua/defaults.lua
@@ -614,7 +614,7 @@ function overlay_mt.update(ov)
     cmd.name = "osd-overlay"
     cmd.res_x = math.floor(cmd.res_x)
     cmd.res_y = math.floor(cmd.res_y)
-    mp.command_native(cmd)
+    return mp.command_native(cmd)
 end
 
 function overlay_mt.remove(ov)