command: add properties for retrieving OSD dimensions

DOCS/man/en/input.rst

@@ -463,6 +463,9 @@ Name                            W Comment
 ``dwidth``                        video width (after filters and aspect scaling)
 ``dheight``                       video height
 ``aspect``                      x video aspect
+``osd-width``                     last known OSD width (can be 0)
+``osd-height``                    last known OSD height (can be 0)
+``osd-par``                       last known OSD display pixel aspect (can be 0)
 ``vid``                         x current video track (similar to ``--vid``)
 ``video``                       x alias for ``vid``
 ``video-align-x``               x see ``--video-align-x``

mpvcore/command.c

@@ -1458,6 +1458,25 @@ static int mp_property_dheight(m_option_t *prop, int action, void *arg,
     return property_vo_wh(prop, action, arg, mpctx, false);
 }
 
+static int mp_property_osd_w(m_option_t *prop, int action, void *arg,
+                             MPContext *mpctx)
+{
+    return m_property_int_ro(prop, action, arg, mpctx->osd->last_vo_res.w);
+}
+
+static int mp_property_osd_h(m_option_t *prop, int action, void *arg,
+                             MPContext *mpctx)
+{
+    return m_property_int_ro(prop, action, arg, mpctx->osd->last_vo_res.w);
+}
+
+static int mp_property_osd_par(m_option_t *prop, int action, void *arg,
+                               MPContext *mpctx)
+{
+    return m_property_double_ro(prop, action, arg,
+                                mpctx->osd->last_vo_res.display_par);
+}
+
 /// Video fps (RO)
 static int mp_property_fps(m_option_t *prop, int action, void *arg,
                            MPContext *mpctx)
@@ -1880,6 +1899,10 @@ static const m_option_t mp_properties[] = {
     { "program", mp_property_program, CONF_TYPE_INT,
       CONF_RANGE, -1, 65535, NULL },
 
+    { "osd-width", mp_property_osd_w, CONF_TYPE_INT },
+    { "osd-height", mp_property_osd_h, CONF_TYPE_INT },
+    { "osd-par", mp_property_osd_par, CONF_TYPE_DOUBLE },
+
     // Subs
     M_OPTION_PROPERTY_CUSTOM("sid", mp_property_sub),
     M_OPTION_PROPERTY_CUSTOM("sub-delay", mp_property_sub_delay),

sub/sub.c

@@ -222,6 +222,9 @@ void osd_draw(struct osd_state *osd, struct mp_osd_res res,
     if (draw_flags & OSD_DRAW_SUB_FILTER)
         draw_flags |= OSD_DRAW_SUB_ONLY;
 
+    if (!(draw_flags & OSD_DRAW_SUB_ONLY))
+        osd->last_vo_res = res;
+
     for (int n = 0; n < MAX_OSD_PARTS; n++) {
         struct osd_object *obj = osd->objs[n];
 

sub/sub.h

@@ -128,6 +128,8 @@ struct osd_state {
     bool render_subs_in_filter;
     bool render_bitmap_subs;
 
+    struct mp_osd_res last_vo_res;
+
     bool want_redraw;
 
     // OSDTYPE_OSD