command: add an ab_loop command

As suggested in #1241; to make using the feature easier.

Also add better OSD-formatting for the ab-loop-a/b properties.

DOCS/man/input.rst

@@ -544,6 +544,11 @@ Input Commands that are Possibly Subject to Change
     (Scripts use this internally to dispatch key bindings, and this can also
     be used in input.conf to reassign such bindings.)
 
+``ab_loop``
+    Cycle through A-B loop states. The first command will set the ``A`` point
+    (the ``ab-loop-a`` property); the second the ``B`` point, and the third
+    will clear both points.
+
 
 Undocumented commands: ``tv_last_channel`` (TV/DVB only), ``get_property`` (?),
 ``vo_cmdline`` (experimental), ``ao_reload`` (experimental/internal).
@@ -779,7 +784,7 @@ Property list
                 "default"           MPV_FORMAT_FLAG
 
 ``ab-loop-a``, ``ab-loop-b`` (TW)
-    Set/get A-B loop points. See corresponding options.
+    Set/get A-B loop points. See corresponding options and ``ab_loop`` command.
 
 ``angle`` (RW)
     Current DVD angle.

DOCS/man/options.rst

@@ -233,7 +233,7 @@ Playback Control
     Set loop points. If playback passes the ``b`` timestamp, it will seek to
     the ``a`` timestamp. Seeking past the ``b`` point doesn't loop (this is
     intentional). The loop-points can be adjusted at runtime with the
-    corresponding properties.
+    corresponding properties. See also ``ab_loop`` command.
 
 ``--ordered-chapters``, ``--no-ordered-chapters``
     Enabled by default.

input/cmd_list.c

@@ -155,6 +155,8 @@ const struct mp_cmd_def mp_cmds[] = {
 
   { MP_CMD_DISCNAV, "discnav", { ARG_STRING } },
 
+  { MP_CMD_AB_LOOP, "ab_loop", },
+
   { MP_CMD_AF, "af", { ARG_STRING, ARG_STRING } },
   { MP_CMD_AO_RELOAD, "ao_reload", },
 

input/cmd_list.h

@@ -78,6 +78,8 @@ enum mp_command_type {
 
     MP_CMD_DISCNAV,
 
+    MP_CMD_AB_LOOP,
+
     /// Audio Filter commands
     MP_CMD_AF,
     MP_CMD_AO_RELOAD,

player/command.c

@@ -3527,6 +3527,8 @@ static const struct property_osd_display {
     { "tv-hue", "Hue", .osd_progbar = OSD_HUE},
     { "tv-saturation", "Saturation", .osd_progbar = OSD_SATURATION },
     { "tv-contrast", "Contrast", .osd_progbar = OSD_CONTRAST },
+    { "ab-loop-a", "A-B loop point A"},
+    { "ab-loop-b", "A-B loop point B"},
     // By default, don't display the following properties on OSD
     { "pause", NULL },
     { "fullscreen", NULL },
@@ -4420,6 +4422,24 @@ int run_command(MPContext *mpctx, mp_cmd_t *cmd)
         mp_nav_user_input(mpctx, cmd->args[0].v.s);
         break;
 
+    case MP_CMD_AB_LOOP: {
+        double now = get_current_time(mpctx);
+        int r = 0;
+        if (opts->ab_loop[0] == MP_NOPTS_VALUE) {
+            r = mp_property_do("ab-loop-a", M_PROPERTY_SET, &now, mpctx);
+            show_property_osd(mpctx, "ab-loop-a", on_osd);
+        } else if (opts->ab_loop[1] == MP_NOPTS_VALUE) {
+            r = mp_property_do("ab-loop-b", M_PROPERTY_SET, &now, mpctx);
+            show_property_osd(mpctx, "ab-loop-b", on_osd);
+        } else {
+            now = MP_NOPTS_VALUE;
+            r = mp_property_do("ab-loop-a", M_PROPERTY_SET, &now, mpctx);
+            r = mp_property_do("ab-loop-b", M_PROPERTY_SET, &now, mpctx);
+            set_osd_msg(mpctx, osdl, osd_duration, "Clear A-B loop");
+        }
+        return r > 0;
+    }
+
     case MP_CMD_VO_CMDLINE:
         if (mpctx->video_out) {
             char *s = cmd->args[0].v.s;