player: add --term-title option

This simply printf()s a concatenation of the provided string and the
relevant escape sequences. No idea what exactly defines this escape
sequence (is it just a xterm thing that is now supported relatively
widely?), and this simply uses information provided on the linked github
issue.

Not much of an advantage over --term-status-msg, though at least this
can have a lower update frequency. Also I may consider setting a default
value, and then it shouldn't conflict with the status message.

Fixes: #1725

DOCS/man/options.rst

@@ -4429,6 +4429,15 @@ Terminal
     Print out a custom string during playback instead of the standard status
     line. Expands properties. See `Property Expansion`_.
 
+``--term-title=<string>``
+    Set the terminal title. Currently, this simply concatenates the escape
+    sequence setting the window title with the provided (property expanded)
+    string. This will mess up if the expanded string contain bytes that end the
+    escape sequence, or if the terminal does not understand the sequence. The
+    latter probably includes the regrettable win32.
+
+    Expands properties. See `Property Expansion`_.
+
 ``--msg-module``
     Prepend module name to each console message.
 

common/msg.c

@@ -230,6 +230,16 @@ void mp_msg_flush_status_line(struct mp_log *log)
     }
 }
 
+void mp_msg_set_term_title(struct mp_log *log, const char *title)
+{
+    if (log->root && title) {
+        // Lock because printf to terminal is not necessarily atomic.
+        pthread_mutex_lock(&log->root->lock);
+        fprintf(stderr, "\e]0;%s\007", title);
+        pthread_mutex_unlock(&log->root->lock);
+    }
+}
+
 bool mp_msg_has_status_line(struct mpv_global *global)
 {
     struct mp_log_root *root = global->log->root;

common/msg_control.h

@@ -14,6 +14,7 @@ bool mp_msg_has_log_file(struct mpv_global *global);
 void mp_msg_set_early_logging(struct mpv_global *global, bool enable);
 
 void mp_msg_flush_status_line(struct mp_log *log);
+void mp_msg_set_term_title(struct mp_log *log, const char *title);
 
 struct mp_log_buffer_entry {
     char *prefix;

options/options.c

@@ -702,6 +702,7 @@ static const m_option_t mp_opts[] = {
 
     {"term-osd-bar", OPT_FLAG(term_osd_bar), .flags = UPDATE_OSD},
     {"term-osd-bar-chars", OPT_STRING(term_osd_bar_chars), .flags = UPDATE_OSD},
+    {"term-title", OPT_STRING(term_title), .flags = UPDATE_OSD},
 
     {"term-playing-msg", OPT_STRING(playing_msg)},
     {"osd-playing-msg", OPT_STRING(osd_playing_msg)},

options/options.h

@@ -217,6 +217,7 @@ typedef struct MPOpts {
     int term_osd;
     int term_osd_bar;
     char *term_osd_bar_chars;
+    char *term_title;
     char *playing_msg;
     char *osd_playing_msg;
     char *status_msg;

player/core.h

@@ -264,6 +264,7 @@ typedef struct MPContext {
     char *term_osd_status;
     char *term_osd_subs;
     char *term_osd_contents;
+    char *term_osd_title;
     char *last_window_title;
     struct voctrl_playback_state vo_playback_state;
 

player/osd.c

@@ -96,6 +96,21 @@ static void term_osd_update(struct MPContext *mpctx)
     }
 }
 
+static void term_osd_update_title(struct MPContext *mpctx)
+{
+    if (!mpctx->opts->use_terminal)
+        return;
+
+    char *s = mp_property_expand_escaped_string(mpctx, mpctx->opts->term_title);
+    if (bstr_equals(bstr0(s), bstr0(mpctx->term_osd_title))) {
+        talloc_free(s);
+        return;
+    }
+
+    mp_msg_set_term_title(mpctx->statusline, s);
+    mpctx->term_osd_title = talloc_steal(mpctx, s);
+}
+
 void term_osd_set_subs(struct MPContext *mpctx, const char *text)
 {
     if (mpctx->video_out || !text || !mpctx->opts->subs_rend->sub_visibility)
@@ -260,6 +275,7 @@ static void term_osd_print_status_lazy(struct MPContext *mpctx)
 {
     struct MPOpts *opts = mpctx->opts;
 
+    term_osd_update_title(mpctx);
     update_window_title(mpctx, false);
     update_vo_playback_state(mpctx);