command: add escape-ass

This adds a command to escape ASS tags to remove code duplication
between sub/osd_libass.c, console.lua, osc.lua, stats.lua and any user
script that calls mp.create_osd_overlay().

A command is used instead of scripting functions so that all clients can
use this and not just use Lua and JS ones.

osd_mangle_ass() also interprets osd-sym-cc and osd-ass-cc/{0,1}, but
since they use invalid UTF-8 characters there is no risk of escape-ass
users using them by accident, like with any OSD message.

Always replacing \n with \\N in mangle_ass() even when it is not called
by escape-ass doesn't seem to cause any issue, but I made it conditional
anyway to avoid changing how all OSD messages are treated unnecessarily.

1 files changed, 10 insertions, 2 deletions

diff --git a/sub/osd_libass.c b/sub/osd_libass.c
index 16d94b3cbf..f2de27bd64 100644
--- a/sub/osd_libass.c
+++ b/sub/osd_libass.c
@@ -193,7 +193,7 @@ void osd_get_function_sym(char *buffer, size_t buffer_size, int osd_function)
     snprintf(buffer, buffer_size, "\xFF%c", osd_function);
 }
 
-static void mangle_ass(bstr *dst, const char *in)
+void osd_mangle_ass(bstr *dst, const char *in, bool replace_newlines)
 {
     const char *start = in;
     bool escape_ass = true;
@@ -213,6 +213,14 @@ static void mangle_ass(bstr *dst, const char *in)
         }
         if (escape_ass && *in == '{')
             bstr_xappend(NULL, dst, bstr0("\\"));
+        // Replace newlines with \N for escape-ass. This is necessary to apply
+        // ASS tags past newlines and to preserve consecutive newlines with
+        // osd-overlay because update_external() adds a ASS event per line.
+        if (replace_newlines && *in == '\n') {
+            bstr_xappend(NULL, dst, bstr0("\\N"));
+            in += 1;
+            continue;
+        }
         // Libass will strip leading whitespace
         if (in[0] == ' ' && (in == start || in[-1] == '\n')) {
             bstr_xappend(NULL, dst, bstr0("\\h"));
@@ -231,7 +239,7 @@ static ASS_Event *add_osd_ass_event_escaped(ASS_Track *track, const char *style,
                                             const char *text)
 {
     bstr buf = {0};
-    mangle_ass(&buf, text);
+    osd_mangle_ass(&buf, text, false);
     ASS_Event *e = add_osd_ass_event(track, style, buf.start);
     talloc_free(buf.start);
     return e;