From d6610a5b2f34e398e2ceba2a4da2b79e556b1c9e Mon Sep 17 00:00:00 2001
From: Guido Cella <guido@guidocella.xyz>
Date: Sun, 1 May 2022 07:29:32 +0200
Subject: 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.
---
 player/lua/console.lua | 14 +-------------
 player/lua/stats.lua   | 14 +-------------
 2 files changed, 2 insertions(+), 26 deletions(-)

(limited to 'player/lua')

diff --git a/player/lua/console.lua b/player/lua/console.lua
index 02cf890791..238216445d 100644
--- a/player/lua/console.lua
+++ b/player/lua/console.lua
@@ -229,19 +229,7 @@ end
 
 -- Escape a string for verbatim display on the OSD
 function ass_escape(str)
-    -- There is no escape for '\' in ASS (I think?) but '\' is used verbatim if
-    -- it isn't followed by a recognised character, so add a zero-width
-    -- non-breaking space
-    str = str:gsub('\\', '\\\239\187\191')
-    str = str:gsub('{', '\\{')
-    str = str:gsub('}', '\\}')
-    -- Precede newlines with a ZWNBSP to prevent ASS's weird collapsing of
-    -- consecutive newlines
-    str = str:gsub('\n', '\239\187\191\\N')
-    -- Turn leading spaces into hard spaces to prevent ASS from stripping them
-    str = str:gsub('\\N ', '\\N\\h')
-    str = str:gsub('^ ', '\\h')
-    return str
+    return mp.command_native({'escape-ass', str})
 end
 
 -- Takes a list of strings, a max width in characters and
diff --git a/player/lua/stats.lua b/player/lua/stats.lua
index 4d25a6c6bf..2feded2808 100644
--- a/player/lua/stats.lua
+++ b/player/lua/stats.lua
@@ -129,9 +129,6 @@ local function graph_add_value(graph, value)
     graph.max = max(graph.max, value)
 end
 
--- "\\<U+2060>" in UTF-8 (U+2060 is WORD-JOINER)
-local ESC_BACKSLASH = "\\" .. string.char(0xE2, 0x81, 0xA0)
-
 local function no_ASS(t)
     if not o.use_ass then
         return t
@@ -139,16 +136,7 @@ local function no_ASS(t)
         -- mp.osd_message supports ass-escape using osd-ass-cc/{0|1}
         return ass_stop .. t .. ass_start
     else
-        -- mp.set_osd_ass doesn't support ass-escape. roll our own.
-        -- similar to mpv's sub/osd_libass.c:mangle_ass(...), excluding
-        -- space after newlines because no_ASS is not used with multi-line.
-        -- space at the beginning is replaced with "\\h" because it matters
-        -- at the beginning of a line, and we can't know where our output
-        -- ends up. no issue if it ends up at the middle of a line.
-        return tostring(t)
-               :gsub("\\", ESC_BACKSLASH)
-               :gsub("{", "\\{")
-               :gsub("^ ", "\\h")
+        return mp.command_native({"escape-ass", tostring(t)})
     end
 end
 
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