osc.lua: use private options to control SUB/OSD offset

DOCS/man/osc.rst

@@ -411,10 +411,9 @@ Configurable Options
 ``sub_margins``
     Default: yes
 
-    Whether to adjust ``--sub-margin-y`` so that subtitles do not overlap
-    with the OSC. The offset is derived from the bottom OSC margin and added
-    on top of the current ``--sub-margin-y`` value. Requires
-    ``dynamic_margins`` or ``visibility=always`` to take effect.
+    Whether to adjust the subtitle margin so that subtitles do not overlap
+    with the OSC. Requires ``dynamic_margins`` or ``visibility=always`` to
+    take effect.
 
     With ``boxvideo`` enabled and ``--sub-use-margins=no``, subtitles are
     already confined to the video area and this option has no additional
@@ -423,11 +422,9 @@ Configurable Options
 ``osd_margins``
     Default: yes
 
-    Whether to adjust ``--osd-margin-y`` so that OSD text does not overlap
-    with the OSC. The offset is derived from the top OSC margin (including
-    window controls when present) and added on top of the current
-    ``--osd-margin-y`` value. Requires ``dynamic_margins`` or
-    ``visibility=always`` to take effect.
+    Whether to adjust the OSD margin so that OSD text does not overlap
+    with the OSC. Requires ``dynamic_margins`` or ``visibility=always`` to
+    take effect.
 
 ``windowcontrols``
     Default: auto (Show window controls if there is no window border)

options/m_config_frontend.c

@@ -400,7 +400,9 @@ static int handle_set_opt_flags(struct m_config *config,
         return M_OPT_INVALID;
 
     // Check if this option isn't forbidden in the current mode
-    if ((flags & M_SETOPT_FROM_CONFIG_FILE) && (optflags & M_OPT_NOCFG)) {
+    if ((flags & M_SETOPT_FROM_CONFIG_FILE) &&
+        (optflags & (M_OPT_NOCFG | M_OPT_PRIVATE)))
+    {
         MP_ERR(config, "The %s option can't be used in a config file.\n",
                co->name);
         return M_OPT_INVALID;
@@ -841,6 +843,8 @@ void m_config_print_option_list(const struct m_config *config, const char *name)
     for (int i = 0; i < config->num_opts; i++) {
         struct m_config_option *co = &sorted[i];
         const struct m_option *opt = co->opt;
+        if (opt->flags & M_OPT_PRIVATE)
+            continue;
         if (strcmp(name, "*") != 0 && !strstr(co->name, name))
             continue;
         MP_INFO(config, " %s%-30s", prefix, co->name);

options/m_option.h

@@ -488,7 +488,11 @@ char *format_file_size(int64_t size);
 // Like M_OPT_TYPE_OPTIONAL_PARAM.
 #define M_OPT_OPTIONAL_PARAM    (UINT64_C(1) << 54)
 
-static_assert(!(UPDATE_OPTS_MASK & M_OPT_OPTIONAL_PARAM), "");
+// Option is private: forbidden in config files and hidden from --help listing.
+// Can still be used as a property by builtin scripts.
+#define M_OPT_PRIVATE           (UINT64_C(1) << 53)
+
+static_assert(!(UPDATE_OPTS_MASK & M_OPT_PRIVATE), "");
 
 // These flags are used to describe special parser capabilities or behavior.
 

player/lua/osc.lua

@@ -543,27 +543,15 @@ local function cache_enabled()
     return state.cache_state and #state.cache_state["seekable-ranges"] > 0
 end
 
-local function set_margin_offset(prop, offset)
-    if offset > 0 then
-        if not state[prop] then
-            state[prop] = mp.get_property_number(prop)
-        end
-        mp.set_property_number(prop, state[prop] + offset)
-    elseif state[prop] then
-        mp.set_property_number(prop, state[prop])
-        state[prop] = nil
-    end
-end
-
 local function reset_margins()
     if state.using_video_margins then
         for _, mopt in ipairs(margins_opts) do
             mp.set_property_number(mopt[2], 0.0)
         end
         state.using_video_margins = false
     end
-    set_margin_offset("sub-margin-y", 0)
-    set_margin_offset("osd-margin-y", 0)
+    mp.set_property_number("sub-margin-y-offset", 0)
+    mp.set_property_number("osd-margin-y-offset", 0)
 end
 
 local function update_margins()
@@ -617,8 +605,8 @@ local function update_margins()
         end
         return margin * osc_param.playresy
     end
-    set_margin_offset("sub-margin-y", get_margin("sub"))
-    set_margin_offset("osd-margin-y", get_margin("osd"))
+    mp.set_property_number("sub-margin-y-offset", get_margin("sub"))
+    mp.set_property_number("osd-margin-y-offset", get_margin("osd"))
 
     mp.set_property_native("user-data/osc/margins", margins)
 end

sub/ass_mp.c

@@ -64,7 +64,7 @@ void mp_ass_set_style(ASS_Style *style, double res_y,
     style->Spacing = opts->spacing * scale;
     style->MarginL = opts->margin_x * scale;
     style->MarginR = style->MarginL;
-    style->MarginV = opts->margin_y * scale;
+    style->MarginV = (opts->margin_y + opts->margin_y_offset) * scale;
     style->ScaleX = 1.;
     style->ScaleY = 1.;
     style->Alignment = 1 + (opts->align_x + 1) + (opts->align_y + 2) % 3 * 4;

sub/osd.c

@@ -60,6 +60,7 @@ static const m_option_t style_opts[] = {
     {"spacing", OPT_FLOAT(spacing), M_RANGE(-10, 10)},
     {"margin-x", OPT_INT(margin_x), M_RANGE(0, INT_MAX)},
     {"margin-y", OPT_INT(margin_y), M_RANGE(0, INT_MAX)},
+    {"margin-y-offset", OPT_INT(margin_y_offset), .flags = M_OPT_PRIVATE},
     {"align-x", OPT_CHOICE(align_x,
         {"left", -1}, {"center", 0}, {"right", +1})},
     {"align-y", OPT_CHOICE(align_y,

sub/osd.h

@@ -155,6 +155,7 @@ struct osd_style_opts {
     float spacing;
     int margin_x;
     int margin_y;
+    int margin_y_offset;
     int align_x;
     int align_y;
     float blur;