Add a missing hint.

[nageru] / nageru / theme.cpp

diff --git a/nageru/theme.cpp b/nageru/theme.cpp
index 8050003b2025459651d20a99dea5f4d120347da3..b53c65bc3434f61aae29904c242254893a672d75 100644 (file)
--- a/nageru/theme.cpp
+++ b/nageru/theme.cpp
@@ -1212,6 +1212,7 @@ int call_num_channels(lua_State *L)
 
        if (lua_pcall(L, 0, 1, 0) != 0) {
                fprintf(stderr, "error running function `num_channels': %s\n", lua_tostring(L, -1));
+               fprintf(stderr, "Try Nageru.set_num_channels(...) at the start of the script instead.\n");
                abort();
        }
 
@@ -1223,6 +1224,29 @@ int call_num_channels(lua_State *L)
 
 }  // namespace
 
+int Nageru_set_channel_name(lua_State *L)
+{
+       // NOTE: m is already locked.
+       Theme *theme = get_theme_updata(L);
+       unsigned channel = luaL_checknumber(L, 1);
+       const string text = checkstdstring(L, 2);
+       theme->channel_names[channel] = text;
+       lua_pop(L, 2);
+       return 0;
+}
+
+int Nageru_set_num_channels(lua_State *L)
+{
+       // NOTE: m is already locked.
+       Theme *theme = get_theme_updata(L);
+       if (theme->startup_finished) {
+               luaL_error(L, "set_num_channels() can only be called at startup.");
+       }
+       theme->num_channels = luaL_checknumber(L, 1);
+       lua_pop(L, 1);
+       return 0;
+}
+
 Theme::Theme(const string &filename, const vector<string> &search_dirs, ResourcePool *resource_pool, unsigned num_cards)
        : resource_pool(resource_pool), num_cards(num_cards), signal_to_card_mapping(global_flags.default_stream_mapping)
 {
@@ -1293,7 +1317,7 @@ Theme::Theme(const string &filename, const vector<string> &search_dirs, Resource
        }
 
        // Set up the API we provide.
-       register_constants();
+       register_globals();
        register_class("Scene", Scene_funcs);
        register_class("Block", Block_funcs);
        register_class("EffectBlueprint", EffectBlueprint_funcs);
@@ -1324,8 +1348,11 @@ Theme::Theme(const string &filename, const vector<string> &search_dirs, Resource
        }
        assert(lua_gettop(L) == 0);
 
-       // Ask it for the number of channels.
-       num_channels = call_num_channels(L);
+       if (num_channels == -1) {
+               // Ask it for the number of channels.
+               num_channels = call_num_channels(L);
+       }
+       startup_finished = true;
 }
 
 Theme::~Theme()
@@ -1334,7 +1361,7 @@ Theme::~Theme()
        lua_close(L);
 }
 
-void Theme::register_constants()
+void Theme::register_globals()
 {
        // Set Nageru.VIDEO_FORMAT_BGRA = bmusb::PixelFormat_8BitBGRA, etc.
        const vector<pair<string, int>> num_constants = {
@@ -1358,6 +1385,14 @@ void Theme::register_constants()
                lua_settable(L, 1);  // t[key] = value
        }
 
+       const luaL_Reg Nageru_funcs[] = {
+               { "set_channel_name", Nageru_set_channel_name },
+               { "set_num_channels", Nageru_set_num_channels },
+               { NULL, NULL }
+       };
+       lua_pushlightuserdata(L, this);
+       luaL_setfuncs(L, Nageru_funcs, 1);        // for (name,f in funcs) { mt[name] = f, with upvalue {theme} }
+
        lua_setglobal(L, "Nageru");  // Nageru = t
        assert(lua_gettop(L) == 0);
 }
@@ -1484,7 +1519,17 @@ Theme::Chain Theme::get_chain(unsigned num, float t, unsigned width, unsigned he
 string Theme::get_channel_name(unsigned channel)
 {
        lock_guard<mutex> lock(m);
+
        lua_getglobal(L, "channel_name");
+       if (lua_isnil(L, -1)) {
+               lua_pop(L, 1);
+               if (channel_names.count(channel)) {
+                       return channel_names[channel];
+               } else {
+                       return "(no title)";
+               }
+       }
+
        lua_pushnumber(L, channel);
        if (lua_pcall(L, 1, 1, 0) != 0) {
                fprintf(stderr, "error running function `channel_name': %s\n", lua_tostring(L, -1));
@@ -1493,6 +1538,7 @@ string Theme::get_channel_name(unsigned channel)
        const char *ret = lua_tostring(L, -1);
        if (ret == nullptr) {
                fprintf(stderr, "function `channel_name' returned nil for channel %d\n", channel);
+               fprintf(stderr, "Try Nageru.set_channel_name(channel, name) at the start of the script instead.\n");
                abort();
        }