Add aegisub.keyframes, which returns a table with all of the frame numbers which are keyframes

Originally committed to SVN as r6129.

aegisub/src/auto4_lua.cpp

@@ -261,6 +261,7 @@ namespace Automation4 {
 			set_field(L, "frame_from_ms", LuaFrameFromMs);
 			set_field(L, "ms_from_frame", LuaMsFromFrame);
 			set_field(L, "video_size", LuaVideoSize);
+			set_field(L, "keyframes", LuaGetKeyframes);
 			set_field(L, "lua_automation_version", 4);
 
 			// store aegisub table to globals
@@ -496,6 +497,20 @@ namespace Automation4 {
 		}
 	}
 
+	int LuaScript::LuaGetKeyframes(lua_State *L)
+	{
+		const agi::Context *c = get_context(L);
+		std::vector<int> const& kf = c->videoController->GetKeyFrames();
+
+		lua_newtable(L);
+		for (size_t i = 0; i < kf.size(); ++i) {
+			lua_pushinteger(L, kf[i]);
+			lua_rawseti(L, -2, i);
+		}
+
+		return 1;
+	}
+
 	static void lua_threaded_call(ProgressSink *ps, lua_State *L, int nargs, int nresults, bool can_open_config, bool *failed)
 	{
 		LuaProgressSink lps(L, ps, can_open_config);

aegisub/src/auto4_lua.h

@@ -309,6 +309,7 @@ namespace Automation4 {
 		static int LuaFrameFromMs(lua_State *L);
 		static int LuaMsFromFrame(lua_State *L);
 		static int LuaVideoSize(lua_State *L);
+		static int LuaGetKeyframes(lua_State *L);
 
 	public:
 		LuaScript(const wxString &filename);