static int l_surface_screenshot(lua_State *L) { THRenderTarget* pCanvas = luaT_testuserdata<THRenderTarget>(L); const char *sFile = luaL_checkstring(L, 2); if(pCanvas->takeScreenshot(sFile)) { lua_settop(L, 1); return 1; } lua_pushnil(L); lua_pushstring(L, pCanvas->getLastError()); return 2; }