Function FCEU_LuaGui

src/lua-engine.cpp:6706–6786

* Given an 8-bit screen with the indicated resolution, * draw the current GUI onto it. * * Currently we only support 256x* resolutions. */

 * Currently we only support 256x* resolutions.
 */
void FCEU_LuaGui(uint8 *XBuf)
{
	if (!L/* || !luaRunning*/)
		return;

	// First, check if we're being called by anybody
	lua_getfield(L, LUA_REGISTRYINDEX, guiCallbackTable);

	if (lua_isfunction(L, -1)) {
		// We call it now
		numTries = 1000;
		int ret = lua_pcall(L, 0, 0, 0);
		if (ret != 0) {
#ifdef __WIN_DRIVER__
			//StopSound();//StopSound(); //mbg merge 7/23/08
			MessageBox(hAppWnd, lua_tostring(L, -1), "Lua Error in GUI function", MB_OK);
#else
			LuaPrintfToWindowConsole("Lua error in gui.register function: %s\n", lua_tostring(L, -1));
			fprintf(stderr, "Lua error in gui.register function: %s\n", lua_tostring(L, -1));
#endif
			// This is grounds for trashing the function
			lua_pushnil(L);
			lua_setfield(L, LUA_REGISTRYINDEX, guiCallbackTable);

		}
	}

	// And wreak the stack
	lua_settop(L, 0);

	if (gui_used == GUI_CLEAR)
		return;

	if (gui_used == GUI_USED_SINCE_LAST_FRAME && !FCEUI_EmulationPaused())
	{
		memset(gui_data, 0, LUA_SCREEN_WIDTH*LUA_SCREEN_HEIGHT*4);
		gui_used = GUI_CLEAR;
		return;
	}

	gui_used = GUI_USED_SINCE_LAST_FRAME;

	int x, y;

	for (y = 0; y < LUA_SCREEN_HEIGHT; y++)
	{
		for (x=0; x < LUA_SCREEN_WIDTH; x++)
		{
			const uint8 gui_alpha = gui_data[(y*LUA_SCREEN_WIDTH+x)*4+3];
			if (gui_alpha == 0)
			{
				// do nothing
				continue;
			}

			const uint8 gui_red   = gui_data[(y*LUA_SCREEN_WIDTH+x)*4+2];
			const uint8 gui_green = gui_data[(y*LUA_SCREEN_WIDTH+x)*4+1];
			const uint8 gui_blue  = gui_data[(y*LUA_SCREEN_WIDTH+x)*4];