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Hi Jerome,
thank you for your reply. I will test it asap and give feedback when I'm ready. 

Best Regards
Micha

Jerome Vuarand schrieb:

2008/11/20 Michael Bauroth <Michael.Bauroth@falcom.de>:

Hi,

I've implemented a working simple callback system between Lua and C++ (Lunar
based). But now I have problems to implement some more sophisticated
features. Google didn't help so far, but eventually can someone can give me
some short hints, links or samples for the following
features ...

My code looks like this at the moment (Questions are located below):


Lua:

function onmousemove( comp )
   comp:doSomthing()
end

btn = Button:new()
btn.Callback = { onmousemove, 1 }; // will call SetCallback(L)



C++:

LRESULT FComponent::OnMouseMove( int x, int y )
{
   if ( m_CbOnMouseMove )
   {
       // Call lua function by stored Reference
       lua_State* L = GetLuaInstance();
       lua_pushvalue(L, 1);

       // push function
       lua_rawgeti( L, LUA_REGISTRYINDEX, m_CbOnMouseMove );

       // push parameter(s)
       pushLuaObject( L );

       // call function
       lua_pcall( L, 1, LUA_MULTRET, 0 )
       return 0;
   }

   return 1L;
}

int FComponent::SetCallback( lua_State *L )
{
   luaL_checktype( L, 1, LUA_TTABLE );

   lua_rawgeti( L, 1, 1 );
   int tType = lua_tonumber( L, -1 );
   lua_pop(L, 1);

   lua_rawgeti(L, 1, 2);
   int tCb = luaL_ref( L, LUA_REGISTRYINDEX );
   lua_pop(L, 1);

   switch ( tType )
   {
   case 1:
       m_CbOnMouseMove = tCb;
       break;
   ...
   }

   lua_pop( L, lua_gettop( L ) );
   return 0;
}


Question 1:
How can I register a callback with a optional parameter, e.g., if Button 3
is pressed, call onmousedown with value 3.

sample:

function onmousedown( number )
 print( number )
end

btn1 = Button:new()
btn1.Callback = { onmousedown( 1 ), 1 }
btn2 = Button:new()
btn2.Callback = { onmousedown( 2 ), 1 }


Try this:

btn1.Callback = { function() onmousedown( 1 ) end, 1 }
btn2.Callback = { function() onmousedown( 2 ) end, 1 }

Lua has closures, use them.


Question2:
How can I pass more than one parameter (e.g. table based) from C++ side to
Lua for callbacks (see above FComponent::OnMouseMove )

sample:

function onmousedown( event )
 print( event[ "x" ] )
 print( event[ "y" ] )
 print( event[ "component" ] )
end


Try this (note that the lua_pushvalue(L, 1) is unnecessary, you can remove it):

LRESULT FComponent::OnMouseMove( int x, int y )
{
   if ( m_CbOnMouseMove )
   {
      // Call lua function by stored Reference
      lua_State* L = GetLuaInstance();
      //lua_pushvalue(L, 1); // this line is unnecessary

      // push function
      lua_rawgeti( L, LUA_REGISTRYINDEX, m_CbOnMouseMove );

      // push parameter(s)
      lua_createtable(L, 0, 3);
      lua_pushnumber(L, x); lua_setfield(L, -2, "x");
      lua_pushnumber(L, y); lua_setfield(L, -2, "y");
      pushLuaObject( L ); lua_setfield(L, -2, "component");

      // call function
      lua_pcall( L, 1, LUA_MULTRET, 0 )
      return 0;
   }
}