How would you create this construct?

[Chris Katko]

void start_draw_calls(BITMAP target_bitmap); //locks onto a 
resource
void end_draw_calls(); //frees previous resource lock

void my_function()
     {
     //...

     start_draw_calls(target_bitmap) //whether this is a function, 
or class, lambda, or a "using"?
         {
         draw_call1();
         draw_call2();
         draw_call3();
         } // end_draw_calls() is automatically called because 
we're hitting the closing curly.

     //...
     }


The key here is, I've got a resource (setting a target bitmap) 
whose handling functions have to occur before, and after a series 
of user calls. (at which point target bitmap is restored to what 
it was before). So it's kind of like RAII (or maybe exactly like).

What I'm trying to do is through this experimental API, is both 
eliminate the user needing to call a clean-up function 
explicitly, and, make the "right way" to use the API basically... 
the only way... to use it.

The way I have written above, there is no way for you to leave 
my_function() without it automatically calling the cleaning up 
call. Even if you did a nested version, it would still work!

At first glance, I could do:

     start_draw_calls( {lambda containing all my code} )

But that's not quite as pretty and you're forcing all code to be 
inside a lambda which... I'm not sure if that has hidden 
implications / gotchas for code.

Thanks!