How to pass a method as callback to a Windows API call?

Question

I\'d like to pass a method of a class as callback to a WinAPI function. Is this possible and if yes, how?

Example case for setting a timer:

TMyClass          


        

Answer 1

Madshi has a MethodToProcedure procedure. It's in the "madTools.pas" which is in the "madBasic" package. If you use it, you should change the calling convention for "TimerProc" to stdcall and DoIt procedure would become,

TMyClass = class
private
  Timer: UINT;
  SetTimerProc: Pointer;
[...]

procedure TMyClass.DoIt;
begin
  SetTimerProc := MethodToProcedure(Self, @TMyClass.TimerProc);
  Timer := SetTimer(0, 0, 8, SetTimerProc);
end;
// After "KillTimer(0, Timer)" is called call:
// VirtualFree(SetTimerProc, 0, MEM_RELEASE);

I've never tried but I think one could also try to duplicate the code in the "classses.MakeObjectInstance" for passing other procedure types than TWndMethod.