Hello yet again,
Is anyone using RegisterClass from Win32API? To Register a class you need to supply the pointer to a callback function. To achieve this, I created a small class in C to provide me with the pointer to a function that I can use in my Ruby code for obtaining the callbacks from windows. This works great on Windows 2000 and 95 when using cygwin, but fails on XP, and will not likely work for those installing the windows version of Ruby. The C code to do this is provided below, incase anyone is interested. I am looking for a more creative way to provide RegisterClass with a function pointer that does not involve any C code. Any suggestions are greatly appreciated. Is there a way to get the function pointer of a Ruby method from within Ruby that DLL functions can call back to?
Thanks, Michael Davis
Here is the small C class for getting the pointer to a function that windows calls. I just have to create a Ruby method called Win32API_MessageHandler(hwnd, iMsg, wParam, lParam) and voila, my Ruby applet can process window events.
#if !defined _MSC_VER && !defined NT
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <stdio.h>
#endif
#include “ruby.h”
#include “rubysig.h”
static LRESULT CALLBACK
locana_mswin32_MessageHandler(hwnd, uMsg, wParam, lParam) // This is a pass through function to the Ruby method called ‘Win32API_MessageHandler’ that will process windows messages
HWND hwnd;
UINT uMsg;
WPARAM wParam;
LPARAM lParam;
{
VALUE rc = Qnil;
ID proc_id;
proc_id = (ID)GetWindowLong(hwnd, (int)GWL_USERDATA); // let’s see if the user has registered a proc name
//printf(“Win32API_MessageHandler(%d, …) - proc_id:’%d’\n”, (int)hwnd, proc_id);
if (!proc_id)
proc_id = rb_intern(“Win32API_MessageHandler”); // the default message handler is a Ruby method that you must create called Win32API_MessageHandler
if (proc_id)
rc = rb_funcall(rb_cObject, proc_id, 4, INT2NUM((long)hwnd), INT2NUM((long)uMsg), INT2NUM((long)wParam), INT2NUM((long)lParam));
if (rc == Qnil)
return DefWindowProc(hwnd,uMsg,wParam,lParam);
else
return (LRESULT)NUM2LONG(rc);
}
static VALUE
locana_mswin32_GetMessageHandler() // RegisterClass needs the C function used for processing messages
{
return INT2NUM((unsigned long)(locana_mswin32_MessageHandler));
}
void
Init_locana_gui_mswin32_ext()
{
VALUE cWin32Ext = rb_define_class(“Locana_gui_mswin32_ext”, rb_cObject);
rb_define_module_function(cWin32Ext, “get_message_handler”, locana_mswin32_GetMessageHandler, 0);
}
