[Sammdahamm]

Hey!
I have a problem with my winAPI GUI I'm coding for my 2nd Year A-Level Computing coursework. I'm still trying to get my head around the winAPI stuff, and I'm sure It's a very simple problem I'm overlooking. The main form works fine, and just has a simple edit-box and button for testing, but when I close and open a new form, the new form takes on the characteristics I outlined in the CreateWindowEx() function (i.e a different size to the main form), but the problem is that it also contains the objects from the first form.

Here is the handle for the main form being initialised:

hwnd = CreateWindowEx (
           0,                   /* Extended possibilites for variation */
           szClassName,         /* Classname */
           "Child-minding App", /* Title Text */
           WS_OVERLAPPEDWINDOW, /* default window */
           CW_USEDEFAULT,       /* Windows decides the position */
           CW_USEDEFAULT,       /* where the window ends up on the screen */
           640,                 /* The programs width */
           480,                 /* and height in pixels */
           HWND_DESKTOP,        /* The window is a child-window to desktop */
           NULL,                /* No menu */
           hThisInstance,       /* Program Instance handler */
           NULL                 /* No Window Creation data */
           );

Here's the handle for the new form I'm opening:

hwndLogin = CreateWindowEx (0, szClassName, "Login Form", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 640, 330, HWND_DESKTOP, NULL, hInst, NULL);

And here's an example of an object which appears on both forms

hwndButton = CreateWindowEx(0,                    /* more or ''extended'' styles */
                          TEXT("BUTTON"),                         /* GUI ''class'' to create */
                          TEXT("Push Me"),                        /* GUI caption */
                          WS_CHILD|WS_VISIBLE|BS_DEFPUSHBUTTON,   /* control styles separated by | */
                          10,                                     /* LEFT POSITION (Position from left) */
                          40,                                     /* TOP POSITION  (Position from Top) */
                          200,                                    /* WIDTH OF CONTROL */
                          30,                                     /* HEIGHT OF CONTROL */
                          hwnd,                                   /* Parent window handle */
                          (HMENU)IDBUTTON,                        /* control''s ID for WM_COMMAND */
                          g_hInst,                                /* application instance */
                          NULL);

So just to clarify, when the hwnd form closes, and the hwndLogin form opens, the hwndLogin form also contains the button, wheras I on'y want the hwnd form to contain the button.
Can anyone see what I've done wrong?

(P.S. sorry if this is worded horribly.)

[snoopy11]

Hi ,

This is happening because you are using the same classname as the previous window

so Windows thinks you want to instantiate a new instance of this class

There are system class names for instance a dialog for a login would be #32770

so you could define a constant call it say DIALOG and do this

hwndLogin = CreateWindowEx (0, DIALOG, "Login Form", WS_OVERLAPPEDWINDOW,
                                             CW_USEDEFAULT, CW_USEDEFAULT, 640, 330, HWND_DESKTOP,
                                              NULL, NULL, NULL);

Regards



Snoopy.

[Sammdahamm]

Hi Snoopy, thanks a lot for the reply.

I'm still having a problem because I didn't quite understand what you meant by defining a constant (I assume you mean define DIALOG as 32770), I tried this (#define DIALOG 32770) and got the error "initializing argument 2 of 'HWND__* CreateWindowExA(DWORD, const CHAR*, const CHAR*, DWORD, int, int, int, int, HWND__*, HMENU__*, HINSTANCE__*, void*)'"

I also took what you said about giving a different classname, and declared (char szLoginClassName[ ] = "LoginForm";" and replaced "szClassName" in the CreateWindowEx() function, but then however, the Login window just doesn't show up when the button is clicked anymore (although the program doesn't crash)

any ideas?

[snoopy11]

No,

Its a string so

#define DIALOG "#32770"

Regards


Snoopy.

[Sammdahamm]

Thank you very much it works with the "#32770" constant.
However, I don't fully understand why replacing the class name with the #32770 string works, and simply giving it a different classname doesn't? Not really important, but if you have time to explain it would be greatly appreciated

[snoopy11]

To give it a different classname

you would have to use the RegisterClass function...

you just cant use anything....

Snoopy.