How do I spawn a new window from a custom control...

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I have a custom control from which I want to spawn a new window. Then I want to pass a substantial graphic to the new window to use as a cursor.

I'm hoping to spawn the new window from within the control's OnLButtonDown message handler.

After having done a fair amount of research into how I might do this I think this article 'Set cursor for a child window' purports to solve most nearly the problem I have than anything else I have found...

http://www.cplusplus.com/forum/windows/61689/[^]

I have replicated the call back function and put it in place.

In my OnLButtonDown function I have

HWND hDialog = CreateWindow(WC_DIALOG, _T("Win32 testing"), WS_OVERLAPPEDWINDOW | WS_VISIBLE,
                            200, 200, 500, 400, NULL, NULL, hInst, NULL);

SetWindowLongPtrW(hDialog, DWLP_DLGPROC, &CScrollBarEx::DialogProc);
::SendMessage(hDialog, WM_INIT, 0, (LPARAM)hInst);

but am having trouble getting the SetWindowLongPtrW call to get past the compiler. I have tried a number of casts etc on the last parameter but can't eliminate the following error...

cannot convert parameter 3 from 'INT_PTR (__stdcall CScrollBarEx::* )(HWND,UINT,WPARAM,LPARAM)' to 'LONG'

I am prepared to accept the probable fact that I am completely out of my depth here. If this is the case then please let me know - preferably with a kindly direction towards shallower water...

Posted 10-Jun-14 21:39pm

Ben Aldhouse

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Richard MacCutchan · Accepted Answer · 2014-06-10T22:25:00

I always have trouble using function pointers like this, and as far as I recall the target must be a static function. You also do not need the & (addressOf operator). Try:

C++

SetWindowLongPtr(hDialog, DWLP_DLGPROC, (LONG)CScrollBarEx::DialogProc);

Note that I have removed the W suffix from SetWindowLongPtr, it is best to let the preprocessor add the A or W suffixes based on your project's setting of the define for UNICODE.

Ben Aldhouse · Accepted Answer · 2014-06-11T21:21:00

Solution 2

Richard, you are my hero. I have added 'static' to my declaration of DialogProg and now my code compiles.

Edit: Oh yes, and I took out the ampersand, too.

Thank you very much.

Posted 11-Jun-14 21:21pm

Ben Aldhouse

Updated 11-Jun-14 21:58pm

v2

Comments

Richard MacCutchan 12-Jun-14 4:01am

Thank you for your kind comments. For the record you should post comments using the "Have a Question or Comment?" link below a suggested solution, rather than posting as a new Solution entry. Not really important in this case, but one to remember.

Richard MacCutchan 12-Jun-14 4:02am

I just noticed your articles, and there are a couple that I am interested in reading.