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Hayri Uğur Koltuk
Hayri Uğur Koltuk

Reputation: 3020

Why not calling window procedure instead of calling CallWindowProc?

Why is there such function CallWindowProc? We are supplying the address of the window procedure, so isn't it better to call the function instead of calling another function which calls the function?

Upvotes: 4

Views: 744

Answers (2)

Mike
Mike

Reputation: 1727

The CallWindowProc function handles Unicode-to-ANSI conversion. You cannot take advantage of this conversion if you call the window procedure directly.

http://msdn.microsoft.com/en-us/library/windows/desktop/ms633571(v=vs.85).aspx

Upvotes: 1

Cat Plus Plus
Cat Plus Plus

Reputation: 129764

Because GetWindowLong (or GetWindowLongPtr) might return a value that is not a function pointer, which CallWindowProc can recognise and translate into a proper call. [1]

Upvotes: 8

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