Difference between WindowProc and CallWindowProc?

Question

What is the difference between WindowProc and CallWindowProc ?

I can imagine when registering a new window class I can specify my own WindowProc for it.
This leaves the question: When and what for do I use CallWindowProc ?

score 4 · Accepted Answer · edited Jul 01 '22 at 07:22

4

When you subclass a window using SetWindowLong/Ptr(GWL_WNDPROC) to assign a new WindowProc() to the window, the replacement WindowProc() uses CallWindowProc() when it needs to call the window's original WindowProc():

Subclassing a window

The preferred way to subclass a window is to use SetWindowSubClass() instead:

Safer subclassing

edited Jul 01 '22 at 07:22

ChrisW

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answered Jun 19 '14 at 15:06

Remy Lebeau

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The example makes it clearer. I also made the mistake to compare a callback function to an API function. – Bitterblue Jun 19 '14 at 15:30

score -1 · Answer 2 · answered Jun 19 '14 at 15:09

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See msdn. CallWindowProc is used for subclassing.

answered Jun 19 '14 at 15:09

ikh

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Difference between WindowProc and CallWindowProc?

2 Answers2