WNDCLASS: cbWndExtra

[Karel Bruneel]

Hi,

Is this right?

1)if I register a WNDCLASS in witch set cbWndExtra to a value greater than
0, this means that every time I create a window of that class there will be
an extra amount of memory alocated.

2)I can put something into that extra memory.

If the two statements are correct:

How can I write and read from that extra memory.

Thank you
Karel Bruneel

[Alf P. Steinbach]

On Sat, 30 Aug 2003 19:36:19 GMT, "Karel Bruneel" <Ka***********@pandora.be> wrote:

Hi,

Is this right?

1)if I register a WNDCLASS in witch set cbWndExtra to a value greater than
0, this means that every time I create a window of that class there will be
an extra amount of memory alocated.
Not necessarily, but there's an extra amount of memory _available_ for
your use.
2)I can put something into that extra memory.
Yes.

But since every Win32 window has room for a user-defined pointer you
generally don't need to specify more storage.

It's a relic from 16-bit Windows.
(Note that there are many other ways to associate data with a window,
including (1) SetProp/GetProp, (2) dynamically generated window proc
stub, and (3) static association table.)

If the two statements are correct:

How can I write and read from that extra memory.

GetWindowLong, SetWindowLong.

[Alf P. Steinbach]

On Sat, 30 Aug 2003 19:54:03 GMT, al***@start.no (Alf P. Steinbach) wrote:

I'm sorry, I didn't notice this was crossposted to [comp.lang.c++].

Karel: DON'T DO THAT.

Or else... ;-)

[Karel Bruneel]

I thank all of you.
"Karel Bruneel" <Ka***********@pandora.be> schreef in bericht
news:T0*******************@phobos.telenet-ops.be...

Hi,

Is this right?

1)if I register a WNDCLASS in witch set cbWndExtra to a value greater than
0, this means that every time I create a window of that class there will be an extra amount of memory alocated.

2)I can put something into that extra memory.

If the two statements are correct:

How can I write and read from that extra memory.

Thank you
Karel Bruneel