Sending WM_PAINT parameters

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3 total messages Started by poojo hackma Tue, 27 Feb 2007 19:23

#2395

Author: poojo hackma
Date: Tue, 27 Feb 2007 19:23

15 lines
1379 bytes

I've got a thread that needs to send a paint message back to the parent.

Right now, I am using:
SendMessage(hParent, WM_PAINT, (WPARAM)0, (LPARAM)0);

It works, but it does not repaint the entire region.

The InvalidateRgn (API?) takes a BOOL bErase parameter that forces the 
background to erase before painting.

How can I modify either WPARAM or LPARAM so that my WM_PAINT message will 
force my OnPaint event handler to repaint the entire region?

Thanks,
PJ

Re: Sending WM_PAINT parameters

#2396

Author: poojo hackma
Date: Tue, 27 Feb 2007 19:53

11 lines
1351 bytes

My mistake!

I just found that I should *never* use SendMessage (or PostMessage) with 
WM_PAINT.

I found a different way to handle this by using an Invalidate() from within 
my main thread then calling UpdateWindow(hParent) from my other thread.

Sorry for taking up your time.

Don't worry. I'm sure I'll have other stupid questions to ask.

Re: Sending WM_PAINT parameters

#2398

Author: danzer
Date: Tue, 27 Feb 2007 22:09

25 lines
1664 bytes

poojo hackma wrote:
> My mistake!
> 
> I just found that I should *never* use SendMessage (or PostMessage) with 
> WM_PAINT.
> 
> I found a different way to handle this by using an Invalidate() from within 
> my main thread then calling UpdateWindow(hParent) from my other thread.
> 
> Sorry for taking up your time.
> 
> Don't worry. I'm sure I'll have other stupid questions to ask. 
> 
> 

Using hParent in your "other thread" is not thread-safe.  See Gambit's 
explanation to me.

http://groups.google.com/group/borland.public.cppbuilder.vcl.components.using/browse_thread/thread/10b36291929e5d80/1cdbd4452defe29c?lnk=st&q=&rnum=6&hl=en#1cdbd4452defe29c

or

http://tinyurl.com/2yunb5

Danzer

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