RE: Why CreateCompatibleDC and CreateCompatibleBitmap?

 
You only need the CreateCompatible* calls when you're doing double
buffering, i.e. drawing onto an offscreen (in memory) bitmap first, then
blitting it to the window's DC, to avoid flicker. If you're using a
CPaintDC in your WTL WM_PAINT handler, you *can* draw directly on that.
 
'Compatible' refers to 'having the same properties' (color depth,
palette, ...) as the original DC. What the CreateCompatible* calls do
exactly is a long and complicated topic. I suggest reading the Petzold
for an accessible (in asfar as an intricate topic like this can be made
accessible) explanation. MSDN has the information too but IMO it's too
dense to be fully understood by a novice.
 
 
cheers,
 
roel
 


  _____  

From: [email protected] [mailto:[email protected]] On Behalf Of
hawkgao
Sent: Thursday, April 16, 2009 11:29
To: [email protected]
Subject: [wtl] Why CreateCompatibleDC and CreateCompatibleBitmap?





I've study windows programming 8 years ago. but, i even don't understand
why windows need CreateCompatibleDC and CreateCompatibleBitmap, when
drawing some thing on view. what is the "compatible" real meaning here?
why windows cannot draw directly on device?

Thanks,
-Hawk






[Non-text portions of this message have been removed]



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