API to freeze screen before updating it

[newAsm]

Hi,

I am asking a stupid question but I am not sure which API is the best. I want to prevent the screen flickering when I am doing drawing on the application window. Which API should I use to save the desktop or application window and then release it for update. Your knowledge would be helpful.

Thanks..newAsm

[Tedd]

Try WM_SETREDRAW, but it depends what you're drawing on.

Code Select Expand


invoke SendMessage, hCtrl,WM_SETREDRAW,FALSE,0
;...do your drawing/modifying...
invoke SendMessage, hCtrl,WM_SETREDRAW,TRUE,0


If you're drawing to the DC yourself, you should create a memory DC, draw to that, and then bitblt to the window DC in one go when you're finished.

[Ghandi]

Yep, double buffering is the way to go if you want to minimize or prevent screen flicker. Tedd is absolutely correct, do your manipulations on the memory DC and then a single BitBlt will paint it in one operation.

HR,
Ghandi

[sysfce2]

Here is a handy reference that might help:

http://catch22.net/tuts/flicker