Re: penalty for double buffering

[Steven Jenkins <steven jenkins ieee org>]

Michael Torrie wrote:
> On Sat, 2003-12-13 at 13:43, Steven Jenkins wrote:
> It seems to me that since you're drawing to the screen 50 times a second
> that double buffering would buy you nothing anyway.  Double buffering is
> mainly to eliminate flickering when the widget redraws or changes size. 
> Since you're drawing yourself, with double buffering on, it seems to me
> that you'd be drawing to the buffer and then to the screen.  Since
> you're taking it upon yourself to handle all the invalidate events, such
> a middle buffer isn't necessary (and won't do anything for you).  So
> turning off the buffering returns you to the speeds you were used to
> under gtk 2.0, and I don't think there would be much flickering.

The rate at which the display is updated is determined by the user. The 
application is a real-time data acquisition package with an interpreter 
for a small programming language. The graphics primitives are there if 
the user wants to draw plots, etc. 50 Hz is the likely uppper limit of 
user requirements, but higher and lower rates are allowed. Sometimes the 
users only update every few seconds.

But you may be right. I don't notice any flicker in the testing I've 
done so far. The widget can't be resized, so maybe I don't need the 
double buffering anyway. I'd like to be sure before I remove it.

Even if I don't need it, I'm still curious why it's so costly.

Steve