Re: Horiz motion: What is faster/better than redrawing pic moved 1 pixel to left 100x?

[John Cupitt ng-london org uk]

Paul Davis wrote:

>>- use gtkcanvas
>>
>>  high level OO canvas widget will do all the work
>>  for you ... it won't be the quickest thing ever
>>  though, since the compositing work is
>>  done on the application side (I think)
>>
> 
> actually, this is what makes the canvas *faster*, not slower. it only
> works this way in "antialias" mode (which is a silly name for what
> really means "application-side drawing mode"). but in that mode, there
> are no calls to the X server until the canvas drawing operations are
> finished and then it just calls XDrawPixmap (or equivalent) to blast
> the bits onto the screen. this is much faster than lots of calls to X
> drawing primitives.
> 
> in addition, it allows you to use drawing techniques not supported by
> the X protocol (such as anti-aliased lines, alpha blending etc.)


That's true Paul, but then all the compositing is done in software 
inside the client. If you do it server-side, you get hardware blitting 
(depends a bit on your Xserver/graphics card).

Also, I often have to run my X apps over a 10mbit ethernet, and this can 
be a bit slow if the client does all drawing with XPutImage()/whatever.

This is probably all a bit moot anyway :-) all machines these days will 
do pretty much any 2D graphics thing far faster than you can see it.

John



========================================================== 
Coming soon: 
Aelbert Cuyp 13 February - 12 May 2002 

For information and tickets: 
http://www.nationalgallery.org.uk