[prev in list] [next in list] [prev in thread] [next in thread] 

List:       kde-devel
Subject:    Re: Image Libs (Was: Re: devel-announce: ImageMagick and KDE to
From:       Steffen Hansen <stefh () mip ! sdu ! dk>
Date:       1999-06-02 16:47:46
[Download RAW message or body]

On Wed, 2 Jun 1999, Mosfet wrote:

> > I see. Does this mean that that the app must copy all pixels in the  
> > region to an ImageMagick data-structure before applying an effect? That
> > doesn't sound optimal to me.
> 
> You have to do this no matter what. X11 Pixmaps displayed on the server need to
> be copied locally to the client before you do any bit-by-bit direct
> manipulation. That applies to everything (XImage and QImage, etc...), not just
> ImageMagick. That is just how X11 works.

That's not what i meant. If the app has the image data in a QImage or so,
you will have to duplicate a region (perhaps the whole image) of it to
apply an ImageMagick effect, and then copy the results back into the
QImage. I think my PC would be comfortable with one 150MB image, but not
with two of them.
 
> The only way to get around this is with XShm, which there *is* support for in
> ImageMagick but we would also need to extend KPixmap.

XShm is a very nice thing -- esp. if the app requires frequent conversion 
between QImage and QPixmap. I hope that Qt will have better support for
XShm in the future.

Qt wishlist: Shared XImage support in QPixmap, and some support for shared
Pixmaps also (for fast pixel manipulation without converting between
QImage and QPixmap). The last one is nessecary for fading menu's ;-)

> > BTW: What about SMP support?
> > 
> 
> If you are running on a SMP kernel it will be SMP ;-) Actually, since the
> effects mostly work linearly on image data, SMP gains would be limited other
> than it possibly getting it's own processor to work on.

If there are more CPU's, they could process a scanline each.
Multithreading/SMP is usually not worth the trouble, but image-manip. is a
"high end" application that needs all the processing power it can get, so
it deserves to get optimized for SMP.

greetings,
--------------
Steffen Hansen                              |
email: stefh@mip.sdu.dk, stefh@imada.sdu.dk,|  
       hansen@kde.org                       | ABC...VWXKZ :)
URL:   http://www.mip.sdu.dk/~stefh         | 

[prev in list] [next in list] [prev in thread] [next in thread]