Re: Scrolling an NSMatrix with 1000+ imageCells

FROM : Nat!
DATE : Mon Jan 27 18:36:19 2003

Am Montag, 27.01.03 um 15:32 Uhr schrieb Florian Soenens:

> Hello,
>
> i posted this question a couple of days ago and got no response so
> far, thus i will try again...
> i have the following problem:
>
> I subclassed NSMatrix to do my own mouse event handling. The NSMatrix
> is part of a scroll view.
> The matrix also has an NSMutableArray that contains images. (1000 or
> more) Depending on the count of images, the Matrix rebuilds itself.
> This goes all well. Then, i fill all the cells of the matrix with the
> images of the array like this:
>
> for(i = 0; i < [theArray count]; i++)
> {
>     [[theMatrix cellAtRow:r column:c] setImage: [theArray
> objectAtIndex:i];
> }
>
> Here comes the problem. (I'm actually not sure if it is a problem at
> all, but it's frustrating nonetheless)
> When all the images are set, and i scroll the matrix, the scrolling is
> slow. (Dual G4 1GHZ) When i compare this to the scrolling speed of 
> iPhoto for example, it's 10x slower.
> When i scrolled to the bottom completely, and then try again, the
> scrolling goes a lot faster, cause the images have been displayed
> already.
>
> The question is: is there a way to let it scroll faster from the
> beginning? Does it have something to do with caching ?


I would suspect yes, that NSImage initializes lazily. You should be
able to force a load by writing:

NSImage  *image;

for(i = 0; i < [theArray count]; i++)
{
    image = [theArray objectAtIndex:i];
    [image representations];
   [[theMatrix cellAtRow:r column:c] setImage:image];
}

This won't make it overall faster, but the slow scrolling effect oughta
vanish.

To make it overall faster, you might want to store a preview of the
image somewhere (may be in the -he he- resource fork of the image file)
and use this for your selection matrix.


Ciao
   Nat!

>

------------------------------------------------------
But didn't I always tell you, honey, if I just stayed
in place and I never spoke up, good things are bound
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