Re: Live scrolling

FROM : Eric Long
DATE : Wed Nov 17 20:03:58 2004

>    Use a separate thread for loading the icons for the whole list.
> When you open a directory send all the files to a worker thread,


Thanks for the feedback, Guy.

After staring at this, I'm thinking along these lines:

I've subclassed the NSScrollView that contains my outline view.  I'm
overriding: -(void) reflectScrolledClipView:(NSClipView*)aClipView.

Here, I can get a notion of when scrolling starts.  Via a timer, I can check
to see how long it's been since the last scroll time, and create a scrolling
stopped threshold.  When the threshold is exceeded,  I decide that it's safe
to start updating.  My outline view is a now a subclass that my custom
NSScrollView can send a message to like this when scrolling begins:

[[self documentView] scrollView:self scrollingStarted:YES];

And this when scrolling ends:

[[self documentView] scrollView:self scrollingStarted:NO];

The idea being that my outline view can now refrain from drawing icons until
scrolling is stopped, then update the display.  Everything else gets drawn,
so I still get most of the benefits of live scrolling, and icon updating
should be fast enough to not be an annoyance or distraction.

I'm hoping that when scrolling stops, I can just call reloadData for the
table to update the display, without having to get picky about which cells
actually require redrawing.

I haven't got this working yet, so I don't know if it'll work.  Just testing
scroll detection, I ran into a caveat with the timer.  While the mouse
remains down on the knob, whether you're still scrolling or not, the timer
doesn't fire.  I figure that's because the main thread is tied up and it's
not getting air time.  So, I'll have to use a secondary thread, like you
suggested.

Fingers crossed...


Eric