Re: [Foxgui-users] jumpy scrolling on the Mac

[John S. <joh...@ja...>]

I passed SCROLLBAR_WHEELJUMP and it was the same and the vertical scroll disappeared.

I used SCROLLERS_DONT_TRACK and this works! It jumps by 1 line each time and there is no blurring/smearing...I assume that is what you meant.

Thanks

Js



-----Original Message-----
From: je...@fo... <je...@fo...> 
Sent: Tuesday, May 21, 2024 10:37 AM
To: joh...@ja...
Cc: 'Roland Hughes' <ro...@lo...>; 'Mathew Robertson' <mat...@gm...>; fox...@li...
Subject: Re: [Foxgui-users] jumpy scrolling on the Mac

On 2024-05-21 08:05, John Selverian wrote:
> I added a repaint timer. It gets called but I don’t notice any 
> difference, it is still jumpy.
> 
> I also tried Adie and see the same problem, i.e., jumpy text.
> 
> I also see this problem in an FXTable not just FXList.

That is important to know, because it would rule out issues specific to your program.  Rather, it seems to have to do with the XQuartz interface then.

> If I scroll using the ‘thumb’ in the scroll bar instead of the 
> mousewheel it looks fine.

The wheel performs some animation, redrawing the widget at inter- mediate positions in order to provide visual clues of the direction of motion.

All this is done via FXScrollBar [a wheel-rotation inside the widget is typically routed to either vertical scrollbar [default], or horizontal scrollbar [if vertical scrolling is disabled].

The wheel animation will be disabled if SCROLLBAR_WHEELJUMP is passed; this will skip the intermediate states and jump straight to the desired scroll position.  You could try that.

Current animated scrolling is "hardwired" to a time-interval of
1/60 (16,666,666 nanoseconds), and eight increments, i.e. you'll reach the desired scroll position in 8 frame times.

Implicit in this assumption is that we can actually perform this act of drawing in one frame time.

   -- JVZ