Re: [Usability] Scrolling virtually infinite windows

[Matthew Thomas <mpt myrealbox com>]

Magnus Bergman wrote:
>
> In many applications the size of the data, and therefore also the
> window, has no particular maximum size. This include vector based
> drawing applications, mathematical graph or fractal viewers and midi
> sequencers. Since it makes sense to scroll as much as you like in at
> least one direction, the common scrollbar is not suitable, I believe. I
> think a new widget is needed. What do other people think?

The most common application in this situation is a spreadsheet. For some 
 unfortunate reason, spreadsheet apps always show you the maximum 
possible number of rows and columns, instead of automatically expanding 
and collapsing to just the extent you're using.

> ...
> * The min/max values are constantly changed to reflect a portion of a
>   canvas that contains "something interesting".

If there are definite limits to "something interesting", I suggest doing 
 what Gnumeric does: use the scrollbar thumb to show the proportion of 
the extent of interesting things being shown, where the current 
insertion/navigation point is included as an interesting thing. So the 
further away you scroll from the other interesting things, the smaller 
the scrollbar thumb becomes.

(Fun fact: the Amiga's standard Workbench file manager also worked this 
way, because a window's scrollbars were always functional regardless of 
where its contents were.)

> ...
> * There is no scrolling widget at all, and only the cursor keys and/or
>   the mouse can be used to scroll the canvas.
> ...

I'd recommend this for applications like graphing tools and fractal 
generators, where there is no obvious limit to what is interesting. But 
be sure to implement an efficient zoom function, for quick navigation to 
another part of the canvas.

--
Matthew Thomas
http://mpt.net.nz/