Subject: Re: [linux-audio-dev] read it and drool
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: Mon Dec 04 2000 - 06:35:23 EET
>Usability studies showed that knobs were the worst possible control for a
>GUI. They are simply too hard to control and too prone to error -- a very
>bad control for a MOUSE. Sliders are much better.
i use a mouse-ball. with the UI model that i have, where kbd modifiers
alter the step size associated with mouse motion, i have incredibly
fine precision with the mouse.
the same thing could be done for sliders, except that these are
typically built-in toolkit types that don't support variable
step-size.
>Sliders are not knobs, and not anywhere close to one. A slider is
>controlled directly 1:1 position of the mouse pointer. You move the mouse
>pointer and the slider goes there.
right, and as a result, you typically have poor value resolution. and
because all the sliders you've been used to in other GUIs tend to
provide that 1:1 feedback, you feel disconcerted when you try to make
minute adjustments and there is no slider motion. and lets not mention
the screen real-estate occupied by a slider that can offer any
actually useful 1:1 relationship between the slider position and the
mouse. A 25x25 pixel knob can offer at most 2*pi*12 = 157 distinct
visuals for the value range. a 25xN slider can offer at most 25.
>A knob with 1:1 position is too hard to control properly with a mouse,
>and one with virtual-linked control (that is, vertical to control
>position and horizontal to control scale of movement) violates intuitive
>design for GUI. That is, why should I move my mouse halfway across the
>screen to twist a tiny knob?
wrong question. "how can i get better resolution out of this slider
because whenever i move it, the value jumps too much?" the same
question applies to both sliders and knobs. the horizontal (or radial)
scaling is one approach to solving this; using kbd modifiers is another.
>Now try adjusting 10 knobs quickly in a row, vs 10 sliders.
if the knobs are vertically linked (to use your term), then only your
1:1 point can contribute to making this easier. there are ways to fix
that too: you can handle mouse clicks on the perimeter of the knob as
"set value" requests. i think you end up with something just as easy
to use as a slider.
--p
This archive was generated by hypermail 2b28 : Mon Dec 04 2000 - 07:32:03 EET