I'm looking for control that allows relative motion.
This isn't what I'm using it for, but you could consider it in the context of a volume control.
- There is a range of acceptable values.
- The user is currently at a specific value.
- The user can move up or down from their current value, but doesn't have visual information about where they are in the range (except perhaps if they're very close to one of the ends).
- The user can control the speed with which they move up/down the range (scrubbing speed).
I have two mental models for this. The first is sort of a slider, but the position of the slider essentially controls the speed of movement, not the absolute value. So pushing the slider all the way up lets the user scroll through very quickly and it snaps back to zero when the user lets go. The second model is that of a wheel protruding from the screen, sort of like a mouse scroll wheel, where the user "rolls" the wheel up and down to get to the desired value.
Is there a name for this type of control? I've had zero luck searching for it.
Are there other models that I should consider? Are either of the above clearly more intuitive, useful, etc. than the other?
Are there implementations of this type of control that I can take a look at? My development will be in Qt for iOS (long story), but any sort of implementation would be a helpful reference.