Comment by baxuz

2 days ago

It's really not. You're looking at it the wrong way, and haven't come across any of the use cases it solves.

If you have limited space and you need to both interact with and see fractional ranges, knobs are the way to go. It's way more glanceable, and the entire range is displayed in the knob itself.

Think of it this way: Both a circular knob and a slider have 2 elements: the interactive area and the range display. However, the slide has the same knob size that is set on a large track displaying the selected range by moving the knob, whereas the circular knob has the track displayed radially inside it.

For the track example — the knob is the only interactive element for all practical purposes when it comes to precise tweaking of values. Single clicks on a track usually don't support further dragging after the initial click on any OS or UI implementation.

This comes with many positive sides:

- The interactive area (handle) is always in the same place.

- The interactive area is in practice always bigger than a knob on a linear slider.

- Adjusting the knob doesn't reposition your cursor, no matter what you do with the mouse.

- The circular track allows for much easier visual identification of fractions compared to a linear track due to its radial nature.

- The indicator can be a single pixel, whereas on the linear track, the knob is a fairly imprecise blob due to its nature of needing to serve a dual purpose. This means it's a lot more precise.

- There is a lot more granularity in the same surface area.

- Interaction precision isn't limited to the size of the track where it needs to scale linearly

- You don't need to dynamic element rendering or resizing which may cover other things you're looking at.

- The area is much smaller. On a 16x16px circular knob, I can get up to hundreds of steps which are clearly visually distinct.

All of that being said, the article is quite bad as it contradicts itself, and uses knobs in ways they are not good at, which is circular interaction and being able to do multiple circles. It beats the point of having a knob, might as well have an interaction handler on the number indicator itself.