Struct WheelGeometry 

pub struct WheelGeometry {
    pub diameter_ratio: f32,
    pub perspective: f32,
}

The shape of the cylinder rows are laid on.

Fields

diameter_ratio: f32

The cylinder’s diameter as a multiple of the viewport’s height. Larger is flatter: at a diameter of twice the viewport only the middle thirty degrees of the cylinder are ever in front of it, and thirty degrees of a turn is a slope rather than a wheel.

perspective: f32

How much a row narrows per pixel it has receded. 0.0 leaves every row the full width, which reads as a fold rather than a turn.

Implementations

impl WheelGeometry

pub fn radius(&self, extent: f32) -> f32

The cylinder’s radius in a viewport extent pixels along.

pub fn row(&self, extent: f32, flat: f32) -> Option<RowOnWheel>

Where a row goes, given the viewport’s extent and where the row’s centre would sit on an unrolled strip, measured from the viewport’s centre.

None once the row has turned past a quarter — it has gone over the horizon, and a row drawn there would be a line of text lying edge-on.

Trait Implementations

impl Clone for WheelGeometry

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for WheelGeometry

impl Debug for WheelGeometry

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for WheelGeometry

fn default() -> Self

A diameter only a little larger than the wheel is tall, which puts the ends of the visible strip most of the way round to the horizon and is what makes a picker look like a picker rather than like a list with the ends dimmed.

These are the reference’s own numbers for its picker, and its comment on them is that they were eyeballed against a real one. That is worth repeating rather than rederiving: the geometry here is deliberately not a cylinder (see the module documentation), so a figure argued from first principles would be arguing about the wrong shape.

impl PartialEq for WheelGeometry

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for WheelGeometry