Struct libcamera::controls::LensPosition

pub struct LensPosition(pub f32);

Acts as a control to instruct the lens to move to a particular position and also reports back the position of the lens for each frame.

The LensPosition control is ignored unless the AfMode is set to AfModeManual, though the value is reported back unconditionally in all modes.

This value, which is generally a non-integer, is the reciprocal of the focal distance in metres, also known as dioptres. That is, to set a focal distance D, the lens position LP is given by

\f$LP = \frac{1\mathrm{m}}{D}\f$

For example:

0 moves the lens to infinity. 0.5 moves the lens to focus on objects 2m away. 2 moves the lens to focus on objects 50cm away. And larger values will focus the lens closer.

The default value of the control should indicate a good general position for the lens, often corresponding to the hyperfocal distance (the closest position for which objects at infinity are still acceptably sharp). The minimum will often be zero (meaning infinity), and the maximum value defines the closest focus position.

\todo Define a property to report the Hyperfocal distance of calibrated lenses.

Tuple Fields

0: f32

Methods from Deref<Target = f32>

pub const RADIX: u32 = 2u32

pub const MANTISSA_DIGITS: u32 = 24u32

pub const DIGITS: u32 = 6u32

pub const EPSILON: f32 = 1.1920929E-7f32

pub const MIN: f32 = -3.40282347E+38f32

pub const MIN_POSITIVE: f32 = 1.17549435E-38f32

pub const MAX: f32 = 3.40282347E+38f32

pub const MIN_EXP: i32 = -125i32

pub const MAX_EXP: i32 = 128i32

pub const MIN_10_EXP: i32 = -37i32

pub const MAX_10_EXP: i32 = 38i32

pub const NAN: f32 = NaN_f32

pub const INFINITY: f32 = +Inf_f32

pub const NEG_INFINITY: f32 = -Inf_f32

pub fn total_cmp(&self, other: &f32) -> Ordering

Returns the ordering between self and other.

Unlike the standard partial comparison between floating point numbers, this comparison always produces an ordering in accordance to the totalOrder predicate as defined in the IEEE 754 (2008 revision) floating point standard. The values are ordered in the following sequence:

• negative quiet NaN
• negative signaling NaN
• negative infinity
• negative numbers
• negative subnormal numbers
• negative zero
• positive zero
• positive subnormal numbers
• positive numbers
• positive infinity
• positive signaling NaN
• positive quiet NaN.

The ordering established by this function does not always agree with the PartialOrd and PartialEq implementations of f32. For example, they consider negative and positive zero equal, while total_cmp doesn’t.

The interpretation of the signaling NaN bit follows the definition in the IEEE 754 standard, which may not match the interpretation by some of the older, non-conformant (e.g. MIPS) hardware implementations.

Example

struct GoodBoy {
    name: String,
    weight: f32,
}

let mut bois = vec![
    GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
    GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
    GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
    GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
    GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
    GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
];

bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));

// `f32::NAN` could be positive or negative, which will affect the sort order.
if f32::NAN.is_sign_negative() {
    assert!(bois.into_iter().map(|b| b.weight)
        .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
        .all(|(a, b)| a.to_bits() == b.to_bits()))
} else {
    assert!(bois.into_iter().map(|b| b.weight)
        .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
        .all(|(a, b)| a.to_bits() == b.to_bits()))
}

Trait Implementations

impl Clone for LensPosition

fn clone(&self) -> LensPosition

Returns a copy of the value.

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

Performs copy-assignment from source.

impl ControlEntry for LensPosition

const ID: u32 = 35u32

impl Debug for LensPosition

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

Formats the value using the given formatter.

impl Deref for LensPosition

type Target = f32

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl DerefMut for LensPosition

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl From<LensPosition> for ControlValue

fn from(val: LensPosition) -> Self

Converts to this type from the input type.

impl TryFrom<ControlValue> for LensPosition

type Error = ControlValueError

The type returned in the event of a conversion error.

fn try_from(value: ControlValue) -> Result<Self, Self::Error>

Performs the conversion.

impl Control for LensPosition