Struct tfm::FixWord

pub struct FixWord(pub i32);

Fixed-width numeric type used in TFM files.

This numeric type has 11 bits for the integer part, 20 bits for the fractional part, and a single signed bit. The inner value is the number multiplied by 2^20. It is called a fix_word in TFtoPL.

In property list files, this type is represented as a decimal number with up to 6 digits after the decimal point. This is a non-lossy representation because 10^(-6) is larger than 2^(-20).

Tuple Fields

0: i32

Implementations

impl FixWord

pub const ZERO: FixWord = _

Representation of the number 0 as a FixWord.

pub const ONE: FixWord = _

Representation of the number 1 as a FixWord.

pub fn is_abs_less_than_16(&self) -> bool

Returns true if the number is less than 16.0 in magnitude according to Knuth.

The number +16.0 is not allowed. This is covered in the E2E tests. See check_fix in TFtoPL.2014.60.

pub fn to_scaled(self, design_size: FixWord) -> Scaled

Calculates the scaled value of this number at the specified design size.

All dimensions in a TFM file are specified as multiples of the design size (with the exception of the design size itself). The scaled value (i.e. the value is scaled points) is the TFM value multiplied by the design size.

The raw value and the design size both have 20 binary fractional bits, so the product has 40 fractional bits. A scaled value has only 16 fractional bits, and how the truncation is performed can effect the result. The specific multiplication algorithm Knuth wrote (TeX.2021.571-572) truncates the design size first and then performs the multiplication and then truncates again. Additionally, the integer division in that algorithm rounds towards zero even for negative numbers (e.g. -1.25 rounds to -1 instead of -2).

In order to ensure the result here matched Knuth’s algorithm, we reimplement Knuth’s algorithm.

Trait Implementations

impl Add for FixWord

type Output = FixWord

The resulting type after applying the + operator.

fn add(self, rhs: FixWord) -> Self::Output

Performs the + operation.

impl<'arbitrary> Arbitrary<'arbitrary> for FixWord

fn arbitrary(u: &mut Unstructured<'arbitrary>) -> Result<Self>

Generate an arbitrary value of Self from the given unstructured data.

fn arbitrary_take_rest(u: Unstructured<'arbitrary>) -> Result<Self>

Generate an arbitrary value of Self from the entirety of the given unstructured data.

fn size_hint(depth: usize) -> (usize, Option<usize>)

Get a size hint for how many bytes out of an Unstructured this type needs to construct itself.

impl Clone for FixWord

fn clone(&self) -> FixWord

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for FixWord

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

Formats the value using the given formatter.

impl Default for FixWord

fn default() -> FixWord

Returns the “default value” for a type.

impl Display for FixWord

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

Formats the value using the given formatter.

impl Div<i32> for FixWord

type Output = FixWord

The resulting type after applying the / operator.

fn div(self, rhs: i32) -> Self::Output

Performs the / operation.

impl From<FixWord> for DesignSize

fn from(value: FixWord) -> Self

Converts to this type from the input type.

impl Hash for FixWord

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Mul<i32> for FixWord

type Output = FixWord

The resulting type after applying the * operator.

fn mul(self, rhs: i32) -> Self::Output

Performs the * operation.

impl Ord for FixWord

fn cmp(&self, other: &FixWord) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized + PartialOrd,

Restrict a value to a certain interval.

impl PartialEq for FixWord

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for FixWord

fn partial_cmp(&self, other: &FixWord) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Sub for FixWord

type Output = FixWord

The resulting type after applying the - operator.

fn sub(self, rhs: FixWord) -> Self::Output

Performs the - operation.

impl Copy for FixWord

impl Eq for FixWord

impl StructuralPartialEq for FixWord