Struct CompactLength 

#[repr(transparent)]
pub struct CompactLength(CompactLengthInner);

A representation of a length as a compact 64-bit tagged pointer

Tuple Fields

0: CompactLengthInner

Implementations

impl CompactLength

Tag layout

Tags are 8 bits. The low 3 bits are shared with pointer variants (such as calc()), which require an 8-byte aligned pointer and so always have those bits clear. They are assigned as follows:

• Bit 0 (NON_POINTER_BIT): set for every variant that is not a pointer. Pointer variants (calc()) have this bit clear, so is_plain_calc() is a single bit test.
• Bit 1 (KEYWORD_BIT): set for every variant that is not a plain length, percentage or calc() value (i.e. everything that cannot be resolved to a length given only a percentage basis).
• Bit 2 (PERCENTAGE_BIT): set for every variant whose resolved value depends on a percentage basis, including all calc() variants. uses_percentage() is a single bit test.

Pointer variants are distinguished by bit 1: calc() is 0b100 and fit-content(calc()) is 0b110. Any pointer variant’s tag() includes address bits 3..7, so pointer variants must be tested with low-bit masks (is_plain_calc(), is_fit_content_calc(), has_calc()) rather than as match arms.

Within the keyword class, bit 3 (SIZING_KEYWORD_BIT) is set for the CSS sizing keywords (min-content, max-content, fit-content, fit-content(), stretch) and clear for auto, fr and content. The remaining high bits distinguish variants within a class.

pub const NON_POINTER_BIT: usize = 0b0001

Bit set for all non-pointer (i.e. not calc()) tags

pub const KEYWORD_BIT: usize = 0b0010

Bit set for all tags that are not a plain length, percentage or calc() value

pub const PERCENTAGE_BIT: usize = 0b0100

Bit set for all tags whose value depends on a percentage basis (including calc())

pub const SIZING_KEYWORD_BIT: usize = 0b1000

Bit set (in addition to KEYWORD_BIT) for all CSS sizing keyword tags

pub const CALC_TAG: usize = 0b0000_0100

The tag indicating a calc() value

pub const FIT_CONTENT_CALC_TAG: usize = 0b0000_0110

The tag indicating a fit-content() value with a calc() limit

pub const LENGTH_TAG: usize = 0b0000_0001

The tag indicating a length value

pub const PERCENT_TAG: usize = 0b0000_0101

The tag indicating a percentage value

pub const AUTO_TAG: usize = 0b0000_0011

The tag indicating an auto value

pub const FR_TAG: usize = 0b0001_0011

The tag indicating an fr value

pub const CONTENT_TAG: usize = 0b0010_0011

The tag indicating a content keyword value

pub const MIN_CONTENT_TAG: usize = 0b0000_1011

The tag indicating a min-content value

pub const MAX_CONTENT_TAG: usize = 0b0001_1011

The tag indicating a max-content value

pub const FIT_CONTENT_PX_TAG: usize = 0b0010_1011

The tag indicating a fit-content value with px limit

pub const FIT_CONTENT_KEYWORD_TAG: usize = 0b0011_1011

The tag indicating a plain fit-content keyword value (no limit)

pub const STRETCH_TAG: usize = 0b0100_1011

The tag indicating a stretch keyword value

pub const FIT_CONTENT_PERCENT_TAG: usize = 0b0000_1111

The tag indicating a fit-content value with percent limit

impl CompactLength

pub const fn length(val: f32) -> Self

An absolute length in some abstract units. Users of Taffy may define what they correspond to in their application (pixels, logical pixels, mm, etc) as they see fit.

pub const fn percent(val: f32) -> Self

A percentage length relative to the size of the containing block.

NOTE: percentages are represented as a f32 value in the range [0.0, 1.0] NOT the range [0.0, 100.0]

pub fn calc(ptr: *const ()) -> Self

A calc() value. The value passed here is treated as an opaque handle to the actual calc representation and may be a pointer, index, etc.

The low 3 bits are used as a tag value and will be returned as 0.

pub fn fit_content_calc(ptr: *const ()) -> Self

A fit-content(calc()) value. The value passed here is treated as an opaque handle to the actual calc representation of the limit and may be a pointer, index, etc.

The low 3 bits are used as a tag value and will be returned as 0.

pub const fn auto() -> Self

The dimension should be automatically computed according to algorithm-specific rules regarding the default size of boxes.

pub const fn fr(val: f32) -> Self

The dimension as a fraction of the total available grid space (fr units in CSS) Specified value is the numerator of the fraction. Denominator is the sum of all fraction specified in that grid dimension Spec: https://www.w3.org/TR/css3-grid-layout/#fr-unit

pub const fn min_content() -> Self

The size should be the “min-content” size. This is the smallest size that can fit the item’s contents with ALL soft line-wrapping opportunities taken

pub const fn max_content() -> Self

The size should be the “max-content” size. This is the smallest size that can fit the item’s contents with NO soft line-wrapping opportunities taken

pub const fn fit_content_px(limit: f32) -> Self

The size should be computed according to the “fit content” formula: max(min_content, min(max_content, limit)) where:

• min_content is the min-content size
• max_content is the max-content size
• limit is a LENGTH value passed to this function

The effect of this is that the item takes the size of limit clamped by the min-content and max-content sizes.

pub const fn fit_content_percent(limit: f32) -> Self

The size should be computed according to the “fit content” formula: max(min_content, min(max_content, limit)) where:

• min_content is the min-content size
• max_content is the max-content size
• limit is a PERCENTAGE value passed to this function

The effect of this is that the item takes the size of limit clamped by the min-content and max-content sizes.

pub const fn fit_content_keyword() -> Self

The size should be computed according to the “fit content” formula: max(min_content, min(max_content, stretch)) where:

• min_content is the min-content size
• max_content is the max-content size
• stretch is the “stretch-fit” size (the size the box would take if it filled the available space)

pub const fn stretch() -> Self

The size should be the “stretch-fit” size: the size the box would take if it filled the available space (https://www.w3.org/TR/css-sizing-4/#stretch-fit-sizing)

pub const fn content() -> Self

The size should be an automatic size based on the box’s content (https://www.w3.org/TR/css-flexbox-1/#valdef-flex-basis-content)

This keyword is only valid for flex-basis. In any other context it behaves as auto.

pub fn tag(self) -> usize

Get the primary tag

pub fn value(self) -> f32

Get the numeric value associated with the CompactLength (e.g. the pixel value for a LENGTH variant)

pub fn calc_value(self) -> *const ()

Get the calc pointer of the CompactLength

pub fn is_plain_calc(self) -> bool

Returns true if the value is a plain calc() value (not a fit-content(calc()) value)

pub fn is_fit_content_calc(self) -> bool

Returns true if the value is a fit-content() value with a calc() limit

pub fn has_calc(self) -> bool

Returns true if the value holds a calc() pointer: either a plain calc() value or a fit-content() value with a calc() limit. calc_value() is valid for exactly these values.

pub fn is_zero(self) -> bool

Returns true if the value is 0 px

pub fn is_length_or_percentage(self) -> bool

Returns true if the value is a length or percentage value

pub fn is_length_percentage_or_calc(self) -> bool

Returns true if the value is a length, a percentage or a plain calc() value (not a fit-content(calc()) value): anything that resolves to a length given a percentage basis

pub fn is_auto(self) -> bool

Returns true if the value is auto

pub fn is_content(self) -> bool

Returns true if the value is the content keyword

pub fn is_min_content(self) -> bool

Returns true if the value is min-content

pub fn is_max_content(self) -> bool

Returns true if the value is max-content

pub fn is_fit_content(self) -> bool

Returns true if the value is a fit-content(…) value

pub fn is_sizing_keyword(self) -> bool

Returns true if the value is min-content, max-content, fit-content, fit-content(…), or stretch

pub fn is_max_or_fit_content(self) -> bool

Returns true if the value is max-content or a fit-content(…) value

pub fn is_max_content_alike(&self) -> bool

Returns true if the max track sizing function is MaxContent, FitContent or Auto else false. “In all cases, treat auto and fit-content() as max-content, except where specified otherwise for fit-content().” See: https://www.w3.org/TR/css-grid-1/#algo-terms

pub fn is_min_or_max_content(&self) -> bool

Returns true if the min track sizing function is MinContent or MaxContent, else false.

pub fn is_intrinsic(self) -> bool

Returns true if the value is auto, min-content, max-content, or fit-content(…)

pub fn is_fr(self) -> bool

Returns true if the value is and fr value

pub fn uses_percentage(self) -> bool

Whether the track sizing functions depends on the size of the parent node

pub fn resolved_percentage_size( self, parent_size: f32, calc_resolver: impl Fn(*const (), f32) -> f32, ) -> Option<f32>

Resolve percentage values against the passed parent_size, returning Some(value) Non-percentage values always return None.

Trait Implementations

impl Clone for CompactLength

fn clone(&self) -> CompactLength

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for CompactLength

impl Debug for CompactLength

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

Formats the value using the given formatter.

impl FromFr for CompactLength

fn from_fr<Input: Into<f64> + Copy>(value: Input) -> Self

Converts into an Into<f64> into Self

impl FromLength for CompactLength

fn from_length<Input: Into<f64> + Copy>(value: Input) -> Self

Converts into an Into<f64> into Self

impl FromPercent for CompactLength

fn from_percent<Input: Into<f64> + Copy>(value: Input) -> Self

Converts into an Into<f64> into Self

impl PartialEq for CompactLength

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for CompactLength

impl TaffyAuto for CompactLength

const AUTO: Self

The auto value for type implementing TaffyAuto

impl TaffyFitContent for CompactLength

fn fit_content(lp: LengthPercentage) -> Self

Converts a LengthPercentage into Self

impl TaffyMaxContent for CompactLength

const MAX_CONTENT: Self

The max_content value for type implementing TaffyZero

impl TaffyMinContent for CompactLength

const MIN_CONTENT: Self

The min_content value for type implementing TaffyZero

impl TaffyZero for CompactLength

const ZERO: Self

The zero value for type implementing TaffyZero