Struct TextMeasurer 

pub struct TextMeasurer { /* private fields */ }

Measures text with a 2D canvas context, caching the results.

Every label in a chart is measured at least once per layout, and layout runs on every data change. Measuring is a cross-language call into the browser, so the results are cached by text and font: a chart with a thousand axis labels makes a thousand calls the first time and none afterwards.

Implementations

impl TextMeasurer

Inherent implementation of TextMeasurer.

pub fn new() -> Option<Self>

Creates a measurer backed by a fresh offscreen canvas.

Returns None when the host has no DOM, which is the case for a native build.

Returns

• Option<Self> - Some(...) on success, None otherwise.

pub fn approximate() -> Self

Creates a measurer that estimates the text instead of measuring it.

The estimate is the average advance of a Latin character, which is close enough for a layout that is not going to be drawn — a server-side render, or a native build.

pub fn measure(&self, text: &str, font: &str) -> TextMetrics

Measures a run of text with the given CSS font shorthand.

Arguments

• &str - Shared reference to a str.

Returns

• TextMetrics - A TextMetrics value.

pub fn cache_size(&self) -> usize

Returns the number of cached measurements.

Returns

• usize - A non-negative integer.

pub fn clear_cache(&self)

Empties the measurement cache.

Trait Implementations

impl Clone for TextMeasurer

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for TextMeasurer

Implements impl std::fmt::Debug for TextMeasurer.

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

Formats the TextMeasurer via the supplied formatter.

Arguments

• &mut std::fmt::Formatter<'_> - The formatter receiving the formatted output.

Returns

• std::fmt::Result - A std::fmt::Result value.