Struct glyph_brush::GlyphCalculator

pub struct GlyphCalculator<'font, H = DefaultSectionHasher> { /* private fields */ }

Cut down version of a GlyphBrush that can calculate pixel bounds, but is unable to actually render anything.

Build using a GlyphCalculatorBuilder.

Example

extern crate glyph_brush;
use glyph_brush::{GlyphCalculatorBuilder, GlyphCruncher, Section};

let dejavu: &[u8] = include_bytes!("../../fonts/DejaVuSans.ttf");
let glyphs = GlyphCalculatorBuilder::using_font_bytes(dejavu).build();

let section = Section {
    text: "Hello glyph_brush",
    ..Section::default()
};

// create the scope, equivalent to a lock on the cache when
// dropped will clean unused cached calculations like a draw call
let mut scope = glyphs.cache_scope();

let bounds = scope.pixel_bounds(section);

Caching behaviour

Calls to GlyphCalculatorGuard::pixel_bounds, GlyphCalculatorGuard::glyphs calculate the positioned glyphs for a section. This is cached so future calls to any of the methods for the same section are much cheaper.

Unlike a GlyphBrush there is no concept of actually drawing the section to imply when a section is used / no longer used. Instead a GlyphCalculatorGuard is created, that provides the calculation functionality. Dropping indicates the ‘cache frame’ is over, similar to when a GlyphBrush draws. Section calculations are cached for the next ‘cache frame’, if not used then they will be dropped.

Implementations

impl<'font, H: BuildHasher + Clone> GlyphCalculator<'font, H>

pub fn cache_scope<'a>(&'a self) -> GlyphCalculatorGuard<'a, 'font, H>

pub fn fonts(&self) -> &[Font<'_>]

Returns the available fonts.

The FontId corresponds to the index of the font data.

Trait Implementations

impl<H> Debug for GlyphCalculator<'_, H>

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

Formats the value using the given formatter.