Trait FontFuncs 

pub trait FontFuncs {
    // Provided methods
    fn nominal_glyph(
        &self,
        font: &ShaperFont<'_, '_>,
        c: u32,
    ) -> Option<GlyphId> { ... }
    fn nominal_glyphs(
        &self,
        font: &ShaperFont<'_, '_>,
        glyphs: NominalGlyphs<'_>,
    ) -> usize { ... }
    fn variation_glyph(
        &self,
        font: &ShaperFont<'_, '_>,
        c: u32,
        vs: u32,
    ) -> Option<GlyphId> { ... }
    fn glyph_h_advance(&self, font: &ShaperFont<'_, '_>, glyph: GlyphId) -> i32 { ... }
    fn glyph_h_advances(
        &self,
        font: &ShaperFont<'_, '_>,
        advances: Advances<'_>,
    ) { ... }
    fn glyph_v_advance(&self, font: &ShaperFont<'_, '_>, glyph: GlyphId) -> i32 { ... }
    fn glyph_v_origin(
        &self,
        font: &ShaperFont<'_, '_>,
        glyph: GlyphId,
    ) -> (i32, i32) { ... }
    fn glyph_extents(
        &self,
        font: &ShaperFont<'_, '_>,
        glyph: GlyphId,
    ) -> Option<GlyphExtents> { ... }
}

Overrides character mapping and glyph metrics for a ShaperFont.

Scalar methods default to queries on the underlying font; batch methods call their scalar counterparts. Implement only the callbacks that need different behavior. Callbacks take &self; mutable state can be managed by the implementation.

Metrics scaling

All font metrics returned by these callbacks must be consistent with the scale factor configured on ShaperFont.

If no scale is set, values must be in unscaled font units (i.e. the same coordinate space as the font’s units_per_em). If a scale is set — for example font_size * 64 for FreeType-style 26.6 — then all returned values must already be in that scaled coordinate space.

Provided Methods

fn nominal_glyph(&self, font: &ShaperFont<'_, '_>, c: u32) -> Option<GlyphId>

Nominal character-to-glyph mapping callback.

fn nominal_glyphs( &self, font: &ShaperFont<'_, '_>, glyphs: NominalGlyphs<'_>, ) -> usize

Batch nominal character-to-glyph mapping callback.

Maps a run of codepoints to glyphs, stopping at the first codepoint the font has no glyph for. Returns the number of consecutive codepoints mapped.

fn variation_glyph( &self, font: &ShaperFont<'_, '_>, c: u32, vs: u32, ) -> Option<GlyphId>

Variation-selector mapping callback.

fn glyph_h_advance(&self, font: &ShaperFont<'_, '_>, glyph: GlyphId) -> i32

Horizontal advance callback.

See “Metrics scaling” in the trait-level docs for details on what value this method should return.

fn glyph_h_advances(&self, font: &ShaperFont<'_, '_>, advances: Advances<'_>)

Batch horizontal-advance callback.

See “Metrics scaling” in the trait-level docs for details on what value this method should return.

fn glyph_v_advance(&self, font: &ShaperFont<'_, '_>, glyph: GlyphId) -> i32

Vertical advance callback.

See “Metrics scaling” in the trait-level docs for details on what value this method should return.

fn glyph_v_origin( &self, font: &ShaperFont<'_, '_>, glyph: GlyphId, ) -> (i32, i32)

Vertical origin callback.

Returns the (x, y) coordinates of the vertical origin for the given glyph.

See “Metrics scaling” in the trait-level docs for details on what values this method should return.

fn glyph_extents( &self, font: &ShaperFont<'_, '_>, glyph: GlyphId, ) -> Option<GlyphExtents>

Glyph extents callback.

See “Metrics scaling” in the trait-level docs for details on what values this method should return.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors