Struct VerticalMetrics 

pub struct VerticalMetrics {
    pub advance: f32,
    pub upright: bool,
}

Vertical-layout metrics for a single glyph.

In vertical text, glyphs advance along the block (Y) axis rather than the inline (X) axis. The advance field reflects the block-direction advance, and upright controls whether the glyph is drawn in its natural orientation or rotated.

Fields

advance: f32

Block-direction advance in the same units as em_size. Ideally sourced from the font’s vmtx table; falls back to 1 em.

upright: bool

true → draw upright (CJK-style); false → rotate 90° clockwise.

Implementations

impl VerticalMetrics

pub fn for_char(c: char, em_size: f32) -> Self

Compute vertical metrics for character c at the given em_size.

The advance defaults to em_size (1 em) when no vmtx data is available. Use VerticalMetrics::for_glyph when font bytes are available for accurate vmtx advances.

pub fn for_glyph(face_data: &[u8], glyph_id: u16, c: char, em_size: f32) -> Self

Compute vertical metrics for glyph_id using the font’s vmtx table. Falls back to em_size if vmtx is unavailable or parsing fails.