Function draw_text_with_fallback 

pub fn draw_text_with_fallback(
    canvas: &Canvas,
    text: &str,
    font: &Font,
    emoji_font: &Option<Font>,
    letter_spacing: f32,
    x: f32,
    y: f32,
    paint: &Paint,
)

Draw a text line with emoji-font and glyph-coverage fallback (#3, #8). If emoji_font is None, falls back to drawing everything with the primary font (plus any #3 system fallback the primary font’s coverage gap needs).