Function style_at 

fn style_at(default: Style, italic: Option<f32>, slant: Option<f32>) -> Style

Returns the style at a location with the given italic and slant values, starting from the font’s default style.

An ital value of 0.5 or more is italic, and a smaller value is not italic. A nonzero slnt value is oblique by that angle unless the style is italic. A slnt value of zero is not oblique.