Function draw_text 

pub fn draw_text(
    ctx: &mut RenderContext,
    rctx: &Ctx<'_>,
    s: &Shape,
    body: &TextBody,
    tr: Rect,
    m: Affine,
    fields: &dyn Fields,
    prompt: Option<Rgba>,
)

Draw a text body into shape space m within the text rect.