module main import gg import gx struct App { mut: gg &gg.Context = 0 radius f64 = 10.0 } fn main() { mut app := &App{} app.gg = gg.new_context( bg_color: gx.white width: 300 height: 300 window_title: 'Circles' frame_fn: frame event_fn: on_event user_data: app ) app.gg.run() } fn on_event(e &gg.Event, mut app App) { match e.typ { .key_down { match e.key_code { .up { app.radius += 1 } .down { app.radius -= 1 } else {} } } else {} } } fn frame(mut app App) { app.gg.begin() app.gg.draw_circle_empty(150, 150, f32(app.radius), gx.blue) app.gg.draw_text(20, 20, 'radius: $app.radius') // app.gg.draw_text(20, 50, 'circle_segment_size: $circle_segment_size') app.gg.end() }