-- create a script resource property 'myfont' referencing a font file
go.property("myfont", resource.font("/assets/text48.font"))

function init(self)
    msg.post(".", "acquire_input_focus")

    -- get the font file on the gui component which is assigned to
    -- the font with id 'default'
    self.default_font = go.get("#gui", "fonts", { key = "default" })
end

function on_input(self, action_id, action)
    if action.pressed then
        -- get the font file currently assigned to the font with id 'default'
        local current_font = go.get("#gui", "fonts", { key = "default" })

        -- toggle between the default font and the font referenced by the
        -- script resource property 'myfont'
        if current_font == self.myfont then
            go.set("#gui", "fonts", self.default_font, { key = "default" })
        else
            go.set("#gui", "fonts", self.myfont, { key = "default" })
        end
    end
end