How to use the trezor.ui.display.bar function in trezor

def layout_u2f():

    if appid in knownapps.knownapps:
        appname = knownapps.knownapps[appid]
        appicon = res.load('apps/fido_u2f/res/u2f_%s.toif' %
                           appname.lower().replace(' ', '_'))
    else:
        appname = hexlify(appid[:4]) + '...' + hexlify(appid[-4:])
        appicon = res.load('apps/fido_u2f/res/u2f_unknown.toif')

    # paint background black
    ui.display.bar(0, 0, 240, 240, ui.BLACK)

    # top header bar
    ui.display.text(10, 28, 'U2F Login', ui.BOLD, ui.WHITE, ui.BLACK)

    # content
    ui.display.text_center(120, 70, '%s:' % action, ui.BOLD, ui.GREY, ui.BLACK)
    ui.display.image((240 - 64) // 2, 90, appicon)
    ui.display.text_center(120, 185, appname, ui.MONO, ui.WHITE, ui.BLACK)

    yield loop.Wait([])

ty = ay + ah // 2 + 8  # y-offset of the content
        maxlen = const(14)  # maximum text length

        # input content
        if len(t) > maxlen:
            t = "<" + t[-maxlen:]  # too long, align to the right
        width = display.text_width(t, text_style)
        display.text(tx, ty, t, text_style, fg_color, bg_color)

        if p:  # pending marker
            pw = display.text_width(t[-1:], text_style)
            px = tx + width - pw
            display.bar(px, ty + 2, pw + 1, 3, fg_color)
        else:  # cursor
            cx = tx + width + 1
            display.bar(cx, ty - 18, 2, 22, fg_color)

t = self.text  # input content

        tx = ax + 24  # x-offset of the content
        ty = ay + ah // 2 + 8  # y-offset of the content
        maxlen = const(14)  # maximum text length

        # input content
        if len(t) > maxlen:
            t = "<" + t[-maxlen:]  # too long, align to the right
        width = display.text_width(t, text_style)
        display.text(tx, ty, t, text_style, fg_color, bg_color)

        if p:  # pending marker
            pw = display.text_width(t[-1:], text_style)
            px = tx + width - pw
            display.bar(px, ty + 2, pw + 1, 3, fg_color)
        else:  # cursor
            cx = tx + width + 1
            display.bar(cx, ty - 18, 2, 22, fg_color)

def test_bar(self):
        display.bar(0, 0, 10, 10, 0xFFFF)

def func_middle(foreground):
        ui.display.bar(106, 222, 28, 4, foreground, ui.BLACK, 2)

def layout_homescreen():

    ui.display.bar(0, 0, 240, 48 * 4, ui.BLACK)
    ui.display.bar(0, 48 * 4, 240, 48, c, ui.BLACK)
    ui.display.text_center(120, 240 - 18, 'Hold to confirm', ui.BOLD, ui.WHITE, c)
    p = 0

    def func(foreground):
        ui.display.loader(p, c, 0, res.load('apps/playground_stick/res/fingerprint.toig'), foreground)
        p = (p + 10) % 1000

    animation = ui.animate_pulse(func, ui.WHITE, ui.GREY, speed=400000)

    yield from animation

def render(self):
        if self.input.content:
            # content button and backspace
            self.input.render()
            self.back.render()
        else:
            # prompt
            display.bar(0, 8, ui.WIDTH, 60, ui.BG)
            display.text(20, 40, self.prompt, ui.BOLD, ui.GREY, ui.BG)
        # key buttons
        for btn in self.keys:
            btn.render()