如何在连续按下按钮 3 秒时更改按钮的文本

Question

让我们考虑以下代码：

#.py file

class Screen:
    def change_text():
        self.ids.btn.text="some text"

#.kv file

<Screen>:
    GridLayout:
        cols:1
        Button:
            id:btn
            on_press: root.change_text()

一旦按下按钮，它的文本就会改变。但是如何更改代码，以便仅在连续按下按钮 3 秒时更改文本？

Answer 1

如果您只想在按住按钮 3 秒钟后更改文本，您可以执行以下操作：

kv:

<Screen>:
    GridLayout:
        cols:1
        Button:
            id:btn
            on_press: root.start_timer()
            on_release: root.cancel_timer()

py:

class Screen(FloatLayout):
    def __init__(self, **kwargs):
        super(Screen, self).__init__(**kwargs)
        self.timer = None

    def start_timer(self):
        if self.timer:
            self.timer.cancel()
        self.timer = Clock.schedule_once(self.change_text, 3.0)

    def cancel_timer(self):
        if self.timer:
            self.timer.cancel()

    def change_text(self, dt):
        self.ids.btn.text="some text"

这使用Clock.schedule_once() 将文本更改安排在 3 秒后。 on_press 和 on_release 都取消任何当前计时器（尽管 on_press 可能没有必要。

Answer 2

您可以在 Screen 类中构建一些逻辑：

class Screen(FloatLayout):
    def __init__(self, **kwargs):
        super(Screen, self).__init__(**kwargs)
        self.start_time = 0
        self.count = 0

    def change_text(self):
        time_now = time.time()
        if time_now - self.start_time > 3.0:
            # longer than 3 seconds since first click, start over
            self.start_time = time_now
            self.count = 1
        else:
            # this click within 3 seconds
            self.count += 1

        if self.count == 3:
            # 3 clicks within 3 seconds, so make the text change
            self.ids.btn.text="some text"
            self.count = 0
            self.start_time = 0