Kivy单按钮秒表：实现长按重置遇AttributeError问题求助

问题原因 #

Kivy标准Button组件未内置on_long_press事件，直接绑定该事件会触发AttributeError: long_press。要实现长按功能，需通过自定义逻辑结合Clock检测触摸时长，区分短按与长按操作。

解决方案：自定义长按按钮类 #

推荐继承Button实现支持长按事件的自定义按钮，组件可复用且逻辑清晰。

修改后的Python代码

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.clock import Clock
from kivy.lang import Builder
from kivy.uix.button import Button
from kivy.properties import NumericProperty, ObjectProperty

class LongPressButton(Button):
    # 长按阈值（秒），可在kv中自定义
    long_press_threshold = NumericProperty(2)
    # 长按触发事件
    on_long_press = ObjectProperty(None)

    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.touch_start_time = None
        self.long_press_schedule = None

    def on_touch_down(self, touch):
        # 检测触摸是否落在按钮范围内
        if self.collide_point(*touch.pos) and touch.is_touch:
            self.touch_start_time = Clock.get_time()
            # 计划长按触发事件
            self.long_press_schedule = Clock.schedule_once(self._trigger_long_press, self.long_press_threshold)
        return super().on_touch_down(touch)

    def on_touch_up(self, touch):
        if self.collide_point(*touch.pos) and touch.is_touch:
            if self.touch_start_time is not None:
                touch_duration = Clock.get_time() - self.touch_start_time
                # 触摸时长小于阈值，判定为短按，触发原on_press事件
                if touch_duration < self.long_press_threshold:
                    self.dispatch('on_press')
                # 取消未触发的长按计划
                if self.long_press_schedule is not None:
                    Clock.unschedule(self.long_press_schedule)
                self.touch_start_time = None
                self.long_press_schedule = None
        return super().on_touch_up(touch)

    def _trigger_long_press(self, dt):
        # 触发长按事件
        if self.on_long_press:
            self.on_long_press()
        self.touch_start_time = None
        self.long_press_schedule = None

class HomeScreen(Screen):
    elapsed_time = 0

    def update_time(self, dt):
        self.elapsed_time += dt
        mins, secs = divmod(round(self.elapsed_time), 60)
        self.ids.stopwatch_display.text = '{:02d}:{:02d}'.format(mins, secs)

    def start_stop(self):
        if self.ids.stopwatch_display.start_or_end == 'Start':
            Clock.schedule_interval(self.update_time, 0.1)
            self.ids.stopwatch_display.start_or_end = 'Stop'
        else:
            Clock.unschedule(self.update_time)
            self.ids.stopwatch_display.start_or_end = 'Start'

    def reset_time(self):
        self.elapsed_time = 0
        self.ids.stopwatch_display.text = '00:00'
        Clock.unschedule(self.update_time)
        self.ids.stopwatch_display.start_or_end = 'Start'

class TheApp(App):
    def build(self):
        sm = ScreenManager()
        sm.add_widget(HomeScreen(name='home_screen'))        
        return sm

def main():
    Builder.load_file('menu.kv')
    app = TheApp()
    app.run()

if __name__ == '__main__':
    main()

修改后的kv代码（menu.kv）

<HomeScreen>:
    LongPressButton:
        id: stopwatch_display
        text: '00:00'
        start_or_end: 'Start'
        # 短按触发启停
        on_press: root.start_stop()
        # 长按触发重置
        on_long_press: root.reset_time()
        # 自定义长按阈值（可选，默认2秒）
        long_press_threshold: 2
        # 布局属性，居中显示
        size_hint: 0.8, 0.2
        pos_hint: {'center_x': 0.5, 'center_y': 0.5}

关键说明 #

1. 自定义按钮逻辑：通过on_touch_down记录触摸开始时间，用Clock.schedule_once计划长按触发；on_touch_up时计算触摸时长，区分短按/长按操作。
2. 事件绑定：短按仍使用原on_press绑定启停逻辑，长按通过自定义的on_long_press绑定重置逻辑。
3. 移除冗余组件：原reset_button可直接删除，所有功能整合到单个按钮中，优化触控体验。

内容的提问来源于stack exchange，提问作者Max Davies