Kivy ProgressBar归零显示异常的解决方案与优化

# 原始的 .kv 文件片段
<MyProgressBar@ProgressBar>:
    thickness: 24
    color: [1, 0, 0, 1]
    canvas:
        # ... 其他背景绘制 ...
        Color:
            rgba: self.color
        RoundedRectangle:
            pos: self.x, self.center_y - self.thickness/2
            # 问题所在：当self.value为0时，size的宽度部分会精确为0
            size: self.width * (self.value / float(self.max)) if self.max else 0, self.thickness
            radius: [self.thickness/4]

# 修正后的 .kv 文件片段
<MyProgressBar@ProgressBar>:
    thickness: 24
    color: [1, 0, 0, 1]
    canvas:
        Color:
            rgb: 0.88, 0.56, 0.89, 1
        RoundedRectangle:
            pos: self.x, self.center_y - self.thickness/2
            size: self.width, self.thickness
            radius: [self.thickness/4]
        Color:
            rgba: self.color
        RoundedRectangle:
            pos: self.x, self.center_y - self.thickness/2
            # 关键修改：在value计算中加入一个极小值 1e-10
            # 确保即使self.value为0，宽度计算结果也不会精确为0
            size: self.width * ((self.value + 1e-10) / self.max) if self.max else 1e-10, self.thickness
            radius: [self.thickness/4]

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import NumericProperty
from kivy.lang import Builder # 导入Builder用于加载kv文件

# 确保kv文件被加载
Builder.load_file('widgets_example.kv')

class WidgetsExample(BoxLayout):
    My_numeric_value = NumericProperty(0) # 绑定到进度条和滑块的值

    def on_slider_value(self, widget):
        """处理滑块值变化的事件"""
        self.My_numeric_value = int(widget.value)

    def Button_on_press(self):
        """处理“set 0”按钮点击事件，将进度条值设置为0"""
        self.My_numeric_value = 0
        print(f"进度条值已设置为: {self.My_numeric_value}")

    def Text_input_on_text_validate(self, widget):
        """处理文本输入框验证事件，将输入值设置为进度条值"""
        try:
            self.My_numeric_value = int(widget.text)
            print(f"进度条值已通过文本输入设置为: {self.My_numeric_value}")
        except ValueError:
            print("请输入有效的数字")

class TheLabApp(App):
    def build(self):
        return WidgetsExample()

if __name__ == '__main__':
    TheLabApp().run()

# widgets_example.kv
<MyProgressBar@ProgressBar>:
    thickness: 24
    color: [1, 0, 0, 1]
    canvas:
        # 进度条背景（固定宽度）
        Color:
            rgb: 0.88, 0.56, 0.89, 1 # 淡紫色背景
        RoundedRectangle:
            pos: self.x, self.center_y - self.thickness/2
            size: self.width, self.thickness
            radius: [self.thickness/4]
        # 进度条填充（动态宽度）
        Color:
            rgba: self.color # 填充颜色（红色）
        RoundedRectangle:
            pos: self.x, self.center_y - self.thickness/2
            # 修正后的宽度计算：添加1e-10以避免精确的零宽度
            size: self.width * ((self.value + 1e-10) / self.max) if self.max else 1e-10, self.thickness
            radius: [self.thickness/4]

<WidgetsExample>:
    canvas.before:
        Color:
            rgba:(0.71, 0.71, 0.7,1) # 灰色背景
        Rectangle:
            pos: self.pos
            size: self.size
    orientation: "vertical"
    padding: "10dp"
    spacing: "10dp"

    TextInput:
        id: text_input
        multiline: False
        hint_text: "输入进度值 (0-100)"
        on_text_validate:root.Text_input_on_text_validate(self)
        size_hint: 1,.1 # 调整大小以便显示更多组件

    MyProgressBar:
        id: my_progress_bar
        thickness: 50
        color: 1, 0, 0.5, 1 # 鲜艳的粉红色填充
        max:100
        value: root.My_numeric_value
        pos_hint: {"center_x" :.5}
        size_hint:.9,.2

    Button:
        text: "设置为 0"
        size_hint:.2,.1 # 调整大小
        pos_hint: {"center_x":.5}
        on_press: root.Button_on_press()

    Slider:
        orientation: "horizontal"
        id: my_slider
        value: root.My_numeric_value
        on_value: root.on_slider_value(self)
        min:0
        max:100
        size_hint_y: .1 # 调整大小