Kivy-InputText上的极限值

Question

我正在尝试使输入文本仅接受浮点值。另外，输入的值必须介于两个值之间。

我创建了一个包含'validate'方法的类。如果该值不在两个值之间，则会显示一个弹出窗口。

但是我有问题。仅当用户单击“ Enter”时才调用该方法。当文本更改时，我尝试调用该方法，但这对用户来说很烦人，因为在用户输入数据时，弹出窗口始终出现。

还有另一种方法可以做这样的事情？

Python文件：

class BoundedInput(BoxLayout):
    value = NumericProperty()

    def validate(self, min_value, max_value):
        status = min_value <= self.value <= max_value
        if not status:
            message = f'Value must be between {min_value} and {max_value}'
            popup = Popup(title='Warning', content=Label(text=message),
                            size_hint=(None, None), size=(300, 200))
            popup.open()

Kv文件：

<NumericInput@TextInput>:
    input_filter: 'float'
    multiline: False

<BoundedInput>:
    orientation: 'horizontal'
    Label:
        text: 'Value'
    NumericInput:
        text: str(root.value)
        on_text_validate:
            root.value = float(self.text)
            root.validate(5, 100)

Answer 1

一种合适的方法除了可以在范围内进行浮动之外，还可以对其进行过滤，为此我们创建了一个继承TextInput并覆盖insert_text方法的类：

from kivy.app import App
from kivy.base import Builder
from kivy.properties import NumericProperty
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.textinput import TextInput


Builder.load_string("""
<BoundedLayout>:
    orientation: 'horizontal'
    Label:
        text: 'Value'
    NumericInput:
        min_value : 5
        max_value : 100
        hint_text : 'Enter values between {} and {}'.format(self.min_value, self.max_value)
""")

class NumericInput(TextInput):
    min_value = NumericProperty()
    max_value = NumericProperty()
    def __init__(self, *args, **kwargs):
        TextInput.__init__(self, *args, **kwargs)
        self.input_filter = 'float'
        self.multiline = False

    def insert_text(self, string, from_undo=False):
        new_text = self.text + string
        if new_text != "":
            if self.min_value <= float(new_text) <= self.max_value:
                TextInput.insert_text(self, string, from_undo=from_undo)

class BoundedLayout(BoxLayout):
    pass

class MyApp(App):
    def build(self):
        return BoundedLayout()

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

Answer 2

您可以使用Bubble，并在输入错误的情况下将其挂起。您甚至可以编辑标签以告诉您出了什么问题。或更改文本颜色（如果已通过验证）。我举了两个例子。

from kivy.app import App
from kivy.uix.textinput import TextInput
from kivy.uix.bubble import Bubble
from kivy.lang import Builder
from kivy.uix.floatlayout import FloatLayout
from kivy.properties import BooleanProperty

KV = """

<ValidateLabel>:
    size_hint: (None, None)
    size: (280, 60)
    Label:
        id: label
        text: "Must be a float"


<MyInput>:
    foreground_color: (0,1,0,1) if root.validated else (1,0,0,1)


FloatInput:

"""


class MyInput(TextInput):
    validated = BooleanProperty(False)


class FloatInput(FloatLayout):
    bubble_showed = True

    def __init__(self, **kwargs):
        super(FloatInput, self).__init__(**kwargs)
        self.input = MyInput()
        self.input.bind(text=self.validate)
        self.add_widget(self.input)
        self.bubble = ValidateLabel()
        self.add_widget(self.bubble)

    def validate(self, input, value, min_value=15., max_value=25.):
        self.bubble.ids.label.text = "Number must be between {} and {}".format(min_value, max_value)
        try:
            print(min_value, max_value)
            status = float(min_value) <= float(value) <= float(max_value)
        except Exception as e:
            status = False
            self.bubble.ids.label.text = "Input must be a number"

        if not status:
            if not self.bubble_showed:
                self.input.validated = False
                self.add_widget(self.bubble)
                self.bubble_showed = True
        else:
            print("bubble removed")
            self.input.validated = True
            self.remove_widget(self.bubble)
            self.bubble_showed = False


class ValidateLabel(Bubble):
    validated = False


class TestApp(App):

    def build(self):
        return Builder.load_string(KV)


TestApp().run()

输出：

小号或大号：

数字没问题：

输入值不是数字：

Answer 3

我尝试了@eyllanesc的代码。它工作得很好，但是当我键入数字以外的其他字符时，出现此错误：ValueError: could not convert string to float: ''。您能帮我解决这个问题吗？