(Python Kivy) 索引哪个按钮被按下

Question

我想找出一种方法来索引在 GridLayout 中按下的按钮，例如，我可以在按下该按钮时将特定图像放在该按钮的背景中。这是我目前正在做的，在添加更多功能之前使用一个函数来尝试打印索引号作为测试：

    for x in range(15):
        self.buttons.append(Button())
        self.ids.grid_1.add_widget(self.buttons[x])
        self.buttons[x].background_normal = 'YOUTUBE.png'
        self.buttons[x].background_down = 'opacity.png'

        # Make the button switch screens to input from calling the function above
        if edit_mode is True:
            self.buttons[x].bind(on_release=self.SwitchScreenInput)
            self.buttons[x].bind(on_release=self.HoldButtonNum(x))

def HoldButtonNum(x):
    print(x)

我收到错误：

TypeError: HoldButtonNum() takes 1 positional argument but 2 were given

Process finished with exit code 1

Answer 1

我会做一些观察：

如果HoldButtonNum是一个实例方法，它的第一个参数必须是self。
您必须使用 functools.partial 或 lambda 函数将参数传递给事件处理程序。
该函数必须接收第三个参数，它是启动事件的按钮的实例。

一个例子：

from kivy.app import App
from kivy.uix.gridlayout import GridLayout
from kivy.uix.button import Button

from functools import partial
class MyGridLayout(GridLayout):
    cols = 5
    def __init__(self):
        super(MyGridLayout, self).__init__()
        self.buttons = []
        for x in range(15):
            self.buttons.append(Button())
            self.add_widget(self.buttons[x])
            self.buttons[x].bind(on_release=partial(self.HoldButtonNum,  x))

    def HoldButtonNum(self, x, instance):
        print('Button instance:',  instance)
        print('Button index in list:',  x)


class MyKivyApp(App):
    def build(self):
        return MyGridLayout()

def main():
    app = MyKivyApp()
    app.run()

if __name__ == '__main__':
    main()

按下按钮时输出如下：

Button index in list: 1    
Button instance: <kivy.uix.button.Button object at 0x0000018C511FC798>

(Python Kivy) 索引哪个按钮被按下

(Python Kivy) Indexing Which Button Was Pressed

python

function

parameter-passing

kivy

kivy-language