绑定函数到Kivy标签时，向函数传递了错误的参数。

huangapple
go评论94阅读模式
英文:

Binding a function to labels in kivy is passing the wrong parameters to the function

问题

以下是您提供的代码的翻译：

  1. 我有一堆标签是使用for循环创建的，每个标签都绑定了一个函数，该函数传递不同的参数。但是，当我单击任何标签时，它调用该函数并使用最后一个标签的参数，无论单击哪个标签。
  3. 这是我的代码：
  5. from kivy.uix.screenmanager import ScreenManager, Screen, NoTransition
  6. from kivy.properties import ObjectProperty, StringProperty
  7. from kivy.core.window import Window
  8. from kivy.uix.label import Label
  9. from kivy.app import App
  11. def findVideos(name): # 返回一个二维数组
  13. class findWindow(Screen):
  14.     songName = ObjectProperty()
  15.     videoInfo = []
  17.     def submitBtn(self):
  18.         findWindow.videoInfo = findVideos(self.songName.text)
  20.         for video in findWindow.videoInfo:
  21.             label = Label(text='[ref=world]world[/ref]', size_hint_y=None, height=12, text_size=(250, 20), markup=True)
  22.             label.bind(on_ref_press=lambda x, y: findWindow.changeScreen(self, 'download', label)) # 我相信这是问题所在
  23.             findWindow.videoInfo[findWindow.videoInfo.index(video)].append(label)
  24.             self.ids.gridLay.add_widget(label)
  26.     def changeScreen(self, screen, label):
  27.         self.parent.current = screen
  28.         for video in findWindow.videoInfo:
  29.             if video[2] == label: self.parent.current_screen.ids.downloadWindowId.text = video[0] # 总是与数组中的最后一个项目匹配
  31. class MyApp(App):
  32.     def build(self):
  33.         sm = ScreenManager(transition=NoTransition())
  34.         sm.add_widget(findWindow(name='find'))
  35.         
  36.         return sm
  38. MyApp().run()

以下是您提供的Kivy部分的翻译：

  1. <findWindow>:
  2. 	songName: songName
  4. 	FloatLayout:
  5. 		TextInput:
  6. 			id: songName
  7. 			hint_text: "搜索"
  8. 			multiline: False
  9. 			font_size: 14
  10. 			size_hint: (0.6, 0.05)
  11. 			pos_hint: {"x":0.075, "y":0.925}
  13. 		Button:
  14. 			text: "提交"
  15. 			on_release: root.submitBtn()
  16. 			font_size: 14
  17. 			size_hint: (0.2, 0.05)
  18. 			pos_hint: {"x":0.675, "y":0.925}
  20. 		ScrollView:
  21. 			do_scroll_x: False
  22. 			do_scroll_y: True
  23. 			size_hint: (0.90, 0.7)
  24. 			pos_hint: {"x":0.05, "y":0.11}
  26. 			GridLayout:
  27. 				id: gridLay
  28. 				cols: 1
  29. 				size_hint_y: None
  30. 				spacing: 14 
  31. 				height: self.minimum_height

请注意，由于代码中的HTML实体（如&amp;和&quot;）未进行翻译，您需要根据需要进行修复。希望这有助于您理解代码并解决问题。如果您有进一步的问题，请随时提出。

英文:

I have a bunch of labels that have been created using a for loop, and each one has a function binded to it that passes a different paramater. However, when I click on any of the labels, it calls the function using the parameters of the last label, no matter which one is clicked.

here is my code:

  1. from kivy.uix.screenmanager import ScreenManager, Screen, NoTransition
  2. from kivy.properties import ObjectProperty, StringProperty
  3. from kivy.core.window import Window
  4. from kivy.uix.label import Label
  5. from kivy.app import App
  7. def findVideos(name): #returns a 2d array
  9. class findWindow(Screen):
  10.     songName = ObjectProperty()
  11.     videoInfo = []
  13.     def submitBtn(self):
  14.         findWindow.videoInfo = findVideos(self.songName.text)
  16.         for video in findWindow.videoInfo:
  17.             label = Label(text=&#39;[ref=world]world[/ref]&#39;, size_hint_y=None, height=12, text_size=(250, 20), markup=True)
  18.             label.bind(on_ref_press=lambda x, y: findWindow.changeScreen(self, &#39;download&#39;, label)) #i believe this is the problem
  19.             findWindow.videoInfo[findWindow.videoInfo.index(video)].append(label)
  20.             self.ids.gridLay.add_widget(label)
  22.     def changeScreen(self, screen, label):
  23.         self.parent.current = screen
  24.         for video in findWindow.videoInfo:
  25.             if video[2] == label: self.parent.current_screen.ids.downloadWindowId.text = video[0] #always matches with the last item in the array
  27. class MyApp(App):
  28.     def build(self):
  29.         sm = ScreenManager(transition=NoTransition())
  30.         sm.add_widget(findWindow(name=&#39;find&#39;))
  31.         
  32.         return sm
  34. MyApp().run()

Here is my kivy:

  1. &lt;findWindow&gt;:
  2. 	songName: songName
  4. 	FloatLayout:
  5. 		TextInput:
  6. 			id: songName
  7. 			hint_text: &quot;Search&quot;
  8. 			multiline: False
  9. 			font_size: 14
  10. 			size_hint: (0.6, 0.05)
  11. 			pos_hint: {&quot;x&quot;:0.075, &quot;y&quot;:0.925}
  13. 		Button:
  14. 			text: &quot;Submit&quot;
  15. 			on_release: root.submitBtn()
  16. 			font_size: 14
  17. 			size_hint: (0.2, 0.05)
  18. 			pos_hint: {&quot;x&quot;:0.675, &quot;y&quot;:0.925}
  20. 		ScrollView:
  21. 			do_scroll_x: False
  22. 			do_scroll_y: True
  23. 			size_hint: (0.90, 0.7)
  24. 			pos_hint: {&quot;x&quot;:0.05, &quot;y&quot;:0.11}
  26. 			GridLayout:
  27. 				id: gridLay
  28. 				cols: 1
  29. 				size_hint_y: None
  30. 				spacing: 14 
  31. 				height: self.minimum_height

I don't know what to try at this point. I don't understand why .bind wouldn't bind the correct label in the function? I've tried using findWindow.changeScreen(self, &#39;download&#39;, video[0])) aswell, however it still used the video[0] from the last label.

答案1

得分: 0

The lambda函数直到引用被按下才被评估，因此label参数将始终是label的最后一个值。修复方法是创建一个临时参数，该参数获取当前的label值，并在lambda中使用它。就像这样：

  1. label.bind(on_ref_press=lambda x, y, lab=label: findWindow.changeScreen(self, 'download', lab))  # 我相信这是问题所在
  3. 临时参数`lab`获取了当前的`label`值。
英文:

The lambda function is not evaluated until the reference is pressed, so the label parameter will always be the last value of the label. The fix is to create a temporary parameter that takes the current value of label and uses that in the lambda. Like this:

  1.         label.bind(on_ref_press=lambda x, y, lab=label: findWindow.changeScreen(self, &#39;download&#39;,
  2.                                                                      lab))  # i believe this is the problem

The temporary parameter lab gets the current value of label.

huangapple
  • 本文由 发表于 2023年5月18日 06:37:01
  • 转载请务必保留本文链接：https://go.coder-hub.com/76276617.html
  • kivy
  • python
匿名

发表评论

匿名网友

:?: :razz: :sad: :evil: :!: :smile: :oops: :grin: :eek: :shock: :???: :cool: :lol: :mad: :twisted: :roll: :wink: :idea: :arrow: :neutral: :cry: :mrgreen:

确定