Question

这个问题经常被问到并得到解答，但我仍然无法让它发挥作用。我想访问一个小部件，它是另一个小部件的子代。为此，我使用了ObjectProperty。当我尝试访问ObjectProperty（通过FileChooser弹出窗口打开任何文件）来更改标签的文本时，我收到此错误：

self.pdfpages.text =＆＃34;更改为＆＃34; AttributeError的：＆＃39; kivy.properties.ObjectProperty＆＃39;对象没有属性＆＃39; text＆＃39;

我是否需要初始化ObjectProperty？或者我的.kv结构有问题吗？

main.py

import kivy
kivy.require('1.10.0') # replace with your current kivy version !
# Kivy Imports
from kivy.app import App
#UI Eleemnts
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.uix.popup import Popup
from kivy.uix.scrollview import ScrollView
from kivy.uix.scatter import Scatter
from kivy.uix.image import Image

#Core Elements
from kivy.core.image import Image as CoreImage
from kivy.properties import ObjectProperty

# Python Imports
import os

class Window(BoxLayout):
    #add child widgets (in kv file)
    pass


class PDFView(ScrollView):
    pdfpages = ObjectProperty()

    def newPage(self, filepath):
         #here the error occurs   
         self.pdfpages.text = "change to this"

class SideBar(BoxLayout):
    def openfile(self):
        print("Button pressed")
        OpenDialog().open()

class OpenDialog(Popup):
    def cancelfile(self):
        #close popup
        self.dismiss()
        print("No file opened")

    def openfile(self, path, selection):
        #selection can contain multiple files, [0] is first or only
        self.dismiss()
        print("Opened File: " + os.path.join(path, selection[0]))
        #open PDFView class
        PDFView.newPage(PDFView, os.path.join(path, selection[0]))        


class PDFEditor(App):
    title = "PDFEditor"
    #gets called on startup
    #load program
    def build(self):
        #return root node
        return Window()

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

PDFEditor.kv

<Window>:
    #this is the main (root) "window"
    orientation: "horizontal"
    SideBar:
        size_hint: (.1, 1)
    PDFView:
        size_hint: (.9, 1)

<PDFView>:
    #handler for ObjectProperty
    pdfpages: pdfpages
    Scatter:
    #only zoom
        BoxLayout:
            #add Images in here somehow
            orientation: "vertical"
            Label:
                id: pdfpages
                text: "hi"


<SideBar>:
    orientation: "vertical"
    Button:
        id: btn_openfile
        on_release: root.openfile()
        text: "Open File"
    Label:
        text: "Hello!"

<OpenDialog>:
    title: "Choose File"
    BoxLayout:
        #Fullscreen
        size: root.size
        pos: root.pos
        orientation: "vertical"
        FileChooserListView:
            id: chsr_open
        BoxLayout:
            size_hint_y: None
            height: 30
            Button:
                text: "Cancel"
                on_release: root.cancelfile()
            Button:
                text: "Open"
                on_release: root.openfile(chsr_open.path, chsr_open.selection)

Answer 1

将您的openfile方法更改为：

def openfile(self, path, selection):
    #selection can contain multiple files, [0] is first or only
    self.dismiss()
    print("Opened File: " + os.path.join(path, selection[0]))
    #open PDFView class
    PDFView().newPage(PDFView, os.path.join(path, selection[0]))

PDFView是类，PDFView()是此类的一个实例，您需要什么

修改

标签不会更改，因为您正在创建新标签而不替换它。因此，如果我完全理解你想要的是替换PDFView的文本。有很多方法可以做到这一点，但我不想编辑你的代码：试试这个：

... class OpenDialog(Popup): ... def openfile(self, path, selection): #selection can contain multiple files, [0] is first or only self.dismiss() print("Opened File: " + os.path.join(path, selection[0])) #open PDFView class app.window.ids.pdfview.newPage(PDFView, os.path.join(path, selection[0])) ... ... class PDFEditor(App): ... def build(self): #return root node self.window = Window() return self.window app = PDFEditor() if __name__ == '__main__': app.run()

在你的kv：

... <Window>: #this is the main (root) "window" orientation: "horizontal" SideBar: size_hint: (.1, 1) PDFView: id: pdfview size_hint: (.9, 1) ...

Answer 2

这里的问题是你设置一个新实例的文本，甚至不是在窗口上，而不是你已经拥有的实例。
要解决此问题，您需要访问您拥有的那个。

首先，将您的Window设为App属性，以便稍后引用。

class PDFEditor(App):
    title = "PDFEditor"
    def build(self):
        self.root = Window()
        return self.root

然后在kv

中提供PDFView和id

<Window>:
    orientation: "horizontal"
    SideBar:
        size_hint: (.1, 1)
    PDFView:
        id: pdfview
        size_hint: (.9, 1)

然后在openfile方法中，您可以获得之前创建的正在运行的应用root属性，如下所示。

def openfile(self, path, selection):
    self.dismiss()
    print("Opened File: " + os.path.join(path, selection[0]))
    app = App.get_running_app()
    pdf = app.root.ids.pdfview
    pdf.newPage(os.path.join(path, selection[0]))

这样您就可以访问ids课程的Window

ObjectProperty没有属性（Kivy，Python 3.x）

2 个答案: