我想从QLabel类更改Label小部件的文本，以显示用户在单击按钮打开文件对话框以从其计算机中选择图像时选择的图像文件的文件路径。这是代码：
class GUI(QMainWindow):
#Load the GUI.
def __init__(self):
super().__init__()
#Define the window icon.
self.window_icon = QIcon("LightMap.png")
#Make the UI.
self.init_ui()
#Fill the GUI.
def init_ui(self):
#Load the UI file.
main_window = uic.loadUi("mainwindow.ui", self)
#Set the window icon.
self.setWindowIcon(self.window_icon)
#Add commands for actions under the submenus.
self.command_file_menu(main_window)
self.command_settings_menu(main_window)
self.command_help_menu(main_window)
#Handle the case that the user clicks on the "Open Image" button.
main_window.button_open_image.setStatusTip("Open Image")
main_window.button_open_image.clicked.connect(self.open_file)
#Make sure this variable has been declared so that we can click "Start Mapping" at any time.
self.file_chosen = None
#Handle the case that the user clicks on the "Start Mapping" button.
main_window.button_start_mapping.setStatusTip("Start Mapping")
main_window.button_start_mapping.clicked.connect(self.start_mapping)
#Show the main window.
self.show()
#Add commands for actions under the File menu.
def command_file_menu(self, main_window):
#Back-end logic for Open Image.
main_window.action_open_image.setShortcut("CTRL+O")
main_window.action_open_image.setStatusTip("Open Image")
main_window.action_open_image.triggered.connect(self.open_file)
#Open an image file.
def open_file(self):
#Select the file dialog design.
dialog_style = QFileDialog.DontUseNativeDialog
dialog_style |= QFileDialog.DontUseCustomDirectoryIcons
#Open the file dialog to select an image file.
self.file_chosen, _ = QFileDialog.getOpenFileName(self, "QFileDialog.getOpenFileName()", "",
"JPEG (*.JPEG *.jpeg *.JPG *.jpg *.JPE *.jpe *JFIF *.jfif);; PNG (*.PNG *.png);; GIF (*.GIF *.gif);; Bitmap Files (*.BMP *.bmp *.DIB *.dib);; TIFF (*.TIF *.tif *.TIFF *.tiff);; ICO (*.ICO *.ico)", options=dialog_style)
#Show the path of the file chosen.
if self.file_chosen:
#Change the text on the label to display the file path chosen.
else:
#Change the text on the label to say that "No file was selected. Please select an image."
#This 'else' statement is used to catch the case where the user presses 'Cancel' after opening the file dialog,
#which will close the file dialog without choosing any file, even if they had already previously chosen a file
#from previously opening the file dialog.
if __name__ == "__main__":
app = QApplication(sys.argv)
ex = GUI()
sys.exit(app.exec_())
我已经尝试直接将main_window传递到open_file()并直接设置标签文本，如下所示：main_window.label_file_name.setText(self.file_chosen)，但是当我启动带有错误的GUI时，文件对话框会立即打开TypeError: argument1 has unexpected type NoneType。
我设法让这个功能与TkInter一起使用，但是我无法弄清楚如何将这个功能重复到PyQt5。这是我工作的TkInter代码的一个例子：
class GUI:
#Structure the GUI.
def __init__(self):
#Create a blank window.
self.root = Tk()
#Create the frame.
frameRoot = Frame(self.root)
frameRoot.pack()
#Create the menu.
menu = Menu(self.root)
self.root.config(menu=menu)
#Create the "File" submenu.
fileMenu = Menu(menu, tearoff=0)
menu.add_cascade(label="File", menu=fileMenu)
fileMenu.add_command(label="Open Image", command=self.openFile)
#Make a button to open the image file.
self.fileChosen = None #Prevent the user from mapping without first selecting an image.
self.buttonFile = Button(frameRoot, text="Open Image...", command=self.openFile)
self.buttonFile.grid(row=3, column=1)
#Display the directory path of the file chosen.
self.fileName = StringVar()
self.fileName.set("No File Selected")
self.labelFileName = Label(frameRoot, textvariable=self.fileName, fg="red")
self.labelFileName.grid(row=4, column=1)
#Keep the window open.
self.root.mainloop()
#Open the image file.
def openFile(self):
#Only accept the following file types.
self.fileChosen = filedialog.askopenfilename(filetypes=[("Bitmap Files", "*.BMP *.bmp *.DIB *.dib"),
("JPEG", "*.JPEG *.jpeg *.JPG *.jpg *.JPE *.jpe *JFIF *.jfif"),
("PNG", "*.PNG *.png"),
("GIF", "*.GIF *.gif"),
("TIFF", "*.TIF *.tif *.TIFF *.tiff"),
("ICO", "*.ICO *.ico")
])
#If a file was selected, show the file path. Else, inform the user.
if self.fileChosen:
self.fileName.set(self.fileChosen)
else:
self.fileName.set("No image was selected. Please select an image.")
if __name__ == "__main__":
#Create an object to access the class.
g = GUI()
我的TkInter实现成功的关键是使用来自TkInter的StringVar（）类。我尝试混合使用TkInter和PyQt5只是为了让这个要求正常工作，但这只是引发了一些错误。
答案 0 :(得分：1)
在你的情况下你应该能够访问变量main_window，因为它允许我访问标签，为此你必须将它作为参数传递，所以我建议你使用lambda函数并修改你的代码：
[...]
main_window.button_open_image.clicked.connect(lambda: self.open_file(main_window))
#Open an image file.
def open_file(self, main_window):
#Select the file dialog design.
dialog_style = QFileDialog.DontUseNativeDialog
dialog_style |= QFileDialog.DontUseCustomDirectoryIcons
#Open the file dialog to select an image file.
self.file_chosen, _ = QFileDialog.getOpenFileName(self, "QFileDialog.getOpenFileName()", "",
"JPEG (*.JPEG *.jpeg *.JPG *.jpg *.JPE *.jpe *JFIF *.jfif);; PNG (*.PNG *.png);; GIF (*.GIF *.gif);; Bitmap Files (*.BMP *.bmp *.DIB *.dib);; TIFF (*.TIF *.tif *.TIFF *.tiff);; ICO (*.ICO *.ico)", options=dialog_style)
#Show the path of the file chosen.
if self.file_chosen:
main_window.label_file_name.setText(self.file_chosen)
#Change the text on the label to display the file path chosen.
else:
main_window.label_file_name.setText("No file was selected. Please select an image.")
#Change the text on the label to say that "No file was selected. Please select an image."
#This 'else' statement is used to catch the case where the user presses 'Cancel' after opening the file dialog,
#which will close the file dialog without choosing any file, even if they had already previously chosen a file
#from previously opening the file dialog.