如何将消息从 QWidget 发送到 QStatusBar？

Posted 2023-02-16

【中文标题】如何将消息从 QWidget 发送到 QStatusBar？

【英文标题】：How to send message from a QWidget to QStatusBar?

【发布时间】：2019-10-12 22:28:28

【问题描述】：

有没有办法在 PySide2 中将消息从 QWidget 发送到 QStatusBar？一种在发生某事时发出消息的方法，另一个对象接收它并相应地更改消息。

我一直在尝试使用 QObject.emit() 和 QObject.connect() 传递字符串并在 QStatusBar 上显示但没有结果，它们都在不同的类中。

我只使用了 emit 和 connect 来进行简单的操作，比如与父窗口一起关闭子窗口，所以如果 emit 和 connect 不是处理此问题的正确方法，请建议另一种传递消息的方法。

import os
import shutil

from PySide2 import QtWidgets
from PySide2.QtCore import SIGNAL, SLOT

class ChildWidget(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(ChildWidget, self).__init__(parent)
        self.initUI()

    def initUI(self):
        self.setLayout(QtWidgets.QGridLayout())
        label_A = QtWidgets.QLabel("Path A: ", self)
        self.text_A = QtWidgets.QLineEdit(self)
        label_B = QtWidgets.QLabel("Path B: ", self)
        self.text_B = QtWidgets.QLineEdit(self)
        button_A = QtWidgets.QPushButton("Copy", self)

        button_A.clicked.connect(self.copy_function)

        self.layout().addWidget(label_A, 0, 0)
        self.layout().addWidget(self.text_A, 0, 1)
        self.layout().addWidget(label_B, 1, 0)
        self.layout().addWidget(self.text_B, 1, 1)
        self.layout().addWidget(button_A, 1, 2)

        self.layout().setColumnStretch(1, 1)
        self.layout().setColumnMinimumWidth(2, 72)

    def copy_function(self):
        source = self.text_A.text()
        destination = self.text_B.text()
        self.message = ''; count = 0

        file_list = os.listdir(source)
        for item in file_list:
            count = count + 1
            source_path = source +'/'+ item
            destination_path = destination +'/'+ item
            if os.path.isfile(source_path):
                shutil.copyfile(source_path, destination_path)
            # message
            self.message = 'Transferred 0 out of 1 files...'.format(
                count, len(file_list)
            )

class ParentWidget(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(ParentWidget, self).__init__(parent)
        self.initUI()

    def initUI(self):
        self.child = ChildWidget()
        self.setLayout(QtWidgets.QGridLayout())
        self.status_bar = QtWidgets.QStatusBar(self)
        self.status_bar.setSizeGripEnabled(False)
        self.h_line = QtWidgets.QFrame(self)
        self.h_line.setFrameShape(self.h_line.HLine)
        self.h_line.setFrameShadow(self.h_line.Sunken)

        # self.status_bar.showMessage(message)

        self.layout().addWidget(self.child, 0, 0)
        self.layout().addWidget(self.h_line, 1, 0)
        self.layout().addWidget(self.status_bar, 2, 0)
        self.layout().setContentsMargins(0, 0, 0, 0)

        self.setWindowTitle("Copy Window")
        self.resize(600, 60)
        self.show()

widget_window = ParentWidget()

【问题讨论】：

提供minimal reproducible example

【参考方案1】：

我在一份 PyQt 文档中找到了它。这行得通。

import os
import shutil

from PySide2 import QtWidgets
from PySide2.QtCore import Signal, Slot

class ChildWidget(QtWidgets.QWidget):
    status_update = Signal(str)
    def __init__(self, parent=None):
        super(ChildWidget, self).__init__(parent)
        self.initUI()

    def initUI(self):
        self.setLayout(QtWidgets.QGridLayout())
        label_A = QtWidgets.QLabel("Path A: ", self)
        self.text_A = QtWidgets.QLineEdit(self)
        label_B = QtWidgets.QLabel("Path B: ", self)
        self.text_B = QtWidgets.QLineEdit(self)
        button_A = QtWidgets.QPushButton("Copy", self)

        button_A.clicked.connect(self.copy_function)

        self.layout().addWidget(label_A, 0, 0)
        self.layout().addWidget(self.text_A, 0, 1)
        self.layout().addWidget(label_B, 1, 0)
        self.layout().addWidget(self.text_B, 1, 1)
        self.layout().addWidget(button_A, 1, 2)

        self.layout().setColumnStretch(1, 1)
        self.layout().setColumnMinimumWidth(2, 72)

    def copy_function(self):
        source = self.text_A.text()
        destination = self.text_B.text()
        count = 0

        file_list = os.listdir(source)
        for item in file_list:
            count = count + 1
            source_path = source +'/'+ item
            destination_path = destination +'/'+ item
            if os.path.isfile(source_path):
                shutil.copyfile(source_path, destination_path)
            message = 'Transferred 0 out of 1 files...'.format(
                count, len(file_list)
            )
            self.status_update.emit(message)

class ParentWidget(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(ParentWidget, self).__init__(parent)
        self.initUI()

    def initUI(self):
        self.child = ChildWidget()
        self.setLayout(QtWidgets.QGridLayout())
        self.status_bar = QtWidgets.QStatusBar(self)
        self.status_bar.setSizeGripEnabled(False)
        self.h_line = QtWidgets.QFrame(self)
        self.h_line.setFrameShape(self.h_line.HLine)
        self.h_line.setFrameShadow(self.h_line.Sunken)

        self.child.status_update.connect(self.status_message)

        self.layout().addWidget(self.child, 0, 0)
        self.layout().addWidget(self.h_line, 1, 0)
        self.layout().addWidget(self.status_bar, 2, 0)
        self.layout().setContentsMargins(0, 0, 0, 0)

        self.setWindowTitle("Copy Window")
        self.resize(600, 60)
        self.show()

    @Slot()
    def status_message(self, message):
        self.status_bar.showMessage(message)

widget_window = ParentWidget()

【讨论】：

什么？你不能从 QWidget 发送信号？这是如何工作的