调整 QDialog 的大小作为 MainWindow 调整大小

Question

There is a QWidget with a button, which brings up a QDialog on click. setParent of the dialog is set to QWidget. Every time the button is clicked, the dialog comes up with a specific size. I don't know why. If a size is set for the dialog, it comes up with that size, of course. But how to make the dialog fill the whole window and take up the size of the window, whatever the window size is? For instance, if the window size is 700, 600, then dialog should inherit that size and if the window is resized or maximized, the dialog should change its size with the window as it is being resized.Here's the code:

import sys
from PySide2.QtWidgets import *
from PySide2 import *


class Dialog(QDialog):
    def __init__(self):
    super(Dialog, self).__init__()
    self.move(0, 0)
    #self.resize(200, 100)
    self.setStyleSheet("background: teal;")
    self.setParent(MainWindow)


 def show_dialog():
    d = Dialog()
    d.exec_()


class MainWindow(QWidget):
    def __init__(self):
    super(MainWindow, self).__init__()
    self.resize(700, 600)

    btn = QPushButton()
    btn.setText("Click")

    layout = QVBoxLayout()
    layout.addWidget(btn)
    self.setLayout(layout)

    btn.clicked.connect(show_dialog)


if __name__ == '__main__':
   app = QApplication(sys.argv)
   MainWindow = MainWindow()
   MainWindow.show()
   sys.exit(app.exec_())

Answer 1

The solution is to set the size with resize() method:

self.setParent(MainWindow)
self.resize(MainWindow.size())

Although I don't like the way to access the elements since it can generate errors, instead I have rewritten your solution as follows:

import sys
from functools import partial

from PySide2.QtWidgets import QApplication, QDialog, QPushButton, QVBoxLayout, QWidget


class Dialog(QDialog):
    def __init__(self, parent=None):
        super(Dialog, self).__init__(parent)
        self.setStyleSheet("background: teal;")


def show_dialog(w):
    d = Dialog(w)
    d.resize(w.size())
    d.exec_()


class MainWindow(QWidget):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.resize(700, 600)
        btn = QPushButton()
        btn.setText("Click")
        layout = QVBoxLayout(self)
        layout.addWidget(btn)
        btn.clicked.connect(partial(show_dialog, self))


if __name__ == "__main__":
    app = QApplication(sys.argv)
    MainWindow = MainWindow()
    MainWindow.show()
    sys.exit(app.exec_())

Update:

Since the OP clarified his question, then the solution remains the same: obtain the size of one element and set it in the other, but in this case, the size of the first must be monitored using an event filter.

import sys
from functools import partial

from PySide2 import QtCore, QtWidgets


class Resizer(QtCore.QObject):
    sizeChanged = QtCore.Signal(QtCore.QSize)

    def __init__(self, widget):
        super(Resizer, self).__init__(widget)
        self._widget = widget
        self.widget.installEventFilter(self)

    @property
    def widget(self):
        return self._widget

    def eventFilter(self, obj, event):
        if self.widget is obj and event.type() == QtCore.QEvent.Resize:
            self.sizeChanged.emit(event.size())
        return super(Resizer, self).eventFilter(obj, event)


class Dialog(QtWidgets.QDialog):
    def __init__(self, parent=None):
        super(Dialog, self).__init__(parent)
        self.setStyleSheet("background: teal;")


def show_dialog(w):
    d = Dialog(w)
    d.resize(w.size())
    resizer = Resizer(w)
    resizer.sizeChanged.connect(d.resize)
    d.exec_()


class MainWindow(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.resize(700, 600)
        btn = QtWidgets.QPushButton()
        btn.setText("Click")
        layout = QtWidgets.QVBoxLayout(self)
        layout.addWidget(btn)
        btn.clicked.connect(partial(show_dialog, self))


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = MainWindow()
    MainWindow.show()
    sys.exit(app.exec_())