关于 QML 和 PySide2 的几个问题

Instead of creating the "change" signal in each element, you can export the backend to QML using setContextProperty and then call the slots directly. To obtain the object using rootObjects() is dangerous since there are qmls that are loaded asynchronously, instead use the objectCreated signal.

ma​​in.py

import os

from PyQt5 import QtCore, QtGui, QtQml

CURRENT_DIR = os.path.dirname(os.path.realpath(__file__))


class Backend(QtCore.QObject):
    def __init__(self, parent=None):
        super().__init__(parent)

        self._engine = QtQml.QQmlApplicationEngine()
        self._welcome = None
        self._wallet = None
        self.engine.objectCreated.connect(self.on_object_created)
        self.engine.rootContext().setContextProperty("backend", self)

        self.load_welcome()

    @property
    def engine(self):
        return self._engine

    @property
    def welcome(self):
        return self._welcome

    @property
    def wallet(self):
        return self._wallet

    @staticmethod
    def create_url(qml):
        return QtCore.QUrl.fromLocalFile(os.path.join(CURRENT_DIR, qml))

    def load_welcome(self):
        self.engine.load(self.create_url("welcome.qml"))

    @QtCore.pyqtSlot(QtCore.QObject, QtCore.QUrl)
    def on_object_created(self, obj, url):
        if url == self.create_url("welcome.qml"):
            self._welcome = obj
        elif url == self.create_url("wallet.qml"):
            self._wallet = obj

    @QtCore.pyqtSlot()
    def create_wallet(self):
        self.welcome.close()
        self.engine.load(self.create_url("wallet.qml"))

    @QtCore.pyqtSlot()
    def add_info(self):
        print("add_info")


if __name__ == "__main__":
    import sys

    app = QtGui.QGuiApplication(sys.argv)
    backend = Backend()

    sys.exit(app.exec_())

welcome.qml

import QtQuick 2.14
import QtQuick.Controls 2.14

ApplicationWindow {
    id: root
    width: 650; height: 390
    opacity: 1
    visible: true
    minimumHeight: 232
    minimumWidth:226
    title: "open account"
    flags: Qt.SplashScreen
    Item {
        id: element
        x: 9
        y: 88
        width: 560
        height: 300
        anchors.horizontalCenter: parent.horizontalCenter
        anchors.verticalCenter: parent.verticalCenter
        Timer {
            interval: 5000; running: true; repeat: false
            onTriggered: backend.create_wallet()
        }
        Image {
            id: image
            x: 130
            y: 60
            width: 342
            height: 188
            anchors.verticalCenterOffset: -56
            anchors.horizontalCenterOffset: 0
            anchors.verticalCenter: parent.verticalCenter
            anchors.horizontalCenter: parent.horizontalCenter
            source: "neirons_logo.png"
            fillMode: Image.PreserveAspectFit
        }

        AnimatedImage {
            id: animatedImage
            x: 236
            y: 200
            width: 100
            height: 100
            source: "loading.gif"
        }
    }
}

wallet.qml

import QtQuick 2.14
import QtQuick.Controls 2.14
import QtQuick.Layouts 1.14


ApplicationWindow {
    id: root
    visible: true
    width: 210; height: 210

    Rectangle {
        id: rectangle
        x: 70
        y: 132
        width: 200
        height: 200
        color: "#72ded8"
        anchors.verticalCenterOffset: 0
        anchors.horizontalCenterOffset: 0
        anchors.horizontalCenter: parent.horizontalCenter
        anchors.verticalCenter: parent.verticalCenter

        ColumnLayout {
            x: 60
            y: 73
            width: 109
            height: 128
            anchors.verticalCenter: parent.verticalCenter
            anchors.horizontalCenter: parent.horizontalCenter

            TextInput {
                id: nameAccount1
                text: qsTr("nameAccount")
                Layout.fillWidth: true
                Layout.alignment: Qt.AlignHCenter | Qt.AlignTop
                Layout.preferredHeight: 20
                Layout.preferredWidth: 80
                verticalAlignment: Text.AlignVCenter
                font.pixelSize: 12
            }

            TextInput {
                id: nameAccount2
                text: qsTr("Name Account")
                Layout.fillWidth: true
                Layout.alignment: Qt.AlignHCenter | Qt.AlignTop
                Layout.preferredHeight: 20
                Layout.preferredWidth: 80
                font.pixelSize: 12
            }
        }

        Button {
            id: submitNameAccount
            x: 50
            y: 134
            width: 81
            height: 23
            text: qsTr("Add")
            font.bold: true
            font.pointSize: 12
            anchors.horizontalCenter: parent.horizontalCenter
            onClicked: backend.add_info()
        }
    }
}