从 Python 发送信号到 Compononent.onCompleted

Question

我正在把事情串起来，慢慢开始变得更有意义了。我了解如何使用 onClick 发送信号等。

目的：GUI，根据点击的按钮，它会读取和 RFID 卡。此代码将被保留并传递到数据库。

有两个按钮。一个是开放的，另一个是关闭的。其中任何一个都会打开相同的 RFID Python 脚本来读取卡片。这些脚本都运行在一个stackView中。下面是卡片 reader 的 stackView 页面。它从上一个屏幕上按下的按钮加载得很好。

要导航到正确的 stackView，stackView.push(Qt.resolvedUrl("**GET URL FROM PYTHON**"))。

因此，根据上一页按下的按钮，它将加载 Welcome QML 或 goodbye QML

主要 QML

///For button OPEN
onClicked: {
    backend.open() ///Here connect to the correct python def
    stackView.push(Qt.resolvedUrl("ReadCard.qml")) ///Go to read card
}

/// For button CLOSE
onClicked: {
    backend.close() ///Here connect to the correct python def
    stackView.push(Qt.resolvedUrl("ReadCard.qml"))///Go to read card
}

Python: main.py

# Signal Set Data
readOpen = Signal(str)
scanOut = Signal(str)

@Slot()
def open(self):
    # Read card code
    # SQL Code
    # Move to Welcome QML if the lock is opened.
    self.readOpen.emit("Welcome.qml")

@Slot()
def close(self):
    # Read card code
    # SQL Code
    # Move to Good-Bye QML when lock is closed.
    self.scanOut.emit("GoodBye.qml")
    print("This is where the code to clock out will go")

QML: reader.qml

import QtQuick 2.0
import QtQuick.Controls 2.15
import "../controls"
import QtQuick.Layouts 1.0

Item {
    Rectangle {
        id: rectangle
        ...Other properties...

        Rectangle {
            id: rectangleTop
            ...Other Properties...
        }

        Rectangle {
            id: rectangleVisible
            color: "#1d2128"
            radius: 10
            anchors.left: parent.left
            anchors.right: parent.right
            anchors.top: rectangleTop.bottom
            anchors.bottom: parent.bottom
            anchors.bottomMargin: 40
            anchors.rightMargin: 50
            anchors.leftMargin: 50
            anchors.topMargin: 10

            //The timer just used to simulate card read as no card reader connected yet
            Timer {
                    id: timer
            }

            function delay(delayTime,cb) {
                timer.interval = delayTime;
                timer.repeat = false;
                timer.triggered.connect(cb);
                timer.start();
            }

            Component.onCompleted: delay(1000, function() {
                stackView.push(Qt.resolvedUrl("URL FROM PYTHON"))
            })

            Text {
                id: text1
                x: 148
                y: 119
                width: 288
                height: 109
                color: "#ffffff"
                text: qsTr("Scan your card")
                anchors.verticalCenter: parent.verticalCenter
                font.pixelSize: 36
                horizontalAlignment: Text.AlignHCenter
                verticalAlignment: Text.AlignVCenter
                anchors.horizontalCenter: parent.horizontalCenter
            }
        }
    }

    Connections{
        target: backend
    }
}

所以最大的问题是。如何从 Python 中获取 URL 并将其输入 Qt.resolvedurl?

Answer 1

据我了解，OP 希望从 python 处理 StackView url，因此一个可能的解决方案是创建一个 qproperty，将 url 通过连接：

import os
import random
import sys
from pathlib import Path

from PySide2.QtCore import Property, QCoreApplication, QObject, Qt, QUrl, Signal, Slot
from PySide2.QtGui import QGuiApplication
from PySide2.QtQml import QQmlApplicationEngine

CURRENT_DIRECTORY = Path(__file__).resolve().parent


class Manager(QObject):
    url_changed = Signal(name="urlChanged")

    def __init__(self, parent=None):
        super().__init__(parent)
        self._url = QUrl()

    @Property(QUrl, notify=url_changed)
    def url(self):
        return self._url

    def _update_url(self, url):
        if self.url == url:
            return
        self._url = url
        self.url_changed.emit()

    @Slot()
    def open(self):
        self._update_url(QUrl("Welcome.qml"))

    @Slot()
    def close(self):
        self._update_url(QUrl("GoodBye.qml"))


def main():
    app = QGuiApplication(sys.argv)

    manager = Manager()

    engine = QQmlApplicationEngine()
    engine.rootContext().setContextProperty("manager", manager)

    filename = os.fspath(CURRENT_DIRECTORY / "main.qml")
    url = QUrl.fromLocalFile(filename)

    def handle_object_created(obj, obj_url):
        if obj is None and url == obj_url:
            QCoreApplication.exit(-1)

    engine.objectCreated.connect(handle_object_created, Qt.QueuedConnection)

    engine.load(url)

    sys.exit(app.exec_())


if __name__ == "__main__":
    main()

main.qml

import QtQuick 2.15
import QtQuick.Controls 2.15
import QtQuick.Layouts 1.15
import QtQuick.Window 2.15

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Qt is awesome!!!")

    RowLayout {
        id: row_layout

        width: parent.width

        Button {
            text: "Open"
            Layout.fillWidth: true
            onClicked: manager.open()
        }

        Button {
            text: "Close"
            Layout.fillWidth: true
            onClicked: manager.close()
        }

    }

    StackView {
        id: stack_view

        anchors.top: row_layout.bottom
        anchors.bottom: parent.bottom
        width: parent.width
    }

    Connections {
        function onUrlChanged() {
            stack_view.pop();
            stack_view.push(Qt.resolvedUrl(manager.url));
        }

        target: manager
    }

}

Welcome.qml

import QtQuick 2.15
import QtQuick.Controls 2.15

Page {
    Text {
        text: "Welcome"
        anchors.centerIn: parent
    }

}

GoodBye.qml

import QtQuick 2.15
import QtQuick.Controls 2.15

Page {
    Text {
        text: "GoodBye"
        anchors.centerIn: parent
    }

}

从 Python 发送信号到 Compononent.onCompleted

Send signal from Python to Compononent.onCompleted

python

qml

pyside2