qml通过注册QML文件来发送信号进行多个QML页面进行交互

在QML编程中，我们知道通过注册C++文件来向qml发送信号进行交互，其实Qml也可以通过注册QML文件，使用qml文件中的信号进行多页面信息交互，下面是简单的示例：

//main.qml
import QtQuick 2.12
import QtQuick.Window 2.12
import QtQuick.Controls 2.12
import QmlEvents 1.0

Window {
    id: mainWindow
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")

    Loader {
        id: loadWindow
        anchors.top: parent.top
        anchors.topMargin: 100
        anchors.right: parent.right
        anchors.rightMargin: 50
        onLoaded: {
                    console.log("SubWinidow.qml============onLoaded============")
                }
    }

    Rectangle {
        width: 400
        height: 50
        anchors.top: parent.top
        anchors.topMargin: 20
        anchors.left: parent.left
        anchors.leftMargin: 50
        Row {
            spacing: 5

            anchors.fill: parent

            Button {
                text: qsTr("Show SubWindow")
                onClicked: {
                    console.log("=============================load SubWindow====")
                    var subParams = {
                        "strText":  qsTr("SubWindow"),
                        "strColor": "red"
                    }
                    loadWindow.setSource("qrc:/SubWindow.qml", subParams)
                    loadWindow.item.show()
                }
            }
            Button {
                text: qsTr("发Json数据")
                onClicked: {
                    console.log("==========================发Json数据===")
                    var jsonParam = {
                        "title": "标题",
                        "length": 12
                    }
                    QmlEvents.sendTitleParam(jsonParam)
                }
            }
            Button {
                text: qsTr("发String")
                onClicked: {
                    console.log("=============================发String")
                    var strTxt = qsTr("普通字符串")
                    QmlEvents.showName(strTxt)
                }
            }
        }


    }


    //显示文字
    Text {
        id: strText
        text: qsTr("text")
        anchors.centerIn: parent
        color: "green"
        font.pixelSize: 16
    }

    Connections{
        target: QmlEvents

        onSendTitleParam: {
            console.log("main.qml=====onSendTitleParam======================:" + JSON.stringify(jsonParam))

        }

        onShowName: {
            console.log("main.qml=====onShowName======================:" + strName)

        }
    }

}

//SubWindow.qml
import QtQuick 2.12
import QtQuick.Window 2.12
import QmlEvents 1.0

Window {
    visible: true
    id: windowView
    width: 200
    height: 200
    //modality: Qt.WindowModal
    //flags: Qt.FramelessWindowHint
    color: "blue"

    property string strText: ""
    property string strColor: ""

    Rectangle {
        anchors.centerIn: parent
        Text {
            id: name
            anchors.fill: parent
            text: strText
            color: strColor
        }
    }

    MouseArea{//关闭按钮
        id: closeBtn
        z: 1
        width: 16
        height: 16
        hoverEnabled: true
        cursorShape: Qt.PointingHandCursor
        anchors.right: parent.right
        anchors.rightMargin: 10
        anchors.top: parent.top
        anchors.topMargin: 6

        Text {
            font.pixelSize: 18
            font.bold: true
            color: parent.containsMouse ? "red" : "#000000"
            text: qsTr("×")
        }

        onClicked: {
            windowView.close();
        }
    }

    Connections{
        target: QmlEvents

        onSendTitleParam: {
            console.log("SubWindow.qml=====onSendTitleParam======================:" + JSON.stringify(jsonParam))

        }

        onShowName: {
            console.log("SubWindow.qml======onShowName======================:" + strName)

        }
    }

}

//QmlEvent.qml
pragma Singleton
import QtQuick 2.12

QtObject {

    //发送标题参数可以是json格式
    signal sendTitleParam(var jsonParam)

    //显示名字
    signal showName(var strName)
}

//main.cpp
#include 
#include 

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    Q_INIT_RESOURCE(qml);
    qmlRegisterSingletonType(QUrl("qrc:/QmlEvent.qml"), "QmlEvents", 1, 0, "QmlEvents"); //qml文件单列注册，然后其他qml文件使用注册过的qml单列

    QQmlApplicationEngine engine;
    const QUrl url(QStringLiteral("qrc:/main.qml"));
    QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                     &app, [url](QObject *obj, const QUrl &objUrl) {
        if (!obj && url == objUrl)
            QCoreApplication::exit(-1);
    }, Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}