qml 与 c++交互

感觉qml，有利有弊，编写业务逻辑，使用起来感觉不爽。

qml界面语言与qt c++交互麻烦。c++到qml都要qmlRegisterType方式，  setContextProperty 方式。

qml到c++，就像解析xml一样，找啊找啊

1，qml调用c++  qmlRegisterType方式

#include "mainwindow.h"
#include <QApplication>
#include <QScrollArea>
#include <QPushButton>
#include <QLabel>
#include <QImage>
#include <QQmlEngine>
#include <QtQml>
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQuickItem>
#include <QMetaObject>
#include <QDebug>
#include <QColor>
#include <QVariant>


int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    qmlRegisterType<ColorMaker>("an.qt.ColorMaker", 1, 0, "ColorMaker");
    QQmlApplicationEngine engine;
    //engine.rootContext()->setContextProperty("colorMaker", new ColorMaker);
    engine.load(QUrl(QStringLiteral("qrc:/cpptoQml.qml")));
    return app.exec();
}

class ColorMaker : public QObject
{
    Q_OBJECT

public:

    int nn = 0;
    Q_INVOKABLE  int setA(int a)
    {
        nn = a;
        return nn;
    }

signals:
    void colorChanged(const QColor & color);

    void currentTime(const QString &strTime);

public slots:
    void start()
    {
        qDebug() << "qqqq" << nn;
    }

    void stop()
    {

    }
};

import QtQuick 2.4
import QtQuick.Window 2.2
import QtQuick.Controls 1.2
import QtQuick.Controls.Styles 1.4
import an.qt.ColorMaker 1.0
Window {
    id:rootid
    objectName: "rootid";
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World qt5")
    color: "gray"
    Item {
        ColorMaker {
        id:colorMaker;

        }
        width: 200
        height: 200
        visible: true
        layer.enabled: true
        id: nonLayered
        focus: true
        Keys.enabled: true
        Keys.onPressed:  {
            var component;
            var sprite;
            if(focus == true)
            {
                console.log("mouse button onSpacePressed 1")

                var n = colorMaker.setA(100);
                console.log("mouse button onSpacePressed " + n );
                colorMaker.start();
            }
            else
                console.log("mouse button onSpacePressed")
        }
    }
    Text {
        objectName: "textID";
        id:textID
        x:100
        y:100
        font { pixelSize: 19; bold: true }
        text: "dddddddddddddddd"

    }
}

2，qml调用c++  setContextProperty 

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修改这里

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    //qmlRegisterType<ColorMaker>("an.qt.ColorMaker", 1, 0, "ColorMaker");
    QQmlApplicationEngine engine;
    engine.rootContext()->setContextProperty("colorMaker", new ColorMaker);
    engine.load(QUrl(QStringLiteral("qrc:/cpptoQml.qml")));

import QtQuick 2.4
import QtQuick.Window 2.2
import QtQuick.Controls 1.2
import QtQuick.Controls.Styles 1.4
//import an.qt.ColorMaker 1.0
Window {
    id:rootid
    objectName: "rootid";
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World qt5")
    color: "gray"
    Item {
        /*ColorMaker {
        id:colorMaker;

        }*/
        width: 200
        height: 200
        visible: true

3，c++调用qml

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    //qmlRegisterType<ColorMaker>("an.qt.ColorMaker", 1, 0, "ColorMaker");
    QQmlApplicationEngine engine;
    engine.rootContext()->setContextProperty("colorMaker", new ColorMaker);
    engine.load(QUrl(QStringLiteral("qrc:/cpptoQml.qml")));



    QObject * rootItem  = 0;
    QList<QObject*> listQ = engine.rootObjects();
    for(  QList<QObject*>::iterator it = listQ.begin();it != listQ.end();++it)
    {
        qDebug() << " return - " << (*it)->objectName();
        if( (*it)->objectName() == "rootid")
        {
            rootItem = *it;
            break;
        }

    }
    if(!rootItem)
        return 0;
    QObject * textLabel = rootItem->findChild<QObject*>("textID");
    if(textLabel)
    {
        bool bRet = QMetaObject::invokeMethod(textLabel, "setText", Q_ARG(QString, "world hello"));
        qDebug() << "call setText return - " << bRet;
        textLabel->setProperty("color", QColor::fromRgb(255,0,0));
        textLabel->setProperty("text",  QString("world hello"));
        bRet = QMetaObject::invokeMethod(textLabel, "doLayout");
        qDebug() << "call doLayout return - " << bRet;

    }
    return app.exec();
}