Qt 5.1通过线程的QML属性

Question

出于解决方案的目的,我创建了一个重复我遇到的问题的TestApp.

我将我的软件从Qt 4.8移植到Qt 5.1.

我的第一个程序是多线程的,并且与QML一起工作顺利,只要这些类是线程安全的.但现在我收到这条消息:

QObject::connect: No such slot TestApp::run() in ..\ThreadingTest\main.cpp:21
QQmlEngine: Illegal attempt to connect to TestApp(0x29cfb8) that is in a different thread than the QML engine QQmlEngine(0x2f3e0f8).

这是重现错误的代码:

main.cpp:

#include <QtGui/QGuiApplication>
#include <QQmlContext>
#include <QThread>
#include "qtquick2applicationviewer.h"
#include "testapp.h"

int main(int argc, char *argv[])
{
    int out;

    QGuiApplication app(argc, argv);

    QtQuick2ApplicationViewer viewer;

    TestApp * testapp = new TestApp();

    QThread * testappThread;

    testappThread = new QThread();

    QObject::connect(testappThread, SIGNAL(started()), testapp, SLOT(run()));

    testapp->moveToThread(testappThread);

    testappThread->start();

    viewer.rootContext()->setContextProperty("TestApp", testapp);

    viewer.setMainQmlFile(QStringLiteral("qml/ThreadingTest/main.qml"));
    viewer.showExpanded();

    out = app.exec();

    testappThread->quit();
    testappThread->wait();

    delete testapp;
    delete testappThread;

    return out;
}

testapp.h:

#ifndef TESTAPP_H
#define TESTAPP_H

#include <QObject>
#include <QString>
#include <QTimer>
#include <QReadWriteLock>

#define HELLOWORLD "Hello World !"

extern QReadWriteLock HelloWorldLock;

class TestApp : public QObject
{
    Q_OBJECT

    Q_PROPERTY(QString HelloWorld READ getHelloWorld WRITE setHelloWorld NOTIFY HelloWorldChanged)
public:
    explicit TestApp(QObject *parent = 0);

    virtual ~TestApp();

    QString getHelloWorld();

    void setHelloWorld(QString);

public slots:

    void run();

    void toggleHelloWorld();

signals:

    void HelloWorldChanged();

private:

    QString m_HelloWorld;
    QTimer * m_Timer;

};

#endif // TESTAPP_H

testapp.cpp:

#include "testapp.h"

QReadWriteLock HelloWorldLock(QReadWriteLock::Recursive);

TestApp::TestApp(QObject *parent) :
    QObject(parent)
{
    HelloWorldLock.lockForWrite();
    m_HelloWorld = HELLOWORLD;
    HelloWorldLock.unlock();

    m_Timer = new QTimer(this);

    connect(m_Timer, SIGNAL(timeout()), this, SLOT(toggleHelloWorld()));
}

TestApp::~TestApp() {
    m_Timer->stop();

    delete m_Timer;
}

QString TestApp::getHelloWorld() {
    HelloWorldLock.lockForRead();
    QString out = m_HelloWorld;
    HelloWorldLock.unlock();

    return out;
}

void TestApp::setHelloWorld(QString text) {
    HelloWorldLock.lockForWrite();
    m_HelloWorld = text;
    HelloWorldLock.unlock();

    emit HelloWorldChanged();
}

void TestApp::run() {
    m_Timer->start(1000);
}

void TestApp::toggleHelloWorld() {
    HelloWorldLock.lockForWrite();
    if(m_HelloWorld == "") {
        m_HelloWorld = HELLOWORLD;
    }
    else {
        m_HelloWorld = "";
    }
    HelloWorldLock.unlock();

    emit HelloWorldChanged();
}

main.qml:

import QtQuick 2.0

Rectangle {
    width: 360
    height: 360
    Text {
        text: TestApp.HelloWorld
        anchors.centerIn: parent
    }
    MouseArea {
        anchors.fill: parent
        onClicked: {
            Qt.quit();
        }
    }
}

我的程序非常复杂(很多属性和类与界面共享)我不想创建一个接口类只是为了连接我的属性...你有什么建议来处理这个问题吗？

Answer 1

你不需要自己编写应用程序,因为在Qt5中,QML 2引擎已经是大规模多线程的,所以只需启动QQuickView,向上下文公开你需要的C++部分,在其中设置QML文件,然后显示() .这就足够了.不要试图自己修改QML线程,这在QML1中实际上更复杂.