第85课 多线程与界面组件的通信（下）

#ifndef STRINGEVENT_H
#define STRINGEVENT_H

#include <QEvent>
#include <QString>
//自定义事件对象
class StringEvent : public QEvent
{
    QString m_data;
public:
    //提供全局唯一的Type值
    static const QEvent::Type TYPE = static_cast<QEvent::Type>(QEvent::User + 0xFF);
    explicit StringEvent(QString data = "");

    QString data();

    //用于测试采用postEvent发送事件对象，被接收后会自动释放！
    ~StringEvent();
};

#endif // STRINGEVENT_H

#include "StringEvent.h"
#include <QDebug>

StringEvent::StringEvent(QString data) : QEvent(TYPE)
{
    m_data = data;
    qDebug() << "StringEvent::StringEvent(QString data)";
}

QString StringEvent::data()
{
    return m_data;
}

StringEvent::~StringEvent()
{
    qDebug() << "StringEvent::~StringEvent()";
}

#ifndef UPDATETHREAD_H
#define UPDATETHREAD_H

#include <QThread>

class UpdateThread : public QThread
{
    Q_OBJECT
protected:
    void run();
public:
    explicit UpdateThread(QObject* parent = 0);

signals:
    void updateUI(QString text);
};

#endif // UPDATETHREAD_H

#include "UpdateThread.h"
#include <QApplication>
#include "StringEvent.h"

UpdateThread::UpdateThread(QObject *parent) : QThread(parent)
{
}

void UpdateThread::run()
{
    //发送事件对象
    QApplication::postEvent(parent(), new StringEvent("Begin"));  //parent为目标widget

    for(int i=0; i<10; i++){
        QApplication::postEvent(parent(), new StringEvent(QString::number(i)));

        sleep(1);
    }

    QApplication::postEvent(parent(), new StringEvent("End"));
}

#ifndef WIDGET_H
#define WIDGET_H
#include <QPlainTextEdit>
#include <QWidget>
#include "UpdateThread.h"

class Widget : public QWidget
{
    Q_OBJECT
    UpdateThread m_thread;
    QPlainTextEdit textEdit;

public:
    Widget(QWidget *parent = 0);
    bool event(QEvent* evt);
    ~Widget();
};

#endif // WIDGET_H

#include "Widget.h"
#include "StringEvent.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
    textEdit.setParent(this);
    textEdit.move(20, 20);
    textEdit.resize(200, 150);
    textEdit.setReadOnly(true);

    connect(&m_thread, SIGNAL(updateUI(QString)), this, SLOT(appendText(QString)));

    //这里使用了一个技巧，将Widget这个组件传入线程中所供子线程访问。
    m_thread.setParent(this);//传这个目标Widget组件给子线程

    m_thread.start();
}

bool Widget::event(QEvent *evt)
{
    bool ret = true;

    if(evt ->type() ==StringEvent::TYPE ){
        StringEvent* se = dynamic_cast<StringEvent*>(evt);

        if(se != NULL){
            textEdit.appendPlainText(se->data());
        }
    }else{
        ret = QWidget::event(evt);
    }

    return ret;
}

Widget::~Widget()
{

}

#include "Widget.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();

    return a.exec();
}