Qt ThreadExample

main.cpp

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

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

    return a.exec();
}

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"

#include "worker.h"
#include "QThread"

#include <QtConcurrent>

#define RAND_MAX = 20;

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    //!QtConcurrent
    connect(ui->btnQtConcurrent, &QPushButton::clicked, this,&MainWindow::startConcurrent);
    connect(this, &MainWindow::newConcurrentValue, this, &MainWindow::updateVonConcurrent);

    //!QThread
    //Initalisierung des Threads und der Workerklasse
    QThread * workerThread = new QThread();
    Worker *workerObject = new Worker();
    workerObject->moveToThread(workerThread);
    connect(workerThread, &QThread::started, workerObject, &Worker::init);

    //QThread und Worker aufräumen bei Programmende
    connect(workerThread, &QThread::finished, workerThread, &QThread::deleteLater);
    connect(workerThread, &QThread::finished, workerObject, &Worker::deleteLater);
    connect(qApp, &QApplication::aboutToQuit, workerThread, &QThread::quit);

    // Interaktion mit der Benutzeroberfläche
    connect(ui->btnQThread, &QPushButton::clicked,                                  workerObject, &Worker::start);
    connect(workerObject,   &Worker::qThreadResult,                                 ui->lblResult,&QLabel::setText);
    connect(ui->dSpinBase,  QOverload<double>::of(&QDoubleSpinBox::valueChanged),   workerObject, &Worker::newBase);
    connect(ui->dSpinExp,   QOverload<double>::of(&QDoubleSpinBox::valueChanged),   workerObject, &Worker::newExponent);

    workerThread->start();
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::startConcurrent()
{
    QtConcurrent::run([=]{
        int i = 0;
        while( i < 10001){
            if (qrand() == 5){
                emit newConcurrentValue(i);
                i++;
            }
        }
    });
}

void MainWindow::updateVonConcurrent(int value)
{
    ui->progressBar->setValue(value);
    ui->lblQtConcurrent->setText(QString::number(value) + "von 10000");
}

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

signals:
    void newConcurrentValue(int value);

private slots:
    void startConcurrent();
    void updateVonConcurrent(int value);

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

mainwindow.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>723</width>
    <height>300</height>
   </rect>
  </property>
  <property name="font">
   <font>
    <pointsize>20</pointsize>
   </font>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralWidget">
   <property name="font">
    <font>
     <pointsize>15</pointsize>
    </font>
   </property>
   <layout class="QVBoxLayout" name="verticalLayout">
    <item>
     <layout class="QHBoxLayout" name="horizontalLayout">
      <item>
       <widget class="QPushButton" name="btnQtConcurrent">
        <property name="text">
         <string>Start QtConcurrent</string>
        </property>
       </widget>
      </item>
      <item>
       <spacer name="horizontalSpacer">
        <property name="orientation">
         <enum>Qt::Horizontal</enum>
        </property>
        <property name="sizeHint" stdset="0">
         <size>
          <width>0</width>
          <height>20</height>
         </size>
        </property>
       </spacer>
      </item>
      <item>
       <widget class="QLabel" name="lblQtConcurrent">
        <property name="text">
         <string>0 von 10000</string>
        </property>
       </widget>
      </item>
      <item>
       <widget class="QProgressBar" name="progressBar">
        <property name="maximum">
         <number>10000</number>
        </property>
        <property name="value">
         <number>0</number>
        </property>
       </widget>
      </item>
     </layout>
    </item>
    <item>
     <layout class="QHBoxLayout" name="horizontalLayout_2">
      <item>
       <widget class="QPushButton" name="btnQThread">
        <property name="text">
         <string>Start QThread</string>
        </property>
       </widget>
      </item>
      <item>
       <spacer name="horizontalSpacer_2">
        <property name="orientation">
         <enum>Qt::Horizontal</enum>
        </property>
        <property name="sizeHint" stdset="0">
         <size>
          <width>40</width>
          <height>20</height>
         </size>
        </property>
       </spacer>
      </item>
      <item>
       <widget class="QDoubleSpinBox" name="dSpinBase">
        <property name="value">
         <double>10.199999999999999</double>
        </property>
       </widget>
      </item>
      <item>
       <widget class="QLabel" name="lblText">
        <property name="text">
         <string>hoch</string>
        </property>
       </widget>
      </item>
      <item>
       <widget class="QDoubleSpinBox" name="dSpinExp">
        <property name="value">
         <double>2.500000000000000</double>
        </property>
       </widget>
      </item>
      <item>
       <spacer name="horizontalSpacer_3">
        <property name="orientation">
         <enum>Qt::Horizontal</enum>
        </property>
        <property name="sizeHint" stdset="0">
         <size>
          <width>40</width>
          <height>20</height>
         </size>
        </property>
       </spacer>
      </item>
      <item>
       <widget class="QLabel" name="lblResult">
        <property name="text">
         <string>Ergebnis</string>
        </property>
       </widget>
      </item>
     </layout>
    </item>
   </layout>
  </widget>
  <widget class="QMenuBar" name="menuBar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>723</width>
     <height>43</height>
    </rect>
   </property>
  </widget>
  <widget class="QToolBar" name="mainToolBar">
   <attribute name="toolBarArea">
    <enum>TopToolBarArea</enum>
   </attribute>
   <attribute name="toolBarBreak">
    <bool>false</bool>
   </attribute>
  </widget>
  <widget class="QStatusBar" name="statusBar"/>
 </widget>
 <layoutdefault spacing="6" margin="11"/>
 <resources/>
 <connections/>
</ui>

ThreadExample.pro

#-------------------------------------------------
#
# Project created by QtCreator 2017-05-31T16:27:44
#
#-------------------------------------------------

QT       += core gui concurrent

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = ThreadExample
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0


SOURCES += \
        main.cpp \
        mainwindow.cpp \
    worker.cpp

HEADERS += \
        mainwindow.h \
    worker.h

FORMS += \
        mainwindow.ui

worker.cpp

#include "worker.h"
#include "qmath.h"

Worker::Worker(QObject *parent) : QObject(parent)
{

}

void Worker::init()
{
    timer = new QTimer(this);
    timer->setInterval(100);
    connect(timer, &QTimer::timeout, this, &Worker::calculate);
}

void Worker::start()
{
    if(timer){
        timer->start();
    }
}

void Worker::newBase(double value)
{
    m_Base = value;
}

void Worker::newExponent(double value)
{
    m_Expo = value;
}

void Worker::calculate()
{
    qreal result = qPow(m_Base, m_Expo);
    emit qThreadResult(QString::number(result) + " um "+QTime::currentTime().toString("mm:hh:ss.zzz"));
}

worker.h

#ifndef WORKER_H
#define WORKER_H

#include <QObject>
#include <QTimer>
#include <QTime>

class Worker : public QObject
{
    Q_OBJECT
public:
    explicit Worker(QObject *parent = nullptr);


public slots:
    void init();
    void start();

public slots:
    void newBase(double value);
    void newExponent(double value);

signals:
    void qThreadResult(QString str);

private slots:
    void calculate();

private:
    double m_Base = 10.5;
    double m_Expo = 2.3;

    QTimer *timer = Q_NULLPTR;
};

#endif // WORKER_H