Demonstrates progress bars

Author: mttwc

HelloQt.pro

@@ -6,9 +6,9 @@
 QT += widgets
 
 SOURCES = src/main.cpp \
-          src/list_demonstration.cpp \
+          src/progress_bar_demonstration.cpp \
 
-HEADERS = src/list_demonstration.h
+HEADERS = src/progress_bar_demonstration.h
 
 CONFIG -= app_bundle
 CONFIG += c++11

src/list_demonstration.cpp

@@ -1,14 +1,15 @@
 #include <QApplication>
 #include <QWidget>
-#include "list_demonstration.h"
+#include "progress_bar_demonstration.h"
 
 int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);
 
-    ListDemonstration window;
-
-    window.setWindowTitle("List Demonstration");
+    ProgressBarDemonstration window;
+    
+    window.resize(250, 150);
+    window.setWindowTitle("Progress Bar Demonstration");
     window.show();
 
     return app.exec();

src/list_demonstration.h

@@ -0,0 +1,67 @@
+#include "progress_bar_demonstration.h"
+#include <QTimer>
+#include <QGridLayout>
+
+ProgressBarDemonstration::ProgressBarDemonstration(QWidget *parent)
+    : QWidget(parent)
+{
+    progress = 0;
+    timer = new QTimer(this);
+    connect(timer, &QTimer::timeout, this, &ProgressBarDemonstration::updateBar);
+    
+    QGridLayout *grid = new QGridLayout(this);
+    grid->setColumnStretch(2, 1);
+    
+    pbar = new QProgressBar();
+    grid->addWidget(pbar, 0, 0, 1, 3);
+    
+    startBtn = new QPushButton("Start", this);
+    connect(startBtn, &QPushButton::clicked, this, &ProgressBarDemonstration::startTimer);
+    grid->addWidget(startBtn, 1, 0, 1, 1);
+    
+    stopBtn = new QPushButton("Stop", this);
+    connect(stopBtn, &QPushButton::clicked, this, &ProgressBarDemonstration::stopTimer);
+    grid->addWidget(stopBtn, 1, 1, 1, 1);
+}
+
+void ProgressBarDemonstration::startTimer()
+{
+    if (progress > MAX_VALUE)
+    {
+        progress = 0;
+        pbar->setValue(0);
+    }
+    
+    if (!timer->isActive())
+    {
+        startBtn->setEnabled(false);
+        stopBtn->setEnabled(true);
+        timer->start(DELAY); // The timeout signal is emitted every DELAY milliseconds
+    }
+}
+
+void ProgressBarDemonstration::stopTimer()
+{
+    if (timer->isActive())
+    {
+        startBtn->setEnabled(true);
+        stopBtn->setEnabled(false);
+        timer->stop();
+    }
+}
+
+void ProgressBarDemonstration::updateBar()
+{
+    progress++;
+    
+    if (progress <= MAX_VALUE)
+    {
+        pbar->setValue(progress);
+    }
+    else
+    {
+        timer->stop();
+        startBtn->setEnabled(true);
+        stopBtn->setEnabled(false);
+    }
+}

src/main.cpp

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <QWidget>
+#include <QProgressBar>
+#include <QPushButton>
+
+class ProgressBarDemonstration : public QWidget
+{
+    Q_OBJECT
+    
+    public:
+        ProgressBarDemonstration(QWidget *parent = 0);
+        
+    private:
+        int progress;
+        QTimer *timer;
+        QProgressBar *pbar;
+        QPushButton *startBtn;
+        QPushButton *stopBtn;
+        static const int DELAY = 200;
+        static const int MAX_VALUE = 100;
+        
+        void updateBar();
+        void startTimer();
+        void stopTimer();
+};