How to make StopWatch in QT c ?-CodePudding

I'm making an app on QT with UI. Also, I have a function. I want to display the running time of a function. I also want to pause the stopwatch. Any ideas on how to properly embed a stopwatch in my application? Here is my code:

void SomeFunc()
{
while (1)
{
// Start Timer
// some code
// Stop Timer
// Start Timer2
// some code
// Stop Timer2
}
}

on_push_button()
{
auto futureWatcher = new QFutureWatcher<void>(this);
    QObject::connect(futureWatcher, &QFutureWatcher<void>::finished, futureWatcher, &QFutureWatcher<void>::deleteLater);
    auto future = QtConcurrent::run( [=]{ PackBytes( file_path, file_name, isProgressBar); });

    futureWatcher->setFuture(future);
}

CodePudding user response：

Use QElapsedTimer for measuring the duration since starting the computation. Judging from your previous questions on very related topics, you do have a MainWindow class that contains the on_push_button function. In that class, declare the QElapsedTimer member; then start it when your computation starts.

Use a QTimer to update the GUI element you use for displaying the current duration (only needs to run once a second or so).

Example code:

in your header file:

#include <QElapsedTimer>
#include <QTimer>
//...

class MainWindow
{
    // ... other stuff you have
private:
    QTimer m_stopwatchUpdate;
    QElapsedTimer m_stopwatchElapsed;
};

in your cpp file:

void MainWindow::on_push_button()
{
    // ideally do this once only in the constructor of MainWindow:
    connect(&m_stopwatchUpdate, &QTimer::timeout, this, [=]{
        //.. update GUI elements here...
    });
    auto futureWatcher = new QFutureWatcher<void>(this);
    connect(futureWatcher, &QFutureWatcher<void>::finished, futureWatcher, &QFutureWatcher<void>::deleteLater);
    auto future = QtConcurrent::run( [=]{
        m_stopwatchElapsed.start();
        PackBytes(file_path, file_name, isProgressBar);
    });
    m_stopwatchUpdate.start(1000);
    futureWatcher->setFuture(future);
}