CODEWITHSUNDEEP
qtbutton
YeP
YeP

Reputation: 211

How to avoid clicking push Button twice in Qt

In my Qt application, I have a push button to launch a job which takes ~10s to complete. I notice that during the 10s period after clicking the button, if I click in the button area again, it is still taken as a click and the job will be launched again as soon as it is concluded from the first click.

Is this expected? What can I do to avoid the button click until the job from the first click is concluded? Thanks.

Upvotes: 0

Views: 4337

Answers (3)

YeP
YeP

Reputation: 211

After poking on it, I think the "QCoreApplication::processEvents()" does the trick. Here is what I find out, also as a conclusion to the subject:

=========================

void MainWindow::on_pushButton_2_clicked()
{
    QDateTime dateTime;
    qDebug()<<"Btn2-Time#1:"<<dateTime.currentDateTime().toString("[yyyyMMdd hh:mm:ss] ");
    QThread::sleep(10);
    qDebug()<<"Btn2-Time#2:"<<dateTime.currentDateTime().toString("[yyyyMMdd hh:mm:ss] ");
}

Originally my code is like above, and as I click the button and click again during the 10s sleep time, I get this and notice the 2nd run start immediately after the 1st run concluded.

Btn2-Time#1: "[20170731 16:07:39] "
Btn2-Time#2: "[20170731 16:07:49] "
Btn2-Time#1: "[20170731 16:07:49] "
Btn2-Time#2: "[20170731 16:07:59] "

=========================

void MainWindow::on_pushButton_clicked()
{
    QDateTime dateTime;
    ui->pushButton->setEnabled(false);

    qDebug()<<"Btn1-Time#1:"<<dateTime.currentDateTime().toString("[yyyyMMdd hh:mm:ss] ");
    QThread::sleep(10);
    qDebug()<<"Btn1-Time#2:"<<dateTime.currentDateTime().toString("[yyyyMMdd hh:mm:ss] ");
    QCoreApplication::processEvents();
    ui->pushButton->setEnabled(true);

}

Following one of the comment, I added the disable and QCoreApplication::processEvents(); as above, now the same operation will not trigger the 2nd run, because the 2nd click is processed before the button is reset to enable.

Btn1-Time#1: "[20170731 16:07:24] "
Btn1-Time#2: "[20170731 16:07:34] "

=========================

void MainWindow::on_pushButton_3_clicked()
{
    QDateTime dateTime;
    ui->pushButton_3->setEnabled(false);

    qDebug()<<"Btn3-Time#1:"<<dateTime.currentDateTime().toString("[yyyyMMdd hh:mm:ss] ");;
    QThread::sleep(10);
    qDebug()<<"Btn3-Time#2:"<<dateTime.currentDateTime().toString("[yyyyMMdd hh:mm:ss] ");
    //QCoreApplication::processEvents();
    ui->pushButton_3->setEnabled(true);
}

Commenting out the QCoreApplication::processEvents();, it processes the 2nd click as original, so just disabling the button isn't the solution, and the QCoreApplication::processEvents(); does the trick!

Btn3-Time#1: "[20170731 16:08:00] "
Btn3-Time#2: "[20170731 16:08:10] "
Btn3-Time#1: "[20170731 16:08:10] "
Btn3-Time#2: "[20170731 16:08:20] "

=========================

Thank you!

Upvotes: 1

Ph03n1x
Ph03n1x

Reputation: 844

I would disable the button until the job is completed and add a label (or GIF animation) to indicate the "work in progress". This is better for the user, as he sees that the button is disabled --> i.e. he has a "feedback" from your system. Then when the process is finished you emit a "finished" signal Signals and Slots, that is connected to an "enableButtons" slot --> i.e. After finishing the process you re-enalbe the button.

void Process(){
 ui->yourButton->setEnabled(false);
/* Maybe play loading gif animation etc*/
/* Do your work here */
emit ProcessFinished();
}

Upvotes: 3

Magnus Wang
Magnus Wang

Reputation: 180

You can use the "setEnabled" and setDisabled" methods to deactivate the button when the job is exectued and then add a callback to activate the button when the job is complete.

Read the documentation for setEnabled here: http://doc.qt.io/qt-5/qwidget.html#enabled-prop

Upvotes: 0

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