Qt handling QPushButton Autorepeat() behavior with

问题:

I'm new to QT and am making a widget that interfaces with a pre-existing gui. I'd like to have my widget continuously output one signal while the user has a pushbutton pressed and then continuously output another when it is released.

By enabling autorepeat I can have the widget output my signal while the user is pressing the pushbutton, however, the output signal switches between pressed() and released(). E.G.

<> Outputs: * pressed signal * released signal * pressed signal * released signal

I've seen this question been asked about keyPressEvents but I'm not sure how to access isAutoRepeat() for PushButtons. Can someone give me advice on this?

回答1:

One way is you can use timer object to achieve this. Below is the example, that will run the 2 slot's when button pressed and released. The code comment will explain in detail. when button pressed & released a text box will show the continuous time in Milli-seconds. Timer is an object that will emit the timeout() signal in a given interval. We need to stop and start the alternate timers in button pressed / released signal. This application created using the QT Creator "QT Widgets Application" wizard. Hope this help.

//Header File

    class MainWindow : public QMainWindow{
    Q_OBJECT
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
private slots:
    //Button slots
    void on_pushButton_pressed(); //Continuous press 
    void on_pushButton_released(); //Continuous release
    void on_pushButton_2_clicked(); //stop both the timer
    //QTimer timeout actions
    void timer1_action(); 
    void timer2_action();

private:
    Ui::MainWindow *ui;
    //Timer object
    QTimer *t1, *t2;
    //Date time object for testing
    QDateTime dt1,dt2;
};

//CPP file

MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow){
    ui->setupUi(this);
    //Parent object will take care of the deallocation of the 2 timer objects
    t1 = new QTimer(this);
    t2 = new QTimer(this);
    //Interval to the timer object
    t1->setInterval(10);
    t2->setInterval(10);
    //Signal slot for the timer
    this->connect(t1,SIGNAL(timeout()),this,SLOT(timer1_action()));
    this->connect(t2,SIGNAL(timeout()),this,SLOT(timer2_action()));
}
MainWindow::~MainWindow(){
    delete ui;
}
void MainWindow::on_pushButton_pressed(){
    //starting and stoping the timer
    t2->stop();
    t1->start();
    //date time when pressed
    dt1 = QDateTime::currentDateTime();
}
void MainWindow::on_pushButton_released(){
    //starting and stoping the timer
    t1->stop();
    t2->start();
    //date time when pressed
    dt2 = QDateTime::currentDateTime();
}
void MainWindow::timer1_action(){
    ui->txtTimer1->setPlainText("Button Pressed for " + QString::number(dt1.msecsTo(QDateTime::currentDateTime())) + " Milli Seconds");
}
void MainWindow::timer2_action(){
    ui->txtTimer2->setPlainText("Button Released for " + QString::number(dt2.msecsTo(QDateTime::currentDateTime())) + " Milli Seconds");
}
void MainWindow::on_pushButton_2_clicked(){
    //stoping both the timer
    t1->stop();
    t2->stop();
}