QTimer and QLCDNumber not working correctly together.

[Jorge]

Hi,
I'm trying to simulate the pulses of a machine we're building and I've decided to do it with a QTimer. I've read the documentation and I've seen how it works, however, I can't seem to get it to display in the QLCDNumber I want it to work with.
I've tried with signals and slots, but in the end the QLCDOutpot is an "A".
Here's the piece of my code where I attempt to make the connection, and then further where the methods are developed:

//Part of the .cpp 
    timer = new QTimer(this);

    ui->lcdLitres->setStyleSheet("background-color: rgb(162, 195, 228)");
    ui->lcdPrice->setStyleSheet("background-color: rgb(162, 195, 228)");
    ui->btnStart->setStyleSheet("background-color: rgb(161, 249, 7)");
    ui->btnCancel->setStyleSheet("background-color: rgb(245, 1, 3)");
    ui->lcdLitres->setDigitCount(10);
    ui->lcdPrice->setDigitCount(10);

    connect(ui->btnStart, SIGNAL(clicked()),
            timer, SLOT(start()));
    connect(timer, SIGNAL(timeout()),
            this, SLOT(elapseLiters()));

//Still .cpp
void QDispenseDisplay::on_btnStart_clicked()
{
    ui->btnCancel->setText("Detener");
    bCancelLoop = false;

    QSqlQuery query;
    query.exec("SELECT id, fPrecioUnit, fLitros, fImporte FROM Servicios WHERE id = last_insert_rowid()");

    query.next();
    QSqlRecord record = query.record();
    fUnitPrice = record.value(1).toFloat();
    fLitres = record.value(2).toFloat();
    fTotal = record.value(3).toFloat();

//    qDebug() << "Last ID: " << sLastId;
    qDebug() << "fPrecioUnit: " << fUnitPrice;
    qDebug() << "fLitros: " << fLitres;
    qDebug() << "fImporte: " << fTotal;
//    qDebug() << query.lastError();

    timer->setInterval(1000);

    QString sLitros = QString::number(fElapsedLitres, 'f', 2);
    QString sPrecio = QString::number(fUnitPrice * fElapsedLitres, 'f', 2);

    ui->lcdLitres->display(sLitros);
    ui->lcdPrice->display(sPrecio);

    if(fElapsedLitres == fLitres)
    {
        timer->stop();
    }
}
float QDispenseDisplay::getFElapsedLitres() const
{
    return fElapsedLitres;
}

void QDispenseDisplay::setFElapsedLitres(float value)
{
    fElapsedLitres = value;
}


void QDispenseDisplay::elapseLiters()
{
    setFElapsedLitres(fElapsedLitres + 1);
}

//header file

#ifndef QDISPENSEDISPLAY_H
#define QDISPENSEDISPLAY_H

#include <QWidget>
#include <QTimer>
#include <QLCDNumber>
#include <QtSql>
#include <QFileInfo>
#include <QElapsedTimer>

namespace Ui {
class QDispenseDisplay;
}

class QDispenseDisplay : public QWidget
{
    Q_OBJECT

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



public slots:
    void cancel(bool bCancel)
    {
        if ( bCancel != this->bCancel )
        {
            this->bCancel = bCancel;
            emit cancelling(this->bCancel);
            this->bCancel = false;
        }
    }

    void delay(int millisecondsToWait);

    void elapseLiters();
    float getFElapsedLitres() const;
    void setFElapsedLitres(float value);

signals:
    cancelling(bool bCancel);

private slots:
    void on_btnCancel_clicked();

    void on_btnNext_clicked();

    void on_btnStart_clicked();

private:
    Ui::QDispenseDisplay *ui;

    bool bCancel;

    bool bCancelLoop;

    QTime *time;

    QTimer *timer;

    QElapsedTimer *eTimer;

    QSqlDatabase sqlLiquascanDB;

    float fUnitPrice;
    float fLitres;
    float fTotal;

    float fElapsedLitres;
};

#endif // QDISPENSEDISPLAY_H

Summarizing (is that a word?), I want the QLCDNumber to display a simple tick every second and stop if it reaches the amount of fLitres.
Thanks in advance.

[SGaist]

Hi,

Unless I'm mistaken your QLCDNumber widget is in hexadecimal mode, change for Dec and you should be good to go.

[Jorge]

@SGaist Thanks for the reply.
I've checked in the designer and it is set to "Dec". It still displays an "A". I´ve updated the signals and slots, but still nothing.

void QDispenseDisplay::elapseLiters()
{
    setFElapsedLitres(fElapsedLitres + 1);
    QString sLitros = QString::number(fElapsedLitres, 'f', 2);
    QString sPrecio = QString::number(fUnitPrice * fElapsedLitres, 'f', 2);

    ui->lcdLitres->display(sLitros);
    ui->lcdPrice->display(sPrecio);

    if(fElapsedLitres == fLitres)
    {
        timer->stop();
    }
}

[SGaist]

When does it start to show that A ?