I ask you an advice on multiple QLabel...

Stefanoxjx

Hi boys,
I would like to ask you an advice about manage of multiple QLabel.
My situation is this:

I've many QLabels.
I receive from a external source some bytes where, any single bit correspond to a QLabel to be made visible or invisible based on the value of each bit (0=invisible/1=visible).

What strategy you can suggest me to reduce at the minimum the code lines and avoid a lot of if/then?

Thanks
Best regards

Stefano

JonB

@Stefanoxjx said in I ask you an advice on multiple QLabel...:

I've many QLabels.

Just how many are you talking about, at least approximately?

Stefanoxjx

@JonB: Hi, I've about 40 QLabels.

SGaist

Hi,

The short version: use a QMap to associate each value with the label you want to show/hide.

JonB

@Stefanoxjx
Oh OK. So store pointers to the labels in an array/vector, in the same order is the matching bit for it. Use that to decide which label to show/hide, no "if"s.

Stefanoxjx

Thanks for your answers.
To a array/vector I was already thought, to QMap no.
But my doubt is, how I can associate the bit to an array pointer.
For example, if I've:

QLabel1
QLabel2
QLabel3
QLabel4
QLabel5
QLabel6
QLabel7
QLabel8

and a pointer vector with any QLabel above.
If I receive a byte with value 25 (decimal) 11001 (binary) means that I must set visible QLabel1, QLabel4 and QLabel5 and make the rest invisible.
Ho I can do this without some if's?
This is my problem :(

JoeCFD

@Stefanoxjx use std::bitset to get 0/1s

? Offline

@Stefanoxjx maybe you can try use QLabel's name to do someting, for example, "QLabel1" is one QLabel's objectName, you can get objectName's last char,the char is '1', so it's visiable is bit1's value.

ChrisW67

@Stefanoxjx Something like this:

// main.cpp
#include "bitbuttons.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    BitButtons w;
    w.show();
    return a.exec();
}

// bitbuttons.h
#ifndef BITBUTTONS_H
#define BITBUTTONS_H

#include <QPushButton>
#include <QWidget>

class BitButtons : public QWidget
{
    Q_OBJECT

public:
    BitButtons(QWidget *parent = nullptr);
    ~BitButtons();

public slots:
    void setBits(unsigned long value);


private:
    QVector<QPushButton*> m_buttons;

    quint8 m_testValue;
};
#endif // BITBUTTONS_H

// bitbuttons.cpp
#include "bitbuttons.h"

#include <QTimer>
#include <QVBoxLayout>
#include <bitset>

namespace {
    const int BUTTON_COUNT = 8;
}

BitButtons::BitButtons(QWidget *parent)
    : QWidget(parent)
    , m_buttons(BUTTON_COUNT, nullptr)
    , m_testValue(0)
{
    QVBoxLayout *layout = new QVBoxLayout(this);
    for (int i = 0; i < m_buttons.size(); ++i) {
        m_buttons[i] = new QPushButton(QString::number(i), this);
        layout->addWidget(m_buttons.at(i));
    }

    setBits(0);

    // Something to generate test data
    QTimer *timer = new QTimer(this);
    connect(timer, &QTimer::timeout,
            this, [this](){setBits(m_testValue++);}
    );
    timer->setInterval(500);
    timer->start();
}

BitButtons::~BitButtons()
{
}

void BitButtons::setBits(unsigned long value)
{
    std::bitset<BUTTON_COUNT> bits(value);
    for (int i = 0; i < BUTTON_COUNT; ++i) {
        m_buttons.at(i)->setEnabled(bits.test(i));
    }
}

Stefanoxjx

Hi boys, thanks at all for help.
In the end, I used the solution with QVector and bitset and works very well.
The code lines are reduced to a minimum how I wanted.
I would say very well :)

Thanks a lot.

Stefano