How to disable a QLineEdit?

[ewwen]

Hi everybody!

I´m using 3 QLineEdits that someone can enter a number in each.

Idea: 1) QLineEdit No. 1 is enabled, and QLE No. 2 and No. 3 are disabled. --> If someone enters a number in QLE No.1, than No. 2 is enabled. No. 3 stays disabled. --> If someone enters a number in QLE No. 2, than even No. 3 is enabled.

I´m not sure at all, if this is possible. So far I haven´t found a thread, where someone was disabling a QLineEdit. In the Qt-Helpfile I only found "dragEnabled" within the properties...

If someone has got an idea, please let me know...

Thanks in advance.

[Zlatomir]

You can use the setDisabled(...); slot.

[ewwen]

Thanks :-)! I try it!

[tinysoft]

use signal and slot :
the signal is when the text of the lineEdit change
the slot is to check if the lineEdit is not empty , then set the lineEdit enabled.

example:

signals:

connect(ui->lineEdit1,SIGNAL(textChanged(QString)),this,SLOT(lineEdit1TextChanged()));
connect(ui->lineEdit2,SIGNALtextChanged(QString)),this,SLOT(lineEdit2TextChanged()));

connect(ui->lineEdit1,SIGNAL(textChanged(QString)),this,SLOT(lineEdit1TextChanged()));
connect(ui->lineEdit2,SIGNALtextChanged(QString)),this,SLOT(lineEdit2TextChanged()));

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slots:

void MainWindow::lineEdit1TextChanged()
{
if(ui->lineEdit1->text()=="")
ui->lineEdit2->setDisabled(1);
else ui->lineEdit2->setEnabled(1);
}
 
void MainWindow::lineEdit2TextChanged()
{
if(ui->lineEdit2->text()=="")
ui->lineEdit3->setDisabled(1);
else ui->lineEdit3->setEnabled(1);
}

void MainWindow::lineEdit1TextChanged()
{
if(ui->lineEdit1->text()=="")
ui->lineEdit2->setDisabled(1);
else ui->lineEdit2->setEnabled(1);
}

void MainWindow::lineEdit2TextChanged()
{
if(ui->lineEdit2->text()=="")
ui->lineEdit3->setDisabled(1);
else ui->lineEdit3->setEnabled(1);
}

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[ewwen]

Hi, thanks for your code-snippet.

I tried (with validator):
-------------

....
in1->setValidator(validator);
in2->setValidator(validator);
.....
 
connect(in1,SIGNAL(textChanged(String)),this,SLOT(in1TextChanged()));
}
 
void Tab::in1TextChanged()
{
if(in1->text()=="")
{
    in2->setDisabled(1);
}
else
{
    in2->setEnabled(1);
}
}

....
in1->setValidator(validator);
in2->setValidator(validator);
.....

connect(in1,SIGNAL(textChanged(String)),this,SLOT(in1TextChanged()));
}

void Tab::in1TextChanged()
{
if(in1->text()=="")
{
    in2->setDisabled(1);
}
else
{
    in2->setEnabled(1);
}
}

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-------------
with
-------------

private slots:
    void in1TextChanged();
 
private:
...
QLineEdit *in1;
QLineEdit *in2;

private slots:
    void in1TextChanged();

private:
...
QLineEdit *in1;
QLineEdit *in2;

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-------------
set as pointers in the headerfile;

and:
--------

void Tab::calculate()
{
.....
    bool ok;
    double number1 = in1->text().toDouble(&ok);
    double number2 = in2->text().toDouble(&ok);
.......

void Tab::calculate()
{
.....
    bool ok;
    double number1 = in1->text().toDouble(&ok);
    double number2 = in2->text().toDouble(&ok);
.......

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--------------

But the "disable"-Function does not work.

Do you have an idea?

[tinysoft]

every thing seems fine ...

make sure that you set the in2 disabled at the bigging of the Tab class after declaration ( in2=new QLineEdit; )

also make sure that the connect statement exist at the same place.

[ewwen]

Hi!

Thanks tinysoft for your reply!

I tried now everything new from scratch.

#include "mainwindow.h"
#include <QObject>
#include <QtGui>
#include <QIntValidator>
#include <QWidget>
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent)
{
    QGridLayout *grid = new QGridLayout;
    grid->addWidget(input(), 0, 0);
    setLayout(grid);
 
    setWindowTitle(tr("QLineEdit example"));
    setMinimumSize(500, 400);
 
}
 
QGroupBox *MainWindow::input()
{
    QGroupBox *groupBox = new QGroupBox(tr("Input"));
    QLabel *fwerl = new QLabel(tr("<font>Insert your values:</font>"));
    in1 = new QLineEdit;
    in2 = new QLineEdit;
    in3 = new QLineEdit;
 
    QFormLayout *formLayout = new QFormLayout;
      formLayout->addRow(fwerl);
      formLayout->addRow(tr("1st value:"), in1);
      formLayout->addRow(tr("2nd value:"), in2);
      formLayout->addRow(tr("3rd value:"), in3);
      groupBox->setLayout(formLayout);
 
      connect(in1,SIGNAL(textChanged(QString)),this,SLOT(in1TextChanged()));
      connect(in2,SIGNAL(textChanged(QString)),this,SLOT(in2TextChanged()));
 
      QValidator *validator = new QDoubleValidator(0.0, 1.0, 10, in1);
      in1->setValidator(validator);
      in2->setValidator(validator);
      in3->setValidator(validator);
      return groupBox;
}
 
void MainWindow::in1TextChanged()
{
if(in1->text()=="")
{
    in2->setDisabled(1);
}
else
{
    in2->setEnabled(1);
}
}
 
void MainWindow::in2TextChanged()
{
if(in2->text()=="")
{
    in3->setDisabled(1);
}
else
{
    in3->setEnabled(1);
}
}
 
MainWindow::~MainWindow()
{
    delete mainWindow;
}

#include "mainwindow.h"
#include <QObject>
#include <QtGui>
#include <QIntValidator>
#include <QWidget>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent)
{
    QGridLayout *grid = new QGridLayout;
    grid->addWidget(input(), 0, 0);
    setLayout(grid);

    setWindowTitle(tr("QLineEdit example"));
    setMinimumSize(500, 400);

}

QGroupBox *MainWindow::input()
{
    QGroupBox *groupBox = new QGroupBox(tr("Input"));
    QLabel *fwerl = new QLabel(tr("<font>Insert your values:</font>"));
    in1 = new QLineEdit;
    in2 = new QLineEdit;
    in3 = new QLineEdit;

    QFormLayout *formLayout = new QFormLayout;
      formLayout->addRow(fwerl);
      formLayout->addRow(tr("1st value:"), in1);
      formLayout->addRow(tr("2nd value:"), in2);
      formLayout->addRow(tr("3rd value:"), in3);
      groupBox->setLayout(formLayout);

      connect(in1,SIGNAL(textChanged(QString)),this,SLOT(in1TextChanged()));
      connect(in2,SIGNAL(textChanged(QString)),this,SLOT(in2TextChanged()));

      QValidator *validator = new QDoubleValidator(0.0, 1.0, 10, in1);
      in1->setValidator(validator);
      in2->setValidator(validator);
      in3->setValidator(validator);
      return groupBox;
}

void MainWindow::in1TextChanged()
{
if(in1->text()=="")
{
    in2->setDisabled(1);
}
else
{
    in2->setEnabled(1);
}
}

void MainWindow::in2TextChanged()
{
if(in2->text()=="")
{
    in3->setDisabled(1);
}
else
{
    in3->setEnabled(1);
}
}

MainWindow::~MainWindow()
{
    delete mainWindow;
}

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Now the problem is, the QLineEdits are not displayed. But I don´t even get a warning - everything compiles fine...

Do you know why? If I use "setCentralWidget(grid)" instead of setLayout(grid) it doesn´t run anymore...

[tinysoft]

i am confused .. is it possible to return QGroupBox ?

QGroupBox *MainWindow::input();

QGroupBox *MainWindow::input();

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you can use the designer you know .. its much more easier .i wrote your example using the designer to create the widgets and the layout .. i uploaded it ( here )

i hope its helpful

[ewwen]

Hi tinysoft!

Thank you very much. With your file and some work I found the problems:
1) I was missing:

in1->setDisabled(1);....

in1->setDisabled(1);....

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2)

QWidget *widget = new QWidget;
         setCentralWidget(widget);

QWidget *widget = new QWidget;
         setCentralWidget(widget);

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because of QMainWindow. QWidget, for example, is a member of it.
and
3) I removed the GroupBox and just used:

QGridLayout *formLayout = new QGridLayout;
  ...
 widget->setLayout(formLayout);

QGridLayout *formLayout = new QGridLayout;
  ...
 widget->setLayout(formLayout);

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Now everything works fine :-)!

Thanks for your hints and have a nice day!

[tinysoft]

i'm glad that you solved it

have a nice day u 2