QlineEdit with some default text for which cursor should not be moved?

Question

In QT, a created lineEdit shows a text using the setText() method.

But the cursor is movable for the default text. I want the cursor should not be movable for the default text.
My lineEdit type has been set as password. Hence the default text('Password') is also displayed as '********'. Whenever user types the type has to be changed as password and when there is no text or until the user have not typed any text, the lineEdit should display the plain text 'password'

Any idea to fix the above two issues? enter image description here

score 15 · Answer 1 · answered May 21 '12 at 07:16

15

In the constructor put

ui->lineEdit->setPlaceholderText("password");
ui->lineEdit->setReadOnly(1);

And in on_lineEdit_selectionChanged() SLOT, put

ui->lineEdit->setText("");
ui->lineEdit->setEchoMode(QLineEdit::Password);
ui->lineEdit->setReadOnly(0);

answered May 21 '12 at 07:16

ScarCode

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3
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32

Thanks spyke. setPlaceholderText() method works good. But whenever the qlineedit widget gets focussed or mouse clicked on qlineedit, default text get hidden. I want to display the default text even when the cursor is in the widget with the condition that the cursor should not be moved until the user type any text.... – Mathan Kumar May 21 '12 at 07:33

answerSeeker · Answer 2 · 2017-02-22T21:00:59.287

9

I noticed this question has tag pyqt so I'll put an actual answer related to that tag for those actually looking for a python way instead of c++.

self.searchEditText = QtGui.QLineEdit()
self.searchEditText.setPlaceholderText("Search for word")

edited Feb 22 '17 at 21:00

answered Feb 21 '17 at 23:20

answerSeeker

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4
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Ammar · Accepted Answer · 2012-05-21T09:39:13.493

I managed to do what you want by deriving a class from QLineEdit as per following..

Constructor..

QCustomLineEdit::QCustomLineEdit(QWidget *parent) :
    QLineEdit(parent)
{
    connect(this, SIGNAL(textChanged(QString)), this, SLOT(onTextChanged(QString)));
    connect(this, SIGNAL(cursorPositionChanged(int,int)), this, SLOT(onCursorPositionChanged(int,int)));

    setEchoMode(QLineEdit::Password);   // Echo mode in your case..

    m_echoMode = echoMode();            // Member variable to store original echo mode..
    m_placeHolderText = "Password";     // Member variable..
    m_isPlaceHolderActive = true;       // Member varible..

    // Default case..
    setPlaceholderText("");
    setStyleSheet("QCustomLineEdit{color: gray;}");
    setEchoMode(QLineEdit::Normal);
    setText(__placeHolderText);
}

Override keyPressEvent..

void QCustomLineEdit::keyPressEvent(QKeyEvent *e)
{
    if(m_isPlaceHolderActive)
    {
        if(e->key() == Qt::Key_Delete || e->key() == Qt::Key_Backspace)
            e->accept();
        else
            QLineEdit::keyPressEvent(e);

        return;
    }

    QLineEdit::keyPressEvent(e);
}

Cursor position change event..

void QCustomLineEdit::onCursorPositionChanged(int /*oldPos*/, int newPos)
{
    if(m_isPlaceHolderActive)
    {
        if(newPos != 0)
            setCursorPosition(0);
    }
}

Text change event..

void QCustomLineEdit::onTextChanged(const QString &text)
{
    if(m_isPlaceHolderActive)
    {
        if(text.compare(m_placeHolderText) != 0)
        {
            m_isPlaceHolderActive = false;

            // Remove the 'placeHolderText' from 'text' itself..
            QString temp = text;
            temp = temp.mid(0, text.lastIndexOf(m_placeHolderText));

            setStyleSheet("QCustomLineEdit{color: black;}");
            setEchoMode(m_echoMode);
            setText(temp);
        }
        else
        {
            setEchoMode(QLineEdit::Normal);
            setText(m_placeHolderText);
            setStyleSheet("QCustomLineEdit{color: gray;}");
            setCursorPosition(0);
        }
    }
    else
    {
        if(text.isEmpty())
        {
            m_isPlaceHolderActive = true;
            setStyleSheet("QCustomLineEdit{color: gray;}");
            setEchoMode(QLineEdit::Normal);
            setText(m_placeHolderText);
        }
    }
}

I have written it very hastily to just show you. Test it yourself and feel free to point any mistake(s) or optimization(s). Hope this helps.

setPlaceholderText() method works good. But whenever the qlineedit widget gets focussed or mouse clicked on qlineedit, default text get hidden. I want to display the default text even when the cursor is in the widget with the condition that the cursor should not be moved until the user type any text. — Mathan Kumar, May 21 '12 at 08:49
Ok. Remove ui->lineEdit->setText(""); and ui->lineEdit->setEchoMode(QLineEdit::Password); from on_lineEdit_selectionChanged(). And add ui->lineEdit->setEchoMode(QLineEdit::Password); in on_lineEdit_textEdited() — ScarCode, May 21 '12 at 09:05
@Ammar : Can i set my lineedit cursor color black when my default text color is grey. Is tat possible? — Mathan Kumar, May 22 '12 at 09:37
@user971306: If you see the source code of `QLineEdit::paintEvent()` then you will notice that cursor is drawn using `QTextLayout::drawCursor()` function, which uses current pen set in `QPainter`, which is `text-color`. So you can override that `paintEvent()` and set the appropriate `pen-color` before drawing cursor.. Bit tricky.. :) — Ammar, May 22 '12 at 10:12

score 4 · Answer 4 · answered Jan 28 '14 at 02:01

4

For question 1, in Qt 5.0 and higher, setPlaceholderText does what you want. https://codereview.qt-project.org/#change,45326

answered Jan 28 '14 at 02:01

Jarrod Lombardo

41
1

Please describe in short here what is given in the link. If you want to help, you could put this link in a comment. This doesn't look really like an answer right now. – Rachcha Jan 28 '14 at 02:21
I would add that `setEchoMode(QLineEdit::Password)` is also works really well with `setPlaceholderText` since Qt 5.4 and higher as well – Shf Apr 04 '17 at 12:31

QlineEdit with some default text for which cursor should not be moved?

4 Answers4