QlineEdit有一些默认文本,不应该移动光标？

Question

在QT中,创建lineEdit的使用该setText()方法显示文本.

1. 但是光标可以移动默认文本.我希望光标不能为默认文本移动.

2. 我的lineEdit类型已设置为密码.因此,默认文本("密码")也显示为"********".每当用户输入类型时,必须将类型更改为密码,当没有文本或用户没有输入任何文本时,lineEdit应显示纯文本"密码"

有什么想法解决上述两个问题？

Answer 1

在构造函数中

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

在on_lineEdit_selectionChanged()SLOT,放

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

Answer 2

我注意到这个问题带有标签pyqt，因此我将为那些实际寻找python而不是c ++的人提供与该标签相关的实际答案。

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

Answer 3

我设法通过QLineEdit按照以下方式派生出一个类来完成您想要的事情..

构造函数..

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);
}

覆盖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);
}

光标位置改变事件..

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

文本更改事件..

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);
        }
    }
}

我写得很匆忙，只是为了给你们看。自己测试一下，并随时指出任何错误或优化。希望这可以帮助。