QLineEdit：显示已处理的文本，而不是输入的文本，但保留它（自定义回显模式）

Question

我希望QLineEdit 不显示输入的文本，而是显示处理后的版本，同时保留原始文本并在通过text() 请求时返回它。就像密码回显模式一样，但我不希望每个字符都被屏蔽。我想对空间进行虚拟化：

E. G。输入some text with spaces in between 时，应显示some·text·with·spaces·in·between，以便可以看到空格。就像当 e。 G。你在 LibreOffice 中激活那个 ¶ 符号。

有QLineEdit::displayText()，但是不能设置，只能读取。另外，echoMode 只能通过枚举设置，而EchoMode::Password 设置后，处理似乎发生在QLineEdit 的私有函数中，所以我也无法覆盖某些处理函数。

这可能吗？

Answer 1

这是最终的结果：

SpacesLineEdit.h：

#include <QPlainTextEdit>

class SpacesLineEdit : public QPlainTextEdit
{
    Q_OBJECT

public:
    explicit SpacesLineEdit(QWidget *parent = nullptr);
    void setText(const QString &text);
    QString text() const;

protected:
    virtual void keyPressEvent(QKeyEvent *event) override;
    virtual QSize sizeHint() const override;
    virtual QSize minimumSizeHint() const override;
    virtual void insertFromMimeData(const QMimeData *source) override;

private: // Variables
    QSize m_sizeHint;

};

SpacesLineEdit.cpp：

#include "SpacesLineEdit.h"
#include <QLineEdit>
#include <QMimeData>

SpacesLineEdit::SpacesLineEdit(QWidget *parent) : QPlainTextEdit(parent)
{
    setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    setLineWrapMode(QPlainTextEdit::NoWrap);
    setTabChangesFocus(true);

    QTextOption option = document()->defaultTextOption();
    option.setFlags(option.flags() | QTextOption::ShowTabsAndSpaces);
    document()->setDefaultTextOption(option);

    // Stealing the sizeHint from a plain QLineEdit will do for now :-P
    QLineEdit lineEdit;
    m_sizeHint = lineEdit.sizeHint();
}

QSize SpacesLineEdit::minimumSizeHint() const
{
    return m_sizeHint;
}

QSize SpacesLineEdit::sizeHint() const
{
    return m_sizeHint;
}

void SpacesLineEdit::keyPressEvent(QKeyEvent *event)
{
    if (event->key() == Qt::Key_Return || event->key() == Qt::Key_Enter) {
        event->ignore();
        return;
    }
    QPlainTextEdit::keyPressEvent(event);
}

void SpacesLineEdit::insertFromMimeData(const QMimeData *source)
{
    QString text = source->text();
    text.replace(QLatin1String("\r\n"), QLatin1String(" "));
    text.replace(QLatin1Char('\n'), QLatin1String(" "));
    text.replace(QLatin1Char('\r'), QLatin1String(" "));

    QMimeData processedSource;
    processedSource.setText(text);
    QPlainTextEdit::insertFromMimeData(&processedSource);
}

void SpacesLineEdit::setText(const QString &text)
{
    setPlainText(text);
}

QString SpacesLineEdit::text() const
{
    return toPlainText();
}

Answer 2

恕我直言，QLineEdit 很难做到这一点。

但是，通过配置QTextEdit QTextEdit 来很容易：

class TextEdit : public QTextEdit
{
    Q_OBJECT
public:
        explicit TextEdit(QWidget* parent=nullptr): QTextEdit (parent)
        {
                QTextDocument* doc = new QTextDocument(this);
                setDocument(doc);
                QTextOption option;
                option.setFlags(QTextOption::ShowLineAndParagraphSeparators | QTextOption::ShowTabsAndSpaces);
                doc->setDefaultTextOption(option);
        }
};

然后，您必须配置 TextEdit 以获得与 QLineEdit 相同的行为（即一行，没有滚动条等）。

一个简单的例子作为一个好的开始：

class OneLineTextEdit : public QTextEdit
{
    Q_OBJECT
public:
        explicit OneLineTextEdit(QWidget* parent=nullptr): QTextEdit (parent)
        {
                setTabChangesFocus(true);
                setWordWrapMode(QTextOption::NoWrap);
                // No scrollbars
                setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
                setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
                setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);

                // One line only
                setFixedHeight(sizeHint().height());

                // Show the space/tabs/return
                QTextDocument* doc = new QTextDocument(this);
                setDocument(doc);
                QTextOption option;
                option.setFlags(QTextOption::ShowLineAndParagraphSeparators | QTextOption::ShowTabsAndSpaces);
                doc->setDefaultTextOption(option);
        }

    // We don't want to write more than one line
    void keyPressEvent(QKeyEvent *event)
    {
        if (event->key() == Qt::Key_Return || event->key() == Qt::Key_Enter)
                return event->ignore();
        return QTextEdit::keyPressEvent(event);
    }

    // Don't display more than one line
    QSize sizeHint() const
    {
        QFontMetrics const fm(font());
        int const h = qMax(fm.height(), 14) + 4;
        int const w = fm.width(QLatin1Char('x')) * 17 + 4;
        QStyleOption opt;
        opt.initFrom(this);
        // Use the current app style to find the size of a real QLineEdit
        return (style()->sizeFromContents(QStyle::CT_LineEdit, &opt, QSize(w, h).
                expandedTo(QApplication::globalStrut()), this));
    }
};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    OneLineTextEdit *editor = new OneLineTextEdit();
    editor->show();

    return app.exec();
};