Issues with blank lines and line breaks in QTextEdit

cuijg

My TextEdit content:
wwwwww

wwwwww

Problem: Pressing Enter once on a line with content creates a new line, but pressing Enter twice on a new blank line creates a new line. Furthermore, only the last blank line has a 108% line spacing set; the other blank lines do not.

I listened to the QTextEdit::cursorPositionChanged event and set the line spacing in the event handler:

void onSigCursorPositionChanged() {

QTextCursor cursor = this->textCursor();

QTextBlockFormat format = cursor.blockFormat();

if (format.lineHeight() != 108) {

format.setLineHeight(108, QTextBlockFormat::ProportionalHeight);

format.setTopMargin(0);

format.setBottomMargin(0);

cursor.setBlockFormat(format);

}
}

This is the content saved to the file via ui->textedit->toHtml():

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN" "http://www.w3.org/TR/REC-html40/strict.dtd">
<html><head><meta name="qrichtext" content="1" /><meta charset="utf-8" /><style type="text/css">
p, li { white-space: pre-wrap; }
hr { height: 1px; border-width: 0; }
li.unchecked::marker { content: "\2610"; }
li.checked::marker { content: "\2612"; }
</style></head><body style=" font-family:'.AppleSystemUIFont'; font-size:16pt; font-weight:400; font-style:normal;">
<p style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; line-height:108%;">wwww</p>
<p style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br /></p>
<p style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br /></p>
<p style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br /></p>
<p style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br /></p>
<p style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; line-height:108%;">wwww</p></body></html>

SGaist

Hi,

Which version of Qt are you using ?
On which platform ?
Please provide minimal compilable example that reproduces this behaviour.

cuijg

@SGaist

I found that as long as I use the default line spacing without modifying it myself, there won't be any issues with line breaks.

@SGaist

class MyTextEdit : public QTextEdit {
    Q_OBJECT
public:
    MyTextEdit(QWidget *parent = nullptr)
        : QTextEdit(parent)
    {
        this->setMouseTracking(true);

        int font_id = QFontDatabase::addApplicationFont(":/font/DIN-Medium.ttf");
        QStringList fontFamilies = QFontDatabase::applicationFontFamilies(font_id);
        QString font_family_name = fontFamilies.at(0);
        QFont customFont(font_family_name, 16);
        this->setFont(customFont);

        this->setStyleSheet("color: #34304b;");
        this->document()->setDefaultStyleSheet("p { line-height:108%; }");

        connect(this, &QTextEdit::cursorPositionChanged, this, &MyTextEdit::onSigCursorPositionChanged);
        connect(this, &QTextEdit::textChanged, this, &MyTextEdit::onSigTextChanged);
    }

protected:
    void insertFromMimeData(const QMimeData *source) override {

        QTextEdit::insertFromMimeData(source);
    }

    void keyPressEvent(QKeyEvent *e) override {
        QTextEdit::keyPressEvent(e);

        if (e->key() == Qt::Key_Return || e->key() == Qt::Key_Enter) {

        }
    }

protected slots:
    void onSigCursorPositionChanged() {
        QTextCursor cursor = this->textCursor();
        QTextBlockFormat format = cursor.blockFormat();
        if (format.lineHeight() != 108) {
            format.setLineHeight(108, QTextBlockFormat::ProportionalHeight);
            cursor.setBlockFormat(format);
        }
    }

    void onSigTextChanged() {

    }
};

save and load

void TestMainWindow::onsig_btn0_clicked()
{
    QFile file(DATA_STORE_DIR() + "test.data");
    if (!file.open(QIODevice::WriteOnly | QIODevice::Text)) {
        qWarning() << "无法打开文件";
        return;
    }

    QString htmlContent = ui->textEdit_3->toHtml();

    QTextStream out(&file);
    out.setEncoding(QStringConverter::Encoding::Utf8); // 确保使用 UTF-8 编码以支持中文
    out << htmlContent;

    file.close();
}

void TestMainWindow::onsig_btn1_clicked()
{
    QFile file(DATA_STORE_DIR() + "test.data");
    if (!file.open(QIODevice::ReadOnly | QIODevice::Text)) {
        qWarning() << "无法打开文件";
        return;
    }

    QTextStream in(&file);
    in.setEncoding(QStringConverter::Encoding::Utf8); // 确保使用 UTF-8 编码
    QString htmlContent = in.readAll();
    ui->textEdit_3->setHtml(htmlContent);
    file.close();

    //ui->textEdit->fix_image_alignment();
}

JonB

@cuijg
Although you have shown what version of Qt Creator you are using, what version of Qt are you compiling/linking with?

cuijg

To avoid affecting the user experience, I removed the code for custom line spacing and replaced it with a font with larger character spacing.

cuijg

@JonB
These two don't need to be consistent, right?

jsulm

@cuijg said in Issues with blank lines and line breaks in QTextEdit:

These two don't need to be consistent

No, they don't have to