“text-overflow” for a QLabel’s text rendering in QT - qt

Question

I have got a QLabel element in a widget which can be resized. The text can overflow boundaries, so I need, for the application to look more elegant, some way to make the text generate an ellipsis (...) after the last totally visible word in the text.
Making layouts in HTML/CSS I used to use text-overflow: ellipsis; for this, but for QT classes I have not found any information on this.

Answer 1

It looks like on your label resize event you can create elided text using the new width of the widget and reset the text. Use QFontMetrics::elidedText method to get the elided version of the string.
QString text("some long text without elipsis");
QFontMetrics metrics(label->font());
QString elidedText = metrics.elidedText(text, Qt::ElideRight, label->width());
label->setText(elidedText);
hope this helps, regards

Answer 2

I've modified solution described above and created a function:
static void SetTextToLabel(QLabel *label, QString text)
{
QFontMetrics metrix(label->font());
int width = label->width() - 2;
QString clippedText = metrix.elidedText(text, Qt::ElideRight, width);
label->setText(clippedText);
}
Hope it will be useful.

Answer 3

Qt-5 includes an example of an elided label class which may be a useful reference when implementing your own.
From the example:
elidedlabel.h:
class ElidedLabel : public QFrame
{
Q_OBJECT
Q_PROPERTY(QString text READ text WRITE setText)
Q_PROPERTY(bool isElided READ isElided)
public:
explicit ElidedLabel(const QString &text, QWidget *parent = 0);
void setText(const QString &text);
const QString & text() const { return content; }
bool isElided() const { return elided; }
protected:
void paintEvent(QPaintEvent *event) Q_DECL_OVERRIDE;
signals:
void elisionChanged(bool elided);
private:
bool elided;
QString content;
};
elidedlabel.cpp:
ElidedLabel::ElidedLabel(const QString &text, QWidget *parent)
: QFrame(parent)
, elided(false)
, content(text)
{
setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Preferred);
}
void ElidedLabel::setText(const QString &newText)
{
content = newText;
update();
}
void ElidedLabel::paintEvent(QPaintEvent *event)
{
QFrame::paintEvent(event);
QPainter painter(this);
QFontMetrics fontMetrics = painter.fontMetrics();
bool didElide = false;
int lineSpacing = fontMetrics.lineSpacing();
int y = 0;
QTextLayout textLayout(content, painter.font());
textLayout.beginLayout();
forever {
QTextLine line = textLayout.createLine();
if (!line.isValid())
break;
line.setLineWidth(width());
int nextLineY = y + lineSpacing;
if (height() >= nextLineY + lineSpacing) {
line.draw(&painter, QPoint(0, y));
y = nextLineY;
//! [2]
//! [3]
} else {
QString lastLine = content.mid(line.textStart());
QString elidedLastLine = fontMetrics.elidedText(lastLine, Qt::ElideRight, width());
painter.drawText(QPoint(0, y + fontMetrics.ascent()), elidedLastLine);
line = textLayout.createLine();
didElide = line.isValid();
break;
}
}
textLayout.endLayout();
if (didElide != elided) {
elided = didElide;
emit elisionChanged(didElide);
}
}

Answer 4

This is how I achive. Behave just like regular QLabel yet with ellipsis.
class EllipsisLabel : public QLabel
{
Q_OBJECT
public:
explicit EllipsisLabel(QWidget *parent = nullptr);
explicit EllipsisLabel(QString text, QWidget *parent = nullptr);
void setText(QString);
protected:
void resizeEvent(QResizeEvent *);
private:
void updateText();
QString m_text;
};
EllipsisLabel::EllipsisLabel(QWidget *parent)
: EllipsisLabel("", parent)
{
}
EllipsisLabel::EllipsisLabel(QString text, QWidget *parent)
: QLabel(parent)
{
setText(text);
}
void EllipsisLabel::setText(QString text)
{
m_text = text;
updateText();
}
void EllipsisLabel::resizeEvent(QResizeEvent *event)
{
QLabel::resizeEvent(event);
updateText();
}
void EllipsisLabel::updateText()
{
QFontMetrics metrics(font());
QString elided = metrics.elidedText(m_text, Qt::ElideRight, width());
QLabel::setText(elided);
}