Qt Reference Documentation

elidedlabel.cpp Example File

widgets/elidedlabel/elidedlabel.cpp
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 #include "elidedlabel.h"

 #include <QPainter>
 #include <QTextLayout>
 #include <QDebug>

 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;
         } 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);
     }
 }