Qt 5.9 | Qt Widgets | Elided Label Example | elidedlabel.cpp Example File

Qt 5.9.9 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);
          }
      }