elidedlabel.cpp Example File | Qt Widgets 5.12.6

Qt 5.12 | Qt Widgets | Elided Label Example | elidedlabel.cpp Example File

Qt 5.12.6 Reference Documentation

# elidedlabel.cpp Example File

widgets/elidedlabel/elidedlabel.cpp

      /****************************************************************************
      **
      ** Copyright (C) 2016 The Qt Company Ltd.
      ** Contact: https://www.qt.io/licensing/
      **
      ** This file is part of the QtCore module of the Qt Toolkit.
      **
      ** $QT_BEGIN_LICENSE:BSD$
      ** Commercial License Usage
      ** Licensees holding valid commercial Qt licenses may use this file in
      ** accordance with the commercial license agreement provided with the
      ** Software or, alternatively, in accordance with the terms contained in
      ** a written agreement between you and The Qt Company. For licensing terms
      ** and conditions see https://www.qt.io/terms-conditions. For further
      ** information use the contact form at https://www.qt.io/contact-us.
      **
      ** BSD License Usage
      ** Alternatively, you may use this file under the terms of the BSD license
      ** as follows:
      **
      ** "Redistribution and use in source and binary forms, with or without
      ** modification, are permitted provided that the following conditions are
      ** met:
      **   * Redistributions of source code must retain the above copyright
      **     notice, this list of conditions and the following disclaimer.
      **   * Redistributions in binary form must reproduce the above copyright
      **     notice, this list of conditions and the following disclaimer in
      **     the documentation and/or other materials provided with the
      **     distribution.
      **   * Neither the name of The Qt Company Ltd nor the names of its
      **     contributors may be used to endorse or promote products derived
      **     from this software without specific prior written permission.
      **
      **
      ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
      ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
      ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
      ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
      ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
      ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
      ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
      ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
      ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
      ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
      ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
      **
      ** $QT_END_LICENSE$
      **
      ****************************************************************************/

      #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);
          }
      }