- Qt 5.5
- Qt Widgets
- Elided Label Example
- elidedlabel.cpp Example File
- Qt 5.5.1 Reference Documentation

# elidedlabel.cpp Example File

widgets/elidedlabel/elidedlabel.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the QtCore module of the Qt Toolkit.
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    ** $QT_BEGIN_LICENSE:BSD$
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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);
        }
    }