- Qt 5.5
- Qt Widgets
- Character Map Example
- characterwidget.cpp Example File
- Qt 5.5.1 Reference Documentation

# characterwidget.cpp Example File

widgets/charactermap/characterwidget.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
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    #include <QtWidgets>

    #include "characterwidget.h"

    CharacterWidget::CharacterWidget(QWidget *parent)
        : QWidget(parent)
    {
        squareSize = 24;
        columns = 16;
        lastKey = -1;
        setMouseTracking(true);
    }

    void CharacterWidget::updateFont(const QFont &font)
    {
        displayFont.setFamily(font.family());
        squareSize = qMax(24, QFontMetrics(displayFont).xHeight() * 3);
        adjustSize();
        update();
    }

    void CharacterWidget::updateSize(const QString &fontSize)
    {
        displayFont.setPointSize(fontSize.toInt());
        squareSize = qMax(24, QFontMetrics(displayFont).xHeight() * 3);
        adjustSize();
        update();
    }

    void CharacterWidget::updateStyle(const QString &fontStyle)
    {
        QFontDatabase fontDatabase;
        const QFont::StyleStrategy oldStrategy = displayFont.styleStrategy();
        displayFont = fontDatabase.font(displayFont.family(), fontStyle, displayFont.pointSize());
        displayFont.setStyleStrategy(oldStrategy);
        squareSize = qMax(24, QFontMetrics(displayFont).xHeight() * 3);
        adjustSize();
        update();
    }

    void CharacterWidget::updateFontMerging(bool enable)
    {
        if (enable)
            displayFont.setStyleStrategy(QFont::PreferDefault);
        else
            displayFont.setStyleStrategy(QFont::NoFontMerging);
        adjustSize();
        update();
    }

    QSize CharacterWidget::sizeHint() const
    {
        return QSize(columns*squareSize, (65536/columns)*squareSize);
    }

    void CharacterWidget::mouseMoveEvent(QMouseEvent *event)
    {
        QPoint widgetPosition = mapFromGlobal(event->globalPos());
        uint key = (widgetPosition.y()/squareSize)*columns + widgetPosition.x()/squareSize;

        QString text = QString::fromLatin1("<p>Character: <span style=\"font-size: 24pt; font-family: %1\">").arg(displayFont.family())
                      + QChar(key)
                      + QString::fromLatin1("</span><p>Value: 0x")
                      + QString::number(key, 16);
        QToolTip::showText(event->globalPos(), text, this);
    }

    void CharacterWidget::mousePressEvent(QMouseEvent *event)
    {
        if (event->button() == Qt::LeftButton) {
            lastKey = (event->y()/squareSize)*columns + event->x()/squareSize;
            if (QChar(lastKey).category() != QChar::Other_NotAssigned)
                emit characterSelected(QString(QChar(lastKey)));
            update();
        }
        else
            QWidget::mousePressEvent(event);
    }

    void CharacterWidget::paintEvent(QPaintEvent *event)
    {
        QPainter painter(this);
        painter.fillRect(event->rect(), QBrush(Qt::white));
        painter.setFont(displayFont);

        QRect redrawRect = event->rect();
        int beginRow = redrawRect.top()/squareSize;
        int endRow = redrawRect.bottom()/squareSize;
        int beginColumn = redrawRect.left()/squareSize;
        int endColumn = redrawRect.right()/squareSize;

        painter.setPen(QPen(Qt::gray));
        for (int row = beginRow; row <= endRow; ++row) {
            for (int column = beginColumn; column <= endColumn; ++column) {
                painter.drawRect(column*squareSize, row*squareSize, squareSize, squareSize);
            }
        }

        QFontMetrics fontMetrics(displayFont);
        painter.setPen(QPen(Qt::black));
        for (int row = beginRow; row <= endRow; ++row) {

            for (int column = beginColumn; column <= endColumn; ++column) {

                int key = row*columns + column;
                painter.setClipRect(column*squareSize, row*squareSize, squareSize, squareSize);

                if (key == lastKey)
                    painter.fillRect(column*squareSize + 1, row*squareSize + 1, squareSize, squareSize, QBrush(Qt::red));

                painter.drawText(column*squareSize + (squareSize / 2) - fontMetrics.width(QChar(key))/2,
                                 row*squareSize + 4 + fontMetrics.ascent(),
                                 QString(QChar(key)));
            }
        }
    }