Qt 4.3: characterwidget.cpp Example File (widgets/charactermap/characterwidget.cpp)

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# characterwidget.cpp Example File
widgets/charactermap/characterwidget.cpp

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     #include <QtGui>

     #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::NoCategory)
                 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)));
             }
         }
     }