characterwidget.cpp Example File

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  #include <QtWidgets>

  #include "characterwidget.h"

  CharacterWidget::CharacterWidget(QWidget *parent)
      : QWidget(parent), columns(16), lastKey(-1)
  {
      calculateSquareSize();
      setMouseTracking(true);
  }

  void CharacterWidget::updateFont(const QFont &font)
  {
      displayFont.setFamily(font.family());
      calculateSquareSize();
      adjustSize();
      update();
  }

  void CharacterWidget::updateSize(const QString &fontSize)
  {
      displayFont.setPointSize(fontSize.toInt());
      calculateSquareSize();
      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);
      calculateSquareSize();
      adjustSize();
      update();
  }

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

  void CharacterWidget::calculateSquareSize()
  {
      squareSize = qMax(16, 4 + QFontMetrics(displayFont, this).height());
  }

  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.horizontalAdvance(QChar(key))/2,
                               row*squareSize + 4 + fontMetrics.ascent(),
                               QString(QChar(key)));
          }
      }
  }