wigglywidget.cpp Example File

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  #include <QtWidgets>

  #include "wigglywidget.h"

  WigglyWidget::WigglyWidget(QWidget *parent)
      : QWidget(parent)
  {
      setBackgroundRole(QPalette::Midlight);
      setAutoFillBackground(true);

      QFont newFont = font();
      newFont.setPointSize(newFont.pointSize() + 20);
      setFont(newFont);

      step = 0;
      timer.start(60, this);
  }

  void WigglyWidget::paintEvent(QPaintEvent * /* event */)
  {
      static const int sineTable[16] = {
          0, 38, 71, 92, 100, 92, 71, 38, 0, -38, -71, -92, -100, -92, -71, -38
      };

      QFontMetrics metrics(font());
      int x = (width() - metrics.width(text)) / 2;
      int y = (height() + metrics.ascent() - metrics.descent()) / 2;
      QColor color;

      QPainter painter(this);
      for (int i = 0; i < text.size(); ++i) {
          int index = (step + i) % 16;
          color.setHsv((15 - index) * 16, 255, 191);
          painter.setPen(color);
          painter.drawText(x, y - ((sineTable[index] * metrics.height()) / 400),
                           QString(text[i]));
          x += metrics.width(text[i]);
      }
  }

  void WigglyWidget::timerEvent(QTimerEvent *event)
  {
      if (event->timerId() == timer.timerId()) {
          ++step;
          update();
      } else {
          QWidget::timerEvent(event);
      }
  }