animation.h Example File

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 #ifndef ANIMATION_H
 #define ANIMATION_H

 #include <QtWidgets>

 #include <QtCore/qpropertyanimation.h>

 class Animation : public QPropertyAnimation {
 public:
     enum PathType {
         LinearPath,
         CirclePath,
         NPathTypes
     };
     Animation(QObject *target, const QByteArray &prop)
         : QPropertyAnimation(target, prop)
     {
         setPathType(LinearPath);
     }

     void setPathType(PathType pathType)
     {
         if (pathType >= NPathTypes)
             qWarning("Unknown pathType %d", pathType);

         m_pathType = pathType;
         m_path = QPainterPath();
     }

     void updateCurrentTime(int currentTime)
     {
         if (m_pathType == CirclePath) {
             if (m_path.isEmpty()) {
                 QPointF to = endValue().toPointF();
                 QPointF from = startValue().toPointF();
                 m_path.moveTo(from);
                 m_path.addEllipse(QRectF(from, to));
             }
             int dura = duration();
             const qreal progress = ((dura == 0) ? 1 : ((((currentTime - 1) % dura) + 1) / qreal(dura)));

             qreal easedProgress = easingCurve().valueForProgress(progress);
             if (easedProgress > 1.0) {
                 easedProgress -= 1.0;
             } else if (easedProgress < 0) {
                 easedProgress += 1.0;
             }
             QPointF pt = m_path.pointAtPercent(easedProgress);
             updateCurrentValue(pt);
             emit valueChanged(pt);
         } else {
             QPropertyAnimation::updateCurrentTime(currentTime);
         }
     }

     QPainterPath m_path;
     PathType m_pathType;
 };

 #endif // ANIMATION_H