For this last animation, we want to display a blue flash on each filter preview when the thumbnail is updated. We do not want to flash all previews at the same time, but in a sequence, one by one. This feature will be achieved in two parts:

Let's start to add the color animation. Update FilterWidget.h as shown in the following snippet:

#include <QGraphicsColorizeEffect> 
 
class FilterWidget : public QWidget 
{ 
    Q_OBJECT 
 
public: 
    explicit FilterWidget(Filter& filter, QWidget *parent = 0); 
    ~FilterWidget(); 
    ... 
    QPropertyAnimation* colorAnimation(); 
 
private: 
    ... 
    QPropertyAnimation mSelectionAnimation; 
    QPropertyAnimation* mColorAnimation; 
    QGraphicsColorizeEffect mColorEffect; 
}; 

This time we do not want to affect the opacity, but rather colorize...