In this chapter, you learned how to define a Filter interface in your own SDK. Your filters are now plugins. You know how to create and load a new plugin, so your application is now modular and can be easily extended. We have also enhanced the application with the Qt Animation framework. You know how to animate the position, the color, and the opacity of any QWidget, using QGraphicsEffect if necessary. We created a sequential animation that starts three animations, one by one, with QSequentialAnimationGroup.
In the next chapter, we will talk about a big subject: threading. The Qt framework can help you build a robust and reliable multithreading application. To illustrate this concept, we will create a Mandelbrot fractal generator using threadpools.