Android OpenGL Effectfactory, how to apply multiple effects?

Question

I want to create a photo editing application and find [1]: https://github.com/android/platform_development/tree/master/samples/HelloEffects "HelloEffect".

Then I try to apply various effects based on the effect already applied. But in this example, the previous effect will be canceled when a new effect is applied. Currently, I have to create several textures and keep each effect in one texture. I think this is the wrong way to do this, right? Any suggestions? I also want to support undo features.