Image and video filters like snapchat in android

Question

I am developing an application where I want the filters to be applied the way snapchat does, From what I can understand is that they are using PagerAdapter but I do not know how

Answer 1

An alternative solution:

Render the image onto a SurfaceTexture. Use that SurfaceTexture as an OpenGL "GL_OES_EGL_image_external" texture input into an OpenGL fragment shader. Draw a full-screen quad using this fragment shader onto a secondary SurfaceTexture. Render the secondary SurfaceTexture into a TextureView.

Getting this first part working is the difficult part. Once you've got that working, you will be able to apply different shaders to images, but not switch between them as shown in the picture. To add smooth swapping between images, render two different fragment shaders onto the secondary SurfaceTexture, using GL_SCISSOR to slice the screen in half depending on an offset value.

The main advantage of this method is that it will use significantly less memory. The bitmap can be loaded once, and after being rendered onto the SurfaceTexture once, may be discarded.

A secondary advantage of this method is that more complicated filters can be applied, and that with a little bit of extra work, you will be able to render videos as well.

If you're interested in seeing an implementation of this technique (which includes video filtering as well), check out the Kfilter library for photo and video filtering/processing.