IME keyboard with emojis

Question

I am making a keyboard with custom images that I need to “copy to clipboard” when clicked. I followed this tutorial to create a working keyboard. When I press a key, I can also change the keyboard layout. Now I want to change the background and font of each keyboard key, and also want to add the specified images to the gridview. I was looking for things, but could not find the perfect one.

Any reference for the tutorial will also be appreciated.

Thanks in advance.