0-9 to adjust filters. D to hide the rainbow barf. A to hide the other filter. Because of the text engine, capitals or special characters don't register as usernames or passwords. Going to have to tilt your head there...
I don't actually have Snapchat, so this is all beamed from my head. The format for login and such is probably way different, but don't accuse me of idiocy... "Loading" symbol borrowed from @MoonSpectrum with some editing... "Slide To Unlock" symbol borrowed from @Yoyle-Jefferson with some editing... You may need to fix your password angling.