S2U2 is the best option for this, it's free and has an option to deactivate all hard buttons with a slide to answer and full screen caller ID. As mentioned above you can also try TouchLockPro but, despite being smaller, I find S2U2's option list and features to be superior. Pocketshield is another option but that's commercial, I bought it a few months back and used it for a bit but eventually went back to S2U2.
Samsung Galaxy S4 I9505 WanamLite
Previous phones - Philips Diga, Nokia 6110, Nokia 3210, Nokia 7110, Nokia 8890, Nokia 9110i, Nokia 8310, Ericsson T28i, Nokia 6310, SE T68i, SE T610, Motorola V600, Nokia 6230, Samsung D500, SE K750, Motorola V3, Samsung D600, Nokia N73, HTC Artemis, LG KU990, Nokia N95 8gb, HTC Leo, Samsung Galaxy SII.
"Have you ever noticed how people who believe in creationism look really unevolved?"