Well, the "set ignoring input" and "stop ignoring input" are just in the .cap to keep the character from moonwalking when both keys are down. It's a side-effect of the default platform movement. If you're making your own controls then you probably won't have to worry about it.
But just in case, you can assume it's moving when the move keys are down. That would be the most simple way.
Or you could put in a couple variables called "lastX" and "lastY." Before your movement routine, put the player's X and Y coordinates in them. After your movement routine, check the player's X and Y coordinates against them. If they're different, the player has moved. If X is bigger than lastX then the player has moved right, and if Y is less than lastY then the player has moved up, etc.