Beg Your Knees ~ ~ ~ Great God! How does the range Finder (distance) tool ranging from the smart Tools tool to the Android phone download???

Problem description
How does the range Finder (distance) tool in the Smart Tools tool measure distances when you download the ranging software from the Android system phone? It uses the camera ranging, alignment to measure the object and so on can get the distance, the principle of the camera ranging is what ah? Can I get any parameters from the camera or use some sensors or something? Please master the Great God to help explain Ah, thank you very much, the urgent need for speed answer Ah, extremely grateful, the urgency Ah ~~~~~~~~~~~~~ solution 1
You're the god of your own.

Beg Your Knees ~ ~ ~ Great God! How does the range Finder (distance) tool ranging from the smart Tools tool to the Android phone download???