Tetris blocks movement with touch

Hi, I am making a game similar to tetris. Right now I am having problem with the way the blocks are moving using touch. I want to have them move right or left at a specific interval (size of each grid). My logic so far is to detect if a finger move a certain distance in x or -x direction, and if it did, the block would jump one grid left or right. However, The problem is when player wants to move the block more than one grid one direction, the control does not feel smooth at all.

So the natural motion for wanting to move a block across the game grid usually end up being a swipe motion rather than moving you finger across the board. The swipe motion often does not produce enough finger movement distance that the block would only move 2-3 grids in the direction of the swipe instead of moving across the entire game board. I was wondering if anyone have a better idea of how to implement this logic. Thanks.