Fix sluggish grid snapping.

Previously the grid snapping could only move one unit per mousemove event.

Author: STRML

lib/draggable.js

@@ -125,21 +125,10 @@ function removeEvent(el, event, handler) {
   }
 }
 
-function snapToGrid(draggable, clientX, clientY) {
-  var stateX = parseInt(draggable.state.clientX, 10);
-  var stateY = parseInt(draggable.state.clientY, 10);
-  var directionX = clientX < stateX ? -1 : 1;
-  var directionY = clientY < stateY ? -1 : 1;
-
-  clientX = Math.abs(clientX - stateX) >= draggable.props.grid[0] ?
-      (stateX + (draggable.props.grid[0] * directionX)) :
-      stateX;
-
-  clientY = Math.abs(clientY - stateY) >= draggable.props.grid[1] ?
-      (stateY + (draggable.props.grid[1] * directionY)) :
-      stateY;
-
-  return [clientX, clientY];
+function snapToGrid(grid, pendingX, pendingY) {
+  var x = Math.round(pendingX / grid[0]) * grid[0];
+  var y = Math.round(pendingY / grid[1]) * grid[1];
+  return [x, y];
 }
 
 // Useful for preventing blue highlights all over everything when dragging.
@@ -435,7 +424,7 @@ module.exports = React.createClass({
 
     // Snap to grid if prop has been provided
     if (Array.isArray(this.props.grid)) {
-      var coords = snapToGrid(this, clientX, clientY);
+      var coords = snapToGrid(this.props.grid, clientX, clientY);
       clientX = coords[0], clientY = coords[1];
     }