add distance option

Author: johnny

source/_limited_drop_targets.html.haml

@@ -12,7 +12,12 @@
         %strong serialization
         of the lists
       %li
-        Decrease sort sensitivity
+        Decrease sort
+        %strong sensitivity
+      %li
+        Start dragging after a
+        %strong distance
+        has been met
     %p= show_code_button
     %h3 Serialize result
     %pre#serialize_output

source/js/examples/limited_drop_targets.js

@@ -15,6 +15,7 @@ $(function  () {
     serialize: function (parent, children, isContainer) {
       return isContainer ? children.join() : parent.text()
     },
-    tolerance: 6
+    tolerance: 6,
+    distance: 10
   })
 })

source/js/jquery-sortable.js

@@ -49,6 +49,7 @@
     },
     // The css selector of the containers
     containerSelector: "ol, ul",
+    distance: 0,
     // The css selector of the drag handle
     handle: "",
     // The css selector of the items
@@ -238,6 +239,9 @@
       e.preventDefault()
 
       if(!this.dragging){
+        if(!this.distanceMet(e))
+          return
+
         processChildContainers(this.item, this.options.containerSelector, "disable", true)
 
         this.options.onDragStart(this.item, this.itemContainer, groupDefaults.onDragStart)
@@ -368,6 +372,12 @@
       this.lastPointer = this.pointer
       this.pointer = pointer
     },
+    distanceMet: function (e) {
+      return (Math.max(
+ 				Math.abs(this.pointer.left - e.pageX),
+				Math.abs(this.pointer.top - e.pageY)
+			) >= this.options.distance)
+    },
     addContainer: function  (container) {
       this.containers.push(container);
     },