Draggable Directive

by Annie Lagang

HTML

<script src="http://code.angularjs.org/1.2.9/angular.min.js"></script>
<div ng-app="test" ng-controller="testCtrl">
    <div id="container">
        <div class="shape" ng-draggable='dragOptions'></div>
    </div>
</div>

CSS

#container {
   width : 300px;
   height: 300px;
   background-color: black;
}

.shape {
    position: absolute;
    width : 40px;
    height: 40px;
    background-color: white;
}

JavaScript

angular.module('test', [])

.directive('ngDraggable', function($document) {
  return {
    restrict: 'A',
    scope: {
      dragOptions: '=ngDraggable'
    },
    link: function(scope, elem, attr) {
      var startX, startY, x = 0, y = 0,
          start, stop, drag, container;

      var width  = elem[0].offsetWidth,
          height = elem[0].offsetHeight;

      // Obtain drag options
      if (scope.dragOptions) {
        start  = scope.dragOptions.start;
        drag   = scope.dragOptions.drag;
        stop   = scope.dragOptions.stop;
        var id = scope.dragOptions.container;
        if (id) {
            container = document.getElementById(id).getBoundingClientRect();
        }
      }

      // Bind mousedown event
      elem.on('mousedown', function(e) {
        e.preventDefault();
        startX = e.clientX - elem[0].offsetLeft;
        startY = e.clientY - elem[0].offsetTop;
        $document.on('mousemove', mousemove);
        $document.on('mouseup', mouseup);
        if (start) start(e);
      });

      // Handle drag event
      function mousemove(e) {
        y = e.clientY - startY;
        x = e.clientX - startX;
        setPosition();
        if (drag) drag(e);
      }

      // Unbind drag events
      function mouseup(e) {
        $document.unbind('mousemove', mousemove);
        $document.unbind('mouseup', mouseup);
        if (stop) stop(e);
      }

      // Move element, within container if provided
      function setPosition() {
        if (container) {
          if (x < container.left) {
            x = container.left;
          } else if (x > container.right - width) {
            x = container.right - width;
          }
          if (y < container.top) {
            y = container.top;
          } else if (y > container.bottom - height) {
            y = container.bottom - height;
          }
        }

        elem.css({
          top: y + 'px',
          left:  x + 'px'
        });
      }
    }
  }

})

.controller('testCtrl',...