svg.draggable.js

A plugin for the svgdotjs.github.io library to make elements draggable.

Svg.draggable.js is licensed under the terms of the MIT License.

Usage

Install the plugin:

bower install svg.draggable.js

Include this plugin after including the svg.js library in your html document.

<script src="svg.js"></script>
<script src="svg.draggable.js"></script>

To make an element draggable just call draggable() in the element

var draw = SVG('canvas').size(400, 400)
var rect = draw.rect(100, 100)

rect.draggable()

Yes indeed, that's it! Now the rect is draggable.

Events

The Plugin fires 4 different events

• beforedrag (cancelable)
• dragstart
• dragmove (cancelable)
• dragend

You can bind/unbind listeners to this events:

// bind
rect.on('dragstart.namespace', function(event){

	// event.detail.event hold the given data explained below

})

// unbind
rect.off('dragstart.namespace')

event.detail

beforedrag, dragstart, dragmove and dragend gives you the event and the handler which calculates the drag. Except for beforedrag the events also give you:

• detail.m transformation matrix to calculate screen coords to coords in the elements userspace
• detail.p pageX and pageY transformed into the elements userspace

cancelable events

You can prevent the default action of beforedrag and dragmove with a call to event.preventDefault() in the callback function. The shape won't be dragged in this case. That is helpfull if you want to implement your own drag handling.

rect.draggable().on('beforedrag', function(e){
  e.preventDefault()
  // no other events are bound
  // drag was completely prevented
})

rect.draggable().on('dragmove', function(e){
  e.preventDefault()
  this.move(e.detail.p.x, e.detail.p.y)
  // events are still bound e.g. dragend will fire anyway
})

Constraint

The drag functionality can be limited within a given box. You can pass the the constraint values as an object:

rect.draggable({
  minX: 10
, minY: 15
, maxX: 200
, maxY: 100
, snapToGrid: 20 
})

For more dynamic constraints a function can be passed as well:

rect.draggable(function(x, y) {
  return { x: x < 1000, y: y < 300 }
})

Note that every constraint given is evaluated in the elements coordinate system and not in the screen-space

Remove

The draggable functionality can be removed calling draggable again with false as argument:

rect.draggable(false)

Restrictions

• If your root-svg is transformed this plugin won't work properly (Viewbox is possible)
• Furthermore it is not possible to move a rotated or flipped group properly. However transformed nested SVGs are possible and should be used instead.

Dependencies

This module requires svg.js >= v2.0.1