A plugin for the svgdotjs.github.io library to make elements draggable.
svg.draggable.js is licensed under the terms of the MIT License.
Install the plugin:
npm install @svgdotjs/svg.js @svgdotjs/svg.draggable.js
Include this plugin after including the svg.js library in your html document.
<script src="node_modules/@svgdotjs/svg.js/dist/svg.js"></script>
<script src="node_modules/@svgdotjs/svg.draggable.js/dist/svg.draggable.js"></script>
Or for esm just require it:
import { SVG } from '@svgdotjs/svg.js'
import '@svgdotjs/svg.draggable.js'
To make an element draggable just call draggable()
on the element
var draw = SVG()
.addTo('#canvas')
.size(400, 400)
var rect = draw.rect(100, 100)
rect.draggable()
Yes indeed, that's it! Now the rect
is draggable.
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
// this == rect
})
// unbind
rect.off('dragstart.namespace')
beforedrag
, dragstart
, dragmove
and dragend
gives you the mouse / touch event
and the handler
which calculates the drag.
Except for beforedrag
the events also give you detail.box
which holds the initial or new bbox of the element before or after the drag.
You can use this property to implement custom drag behavior as seen below.
Please note that the bounding box is not what you would expect for nested svgs because those calculate their bbox based on their content and not their x, y, width and height values. Therefore stuff like constraints needs to be implemented a bit differently.
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', e => {
e.preventDefault()
// no other events are bound
// drag was completely prevented
})
rect.draggable().on('dragmove', e => {
e.preventDefault()
e.detail.handler.move(100, 200)
// events are still bound e.g. dragend will fire anyway
})
// Some constraints (x, y, width, height)
const constraints = new SVG.Box(100, 100, 400, 400)
rect.on('dragmove.namespace', e => {
const { handler, box } = e.detail
e.preventDefault()
let { x, y } = box
// In case your dragged element is a nested element,
// you are better off using the rbox() instead of bbox()
if (x < constraints.x) {
x = constraints.x
}
if (y < constraints.y) {
y = constraints.y
}
if (box.x2 > constraints.x2) {
x = constraints.x2 - box.w
}
if (box.y2 > constraints.y2) {
y = constraints.y2 - box.h
}
handler.move(x - (x % 50), y - (y % 50))
})
rect.on('dragmove.namespace', e => {
const { handler, box } = e.detail
e.preventDefault()
handler.move(box.x - (box.x % 50), box.y - (box.y % 50))
})
The draggable functionality can be removed calling draggable again with false as argument:
rect.draggable(false)
- If your root-svg is transformed this plugin won't work properly in Firefox. Viewbox however is not affected.
This module requires svg.js >= v3.0.10