Pan and Zoom in jsPlumb Community Edition with Dagre and jQueryUI Draggable

See the Pen Pan and Zoom in jsPlumb Community Edition with Dagre and jQueryUI Draggable by Yuri Gor (@yurigor) on CodePen.0

Chart with draggable HTML elements as nodes, connected by jsPlumb library.
“Pan&Zoom” feature missing in Comunity Edition implemented by using “jQuery Panzoom” plugin.
Nodes dragging implemented by jQueryUI Draggable, to compensate scale distortion.
Dagre layout library used for demonstration.

I use static predefined html in this example:

<!-- .container - just part of your page,
where you want to render diagram -->
<div class="container">
  <!-- .panzoom - wrapper div, panzoom plugin will transform it.
        Use it for worksheet element styling -->
  <div class="panzoom">
    <!-- .diagram - wrapper div to be used by jsPlumb.
         It will have zero height, so no visual CSS works here. -->
    <div class="diagram">
      <!-- .item - diagram nodes, must have unique id's
           to be able connect them by jsPlumb. -->
      <div id="i0"  class="item">Root</div>
      <div id="i1" class="item">Child 1</div>
      <div  id="i11" class="item">Child 1.1</div>
      <div  id="i12" class="item">Child 1.2</div>
      <div id="i2" class="item">Child 2</div>
      <div id="i21" class="item">Child 2.1</div>
      <div id="i3" class="item">Child 3</div>
    </div>
  </div>
</div>

Links between nodes declared in js array:

var links = [
  { from: "i0", to: "i1" },
  { from: "i1", to: "i11" },
  { from: "i1", to: "i12" },
  { from: "i0", to: "i2" },
  { from: "i2", to: "i21" },
  { from: "i0", to: "i3" },
];

Initializing of panzoom:

$panzoom = $container.find('.panzoom').panzoom({
      minScale: minScale,//0.4
      maxScale: maxScale,//2
      increment: incScale,//0.1
      cursor: "",/*empty string prevents panzoom
          from changing cursor styles defined in your css.*/
    }).on("panzoomstart",function(e,pz,ev){
      $panzoom.css("cursor","move");//set "move" cursor on start only
    })
    .on("panzoomend",function(e,pz){
      $panzoom.css("cursor","");//restore cursor
    });

Mouse wheel support and pan while drag begins outside diagram:

$panzoom.parent()
    .on('mousewheel.focal', function( e ) {
      //if Control pressed then zoom
      if(e.ctrlKey||e.originalEvent.ctrlKey)
      {
        e.preventDefault();
        var delta = e.delta || e.originalEvent.wheelDelta;
        var zoomOut = delta ? delta < 0 : e.originalEvent.deltaY > 0;
        $panzoom.panzoom('zoom', zoomOut, {
           animate: true,
           exponential: false,
        });
      }else{//else pan (touchpad and Shift key works)
        e.preventDefault();
        var deltaY = e.deltaY || e.originalEvent.wheelDeltaY || (-e.originalEvent.deltaY);
        var deltaX = e.deltaX || e.originalEvent.wheelDeltaX || (-e.originalEvent.deltaX);
        $panzoom.panzoom("pan",deltaX/2,deltaY/2,{
          animate: true,
          relative: true,
        });
      }
    })
    //on start store initial offsets and mouse coord
    .on("mousedown touchstart",function(ev){
      var matrix = $container.find(".panzoom").panzoom("getMatrix");
      var offsetX = matrix[4];
      var offsetY = matrix[5];
      var dragstart = {x:ev.pageX,y:ev.pageY,dx:offsetX,dy:offsetY};
      $(ev.target).css("cursor","move");
      $(this).data('dragstart', dragstart);
    })
    //calculate mouse offset from starting pos and apply it to panzoom matrix
    .on("mousemove touchmove", function(ev){
      var dragstart = $(this).data('dragstart');
      if(dragstart)
      {
        var deltaX = dragstart.x-ev.pageX;
        var deltaY = dragstart.y-ev.pageY;
        var matrix = $container.find(".panzoom").panzoom("getMatrix");
        matrix[4] = parseInt(dragstart.dx)-deltaX;
        matrix[5] = parseInt(dragstart.dy)-deltaY;
        $container.find(".panzoom").panzoom("setMatrix",matrix);
      }
    })
    .on("mouseup touchend touchcancel", function(ev){
      $(this).data('dragstart',null);
      $(ev.target).css("cursor","");
    });
  });

Make nodes draggable by jQueryUI/draggable:

var currentScale = 1;
  $container.find(".diagram .item").draggable({
    start: function(e){
      var pz = $container.find(".panzoom");
      //save current scale factor to consider it later
      currentScale = pz.panzoom("getMatrix")[0];
      $(this).css("cursor","move");
      //disable panzoom, to avoid panning while dragging node
      pz.panzoom("disable");
    },
    drag:function(e,ui){
      /*compensate current scale while dragging,
           else pointer and node will have different speeds*/
      ui.position.left = ui.position.left/currentScale;
      ui.position.top = ui.position.top/currentScale;
      //it's possible to have not connected nodes, so let's check it.
      if($(this).hasClass("jsplumb-connected"))
      {
        plumb.repaint($(this).attr('id'),ui.position);
      }
    },
    stop: function(e,ui){
      var nodeId = $(this).attr('id');
      if($(this).hasClass("jsplumb-connected"))
      {
        plumb.repaint(nodeId,ui.position);
      }
      $(this).css("cursor","");
      $container.find(".panzoom").panzoom("enable");
    }
  });

  7 comments for “Pan and Zoom in jsPlumb Community Edition with Dagre and jQueryUI Draggable

  1. Itso
    April 10, 2017 at 6:51 pm

    Good job!

  2. Zo
    July 26, 2017 at 8:41 am

    So useful

  3. qingtong
    November 14, 2017 at 8:17 am

    hi,this is really good job you have done。
    actually i have used jsplumb in React, SO, how can i use this in my react code?

    thanks for what you have done

  4. Daniel
    August 2, 2018 at 7:51 pm

    Hey Yuri,

    Was wondering, is the issue with child nodes not being movable still a problem natively in JqueryUI?

    • Yuri Gor
      August 2, 2018 at 7:59 pm

      Hi Daniel, looks like no.
      But it’s not a problem of Jquery, it’s a panzoom issue
      In this demo I use my own fork
      https://github.com/YuriGor/jquery.panzoom/tree/ignoreChildrensEvents
      Look this discussion for details
      https://github.com/timmywil/jquery.panzoom/issues/299

      • Daniel
        August 3, 2018 at 3:09 pm

        I have pretty much replicated your code in my own project for this, and I used your forked repo, but I still cant seem to click on child elements of my panzoom container. All clicks in the panzoom container are read as clicks on the panzoom container.

        • Daniel
          August 3, 2018 at 3:31 pm

          Oh my god I hadn’t committed the changes in my code editor. It works! You’re a freaking genius!

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