Eu também tive a mesma exigência alguns dias atrás
Eu usei um SVG de largura e altura total e o adicionei abaixo de todos os meus divs e adicionei linhas a esses SVG dinamicamente.
Veja como fiz aqui usando svg
HTML
<div id="ui-browser"><div class="anchor"></div>
<div id="control-library" class="library">
<div class="name-title">Control Library</div>
<ul>
<li>Control A</li>
<li>Control B</li>
<li>Control C</li>
<li>Control D</li>
</ul>
</div><!--
--></div><!--
--><div id="canvas">
<svg id='connector_canvas'></svg>
<div class="ui-item item-1"><div class="con_anchor"></div></div>
<div class="ui-item item-2"><div class="con_anchor"></div></div>
<div class="ui-item item-3"><div class="con_anchor"></div></div>
<div class="ui-item item-1"><div class="con_anchor"></div></div>
<div class="ui-item item-2"><div class="con_anchor"></div></div>
<div class="ui-item item-3"><div class="con_anchor"></div></div>
</div><!--
--><div id="property-browser"></div>
https://jsfiddle.net/kgfamo4b/
$('.anchor').on('click',function(){
var width = parseInt($(this).parent().css('width'));
if(width==10){
$(this).parent().css('width','20%');
$('#canvas').css('width','60%');
}else{
$(this).parent().css('width','10px');
$('#canvas').css('width','calc( 80% - 10px)');
}
});
$('.ui-item').draggable({
drag: function( event, ui ) {
var lines = $(this).data('lines');
var con_item =$(this).data('connected-item');
var con_lines = $(this).data('connected-lines');
if(lines) {
lines.forEach(function(line,id){
$(line).attr('x1',$(this).position().left).attr('y1',$(this).position().top+1);
}.bind(this));
}
if(con_lines){
con_lines.forEach(function(con_line,id){
$(con_line).attr('x2',$(this).position().left)
.attr('y2',$(this).position().top+(parseInt($(this).css('height'))/2)+(id*5));
}.bind(this));
}
}
});
$('.ui-item').droppable({
accept: '.con_anchor',
drop: function(event,ui){
var item = ui.draggable.closest('.ui-item');
$(this).data('connected-item',item);
ui.draggable.css({top:-2,left:-2});
item.data('lines').push(item.data('line'));
if($(this).data('connected-lines')){
$(this).data('connected-lines').push(item.data('line'));
var y2_ = parseInt(item.data('line').attr('y2'));
item.data('line').attr('y2',y2_+$(this).data('connected-lines').length*5);
}else $(this).data('connected-lines',[item.data('line')]);
item.data('line',null);
console.log('dropped');
}
});
$('.con_anchor').draggable({drag: function( event, ui ) {
var _end = $(event.target).parent().position();
var end = $(event.target).position();
if(_end&&end)
$(event.target).parent().data('line')
.attr('x2',end.left+_end.left+5).attr('y2',end.top+_end.top+2);
},stop: function(event,ui) {
if(!ui.helper.closest('.ui-item').data('line')) return;
ui.helper.css({top:-2,left:-2});
ui.helper.closest('.ui-item').data('line').remove();
ui.helper.closest('.ui-item').data('line',null);
console.log('stopped');
}
});
$('.con_anchor').on('mousedown',function(e){
var cur_ui_item = $(this).closest('.ui-item');
var connector = $('#connector_canvas');
var cur_con;
if(!$(cur_ui_item).data('lines')) $(cur_ui_item).data('lines',[]);
if(!$(cur_ui_item).data('line')){
cur_con = $(document.createElementNS('http://www.w3.org/2000/svg','line'));
cur_ui_item.data('line',cur_con);
} else cur_con = cur_ui_item.data('line');
connector.append(cur_con);
var start = cur_ui_item.position();
cur_con.attr('x1',start.left).attr('y1',start.top+1);
cur_con.attr('x2',start.left+1).attr('y2',start.top+1);
});