fabricjs.com stickman: move the lines and affect the related circles - coordinates

Question

using the stickman example of http://fabricjs.com/,
I have been trying to achieve moving the related circles when a line is moved. The code in the example is not well structured, heavy & with errors :), as I can not to move the the related circles symmetrically.
If in the //move the other circle part is used next line
obj.set({
'left': (s.calcLinePoints().x1 + _l),
'top': (-s.calcLinePoints().y1 + _t)
});
the difference is in the sign of collected information for y1 and we move some horizontal line visually the result OK, but in my opinion this type of "adjustment" is not the correct one...
[example code]
$(function() {
//create the fabriccanvas object & disable the canvas selection
var canvas = new fabric.Canvas('c', {
selection: false
});
//move the objects origin of transformation to the center
fabric.Object.prototype.originX = fabric.Object.prototype.originY = 'center';
function makeCircle(left, top, line1, line2, usedLine, usedEnd) {
//used line - used line for the center
//usedEnd - fromt the used line
var c = new fabric.Circle({
left: left,
top: top,
strokeWidth: 2,
radius: 6,
fill: '#fff',
stroke: '#666'
});
c.hasControls = c.hasBorders = false;
c.line1 = line1;
c.line2 = line2;
//add information which line end is used for center
var _usedLineName;
if (usedLine == 1) {
_usedLineName = line1.name;
} else {
_usedLineName = line2.name;
}
c.usedLineName = _usedLineName;
c.usedEndPoint = usedEnd;
return c;
}
function makeLine(coords, name) {
var l = new fabric.Line(coords, {
stroke: 'red',
strokeWidth: 4,
selectable: true, //false
name: name
});
l.hasControls = l.hasBorders = false;
return l;
}
//initial shape information
var line = makeLine([250, 125, 350, 125], "l1"),
line2 = makeLine([350, 125, 350, 225], "l2"),
line3 = makeLine([350, 225, 250, 225], "l3"),
line4 = makeLine([250, 225, 250, 125], "l4");
canvas.add(line, line2, line3, line4);
canvas.add(
makeCircle(line.get('x1'), line.get('y1'), line4, line, 1, 2),
makeCircle(line.get('x2'), line.get('y2'), line, line2, 1, 2),
makeCircle(line2.get('x2'), line2.get('y2'), line2, line3, 1, 2),
makeCircle(line3.get('x2'), line3.get('y2'), line3, line4, 1, 2));
canvas.on('object:moving', function(e) {
//find the moving object type
var objType = e.target.get('type');
var p = e.target;
if (objType == 'circle') {
p.line1 && p.line1.set({
'x2': p.left,
'y2': p.top
});
p.line2 && p.line2.set({
'x1': p.left,
'y1': p.top
});
//set coordinates for the lines - should be done if element is moved programmely
p.line2.setCoords();
p.line1.setCoords();
canvas.renderAll();
} else if (objType == 'line') {
//loop all circles and if some is with coordinates as some of the ends - to change them
for (var i = 0; i < canvas.getObjects('circle').length; i++) {
var currentObj = canvas.getObjects('circle')[i];
if (currentObj.get("usedLineName") == e.target.get('name')) {
//usedEndPoint=2
for (var ss = 0; ss < canvas.getObjects('line').length; ss++) {
var s = canvas.getObjects('line')[ss];
//console.log(s.calcLinePoints())
//console.log(s.calcLinePoints().y2)
var _l = s.left;
var _t = s.top;
if (s.get("name") == currentObj.get("usedLineName")) {
currentObj.set({
'left': (s.calcLinePoints().x2 + _l),
'top': (s.calcLinePoints().y2 + _t)
});
console.log(s.calcLinePoints().y2 + _t)
currentObj.setCoords();
currentObj.line1 && currentObj.line1.set({
'x2': currentObj.left,
'y2': currentObj.top
});
currentObj.line2 && currentObj.line2.set({
'x1': currentObj.left,
'y1': currentObj.top
});
currentObj.line2.setCoords();
currentObj.line1.setCoords();
//move the other circle
canvas.forEachObject(function(obj) {
var _objType = obj.get('type');
if (_objType == "circle" && obj.line2.name == s.get("name")) {
obj.set({
'left': (s.calcLinePoints().x1 + _l),
'top': (s.calcLinePoints().y1 + _t)
});
console.log(s.calcLinePoints().y1 + _t)
obj.setCoords();
obj.line1 && obj.line1.set({
'x2': obj.left,
'y2': obj.top
});
obj.line2 && obj.line2.set({
'x1': obj.left,
'y1': obj.top
});
obj.line2.setCoords();
obj.line1.setCoords();
//canvas.renderAll();
}
});
canvas.renderAll();
//end move oter
}
}
}
}
}
});
});
<script src="http://cdnjs.cloudflare.com/ajax/libs/fabric.js/1.5.0/fabric.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<canvas id="c" width="500" height="500"></canvas>
Here it is the code on jsfiddle, too:
https://jsfiddle.net/muybien/mzsa3z9L/
I want previously to thank you, even only for reading the question.

Answer 1

Thanks of MiltoxBeyond's suggestion, the problem is fixed.
Here it is a working and little cleaned example:
//to save the old cursor position: used on line mooving
var _curX, _curY;
$(function() {
//create the fabriccanvas object & disable the canvas selection
var canvas = new fabric.Canvas('c', {
selection: false
});
//move the objects origin of transformation to the center
fabric.Object.prototype.originX = fabric.Object.prototype.originY = 'center';
function makeCircle(left, top, line1, line2) {
var c = new fabric.Circle({
left: left,
top: top,
strokeWidth: 2,
radius: 6,
fill: '#fff',
stroke: '#666'
});
c.hasControls = c.hasBorders = false;
c.line1 = line1;
c.line2 = line2;
return c;
}
function makeLine(coords, name) {
var l = new fabric.Line(coords, {
stroke: 'red',
strokeWidth: 4,
selectable: true, //false
name: name
});
l.hasControls = l.hasBorders = false;
return l;
}
//initial shape information
var line = makeLine([250, 125, 350, 125], "l1"),
line2 = makeLine([350, 125, 350, 225], "l2"),
line3 = makeLine([350, 225, 250, 225], "l3"),
line4 = makeLine([250, 225, 250, 125], "l4");
canvas.add(line, line2, line3, line4);
canvas.add(
makeCircle(line.get('x1'), line.get('y1'), line4, line), makeCircle(line.get('x2'), line.get('y2'), line, line2), makeCircle(line2.get('x2'), line2.get('y2'), line2, line3), makeCircle(line3.get('x2'), line3.get('y2'), line3, line4)
);
canvas.on('object:selected', function(e) {
//find the selected object type
var objType = e.target.get('type');
if (objType == 'line') {
_curX = e.e.clientX;
_curY = e.e.clientY;
//console.log(_curX);
//console.log(_curY);
}
});
canvas.on('object:moving', function(e) {
//find the moving object type
var p = e.target;
var objType = p.get('type');
if (objType == 'circle') {
p.line1 && p.line1.set({
'x2': p.left,
'y2': p.top
});
p.line2 && p.line2.set({
'x1': p.left,
'y1': p.top
});
//set coordinates for the lines - should be done if element is moved programmely
p.line2.setCoords();
p.line1.setCoords();
canvas.renderAll();
} else if (objType == 'line') {
var _curXm = (_curX - e.e.clientX);
var _curYm = (_curY - e.e.clientY);
//console.log("moved: " + _curXm);
//console.log("moved: " + _curYm);
//loop all circles and if some contains the line - move it
for (var i = 0; i < canvas.getObjects('circle').length; i++) {
var currentObj = canvas.getObjects('circle')[i];
if (currentObj.line1.get("name") == p.get('name') || currentObj.line2.get("name") == p.get('name')) {
currentObj.set({
'left': (currentObj.left - _curXm),
'top': (currentObj.top - _curYm)
});
currentObj.setCoords();
currentObj.line1 && currentObj.line1.set({
'x2': currentObj.left,
'y2': currentObj.top
});
currentObj.line2 && currentObj.line2.set({
'x1': currentObj.left,
'y1': currentObj.top
});
currentObj.line2.setCoords();
currentObj.line1.setCoords();
}
}
_curX = e.e.clientX;
_curY = e.e.clientY;
}
});
});
canvas {
border: 1px solid #808080;
}
<script src="http://cdnjs.cloudflare.com/ajax/libs/fabric.js/1.5.0/fabric.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<canvas id="c" width="500" height="500"></canvas>