Fabric JS父子对象

Question

I'm trying to use fabric JS for a seating chart application. I have individual objects for the floor plan and for each of the users. I can move them all independently of each other. I'd like the users to be parented to the floor plan so that when I move the floor plan object all the users will move with it. Is there any way to do this with fabric?

Answer 1

Found a way to do it; though I still wonder whether the fabric framework has a way to automatically handle this rather than creating it myself for all the parent-child relationships.

// Create canvas
canvas = new fabric.Canvas('c');
img = document.getElementById("cur_image");

// Create parent object
background = new fabric.Image(img, {
    left: 0,
    top: 0,
    angle: 0,
    opacity: 1.0
});
canvas.add(background);

// Connect move handler that will move the children
background.on('moving', backgroundMoveHandler);

children = [];
function addItem() {
    var rect = new fabric.Rect({
        left: 100,
        top: 100,
        fill: 'red',
        width: 50,
        height: 50
    });
    canvas.add(rect);
    children.push(rect);
}

// Add some children
addItem();
addItem();

// Whenever the parent is moved, move the children as well.
function backgroundMoveHandler(options) {
    var x = options.e.movementX;
    var y = options.e.movementY;
    $.each(children, function(i, obj) {
        obj.set('left', obj.left + x);
        obj.set('top', obj.top + y);
        obj.setCoords();
    });
}