在 Fabric.js 中控制 z-index

在fabricjs中，我想创建一个场景，其中鼠标下方的对象在z-index中上升到场景的顶部，然后一旦鼠标离开该对象，它就会返回到它来自的z-index。无法设置 object.zindex （这很好）。相反，我使用一个占位符对象，将其放入旧位置的对象列表中，然后使用 canvas.insertAt 将旧对象放回其在列表中的位置。然而这不起作用。

See http://jsfiddle.net/rFSEV/ http://jsfiddle.net/rFSEV/对于这个状态。

var canvasS = new fabric.Canvas('canvasS', { renderOnAddition: false, hoverCursor: 'pointer', selection: false });
var bars = {}; //storage for bars (bar number indexed by group object)
var selectedBar = null; //selected bar (group object)
var placeholder = new fabric.Text("XXXXX", { fontSize: 12 });

//pass null or a bar
function selectBar(bar) {
    if (selectedBar) {
        //remove the old topmost bar and put it back in the right zindex
        //PROBLEM: It doesn't go back; it stays at the same zindex
        selectedBar.remove();
        canvasS.insertAt(selectedBar, selectedBar.XZIndex, true);
        selectedBar = null;
        }
    if (bar) {
        //put a placeholder object ("XXX" for now) in the position
        //where the bar was, and put the bar in the top position
        //so it shows topmost
        selectedBar = bar;
        canvasS.insertAt(placeholder, selectedBar.XZIndex, true);
        canvasS.add(bar);
        canvasS.renderAll();
        }
    }

canvasS.on({
     'mouse:move': function(e) {
        //hook up dynamic zorder
        if (!e.target) return;
        if (bars[e.target])
            selectBar(e.target);
        else
            selectBar(null);
        },
    });

var objcount = canvasS.getObjects().length;

//create bars
for (var i = 0; i < 20; ++i) {
    var rect = new fabric.Rect({
      left: 0,
      top: 0,
      rx: 3,
      ry: 3,
      stroke: 'red',
      width: 200,
      height: 25
    });
    rect.setGradientFill({
      x1: 0,
      y1: 0,
      x2: 0,
      y2: rect.height,
      colorStops: {
        0: '#080',
        1: '#fff'
      }
    });    
    var text = new fabric.Text("Bar number " + (i+1), {
        fontSize: 12
    });
    var group = new fabric.Group([ rect, text ], {
      left: i + 101,
      top: i * 4 + 26
    });
    group.hasControls = group.hasBorders = false;

    //our properties (not part of fabric)
    group.XBar = rect;
    group.XZIndex = objcount++;

    canvasS.add(group);
    bars[group] = i;
    }
canvasS.renderAll();

从 Fabric.js 版本 1.1.4 开始，可以使用 zIndex 操作的新方法：

canvas.moveTo(object, index);
object.moveTo(index);

我认为这对您的用例很有帮助。我已经更新了你的 jsfiddle - 我希望这是你想要的：
jsfiddle http://jsfiddle.net/RRv3g/3/