问Fabric JS:当直线在一个组中移动时计算线坐标

EN

'Absolute Line TL X' = 'Group top X left value' + (('Group width' / 2) + 'Line top left X value') 
'Absolute Line TL Y' = 'Group top Y left value' + (('Group height' / 2) + 'Line top left Y value') 

canvas.on("object:moving", function(e) {
  var target;
  var coords;

  if (e.target._objects) {
    target = e.target._objects[0];
    coords = calcLineCoords(target, e.target);
  } else {
    target = e.target;
    coords = calcLineCoords(target);
  }

  caption.text = coords + "";
});

function calcLineCoords(line, groupContainer) {
  const { tl } = line.calcCoords();
  let coordsStart = tl;

  if (!!groupContainer) {
    const groupCoordinates = groupContainer.calcCoords();
    let groupCoordsStart = groupCoordinates.tl;

    var lineTopLeftX =
      groupCoordsStart.x + (groupContainer.get("width") / 2 + coordsStart.x);
    var lineTopLeftY =
      groupCoordsStart.y + (groupContainer.get("height") / 2 + coordsStart.y);

    return [lineTopLeftX, lineTopLeftY];
  } else {
    return [coordsStart.x, coordsStart.y];
  }
}