Leaftet坐标绘制轴问题

Question

我试图使用传单库在图像上绘制标记，我面临的问题如下：

Leaflet从左下角绘制x，y坐标，而我从服务中获得的坐标绘制坐标，假设轴在左上角。

var pixelsPerUnit = site.siteImageHeightinPX  / site.height;

    for (var i = 0; i < ap.length; i++) {
                 var x = ap[i].xPos * pixelsPerUnit;
                 var y = ap[i].yPos * pixelsPerUnit; 
                    console.log(x+"   "+y);
                    var m = L.marker(xy(x,y), {icon: apIcon});
                    markers.addLayer(m);
                }

JSON

{
  "site": {
    "width": 308.44,
    "height": 205.63,
    "siteImageWidthinPX": 3456,
    "siteImageHeightinPX": 2304,
    "testPoints": [
      {
        "testPointID": "1712",
        "xPos": 44.366,
        "yPos": 52.114
      },
      {
        "testPointID": "1701",
        "xPos": 94.87,
        "yPos": 54.276
      }
    ]
  }
}

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