如何在使用Google地图缩小世界地图时限制无限制平移？

Question

Google地图在完全缩小时无限制平移。我将最小缩放级别限制为2：

// Limit the zoom level
    google.maps.event.addListener(map, 'zoom_changed', function () {
        // This is the minimum zoom level that we'll allow
        var minZoomLevel = 2;
        if (map.getZoom() < minZoomLevel) map.setZoom(minZoomLevel);
    });

现在的问题是地图上方和下方都有灰色区域。我想将平移限制为仅限地图边界。好的例子是原始的Google Maps。

这里是地图的上半部分：

地图的下半部分：

我尝试使用从Northeast到Southwest的世界地图范围：

var allowableBounds = new google.maps.LatLngBounds(
    new google.maps.LatLng(85, -180),           // top left corner of map
    new google.maps.LatLng(-85, 180)            // bottom right corner
);

使用此对象allowableBounds限制可视区域：

// bounds of the desired area
var allowedBounds = new google.maps.LatLngBounds(
     new google.maps.LatLng(70.33956792419954, 178.01171875), 
     new google.maps.LatLng(83.86483689701898, -88.033203125)
);
var lastValidCenter = map.getCenter();

google.maps.event.addListener(map, 'center_changed', function() {

    var mapBounds = map.getBounds();
    var mapNe = mapBounds.getNorthEast();
    var mapSw = mapBounds.getSouthWest();
    var center = map.getCenter();

    if( allowedBounds.contains(mapNe) && allowedBounds.contains(mapSw) ) {
        //the user is scrolling within the bounds.
        lastValidCenter = center;
        return;
    }

    //the user has scrolled beyond the edge.

    var mapWidth = mapNe.lng() - mapSw.lng();
    var mapHeight = mapNe.lat() - mapSw.lat();

    var x = center.lng();
    var y = center.lat();

    var maxX = allowedBounds.getNorthEast().lng();
    var maxY = allowedBounds.getNorthEast().lat();
    var minX = allowedBounds.getSouthWest().lng();
    var minY = allowedBounds.getSouthWest().lat();

    //shift the min and max dimensions by 1/2 of the screen size, so the bounds remain at the edge of the screen

    maxX -= (mapWidth / 2);
    minX += (mapWidth / 2);

    maxY -= (mapHeight / 2);
    minY += (mapHeight / 2);


    if (x < minX) {
        x = minX;
    }
    if (x > maxX) {
        x = maxX;
    }
    if (y < minY){
        y = minY;
    }
    if (y > maxY){
        y = maxY;
    }

    map.panTo(new google.maps.LatLng(y, x));

});

但是我收到了这个错误：Uncaught RangeError: Maximum call stack size exceeded

似乎限制了最小缩放级别没有引用它。是否有更简单的谷歌地图属性来限制类似于谷歌地图的无限平移？