Question

我试图从数据库中绘制几个单独的多边形（建筑物）。我从数据库中获取的数据如下所示：

<buildings>
    <building build_id="94" build_gebaeude="A"
        build_geoX="49.26173942769648" build_geoY="7.350542675857582"
    />
    <building build_id="95" build_gebaeude="A"
        build_geoX="49.26173942769648" build_geoY="7.3524094933319475"
    />
    <building build_id="96" build_gebaeude="A"
        build_geoX="49.26019903253632" build_geoY="7.35234512031559"
    />
    <building build_id="97" build_gebaeude="A"
        build_geoX="49.26032506667364" build_geoY="7.350692879562416"
    />
    <building build_id="98" build_gebaeude="B"
        build_geoX="49.26155738350112" build_geoY="7.362129818801918"
    />
    <building build_id="99" build_gebaeude="B"
        build_geoX="49.26157138692462" build_geoY="7.364275586013832"
    />
    <building build_id="100" build_gebaeude="B"
        build_geoX="49.260255047748224" build_geoY="7.364361416702309"
    />
    <building build_id="101" build_gebaeude="B"
        build_geoX="49.260311062896506" build_geoY="7.362065445785561"
    />
</buildings>

以下代码显示了我在绘制建筑物时所做的工作：

for (var i = 0; i < building.length-1; i++) {
    var point = new google.maps.LatLng(
        parseFloat(building[i].getAttribute("build_geoX")),
        parseFloat(building[i].getAttribute("build_geoY"))
    );

    latlngbounds.extend(point);

    if( building[i].getAttribute("build_gebaeude") == 
        building[i+1].getAttribute("build_gebaeude") )
    {
        path.push(point);
    }
    else {
        path.push(point);
        poly = new google.maps.Polygon({
            paths: path,
            strokeWeight: 5,
            strokeOpacity: 1,
            fillOpacity: 0.30,
            strokeColor:'#FFFFFF',
            fillColor: '#a3141d'
        }); 
        polygons.push(poly);
        path.clear();
    }
}   
polygons[0].setMap(map);
polygons[1].setMap(map);

问题是并非所有的点都被绘制出来了吗？我不明白问题在哪里？

Answer 1

看起来paths数组可能存在问题。从您所包含的代码中不清楚paths是JavaScript Array还是类似数组的对象，但是因为您在paths循环中使用for并且然后尝试清除循环中的paths，我建议：

根据需要在循环中创建新的paths Array
添加代码以管理数组循环的状态
更改用于检查建筑物属性和测试平等的代码
由于您将paths数组传递给Polygon构造函数，因此请勿清除数组

var paths = null;
var aNewPathIsNeeded = true;
for ( var i = 0; i < building.length-1; i++) {
    //Create your point
    //Extend your bounds
    //Since you always add the point to the paths array, move it out of the if
    //check and perform some array state management:

    if ( aNewPathIsNeeded ) {
        paths = new Array( point );
        aNewPathIsNeeded = false;
    }
    else { paths.push( point ); }

    //Change the if condition to deal with just the specific case of interest:

    var currentBldgAttr = building[i].getAttribute("build_gebaeude");
    var nextBldgAttr = building[i+1].getAttribute("build_gebaeude");
    if ( !( currentBldgAttr === nextBldgAttr ) ) { //Change to use: '==='
        //Create your polygon
        //Add the polygon to the polygons array
        //New code to manage paths state:
        aNewPathIsNeeded = true;
    }
}

我不确定你的问题究竟是什么，但我相信这段代码会帮助你前进。另请注意，clear()不是JavaScript Array方法;当您要清空Array时，请使用：array.length = 0，如下所述：Is JavaScript's array.clear() not a function?

多个多边形MySQL

1 个答案: