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Using JavaScript and Tencent Maps to implement map line drawing function

PHPzOriginal: 2023-11-21 12:59:011453browse

Use JavaScript and Tencent Maps to implement map line drawing function

Introduction:
Map line drawing is one of the common functions in many online map applications. In this article, we will introduce how to use JavaScript and Tencent Map API to implement the map line drawing function.

Introduction to Tencent Map API:
Tencent Map API is a set of map service interfaces developed based on JavaScript provided by Tencent. It provides rich map display functions and various geographical information query and operation functions.

Step 1: Obtain Tencent Map API Key
First, we need to register a developer account on the Tencent Map open platform and apply for an API key. API keys are used to identify developers and limit the frequency of API calls.

Step 2: Create an HTML page
We need to introduce the Javascript library of Tencent Map API into the HTML page and create a map container to display the map. The following is a simple HTML code example:

<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>地图线路绘制</title>
    <style type="text/css">
        #mapContainer {
            width: 100%;
            height: 800px;
        }
    </style>
</head>
<body>
    <div id="mapContainer"></div>

    <script type="text/javascript" src="https://map.qq.com/api/js?v=2.exp&key=YOUR_API_KEY"></script>
    <script type="text/javascript">
        // 在这里编写Javascript代码
    </script>
</body>
</html>

Step 3: Draw the map
In the Javascript code part, we first need to initialize the map, and then add a drawing control. The following is a simple code example:

// 初始化地图
var map = new qq.maps.Map(document.getElementById("mapContainer"), {
    center: new qq.maps.LatLng(39.908823, 116.397470), // 地图中心点坐标
    zoom: 12 // 地图缩放级别
});

// 添加绘制控件
var drawingManager = new qq.maps.drawing.DrawingManager({
    drawingMode: qq.maps.drawing.OverlayType.POLYLINE, // 设置绘制模式为折线
    drawingControl: true,
    drawingControlOptions: {
        position: qq.maps.ControlPosition.TOP_CENTER,
        drawingModes: [
            qq.maps.drawing.OverlayType.POLYLINE, // 折线
            qq.maps.drawing.OverlayType.POLYGON, // 多边形
            qq.maps.drawing.OverlayType.CIRCLE // 圆形
        ]
    },
    polylineOptions: {
        strokeColor: "#FF0000",
        strokeWeight: 5
    }
});

drawingManager.setMap(map);

With the above code, we can see the drawing control on the map. Users can select polyline mode through the drawing control and draw lines on the map.

Step 4: Draw the line
Before drawing the line, we need to store the drawn line for subsequent use. The following is a simple code example:

// 监听折线绘制完成事件
qq.maps.event.addListener(drawingManager, 'overlaycomplete', function(event) {
    // 判断绘制的是否为折线
    if (event.overlay instanceof qq.maps.Polyline) {
        var path = event.overlay.getPath(); // 获取折线的路径坐标数组
        var polyline = new qq.maps.Polyline({
            path: path, // 设置折线的路径坐标数组
            strokeColor: "#FF0000",
            strokeWeight: 5,
            map: map
        });

        // 存储折线的路径坐标数组
        var polylineCoordinates = [];
        path.forEach(function(point) {
            polylineCoordinates.push({
                lat: point.getLat(),
                lng: point.getLng()
            });
        });

        // 将坐标数组存储在localStorage中
        localStorage.setItem("polylineCoordinates", JSON.stringify(polylineCoordinates));
    }
});

In the above code, we listen to the polyline drawing completion event, obtain the coordinate array of the drawn polyline path, and store it in localStorage. Later, we can get these coordinate arrays from localStorage and use them for other operations, such as calculating the length of the line.

Conclusion:
By using JavaScript and Tencent Map API, we can realize the map line drawing function. We can draw polylines, polygons, and circles and store them for later use. With these features, we can build more complex and useful map applications.

The above is just a simple example. In actual applications, more functions and business requirements may need to be considered. But through the above code and ideas, we can easily implement the map line drawing function in the project. Hope this article helps you!

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