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Using Baidu Map API in PHP to realize the display and control of map scale

王林Original: 2023-07-31 14:10:511330browse

The map scale is a control used to display the scale size of the map on the map. It helps users understand the zoom level and actual value of the map. distance relationship. When developing applications based on Baidu Maps, how to use PHP to display and control the map scale is an important skill. This article will introduce how to use PHP and Baidu Map API to implement the map scale function, and provide corresponding code examples.

First, we need to introduce Baidu Map’s JavaScript library and CSS style files into the HTML page. You can download relevant files from the official website of Baidu Map Open Platform, or use the CDN link directly.

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>地图比例尺示例</title>
    <link rel="stylesheet" href="http://api.map.baidu.com/library/ScaleControl/1.4/src/ScaleControl_min.css"/>
    <script src="http://api.map.baidu.com/api?v=2.0&ak=您的百度地图API密钥"></script>
</head>
<body>
    <div id="map" style="width: 100%; height: 500px;"></div>
</body>
</html>

In the above code, we introduced the JavaScript library of Baidu Map API and the CSS style file of the map scale, and created a container div for displaying the map.

Next, we need to write PHP code to initialize the map. In the PHP file, we can use the Map class provided by Baidu Map API to create a map instance and set its scale control.

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>地图比例尺示例</title>
    <link rel="stylesheet" href="http://api.map.baidu.com/library/ScaleControl/1.4/src/ScaleControl_min.css"/>
    <script src="http://api.map.baidu.com/api?v=2.0&ak=您的百度地图API密钥"></script>
</head>
<body>
    <div id="map" style="width: 100%; height: 500px;"></div>

    <script>
        var map = new BMap.Map("map"); // 创建地图实例
        var point = new BMap.Point(116.404, 39.915); // 创建点坐标
        map.centerAndZoom(point, 15); // 初始化地图，设置中心点和缩放级别

        var scaleControl = new BMap.ScaleControl({anchor: BMAP_ANCHOR_BOTTOM_LEFT}); // 创建比例尺控件
        map.addControl(scaleControl); // 添加比例尺控件
    </script>
</body>
</html>

In the above code, we create a BMap.Map instance and use BMap.Point to set the center point coordinates and zoom level of the map. Then, we created a BMap.ScaleControl instance, added it to the map, and set its display position to the lower left corner of the map (BMAP_ANCHOR_BOTTOM_LEFT).

Run the above code and you will see a Baidu map with a scale on the page.

In addition to adding the scale control when initializing the map, we can also use the addControl method of the map instance to dynamically add and remove the scale control. The following sample code demonstrates how to control the display and hiding of the scale control by clicking a button.

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>地图比例尺示例</title>
    <link rel="stylesheet" href="http://api.map.baidu.com/library/ScaleControl/1.4/src/ScaleControl_min.css"/>
    <script src="http://api.map.baidu.com/api?v=2.0&ak=您的百度地图API密钥"></script>
</head>
<body>
    <div id="map" style="width: 100%; height: 500px;"></div>
    <button onclick="toggleScaleControl()">切换比例尺</button>

    <script>
        var map = new BMap.Map("map"); // 创建地图实例
        var point = new BMap.Point(116.404, 39.915); // 创建点坐标
        map.centerAndZoom(point, 15); // 初始化地图，设置中心点和缩放级别

        var scaleControl = new BMap.ScaleControl({anchor: BMAP_ANCHOR_BOTTOM_LEFT}); // 创建比例尺控件
        map.addControl(scaleControl); // 添加比例尺控件

        function toggleScaleControl() {
            if (scaleControl.isVisible()) {
                map.removeControl(scaleControl); // 隐藏比例尺控件
            } else {
                map.addControl(scaleControl); // 显示比例尺控件
            }
        }
    </script>
</body>
</html>

In the above code, we added a new button and switched the display and hiding of the scale control by calling the toggleScaleControl function. This function determines the current display state of the scale control by judging its isVisible method, and uses the map's removeControl and addControl methods to implement the display and hide functions.

Through the above sample code, we can use Baidu Map API to display and control the map scale in PHP. Readers can make corresponding modifications and extensions according to their own needs and actual situations to meet the needs of specific applications.

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