Using JavaScript and Tencent Maps to implement map marking function

Using JavaScript and Tencent Maps to implement the map marking function

The map marking function is one of the common functions in modern web applications. It can be used to mark points, areas, or line segments on a map to make it easier for users to perceive and understand geographic information. Map markers are useful for showing businesses or public facilities on the map, marking travel routes, or showing areas of focus.

This article will introduce how to use JavaScript and Tencent Maps to implement the map marking function. The first thing to do is to introduce the Tencent Map API into the web page. This can be done using the following code in the header of the HTML page:

<script src="https://map.qq.com/api/js?v=2.exp&key=YOUR_KEY"></script>

To use the API, you need to register on the Tencent Map Open Platform and obtain an API password. key.

Once the API is introduced, the functions and methods it provides can be called in JavaScript code. In order to implement the map marker function, we need to do the following steps:

1. Automatically load the map and set the center and zoom level
2. Define the map marker style
3. In the map Adding a map marker
4. Binding the event of the map marker

The following is a detailed introduction to each step and the corresponding code example.

1. Automatically load the map and set the center and zoom level

To add a map to a web page, you need to define a container element and call the Tencent Map constructor in JavaScript to create a new map object.

Here is a simple HTML code example:

<div id="map-container" style="height: 500px;"></div>

To load a map in Javascript, you can use the following code:

var map = new qq.maps.Map(document.getElementById("map-container"), {
    center: new qq.maps.LatLng(39.916527, 116.397128),
    zoom: 15
});

In the above code, pass in A DOM element and map options object initialize a new map instance. The options object contains two properties: center and zoom level. The center property is the center coordinate of the map, and the zoom level is the zoom level of the map. In this example, we set the center to the city of Beijing and the zoom level to 15.

2. Define map marker style

Before adding a marker on the map, you need to define the marker style. This is accomplished by creating a new marker icon object. The following is an example of defining a marker style:

var markerIcon = new qq.maps.MarkerImage(
    "/path/to/icon.png",
    new qq.maps.Size(40, 40),
    new qq.maps.Point(0, 0),
    new qq.maps.Point(20, 40),
    new qq.maps.Size(40, 40)
);

In this example, we create a new marker icon object using the MarkerImage constructor. The constructor accepts five parameters:

1. The URL of the icon (icon.png)
2. The width and height of the icon (40x40)
3. The anchor point of the icon ( 0,0)
4. The anchor point of the marker (20,40)
5. The size of the marker (40x40)

The anchor point is to specify the "anchoring point" of the marker ”, they are based on the marker icon itself. The anchor point is defined as a pixel offset relative to the upper left corner of the icon. A marker's anchor point is also a pixel offset that specifies the direction in which the marker's "arrow" points. The size of the marker is the size of the marker icon. These parameters can be adjusted according to your needs to get the desired effect.

3. Adding map markers on the map

Once you have defined the marker's style, you can add the marker to the map. For example, you can add a marker to the map using the following code:

var marker = new qq.maps.Marker({
    position: new qq.maps.LatLng(39.916527, 116.397128),
    map: map,
    icon: markerIcon
});

In this example, we use the Marker constructor to create a new marker. The constructor accepts three parameters:

1. The location of the marker (LatLng)
2. Map instance
3. The icon of the marker

In In this marker example, we set the marker's location to Beijing, the map instance to the "map" variable created earlier, and the marker's icon to the "markerIcon" variable defined earlier. Markers can be added to the map by specifying the "map" attribute.

4. Bind events of map markers

To handle user interaction events of map markers (such as click or drag), you need to bind the callback function to the appropriate on events. For example, you can use the following code to bind a click event to the marker created above:

qq.maps.event.addListener(marker, 'click', function() {
    alert('You clicked on the marker');
});

In this example, we use the addListener method to bind an anonymous function to the marker's click event. In this function, we use JavaScript’s alert method to display a message box. This is a very simple example, you can customize this callback function to achieve the interactive behavior you need.

To sum up, using JavaScript and Tencent Maps to mark maps is very simple. In a few simple steps, you can set map centers, styles and markers, and respond to user interaction events. The following is the complete sample code:

<meta charset="utf-8">
<title>腾讯地图标记示例</title>
<script src="https://map.qq.com/api/js?v=2.exp&key=YOUR_KEY"></script>


<div id="map-container" style="height: 500px;"></div>
<script>
    var map = new qq.maps.Map(document.getElementById("map-container"), {
        center: new qq.maps.LatLng(39.916527, 116.397128),
        zoom: 15
    });
    var markerIcon = new qq.maps.MarkerImage(
        "path/to/icon.png",
        new qq.maps.Size(40, 40),
        new qq.maps.Point(0, 0),
        new qq.maps.Point(20, 40),
        new qq.maps.Size(40, 40)
    );
    var marker = new qq.maps.Marker({
        position: new qq.maps.LatLng(39.916527, 116.397128),
        map: map,
        icon: markerIcon
    });
    qq.maps.event.addListener(marker, 'click', function() {
        alert('You clicked on the marker');
    });
</script>

Please note that the "YOUR_KEY" placeholder is used in this example and must be replaced with a valid API key that you registered and obtained on the Tencent Map Open Platform .

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