Simple use of Baidu map - add polylines, circles, etc. (html, js)_html/css_WEB-ITnose

Overview of map overlays

All content that is superimposed or covered on the map is collectively referred to as map overlays. Such as annotations, vector graphic elements (including polylines, polygons and circles), information windows, etc. Overlays have their own geographic coordinates, and when you drag or zoom the map, they move accordingly.

The map API provides the following types of overlays:

Overlay: The abstract base class of overlays. All overlays inherit the methods of this class.

Marker: Marker represents a point on the map, and the mark icon can be customized.

Label: Represents a text label on the map. You can customize the text content of the label.

Polyline: Represents a polyline on the map.

Polygon: Represents a polygon on the map. A polygon is similar to a closed polyline, but you can also add a fill color to it.

Circle: Represents a circle on the map.

InfoWindow: The information window is also a special overlay that can display richer text and multimedia information. Note: Only one information window can be open on the map at the same time.

You can use the map.addOverlay method to add an overlay to the map, and the map.removeOverlay method to remove the overlay. Note that this method does not apply to InfoWindow.

One. Polyline

Polyline represents the polyline overlay on the map. It consists of a set of points and connects these points to form a polyline.

Add polyline

Polyline is drawn as a series of straight segments on the map. The color, thickness, and transparency of these segments can be customized. The color can be a hexadecimal number (for example: #ff0000) or a color keyword (for example: red).

Polyline drawing requires the browser to support the vector drawing function. In Internet Explorer, the map uses VML to draw polylines; in other browsers, use SVG or Canvas

The following code snippet creates a 6-pixel-wide blue polyline between two points:

var polyline = new BMap.Polyline([       new BMap.Point(116.399, 39.910),       new BMap.Point(116.405, 39.920)     ],     {strokeColor:"blue", strokeWeight:6, strokeOpacity:0.5}    );    map.addOverlay(polyline);

Two. Custom overlay

API supports user-defined overlays since version 1.1.

To create a custom overlay , you need to do the following:

　1. Define a constructor of the custom overlay, and pass some constructor parameters Free variables.

2. Set the prototype attribute of the custom overlay object to an instance of Overlay so that it can inherit the overlay base class.

　3. Implement the initialize method. When the map.addOverlay method is called, the API will call this method.

　4. Implement the draw method.

Define the constructor and inherit Overlay

First you need to define the constructor of the custom overlay, in the example below we define a constructor called SquareOverlay , which contains two parameters: center point and side length, and is used to create a square overlay on the map.

// 定义自定义覆盖物的构造函数  function SquareOverlay(center, length, color){     this._center = center;     this._length = length;     this._color = color;    }    // 继承API的BMap.Overlay    SquareOverlay.prototype = new BMap.Overlay();

Initialize the custom overlay

When calling the map.addOverlay method When adding a custom overlay, the API will call the object's initialize method to initialize the overlay. During the initialization process, the DOM elements required for the overlay need to be created and added to the corresponding container of the map.

The map provides several containers for overlay display. These container elements can be obtained through the map.getPanes method. They include:

floatPane

markerMouseTarget

floatShadow

labelPane

markerPane

mapPane

These objects represent different cover container elements, and there is an overlay relationship between them. The top layer It is a floatPane, used to display the content of the information window. The following is the annotation click area layer, the information window shadow layer, the text annotation layer, the annotation layer and the vector graphics layer.

Our custom square cover can be added to any layer. Here we choose to add it to the markerPane as one of its child nodes.

// 实现初始化方法  SquareOverlay.prototype.initialize = function(map){    // 保存map对象实例    this._map = map;         // 创建div元素，作为自定义覆盖物的容器    var div = document.createElement("div");     div.style.position = "absolute";         // 可以根据参数设置元素外观    div.style.width = this._length + "px";     div.style.height = this._length + "px";     div.style.background = this._color;      // 将div添加到覆盖物容器中    map.getPanes().markerPane.appendChild(div);      // 保存div实例    this._div = div;      // 需要将div元素作为方法的返回值，当调用该覆盖物的show、   // hide方法，或者对覆盖物进行移除时，API都将操作此元素。    return div;    }

Drawing the overlay

So far we have only added the overlay to the map, but not placed it in the right position. You need to set the position of the overlay in the draw method. Whenever the map state changes (for example, position movement, level change), the API will call the overlay's draw method to recalculate the position of the overlay. The map.pointToOverlayPixel method can be used to convert geographic coordinates to the required pixel coordinates of the overlay.

// 实现绘制方法   SquareOverlay.prototype.draw = function(){    // 根据地理坐标转换为像素坐标，并设置给容器     var position = this._map.pointToOverlayPixel(this._center);     this._div.style.left = position.x - this._length / 2 + "px";     this._div.style.top = position.y - this._length / 2 + "px";    }

Add Overlay

You have now completed a complete Custom overlays can be written and added to the map.

// 初始化地图  var map = new BMap.Map("container");    var point = new BMap.Point(116.404, 39.915);    map.centerAndZoom(point, 15);    // 添加自定义覆盖物   var mySquare = new SquareOverlay(map.getCenter(), 100, "red");    map.addOverlay(mySquare);

Three. Add an ellipse

<!DOCTYPE html><html><head>    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />    <meta name="viewport" content="initial-scale=1.0, user-scalable=no" />    <style type="text/css">        body, html {width: 100%;height: 100%;margin:0;font-family:"微软雅黑";}        #allmap{width:100%;height:500px;}        p{margin-left:5px; font-size:14px;}    </style>    <script type="text/javascript" src="http://api.map.baidu.com/api?v=2.0&ak=您的密钥"></script>    <script type="text/javascript" src="http://api.map.baidu.com/library/CurveLine/1.5/src/CurveLine.min.js"></script>    <title>添加椭圆</title></head><body>    <div id="allmap"></div>    <p>在地图上添加一个椭圆，圆的颜色为蓝色、线宽6px、透明度为1，填充颜色为白色，透明度为0.5</p></body></html><script type="text/javascript">    // 百度地图API功能    var map = new BMap.Map("allmap");    var point = new BMap.Point(116.404, 39.915);    map.centerAndZoom(point, 10);        //centre:椭圆中心点,X:横向经度,Y:纵向纬度    function add_oval(centre,x,y)    {        var assemble=new Array();        var angle;        var dot;        var tangent=x/y;        for(i=0;i<36;i++)        {            angle = (2* Math.PI / 36) * i;            dot = new BMap.Point(centre.lng+Math.sin(angle)*y*tangent, centre.lat+Math.cos(angle)*y);            assemble.push(dot);        }        return assemble;    }    var oval = new BMap.Polygon(add_oval(point,0.1,0.3), {strokeColor:"blue", strokeWeight:6, strokeOpacity:0.5});    map.addOverlay(oval);</script>

Effect:

Thank you for reading !

Basic knowledge can be found at: http://www.cnblogs.com/0201zcr/p/4687220.html Baidu Map Incident

http://www.cnblogs.com/0201zcr/p /4680461.html Add tag

　　　http://www.cnblogs.com/0201zcr/p/4679444.html Add map service