OpenLayers3基础教程——OL3之Popup

概述：

本节重点讲述OpenLayers3中Popup的调用时实现，OL3改用Overlay取代OL2的Popup功能。

接口简单介绍：

overlay跟ol.control.Control一样，是一个可见的窗体，可是不和Control一样，不是固定在地图区域的某个部分，而是显示在一个地图坐标上，随着地图的移动或者缩放而移动的。其调用方式例如以下：

var popup = new ol.Overlay({
  element: document.getElementById('popup')
});
popup.setPosition(coordinate);
map.addOverlay(popup);

new ol.Overlay(options)

src/ol/overlay.js, line 69

Name

Type

Description

options

Overlay options.

Name	Type	Description
element	Element | undefined	The overlay element.
offset	Array.<number> |undefined	Offsets in pixels used when positioning the overlay. The fist element in the array is the horizontal offset. A positive value shifts the overlay right. The second element in the array is the vertical offset. A positive value shifts the overlay down. Default is [0, 0].
position	ol.Coordinate |undefined	The overlay position in map projection.
positioning	ol.OverlayPositioning| string | undefined	Defines how the overlay is actually positioned with respect to its position property. Possible values are'bottom-left', 'bottom-center', 'bottom-right', 'center-left', 'center-center','center-right', 'top-left', 'top-center', and 'top-right'. Default is 'top-left'.
stopEvent	boolean | undefined	Whether event propagation to the map viewport should be stopped. Default is true. If true the overlay is placed in the same container as that of the controls (CSS class name ol-overlaycontainer-stopevent); iffalse it is placed in the container with CSS class name ol-overlaycontainer.
insertFirst	boolean | undefined	Whether the overlay is inserted first in the overlay container, or appended. Default is true. If the overlay is placed in the same container as that of the controls (see the stopEvent option) you will probably setinsertFirst to true so the overlay is displayed below the controls.

Fires:

• change:element (ol.ObjectEvent)
• change:map (ol.ObjectEvent)
• change:offset (ol.ObjectEvent)
• change:position (ol.ObjectEvent)
• change:positioning (ol.ObjectEvent)

Extends

• ol.Object

Observable Properties

Name	Type	Settable	ol.ObjectEvent type	Description
element	Element | undefined	yes	change:element	The Element containing the overlay.
map	ol.Map | undefined	yes	change:map	The map that the overlay is part of.
offset	Array.<number>	yes	change:offset	The offset.
position	ol.Coordinate | undefined	yes	change:position	The spatial point that the overlay is anchored at.
positioning	ol.OverlayPositioning	yes	change:positioning	How the overlay is positioned relative to its point on the map.

Methods

getElement(){Element|undefined}

src/ol/overlay.js, line 160

Get the DOM element of this overlay.

Returns:

The Element containing the overlay. 

getMap(){ol.Map|undefined}

src/ol/overlay.js, line 176

Get the map associated with this overlay.

Returns:

The map that the overlay is part of. 

getOffset(){Array.<number>}

src/ol/overlay.js, line 192

Get the offset of this overlay.

Returns:

The offset. 

getPosition(){ol.Coordinate|undefined}

src/ol/overlay.js, line 209

Get the current position of this overlay.

Returns:

The spatial point that the overlay is anchored at. 

getPositioning(){ol.OverlayPositioning}

src/ol/overlay.js, line 226

Get the current positioning of this overlay.

Returns:

How the overlay is positioned relative to its point on the map. 

on(type, listener, opt_this){goog.events.Key} inherited

src/ol/observable.js, line 65

Listen for a certain type of event.

Name	Type	Description
type	string | Array.<string>	The event type or array of event types.
listener	function	The listener function.
this	Object	The object to use as this in listener.

Returns:

Unique key for the listener. 

once(type, listener, opt_this){goog.events.Key} inherited

src/ol/observable.js, line 78

Listen once for a certain type of event.

Name	Type	Description
type	string | Array.<string>	The event type or array of event types.
listener	function	The listener function.
this	Object	The object to use as this in listener.

Returns:

Unique key for the listener. 

setElement(element)

src/ol/overlay.js, line 312

Set the DOM element to be associated with this overlay.

Name	Type	Description
element	Element | undefined	The Element containing the overlay.

setMap(map)

src/ol/overlay.js, line 327

Set the map to be associated with this overlay.

Name	Type	Description
map	ol.Map | undefined	The map that the overlay is part of.

setOffset(offset)

src/ol/overlay.js, line 342

Set the offset for this overlay.

Name	Type	Description
offset	Array.<number>	Offset.

setPosition(position)

src/ol/overlay.js, line 358

Set the position for this overlay.

Name	Type	Description
position	ol.Coordinate | undefined	The spatial point that the overlay is anchored at.

setPositioning(positioning)

src/ol/overlay.js, line 374

Set the positioning for this overlay.

Name	Type	Description
positioning	ol.OverlayPositioning	how the overlay is positioned relative to its point on the map.

un(type, listener, opt_this) inherited

src/ol/observable.js, line 91

Unlisten for a certain type of event.

Name	Type	Description
type	string | Array.<string>	The event type or array of event types.
listener	function	The listener function.
this	Object	The object which was used as this by the listener.

unByKey(key) inherited

src/ol/observable.js, line 101

Removes an event listener using the key returned by on() or once().

Name	Type	Description
key	goog.events.Key	Key.

上面的内容是OL3 的API中关于overlay的部分。

调用演示样例：

1、popup样式

		body, #map {
			border: 0px;
			margin: 0px;
			padding: 0px;
			width: 100%;
			height: 100%;
			font-size: 13px;
		}

		.ol-popup {
			display: none;
			position: absolute;
			background-color: white;
			-moz-box-shadow: 0 1px 4px rgba(0,0,0,0.2);
			-webkit-filter: drop-shadow(0 1px 4px rgba(0,0,0,0.2));
			filter: drop-shadow(0 1px 4px rgba(0,0,0,0.2));
			border: 1px solid #cccccc;
			bottom: 12px;
			left: -50px;
			width: 200px;
		}
		.ol-popup:after, .ol-popup:before {
			top: 100%;
			border: solid transparent;
			content: " ";
			height: 0;
			width: 0;
			position: absolute;
			pointer-events: none;
		}
		.ol-popup:after {
			border-top-color: white;
			border-width: 10px;
			left: 48px;
			margin-left: -10px;
		}
		.ol-popup:before {
			border-top-color: #cccccc;
			border-width: 11px;
			left: 48px;
			margin-left: -11px;
		}
		.popup-title{
			font-weight: bold;
			border-bottom:1px solid #cccccc;
			padding: 5px 8px;
		}
		.popup-content{
			padding: 5px 8px;
		}
		.ol-popup-closer {
			text-decoration: none;
			position: absolute;
			top: 6px;
			right: 6px;
		}
		.ol-popup-closer:after {
			content: "✖";
		}

2、popup容器

<div id="map">
	<div id="popup" class="ol-popup">
		<a href="#" id="popup-closer" class="ol-popup-closer"></a>
		<div id="popup-title" class="popup-title"></div>
		<div id="popup-content" class="popup-content"></div>
	</div>
</div>

3、实现js

			var container = document.getElementById('popup');
			var content = document.getElementById('popup-content');
			var title = document.getElementById('popup-title');
			var closer = document.getElementById('popup-closer');
			closer.onclick = function(){
				container.style.display = 'none';
				closer.blur();
				return false;
			};
			var overlay = new ol.Overlay({
				element: container
			});
			map.addOverlay(overlay);

			map.on('click', function(evt) {
				var coordinate = evt.coordinate;
				var hdms = ol.coordinate.toStringHDMS(ol.proj.transform(
						coordinate, 'EPSG:4326', 'EPSG:4326'));
				overlay.setPosition(coordinate);
				content.innerHTML = '<p>You clicked here:</p><code>' + hdms +
				'</code>';
				container.style.display = 'block';
				title.innerHTML = "提示信息";
				title.style.display = 'block';
				map.getView().setCenter(coordinate);
			});

演示样例完整代码例如以下：

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
	<title>Ol3 popup</title>
	<link rel="stylesheet" type="text/css" href="http://localhost/ol3/css/ol.css"/>
	<style type="text/css">
		body, #map {
			border: 0px;
			margin: 0px;
			padding: 0px;
			width: 100%;
			height: 100%;
			font-size: 13px;
		}

		.ol-popup {
			display: none;
			position: absolute;
			background-color: white;
			-moz-box-shadow: 0 1px 4px rgba(0,0,0,0.2);
			-webkit-filter: drop-shadow(0 1px 4px rgba(0,0,0,0.2));
			filter: drop-shadow(0 1px 4px rgba(0,0,0,0.2));
			border: 1px solid #cccccc;
			bottom: 12px;
			left: -50px;
			width: 200px;
		}
		.ol-popup:after, .ol-popup:before {
			top: 100%;
			border: solid transparent;
			content: " ";
			height: 0;
			width: 0;
			position: absolute;
			pointer-events: none;
		}
		.ol-popup:after {
			border-top-color: white;
			border-width: 10px;
			left: 48px;
			margin-left: -10px;
		}
		.ol-popup:before {
			border-top-color: #cccccc;
			border-width: 11px;
			left: 48px;
			margin-left: -11px;
		}
		.popup-title{
			font-weight: bold;
			border-bottom:1px solid #cccccc;
			padding: 5px 8px;
		}
		.popup-content{
			padding: 5px 8px;
		}
		.ol-popup-closer {
			text-decoration: none;
			position: absolute;
			top: 6px;
			right: 6px;
		}
		.ol-popup-closer:after {
			content: "✖";
		}
	</style>
	<script type="text/javascript" src="http://localhost/ol3/build/ol.js"></script>
	<script type="text/javascript" src="http://localhost/jquery/jquery-1.8.3.js"></script>
	<script type="text/javascript">
		function init(){
			var format = 'image/png';
			var bounds = [73.4510046356223, 18.1632471876417,
				134.976797646506, 53.5319431522236];
			var untiled = new ol.layer.Image({
				source: new ol.source.ImageWMS({
					ratio: 1,
					url: 'http://localhost:8081/geoserver/lzugis/wms',
					params: {'FORMAT': format,
						'VERSION': '1.1.1',
						LAYERS: 'lzugis:capital',
						STYLES: ''
					}
				})
			});
			var projection = new ol.proj.Projection({
				code: 'EPSG:4326',
				units: 'degrees'
			});
			var container = document.getElementById('popup');
			var content = document.getElementById('popup-content');
			var title = document.getElementById('popup-title');
			var closer = document.getElementById('popup-closer');
			closer.onclick = function(){
				container.style.display = 'none';
				closer.blur();
				return false;
			};
			var overlay = new ol.Overlay({
				element: container
			});
			map.addOverlay(overlay);

			var map = new ol.Map({
				controls: ol.control.defaults({
					attribution: false
				}),
				target: 'map',
				layers: [untiled],
				overlays: [overlay],
				view: new ol.View({
					projection: projection
				})
			});
			map.getView().fitExtent(bounds, map.getSize());

			map.on('click', function(evt) {
				var coordinate = evt.coordinate;
				var hdms = ol.coordinate.toStringHDMS(ol.proj.transform(
						coordinate, 'EPSG:4326', 'EPSG:4326'));
				overlay.setPosition(coordinate);
				content.innerHTML = '<p>You clicked here:</p><code>' + hdms +
				'</code>';
				container.style.display = 'block';
				title.innerHTML = "提示信息";
				title.style.display = 'block';
				map.getView().setCenter(coordinate);
			});
		}
	</script>
</head>
<body onLoad="init()">
<div id="map">
	<div id="popup" class="ol-popup">
		<a href="#" id="popup-closer" class="ol-popup-closer"></a>
		<div id="popup-title" class="popup-title"></div>
		<div id="popup-content" class="popup-content"></div>
	</div>
</div>
</body>
</html>

实现后的效果例如以下：

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相关文章：

OpenLayers3基础教程——OL3基本概念

OpenLayers3基础教程——载入资源

OpenLayers3基础教程——OL3 介绍control

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