用C#创建一个封装Google Map API的GoogleMap Web服务器控件(一)
最近想搞两个基于Google Map的网站玩玩,觉得直接操作Google Map API实在麻烦,于是就想用C#写一个封装Google Map API的GoogleMap Web服务器控件,这样,用https://www.doczj.com/doc/2614185972.html,创建基于Google Map 的网站就非常简单啦!
下面就让我们从头开始吧!
一. 首先打开Visual Studio 2008(其他IDE也可以),创建一个C#类库项目,命名为WindEagle.GoogleMap,勾选"创建解决方案目录"选项.
二. 删除默认的Class1.cs,修改项目属性,设置默认命名空间为"WindEagle.Web.UI.Controls".打开AssemblyInfo.cs,作如下修改:
using System.Reflection;
[assembly: AssemblyTitle("WindEagle.GoogleMap")]
[assembly: AssemblyDescription("封装Google Map API的GoogleMap https://www.doczj.com/doc/2614185972.html, Web服务器控件")]
[assembly: AssemblyCompany("WindEagle")]
[assembly: AssemblyProduct("WindEagle.GoogleMap")]
[assembly: AssemblyCopyright("Copyright ? WindEagle 2008")]
[assembly: AssemblyVersion("2.0.0.0")]
[assembly: AssemblyFileVersion("2.0.0.0")]
三. 在项目中添加一个https://www.doczj.com/doc/2614185972.html, Server Control,命名为GoogleMap.cs.
导入如下命名空间:
using System;
using https://www.doczj.com/doc/2614185972.html,ponentModel;
using System.Security.Permissions;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;
using System.Drawing.Design;
我们初步设计的GoogleMap控件应该有以下这些属性:
1. Height和Width, 因为Google Map的大小不能为零,且高宽比例一定,所以我决定重写继承于WebControl的Height和Width属性.
private static readonly Unit DefaultWidth = new Unit("1200px");
private static readonly Unit DefaultHeight = new Unit("960px");
public override Unit Height
{
get
{
return (base.Height != Unit.Empty) ? base.Height : DefaultHeight;
}
set
{
base.Height = value;
}
}
public override Unit Width
{
get
{
return (base.Width != Unit.Empty) ? base.Width : DefaultWidth;
}
set
{
base.Width = value;
}
}
2. Zoom, Google Map的固有属性,表示Map的显示等级.
[
Bindable(true),
Category("Google"),
DefaultValue(0),
Description("The zoom.")
]
public virtual int Zoom
{
get
{
object zoom = ViewState["Zoom"];
return (zoom == null) ? 0 : (int)price;
}
set
{
ViewState["Zoom"] = value;
}
}
3. Latitude和Longitude, Google Map的固有属性,表示Map中心点的纬度和经度.
[
Bindable(true),
Category("Google"),
DefaultValue(0),
Description("The latitude.")
]
public virtual double Latitude
{
get
{
object latitude = ViewState["Latitude"];
return (latitude == null) ? 0 : (double)latitude;
}
set
{
ViewState["Latitude"] = value;
}
}
[
Bindable(true),
Category("Google"),
DefaultValue(0),
Description("The longitude.")
]
public virtual double Longitude
{
get
{
object longitude = ViewState["Longitude"];
return (longitude == null) ? 0 : (double)longitude;
}
set
{
ViewState["Longitude"] = value;
}
}
4. Address, 当没有指定Latitude和Longitude的时候,自动根据本属性查询得到Latitude和Longitude的值.
[
Bindable(true),
Category("Google"),
DefaultValue(""),
Description("The address."),
Localizable(true)
]
public virtual string Address
{
get
{
String s = (String)ViewState["Address"];
return (s == null) ? String.Empty : s;
}
set
{
ViewState["Address"] = value;
}
}
5. Key, 从Google那里得到的用户key.
[
Bindable(true),
Category("Google"),
DefaultValue(""),
Description("The user key obtained from google map api.")
]
public virtual string Key
{
get
{
String s = (String)ViewState["Key"];
return (s == null) ? String.Empty : s;
}
set
{
ViewState["Key"] = value;
}
}
6. TagKey, 重写的只读TagKey属性,将Map的Tag从默认的HtmlTextWriterTag.Span改为HtmlTextWriterTag.Div.
protected override HtmlTextWriterTag TagKey
{
get
{
return HtmlTextWriterTag.Div;
}
}
四. 給GoogleMap控件添加设计器,参考演练：为Web 服务器控件创建基本控件设计器,设计器的源代码为:
using System.Web.UI.Design;
namespace WindEagle.Web.UI.Controls
{
///
/// GoogleMap Designer
///
public class GoogleMapDesigner : ControlDesigner
{
#region Properties //////////////////////////////////////////////////////
#endregion
#region Methods ////////////////////////////////////////////////////// /
///
/// Get the design-time Html.
///
///
public override string GetDesignTimeHtml()
{
GoogleMap map = https://www.doczj.com/doc/2614185972.html,ponent as GoogleMap;
if (map != null)
return string.Format("Google Map points to {0}:{1} (latitude :longitude)", https://www.doczj.com/doc/2614185972.html,titude, map.Longitude);
else
return"Google Map";
}
#endregion
}
}
五. 修改GoogleMap的声明为:
[AspNetHostingPermission(SecurityAction.LinkDemand, Level = AspNetHostin gPermissionLevel.Minimal)]
[ToolboxData("<{0}:GoogleMap runat=\"server\">")]
[Designer(typeof(GoogleMapDesigner))]
public class GoogleMap : WebControl