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ASP.NET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 ASP.NET 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ASP.NET Server Control,命名为GoogleMap.cs.
导入如下命名空间:
using
System;
using
System.ComponentModel;
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
{
/// <summary>
/// GoogleMap Designer
/// </summary> public class GoogleMapDesigner : ControlDesigner {
Properties ////////////////////////////////////////////////////// Methods /////////////////////////////////////////////////////// }
}
五. 修改GoogleMap的声明为:
[AspNetHostingPermission(SecurityAction.LinkDemand, Level
=
AspNetHostingPermissionLevel.Minimal)] [ToolboxData(
"
<{0}:GoogleMap runat=\
"
server\
"
></{0}:GoogleMap>
"
)] [Designer(
typeof
(GoogleMapDesigner))]
public
class
GoogleMap : WebControl
好了,下一篇文章中我将给GoogleMap类添加更多实用的属性.