CS版本程序，如果使用本地地图的话，不需要查询数据库地物点

最新推荐文章于 2025-09-11 20:53:34 发布

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最新推荐文章于 2025-09-11 20:53:34 发布

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文章标签：数据库

原文链接：http://www.cnblogs.com/shanghaif/archive/2008/10/13/1310189.html

本文介绍了一个地图应用程序中关于发送宾馆大厦数据请求的实现方法。重点在于根据地图的缩放等级和墨卡托坐标范围来发送数据请求，并通过一个布尔变量控制是否进行数据库查询。

涉及到的文件及更改信息：

1，D:\Cs\UniGuard_ComponentCompiled\UniguardCommon\Socket\UniguardWebRequest.vb下的方法SendPointFeatureReq是真正的代码

''' <summary>
''' 地图漂定后，发送宾馆大厦数据的请求
''' </summary>
''' <param name="zoomLevel">缩放等级</param>
''' <param name="mercatorBound">墨卡托范围</param>
''' <param name="handler"></param>
''' <remarks></remarks>
Public Sub SendPointFeatureReq(ByVal zoomLevel As Integer, ByVal mercatorBound As System.Drawing.Rectangle, ByVal handler As EventHandler(Of TableEventArgs))
    Dim adp As New SimpleTableAdapter(Me, New DataTable, "cs/atlas")
    adp.WorkMode = WebSubmitee.WorkModeEnum.Async
    AddHandler adp.OnFillComplete, handler
    Dim args As New Specialized.NameValueCollection
    args("zoom_level") = zoomLevel
    args("min_x") = mercatorBound.Left
    args("max_x") = mercatorBound.Right
    args("min_y") = mercatorBound.Top
    args("max_y") = mercatorBound.Bottom
    adp.Fill("queryPoints", args)
End Sub

2，更改D:\Cs\UniGuard_ComponentCompiled\UniguardCommon\Map\UniguardMap.vb下的UniguardMap_OnMapViewChanged方法到如下

Dim lastChangeTime As DateTime = DateTime.MinValue
Private Sub UniguardMap_OnMapViewChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.OnMapViewChanged
    If DateTime.Now.Subtract(lastChangeTime).TotalMilliseconds > 500 Then
        If mWebRequest Is Nothing Then Return
        If Me.ZoomLevel >= POINT_FEATURE_MIN_LEVEL And mSendPointFeatureReq Then
            mWebRequest.SendPointFeatureReq(Me.ZoomLevel, Me.MercatorBound, AddressOf ProcessPointsArrive)
        End If
        lastChangeTime = DateTime.Now
    End If
End Sub

主要是增加了一个判断条件mSendPointFeatureReq

3，该判断条件是在D:\Cs\UniGuard_ComponentCompiled\UniguardStart\LoginForm.vb的InitTileProviders函数里面定义的，主要代码如下：

Private Sub InitTileProviders(ByVal mapServerUri As String, ByVal eagleMapUri As String)
    ' 初始化大地图提供器
    Dim provider As RasterMap.TileProvider.ITileProvider
    With My.Application
        If My.Settings.GeosetLocation IsNot Nothing AndAlso My.Settings.GeosetLocation.Length > 0 Then
            UniguardMap.InitGeoFactoryPool(My.Settings.GeosetLocation, My.Settings.LocalMapPath)
            UniguardMap.isSendPointFeatureReq(False)
            provider = New GeosetTileProvider(UniguardMap.GeoFactoryPool)
        Else
            provider = New TileProvider.WebTileProvider(mapServerUri)
            UniguardMap.isSendPointFeatureReq(True)
        End If
    End With
    Dim tp As New TileProvider.FileCacheTileProvider(provider)
    tp.CacheDirectory = My.Settings.LocalMapPath
    If tp.CacheDirectory IsNot Nothing AndAlso tp.CacheDirectory.Length > 0 Then
        If IO.Directory.Exists(tp.CacheDirectory) = False Then
            IO.Directory.CreateDirectory(tp.CacheDirectory)
        End If
        UniguardMap.MapProvider = tp
    End If
    ' 初始化鹰眼图提供器
    provider = New TileProvider.WebTileProvider(eagleMapUri)
    tp = New TileProvider.FileCacheTileProvider(provider)
    tp.CacheDirectory = System.IO.Path.Combine(Application.StartupPath, "eaglemap")
    EagleMap.EagleProvider = tp
End Sub

4，增加了函数isSendPointFeatureReq。位置在D:\Cs\UniGuard_ComponentCompiled\UniguardCommon\Map\UniguardMap.vb。代码如下：

Private Shared mSendPointFeatureReq As Boolean

''' <summary>
''' 是否查询数据库里面存储的点信息
''' </summary>
''' <param name="isQuery"></param>
''' <remarks>是否需要查询</remarks>
Public Shared Sub isSendPointFeatureReq(ByVal isQuery As Boolean)
mSendPointFeatureReq = isQuery
End Sub

转载于:https://www.cnblogs.com/shanghaif/archive/2008/10/13/1310189.html