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ImageMapEventArgs Class

Provides data for the Click event of an ImageMap control.

Namespace:  System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)

'Declaration
<AspNetHostingPermissionAttribute(SecurityAction.InheritanceDemand, Level := AspNetHostingPermissionLevel.Minimal)> _
<AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level := AspNetHostingPermissionLevel.Minimal)> _
Public Class ImageMapEventArgs _
	Inherits EventArgs
'Usage
Dim instance As ImageMapEventArgs

The Click event is raised when a HotSpot object in an ImageMap control is clicked. To allow a HotSpot object to raise the Click event, you must first set either the ImageMap.HotSpotMode property or the HotSpot.HotSpotMode property to HotSpotMode.PostBack. To control the actions programmatically that are performed when a postback HotSpot is clicked, provide an event handler for the Click event.

A PostBackValue property stores a string that is associated with the behavior of the HotSpot object when clicked. This string is passed in the ImageMapEventArgs event data when the HotSpot is clicked.

The following code example demonstrates how to create an event handler for the Click event. The ImageMap control contains two RectangleHotSpot objects. The ImageMap.HotSpotMode property is set to HotSpotMode.PostBack, which causes the page to post back to the server each time a user clicks one of the RectangleHotSpot objects. The Click event is handled by the VoteMap_Clicked event handler. The VoteMap_Clicked examines the PostBackValue property, sent in the ImageMapEventArgs data, to determine which RectangleHotSpot object is associated with the event. For this example to work correctly, you must supply your own image for the ImageUrl property and update the path to the image appropriately so that the application can locate it.

<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  Sub VoteMap_Clicked(ByVal sender As Object, ByVal e As ImageMapEventArgs)
    Dim coordinates As String 
    Dim hotSpotType As String 
    Dim yescount As Integer 
    Dim nocount As Integer 

    If (ViewState("yescount") IsNot Nothing) Then
      yescount = Convert.ToInt32(ViewState("yescount"))
    Else
      yescount = 0
    End If 
    If (ViewState("nocount") IsNot Nothing) Then
      nocount = Convert.ToInt32(ViewState("nocount"))
    Else
      nocount = 0
    End If 


    ' When a user clicks the "Yes" hot spot, 
    ' display the hot spot's name and coordinates. 
    If (e.PostBackValue.Contains("Yes")) Then

      yescount += 1
      coordinates = Vote.HotSpots(0).GetCoordinates()
      hotSpotType = Vote.HotSpots(0).ToString()
      Message1.Text = "You selected " & hotSpotType & " " & e.PostBackValue & ".<br />" & _
                      "The coordinates are " & coordinates & ".<br />" & _
                      "The current vote count is " & yescount.ToString() & _
                      " yes votes and " & nocount.ToString() & " no votes." 

      ' When a user clicks the "No" hot spot, 
      ' display the hot spot's name and coordinates. 
    ElseIf (e.PostBackValue.Contains("No")) Then

      nocount += 1
      coordinates = Vote.HotSpots.Item(1).GetCoordinates()
      hotSpotType = Vote.HotSpots.Item(1).ToString()
      Message1.Text = "You selected " & hotSpotType & " " & e.PostBackValue & ".<br />" & _
                     "The coordinates are " & coordinates & ".<br />" & _
                      "The current vote count is " & yescount.ToString() & _
                      " yes votes and " & nocount.ToString() & " no votes." 

    Else

      Message1.Text = "You did not click a valid hot spot region." 

    End If

    ViewState("yescount") = yescount
    ViewState("nocount") = nocount

  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="head1" runat="server">
  <title>ImageMap Class Post Back Example</title>
</head>
  <body>
    <form id="form1" runat="server">

      <h3>ImageMap Class Post Back Example</h3>

      <asp:imagemap id="Vote"           
        imageurl="Images/VoteImage.jpg"
        width="400" 
        height="200" 
        alternatetext="Vote Yes or No"
        hotspotmode="PostBack"
        onclick="VoteMap_Clicked"
        runat="Server">            

        <asp:RectangleHotSpot          
          top="0"
          left="0"
          bottom="200"
          right="200"
          postbackvalue="Yes"
          alternatetext="Vote yes">
        </asp:RectangleHotSpot>

        <asp:RectangleHotSpot 
          top="0"
          left="201"
          bottom="200"
          right="400"
          postbackvalue="No"
          alternatetext="Vote no">
        </asp:RectangleHotSpot>

      </asp:imagemap>

      <br /><br />

      <asp:label id="Message1"
        runat="Server">
      </asp:label>                 

    </form>      
  </body>
</html>

System.Object
  System.EventArgs
    System.Web.UI.WebControls.ImageMapEventArgs

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0
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