ImageMap.Click Event
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
public:
event System::Web::UI::WebControls::ImageMapEventHandler ^ Click;public event System.Web.UI.WebControls.ImageMapEventHandler Click;member this.Click : System.Web.UI.WebControls.ImageMapEventHandler Public Custom Event Click As ImageMapEventHandler Event Type
Examples
The following code example demonstrates how to create an ImageMap control that 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 hot spot regions. The VoteMap_Clicked event handler handles the click event for the ImageMap control. 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="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
void VoteMap_Clicked (Object sender, ImageMapEventArgs e)
{
string coordinates;
string hotSpotType;
int yescount = ((ViewState["yescount"] != null)? (int)ViewState["yescount"] : 0);
int nocount = ((ViewState["nocount"] != null)? (int)ViewState["nocount"] : 0);
// When a user clicks the "Yes" hot spot,
// display the hot spot's name and coordinates.
if (e.PostBackValue.Contains("Yes"))
{
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.
else if (e.PostBackValue.Contains("No"))
{
nocount += 1;
coordinates = Vote.HotSpots[1].GetCoordinates();
hotSpotType = Vote.HotSpots[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.";
}
ViewState["yescount"] = yescount;
ViewState["nocount"] = nocount;
}
</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>
<%@ 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>
Remarks
The Click event is raised when a HotSpot object in an ImageMap control is clicked. To allow a HotSpot to raise the Click event, you must first set either the HotSpotMode property on the ImageMap control or the HotSpotMode property on the HotSpot object to HotSpotMode.Postback.
To programmatically control the actions performed when a postback HotSpot is clicked, provide an event handler for the Click event that contains the code to run when the event is raised.
Raising an event invokes the event handler through a delegate. For more information about how to handle events, see Handling and Raising Events.
