Activate Event

Occurs when a form becomes active.

public event EventHandler Activate

Remarks

A form becomes active under the following circumstances:

• When a page is first requested. This activates the first form; it does not occur on postback.
• When the ActiveForm property of the page is programmatically set.
• When the user navigates to a form through a Link control whose target is a form.

This event's position in the event chain makes it very important for binding child controls to data sources or for setting the property of a form that can be inherited to all child controls.

Example

The following example demonstrates how to trap the Activate event to set properties on a form upon activation.

<Script language="vb" runat="server">

 ' Persist across multiple postbacks.
Public Shared count As Integer = 0

Class Task
   Private _TaskName As [String]
   Private _Status As [String]
   
   
   Public Sub New(TaskName As [String], Status As [String])
      _TaskName = TaskName
      _Status = Status
   End Sub
   
   
   Public ReadOnly Property TaskName() As [String]
      Get
         Return _TaskName
      End Get
   End Property
   
   Public ReadOnly Property Status() As [String]
      Get
         Return _Status
      End Get
   End Property 
   
End Class


Sub Form_Activate(sender As Object, e As EventArgs)
   
   If count = 0 Then
      message2.Text = "Welcome to the Form Sample"
   Else
      message2.Text = "You viewed this Form " +(count + 1).ToString() + " times."
   End If
   
   myForm.Alignment = System.Web.UI.MobileControls.Alignment.Center
   myForm.Wrapping = System.Web.UI.MobileControls.Wrapping.NoWrap
   myForm.BackColor = System.Drawing.Color.LightBlue
   myForm.ForeColor = System.Drawing.Color.Blue
   myForm.Paginate = True
   ' When the user clicks the submit button, switch forms.
   myForm.Action = ""newpage.aspx"
   
   SelectionList1.DataValueField = "Status"
   SelectionList1.DataTextField = "TaskName"
   
   ' Create array and add the tasks to it.
   Dim arr As New ArrayList()
   arr.Add(New Task("Verify transactions", "Done"))
   arr.Add(New Task("Check balance sheet", "Scheduled"))
   arr.Add(New Task("Send report", "Pending"))
   
   ' Associate and bind the SelectionList object to the array.
   ' An Activate event is a good section to add data binding code for 
   ' child controls.
   SelectionList1.DataSource = arr
   SelectionList1.DataBind()

End Sub


Sub Form_Deactivate(sender As Object, e As EventArgs)
   
   count += 1

End Sub


Sub Form2_Activate(sender As Object, e As EventArgs)
   
   yourForm.BackColor = System.Drawing.Color.Black
   yourForm.ForeColor = System.Drawing.Color.White

End Sub

</script>

<mobile:form id="myForm" runat=server OnActivate="Form_Activate"
   OnDeactivate="Form_Deactivate">
   <mobile:label id="message1" runat=server>
      Welcome to ASP.NET
   </mobile:label> 
   <mobile:label id="message2" runat=server></mobile:label>
   <mobile:SelectionList runat=server id="SelectionList1" 
      ForeColor=red SelectType=CheckBox/>
   <mobile:link id="link1" runat=server NavigateURL=#yourForm 
      Text="Next Form"></mobile:link><br/><br/>
   <mobile:Command runat=server Text="Submit" />
</mobile:form>

<mobile:form id="yourForm" runat=server OnActivate="Form2_Activate">
   <mobile:label id="message4" runat=server>
      Welcome to ASP.NET
   </mobile:label> 
   <mobile:link id="link2" runat=server NavigateURL=#myForm Text="Back"/>
</mobile:form>

<script language="c#" runat=server>

class Task
{
   private String _TaskName;
   private String _Status;

   public Task(String TaskName, String Status) 
   { 
      _TaskName = TaskName; 
      _Status = Status;
   }

   public String TaskName { get { return _TaskName; } }
   public String Status { get { return _Status; } }
}

// Persist across multiple postbacks.
public static int count = 0;

void Form_Activate(object sender, EventArgs e)
{

   if (count==0)
      message2.Text = "Welcome to the Form Sample";
   else
      message2.Text = "You viewed this Form "
        + (count+1) + " times.";

   myForm.Alignment=System.Web.UI.MobileControls.Alignment.Center;
   myForm.Wrapping=System.Web.UI.MobileControls.Wrapping.NoWrap;
   myForm.BackColor = System.Drawing.Color.LightBlue; 
   myForm.ForeColor = System.Drawing.Color.Blue;  
   myForm.Paginate = true;
   // When the user clicks the submit button, switch forms.
   myForm.Action = "newpage.aspx";
   
   SelectionList1.DataValueField="Status";
   SelectionList1.DataTextField="TaskName";

   // Create array and add the tasks to it.
   ArrayList arr = new ArrayList();
   arr.Add (new Task ("Verify transactions", "Done"));
   arr.Add (new Task ("Check balance sheet", "Scheduled"));
   arr.Add (new Task ("Send report", "Pending"));

   // Associate and bind the SelectionList object to the array.
   // An Activate event is a good section to add data binding code for 
   // child controls.
   SelectionList1.DataSource = arr;
   SelectionList1.DataBind ();

}

void Form_Deactivate(object sender, EventArgs e)
{   
   
   count++;         
}

void Form2_Activate(object sender, EventArgs e)
{
   yourForm.BackColor = System.Drawing.Color.Black; 
   yourForm.ForeColor = System.Drawing.Color.White; 
}

</script>

<mobile:form id="myForm" runat=server OnActivate="Form_Activate"
   OnDeactivate="Form_Deactivate">
   <mobile:label id="message1" runat=server>
      Welcome to ASP.NET
   </mobile:label> 
   <mobile:label id="message2" runat=server></mobile:label>
   <mobile:SelectionList runat=server id="SelectionList1" 
      ForeColor=red SelectType=CheckBox/>
   <mobile:link id="link1" runat=server NavigateURL=#yourForm 
      Text="Next Form"></mobile:link><br/><br/>
   <mobile:Command runat=server Text="Submit" />
</mobile:form>

<mobile:form id="yourForm" runat=server OnActivate="Form2_Activate">
   <mobile:label id="message4" runat=server>
      Welcome to ASP.NET
   </mobile:label> 
   <mobile:link id="link2" runat=server NavigateURL=#myForm Text="Back"/>
</mobile:form>

See Also

Deactivate Event | OnActivate Method

Form Class