[ASP. NET Control for day16] inherit webcontrol for Toolbar Control

We have discussed "inherit from compositecontrol to implement Toolbar Control". This article will inherit webcontrol to implement Toolbar Control with the same function and implement the same control in different ways, then compare the differences between the two.

Download program code: ASP. NET Server Control-day16.rar

1. Inheritance WebcontrolImplementation TbtoolbarWidget

Step1.New inheritance WebcontrolOf TbtoolbarWidget

Added the tbtoolbar control that inherits webcontrol. You can also directly modify the original tbtoolbar control and change the inherited object from compositecontrol to webcontrol. Add the items attribute and click event to the tbtoolbar control as before.

In addition, the tbtoolbar control must be implemented as the inamingcontainer interface, which has no special attributes or methods. The inamingcontainer interface is used to add the clickid of the parent control to the clientid of the child control, each sub-control has a unique clientid.

 

 

Step2.Create a tool column button set

Override the rendercontents method and move the code of the tool column button program created in the createchildcontrols method of the original tbtoolbar (Composite Control) to the rendercontents method.

        Private Sub ButtonClickEventHandler(ByVal sender As Object, ByVal e As EventArgs)

            Dim oButton As Button

            Dim oEventArgs As ClickEventArgs

            oButton = CType(sender, Button)

            oEventArgs = New ClickEventArgs()

            oEventArgs.Key = oButton.ID

            OnClick(oEventArgs)

        End Sub

        ''' <summary>

''' Override the rendercontents method.

        ''' </summary>

        Protected Overrides Sub RenderContents(ByVal writer As System.Web.UI.HtmlTextWriter)

            Dim oItem As TBToolbarItem

            Dim oButton As Button

            For Each oItem In Me.Items

                oButton = New Button()

                oButton.Text = oItem.Text

                oButton.Enabled = oItem.Enabled

                oButton.ID = oItem.Key

                AddHandler oButton.Click, AddressOf ButtonClickEventHandler

                Me.Controls.Add(oButton)

            Next

            If Me.Items.Count = 0 AndAlso Me.DesignMode Then

                oButton = New Button()

Obutton. Text = "Please set items adequacy. "

                Me.Controls.Add(oButton)

            End If

            MyBase.RenderContents(writer)

        End Sub

 

 

Another problem with the Code directly moved above is that the original method of using addhandler to handle button events becomes useless? Because it is not a compound control, when the current button PostBack is returned to the servo end, tbtoolbar does not create a sub-control bar in advance, so the mechanism will not find the original button, you cannot use addhandler to handle events.

AddHandler oButton.Click, AddressOf ButtonClickEventHandler

 

Step3.Processing ClickEvent

Because you cannot use addhandler to process button events, we use the page. clientscript. getpostbackeventreference method to generate the client instruction code for the PostBack action. The onclientclick of the button executes the PostBack action.

            For Each oItem In Me.Items

                oButton = New Button()

                oButton.Text = oItem.Text

                oButton.Enabled = oItem.Enabled

                oButton.ID = oItem.Key

                sScript = Me.Page.ClientScript.GetPostBackEventReference(Me, oItem.Key)

                oButton.OnClientClick = sScript

                Me.Controls.Add(oButton)

            Next

 

The HTML code output by the tbtoolar control is as follows:

<span id="TBToolbar1">

<Input type = "Submit" name = "tbtoolbar1 $ Add" value = "add" onclick = "_ dopostback ('tbtoolbar1', 'add '); "id =" tbtoolbartailadd "/>

<Input type = "Submit" name = "tbtoolbar1 $ edit" value = "modify" onclick = "_ dopostback ('tbtoolbar1', 'edit '); "id =" tbtoolbar#edit "/>

<Input type = "Submit" name = "tbtoolbar1 $ Delete" value = "except" onclick = "_ dopostback ('tbtoolbar1', 'delete '); "id =" tbtoolbarrentdelete "/>

</span>

 

To handle PostBack events on your own, you must implement the ipostbackeventhandler interface to trigger the Click Event of the tbtoolbar in the raisepostbackevent method.

    Public Class TBToolbar

        Inherits WebControl

        Implements INamingContainer

        Implements IPostBackEventHandler

        Public Sub RaisePostBackEvent(ByVal eventArgument As String) Implements System.Web.UI.IPostBackEventHandler.RaisePostBackEvent

            Dim oEventArgs As ClickEventArgs

            oEventArgs = New ClickEventArgs()

            oEventArgs.Key = eventArgument

            Me.OnClick(oEventArgs)

        End Sub

    End Class

Ii. Test Procedure

Place the tbtoolbar control on the test page and write the test program code in the click event.

    Protected Sub TBToolbar1_Click(ByVal sender As Object, ByVal e As Bee.Web.WebControls.TBToolbar.ClickEventArgs) Handles TBToolbar1.Click

        Me.Response.Write("Toolbar1 Click - " & e.Key)

    End Sub

 

When we press the button on the tool column, the corresponding cliek event will be triggered.

 

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