Page event in .NET framework

Generating PDF417 in .NET framework Page event

Page event
PDF417 Drawer In .NET
Using Barcode maker for ASP.NET Control to generate, create PDF417 image in ASP.NET applications.
www.OnBarcode.com
Painting Barcode In Visual Studio .NET
Using Barcode creator for ASP.NET Control to generate, create Barcode image in ASP.NET applications.
www.OnBarcode.com
Init Load
Barcode Encoder In .NET Framework
Using Barcode maker for ASP.NET Control to generate, create Barcode image in ASP.NET applications.
www.OnBarcode.com
Barcode Creator In .NET
Using Barcode drawer for ASP.NET Control to generate, create Barcode image in ASP.NET applications.
www.OnBarcode.com
PreRender
Encoding UPC-A Supplement 5 In Visual Studio .NET
Using Barcode encoder for ASP.NET Control to generate, create GS1 - 12 image in ASP.NET applications.
www.OnBarcode.com
Generating Code-39 In VS .NET
Using Barcode printer for ASP.NET Control to generate, create Code 3 of 9 image in ASP.NET applications.
www.OnBarcode.com
Unload
Painting Linear Barcode In .NET
Using Barcode drawer for ASP.NET Control to generate, create Linear 1D Barcode image in ASP.NET applications.
www.OnBarcode.com
C 2 Of 5 Drawer In .NET Framework
Using Barcode creator for ASP.NET Control to generate, create Code 2/5 image in ASP.NET applications.
www.OnBarcode.com
This event is fired after the page is removed from memory but hasn t yet been disposed.
Scan PDF-417 2d Barcode In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
PDF-417 2d Barcode Scanner In VS .NET
Using Barcode reader for .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
Custom control developers and page developers who wish to extend existing controls must be intimately familiar with the page lifecycle events in order to correctly initialize, maintain state, and execute control actions. For more information about the ASP.NET page lifecycle, see http:// msdn2.microsoft.com/en-us/library/7949d756-1a79-464e-891f-904b1cf c7991.aspx.
Scanning UCC - 12 In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
QR Code 2d Barcode Creation In .NET Framework
Using Barcode generator for Reporting Service Control to generate, create Denso QR Bar Code image in Reporting Service applications.
www.OnBarcode.com
You should have a general, high-level grasp of what goes on during the page lifecycle with the UpdatePanel. Examining the stages in the cycle should give you insight as to when certain actions are permitted. Speaking of events, you ve built a solid foundation and will now learn about a important part of the UpdatePanel: triggers.
QR Maker In None
Using Barcode maker for Online Control to generate, create QR Code JIS X 0510 image in Online applications.
www.OnBarcode.com
Barcode Generation In Objective-C
Using Barcode creator for iPhone Control to generate, create Barcode image in iPhone applications.
www.OnBarcode.com
Partial-page rendering with UpdatePanels
Scanning Barcode In Visual Basic .NET
Using Barcode scanner for VS .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Make Barcode In Java
Using Barcode drawer for Java Control to generate, create Barcode image in Java applications.
www.OnBarcode.com
Triggers
Make Barcode In Java
Using Barcode creator for Android Control to generate, create Barcode image in Android applications.
www.OnBarcode.com
Barcode Recognizer In VS .NET
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
A trigger is an event coming from a control that causes an UpdatePanel to refresh its contents. The following types of triggers can be associated with an UpdatePanel:
Barcode Drawer In Java
Using Barcode encoder for BIRT reports Control to generate, create Barcode image in BIRT applications.
www.OnBarcode.com
Print European Article Number 13 In Java
Using Barcode generation for Java Control to generate, create EAN-13 image in Java applications.
www.OnBarcode.com
AsyncPostBackTrigger Invokes an asynchronous postback for the associ-
ated UpdatePanel and any other UpdatePanels on the form that have the
UpdateMode property set to Always
PostBackTrigger Invokes a traditional postback to the page that causes the page to refresh
Similar to specifying content for an UpdatePanel, you can add triggers declaratively or programmatically. Let s start by examining the most common trigger you ll use: an asynchronous trigger.
Asynchronous triggers
Each child control of an UpdatePanel is by default an asynchronous trigger. This means postbacks resulting from interaction with these controls are replaced with asynchronous postbacks that invoke the UpdatePanel to render its contents. But what about controls that haven t been specified as content in an UpdatePanel For example, say you want to refresh the contents of an UpdatePanel based on the click event of a button that isn t a child control. This can be accomplished by registering the control as an asynchronous trigger. Listing 6.7 demonstrates how to achieve this programmatically when the UpdatePanel has its UpdateMode set to Conditional.
Listing 6.7 Programmatically registering a trigger with an UpdatePanel Must be done during Init
protected override void OnInit(EventArgs e) { base.OnInit(e);
AsyncPostBackTrigger outsideTrigger = new AsyncPostBackTrigger(); outsideTrigger.ControlID = "Button1"; outsideTrigger.EventName = "Click"; Create new UpdatePanel1.Triggers.Add(outsideTrigger); trigger }
Add to trigger collection
If you go back to the page lifecycle in the previous section, you ll notice that during the Load event, the ScriptManager initializes the triggers for each UpdatePanel on the page. This tells you that any triggers you want to add to an UpdatePanel must
Triggers
be added before the Load event is fired. Registering a trigger in the B Init event seems like the most logical place. To do so, you need to create a new C asynchronous trigger and add it to the triggers collection of that D UpdatePanel. An AsyncPostBackTrigger has two properties. The first is ControlID, which is the ID of the control that will raise the event. The second, optional, property is the EventName, which as you can guess, is the name of the event that the control raises for an asynchronous postback. If EventName isn t initialized, it defaults to the event that the control is most known for (for example, the click event for a button). This approach is used primarily for adding triggers to a panel that has UpdateMode set to Conditional. It also works for panels that have UpdateMode set to Always, but another approach is available for those situations that makes more sense:
ScriptManager1.RegisterAsyncPostBackControl(this.FindControl ("Button1"));
Calling the RegisterAsyncPostBackControl method of the ScriptManager registers the postback for all the UpdatePanel controls on the form that have UpdateMode set to Always. Panels that have the property set to Conditional aren t rendered when this asynchronous postback occurs. Adding triggers declaratively is even simpler; see listing 6.8.
Listing 6.8 Controls outside the UpdatePanel s declaration invoking asynchronous postbacks
<asp:UpdatePanel ID="UpdatePanel2" runat="server" UpdateMode="Conditional"> <ContentTemplate> <div> Last Updated: <%= DateTime.Now.ToLongTimeString() %> </div> <div> <asp:Button ID="Update2" runat="server" Text="Update" /> </div> </ContentTemplate> <Triggers> <asp:AsyncPostBackTrigger ControlID="Button1" Add button click to EventName="Click" /> trigger collection </Triggers> </asp:UpdatePanel> <hr /> <asp:Button ID="Button1" runat="server" Text="Update" />
Not a child control
Adding a trigger declaratively is as easy as adding it to the Triggers collection of the UpdatePanel.
Copyright © OnBarcode.com . All rights reserved.