NOTE in VS .NET

Draw EAN-13 Supplement 5 in VS .NET NOTE
NOTE
European Article Number 13 Printer In VS .NET
Using Barcode generator for ASP.NET Control to generate, create GS1 - 13 image in ASP.NET applications.
PageRequestManager
Printing Barcode In .NET
Using Barcode drawer for ASP.NET Control to generate, create barcode image in ASP.NET applications.
The client PageRequestManager object is the object that is responsible for handling UpdatePanels It is contained within the MicrosoftWeb Formsjs le and is responsible for creating the partial postback request and for processing the partial postback response
EAN / UCC - 13 Printer In Visual Studio .NET
Using Barcode drawer for .NET Control to generate, create EAN / UCC - 13 image in .NET applications.
Problems with the ImageRotator Extender
Paint Barcode In VS .NET
Using Barcode maker for ASP.NET Control to generate, create bar code image in ASP.NET applications.
Now that we understand how placing an ASPNET AJAX server control inside an UpdatePanel affects when and how behaviors and controls will
Creating GTIN - 12 In .NET Framework
Using Barcode generator for ASP.NET Control to generate, create UPC Symbol image in ASP.NET applications.
The Effe cts of a Partial Postback on Client Components
Code 39 Full ASCII Creator In VS .NET
Using Barcode drawer for ASP.NET Control to generate, create ANSI/AIM Code 39 image in ASP.NET applications.
automatically be disposed and re-created, let s take a look at one of our previous examples, the ImageRotator extender that we created in 5, Adding Client Capabilities to Server Controls, and see how it acts when we place it inside an UpdatePanel Walking through this example will allow us to see how a common programming mistake hidden in a normal postback environment can have a drastic impact in a partial postback environment To start, Listing 79 shows the page with the ImageRotator extender inside an UpdatePanel
Data Matrix Maker In Visual Studio .NET
Using Barcode generation for ASP.NET Control to generate, create Data Matrix 2d barcode image in ASP.NET applications.
Listing 79 ImageRotator Extender in an UpdatePanel
Making GS1 128 In VS .NET
Using Barcode encoder for ASP.NET Control to generate, create UCC - 12 image in ASP.NET applications.
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Defaultaspxcs" Inherits="PartialPostBackWeb_Default" %> <%@ Register assembly="ImageRotatorExtender" namespace="ImageRotatorExtender" tagprefix="cc1" %> <html> <head runat="server"> <title>Image Rotator Update Panel Example</title> </head> <body> <form id="form1" runat="server"> <h2>Pictures of Florence provided by <asp:Image ID="Image2" runat="server" ImageUrl="~/images/freeDigitalPhotoslogogif" /> </h2> <h3> Page Last Updated: <asp:Label ID="Label1" runat="server" Text="Label" /> </h3> <asp:ScriptManager ID="ScriptManager1" runat="server" /> <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional"> <ContentTemplate> <h4>Update Panel Last Updated <%=DateTimeNow %> </h4> <asp:Image ID="Image1" runat="server" ImageUrl="~/images/1jpg" />
Bar Code Creation In Visual Studio .NET
Using Barcode creator for ASP.NET Control to generate, create barcode image in ASP.NET applications.
7: Control Development in a Partial Postback Environment
Creating Identcode In Visual Studio .NET
Using Barcode creation for ASP.NET Control to generate, create Identcode image in ASP.NET applications.
Listing 79 continued
Encode UPC-A Supplement 2 In VS .NET
Using Barcode maker for Visual Studio .NET Control to generate, create UCC - 12 image in Visual Studio .NET applications.
<cc1:ImageRotator ID="Image1_ImageRotator" runat="server" ImageList="images/2jpg, images/3jpg, images/4jpg, images/1jpg" TargetControlID="Image1" /> </ContentTemplate> <Triggers> <asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" /> </Triggers> </asp:UpdatePanel> <div> <asp:Button ID="Button1" runat="server" Text="Post Back Update Panel" /> </div> <div> <asp:Button ID="Button2" runat="server" Text="Post Back Page" /> </div> <p> <a href="http://wwwfreedigitalphotosnet">Royalty free stock Photography</a> for websites, PowerPoint, newletters, forums, blogs, schools and homework - FreeDigitalPhotos net </p> </div> </form> </body> </html>
Reading UCC - 12 In VS .NET
Using Barcode decoder for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
When we cause the UpdatePanel to refresh multiple times by clicking Button1 (Postback Update Panel), we start to get some interesting results Figure 79 shows the odd-looking image that we get after we ve caused the UpdatePanel to refresh a few times We see this odd-looking image because whenever an instance of the ImageRotator is created, which occurs every time we cause the UpdatePanel to refresh, a new interval is attached to the window Listing 710 highlights the code that creates the interval
Barcode Drawer In Visual Basic .NET
Using Barcode creator for VS .NET Control to generate, create bar code image in VS .NET applications.
The Effe cts of a Partial Postback on Client Components
Barcode Generation In Java
Using Barcode printer for Java Control to generate, create bar code image in Java applications.
Figure 79 ImageRotator extender in an UpdatePanel
Scanning Code 128C In .NET Framework
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in Visual Studio .NET applications.
Listing 710 Improperly Disposed WindowsetInterval call
Barcode Recognizer In Visual Studio .NET
Using Barcode recognizer for Visual Studio .NET Control to read, scan read, scan image in .NET applications.
_setupRotation: function(){ var expression = Stringformat("$get('{0}') ImageRotator_rotateImage()", thisget_element()id); windowsetInterval(expression,thisget_rotationInterval()*1000); }
Encoding EAN13 In Java
Using Barcode creation for Java Control to generate, create EAN 13 image in Java applications.
NOTE
Drawing Code 128A In Java
Using Barcode printer for Java Control to generate, create Code 128B image in Java applications.
Full Source Code
EAN13 Reader In .NET Framework
Using Barcode scanner for VS .NET Control to read, scan read, scan image in VS .NET applications.
5 contains the full source code of the ImageRotator extender
Making Barcode In Java
Using Barcode generator for Java Control to generate, create bar code image in Java applications.
7: Control Development in a Partial Postback Environment
Because we do not clear the interval when the ImageRotator behavior disposes, we create a race condition of sorts between the different registered intervals One interval expires, and it updates the image; the next one expires shortly thereafter, and it updates the image; and so on The more times we refresh the UpdatePanel, the more intervals that get attached and the faster the image is updated Cause the UpdatePanel to refresh enough and the image becomes a blur If we had not placed the ImageRotator extender in an UpdatePanel, not clearing the interval really isn t a problem because when the page unloads the window object is destroyed and therefore so are all of its registered intervals But now that we are effectively causing our ImageRotator behavior to go through repeated initialize and dispose cycles without the page fully unloading, our programming mistake becomes obvious We can easily solve our interval problem by properly clearing the interval in the dispose method The highlighted sections in Listing 711 show the changes needed to save the interval s ID and then use it in a windowclearInterval call in the dispose method
Listing 711 Clearing the Interval
/// <reference name="MicrosoftAjaxjs"/> TyperegisterNamespace("ImageRotatorExtender"); ImageRotatorExtenderImageRotator = function(element) { ImageRotatorExtenderImageRotatorinitializeBase(this, [element]); this_imageIndex = 0; this_imageList = null; this_rotationInterval = 3; this_intervalId = null; } ImageRotatorExtenderImageRotatorprototype = { dispose: function() { this_imageList = null; if (this_intervalId !== null) { windowclearInterval(this_intervalId); this_intervalId = null; } ImageRotatorExtenderImageRotatorcallBaseMethod(this, 'dispose'); }, _setupRotation: function(){