generate pdf417 c# BusinessListBase Class in Visual C#.NET

Print PDF417 in Visual C#.NET BusinessListBase Class

BusinessListBase Class
PDF417 Printer In C#
Using Barcode drawer for Visual Studio .NET Control to generate, create PDF-417 2d barcode image in .NET applications.
www.OnBarcode.com
Recognize PDF417 In C#
Using Barcode reader for .NET framework Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
The BusinessListBase class combines some of what UndoableBase does and some of what you ve seen in BusinessBase. Like UndoableBase, the BusinessListBase class implements IUndoableObject, and like BusinessBase it implements ISupportUndo and the three public undo methods. The implementation of this functionality in a collection isn t as complex as it is for editable objects, however, because a collection is primarily responsible for cascading the method calls to all the child objects it contains.
Encode Code 128B In Visual C#
Using Barcode generation for Visual Studio .NET Control to generate, create Code 128C image in .NET framework applications.
www.OnBarcode.com
Encoding Linear 1D Barcode In C#.NET
Using Barcode creation for VS .NET Control to generate, create Linear image in .NET framework applications.
www.OnBarcode.com
Edit Level Tracking
Encode EAN-13 Supplement 5 In Visual C#
Using Barcode maker for .NET framework Control to generate, create EAN-13 image in .NET applications.
www.OnBarcode.com
PDF 417 Maker In Visual C#
Using Barcode printer for .NET Control to generate, create PDF-417 2d barcode image in .NET applications.
www.OnBarcode.com
The hardest part of implementing n-level undo functionality is that not only can child objects be added or deleted but they can be undeleted or unadded in the case of an undo operation. Csla. Core.BusinessBase and UndoableBase use the concept of an edit level. The edit level allows the object to keep track of how many BeginEdit() calls have been made to take a snapshot of its state without corresponding CancelEdit() or ApplyEdit() calls. More specifically, it tells the object how many states have been stacked up for undo operations. BusinessListBase needs the same edit level tracking as in BusinessBase. However, a collection won t actually stack its states. Rather, it cascades the call to each of its child objects so that they can stack their own states. Because of this, the edit level can be tracked using a simple numeric counter. It merely counts how many unpaired BeginEdit() calls have been made: // keep track of how many edit levels we have private int _editLevel; The implementations of CopyState(), UndoChanges(), and AcceptChanges() alter this value accordingly.
Draw Code-39 In Visual C#
Using Barcode maker for .NET Control to generate, create ANSI/AIM Code 39 image in .NET framework applications.
www.OnBarcode.com
UPC Shipping Container Symbol ITF-14 Creation In C#
Using Barcode printer for .NET framework Control to generate, create UCC - 14 image in .NET framework applications.
www.OnBarcode.com
CHAPTER 13 N-LEV EL UNDO
PDF-417 2d Barcode Generator In None
Using Barcode creator for Font Control to generate, create PDF417 image in Font applications.
www.OnBarcode.com
Print PDF 417 In Visual C#
Using Barcode drawer for Visual Studio .NET Control to generate, create PDF 417 image in .NET framework applications.
www.OnBarcode.com
Reacting to Insert, Remove, or Clear Operations
Quick Response Code Generation In Objective-C
Using Barcode printer for iPhone Control to generate, create QR image in iPhone applications.
www.OnBarcode.com
Drawing QR Code In VB.NET
Using Barcode generation for Visual Studio .NET Control to generate, create QR Code image in .NET framework applications.
www.OnBarcode.com
Collection base classes don t implement Add() or Remove() methods directly because those are implemented by Collection<T>, which is the base class for BindingList<T>. However, they do need to perform certain operations any time that an insert or remove operation occurs. To accommodate this, BindingList<T> invokes certain virtual methods when these events occur. These methods can be overridden to respond to the events. Child objects also must have the ability to remove themselves from the collection. Remember the implementation of System.ComponentModel.IEditableObject in Clsa.Core.BusinessBase that code included a parent reference to the collection object and code to call a RemoveChild() method. This RemoveChild() method is part of the IEditableCollection interface implemented by BusinessListBase. The important thing to realize is that BusinessListBase does extra processing in addition to the default behavior of the BindingList base class: It moves deleted items to and from a DeletedList so items can be undeleted. It completely removes deleted items that are new (and thus not undeleted in an undo operation). It maintains any LINQ to CSLA indexes (as discussed in 14). It ensures that newly added child objects have an edit level corresponding to the collection s edit level. To do this, the methods listed in Table 13-3 are implemented.
UPC - 13 Drawer In Objective-C
Using Barcode creator for iPhone Control to generate, create EAN13 image in iPhone applications.
www.OnBarcode.com
UPC-A Supplement 2 Decoder In None
Using Barcode reader for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Table 13-3. Methods Implemented for Insert, Remove, and Clear Operations
Decode Code39 In C#.NET
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Barcode Creation In None
Using Barcode drawer for Font Control to generate, create Barcode image in Font applications.
www.OnBarcode.com
Method
Printing EAN / UCC - 13 In None
Using Barcode drawer for Online Control to generate, create UPC - 13 image in Online applications.
www.OnBarcode.com
Printing EAN / UCC - 13 In Visual Basic .NET
Using Barcode generation for VS .NET Control to generate, create UCC-128 image in Visual Studio .NET applications.
www.OnBarcode.com
RemoveChild() RemoveItem() InsertItem()
Recognize Code 128 In Visual C#
Using Barcode reader for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
GS1 DataBar Expanded Printer In Visual Studio .NET
Using Barcode drawer for .NET framework Control to generate, create GS1 DataBar-14 image in .NET applications.
www.OnBarcode.com
Source
IEditableCollection base base
Description
Removes a child object from the list Removes an item (by index) from the list Inserts a new child into the list
The RemoveChild() method is called by a child object contained within the collection. This is called when a Windows Forms grid control requests that the child remove itself from the collection via the System.ComponentModel.IEditableObject interface.
Note In reality, this shouldn t be a common occurrence. Windows Forms 2.0 uses a new interface, ICancelAddNew, that is implemented by BindingList<T>. This interface notifies the collection that the child should be removed rather than notifying the child object itself. The code in the RemoveItem() method takes care of the ICancelAddNew case automatically, so this code is really here to support backward compatibility for anyone explicitly calling the IEditableObject interface on child objects.
The RemoveItem() method is called when an item is being removed from the collection. To support the concept of undo, the object isn t actually removed because it might need to be restored later. Rather, a DeleteChild() method is called, passing the object being removed as a parameter. You ll see the implementation of this method shortly. For now, it s enough to know that it keeps track of the object in case it must be restored later. The InsertItem() method is called when an item is being added to the collection. The EditLevelAdded property is changed when a new child object is added to the collection, thus telling
Copyright © OnBarcode.com . All rights reserved.