3: Components in Visual Studio .NET

Drawer GS1 - 13 in Visual Studio .NET 3: Components
3: Components
Making UPC - 13 In .NET
Using Barcode generator for ASP.NET Control to generate, create European Article Number 13 image in ASP.NET applications.
Table 31 Differences between Components, Controls, and Behaviors Can Be Associated to a DOM Element A DOM Element Can Have More Than One Associated to It Access to Object from DOM Element
Encode Bar Code In Visual Studio .NET
Using Barcode maker for ASP.NET Control to generate, create bar code image in ASP.NET applications.
Object Type
Making EAN13 In VS .NET
Using Barcode creator for .NET framework Control to generate, create GTIN - 13 image in Visual Studio .NET applications.
Component Not allowed
Paint UPC A In VS .NET
Using Barcode creation for ASP.NET Control to generate, create UPC-A image in ASP.NET applications.
N/A (not directly associated to a DOM element)
Bar Code Maker In .NET
Using Barcode printer for ASP.NET Control to generate, create barcode image in ASP.NET applications.
N/A (not directly associated to a DOM element) Yes, a control can be accessed through a control expando property attached to the DOM element
UPC - 13 Creation In Visual Studio .NET
Using Barcode drawer for ASP.NET Control to generate, create UPC - 13 image in ASP.NET applications.
Control
Make Data Matrix In .NET Framework
Using Barcode maker for ASP.NET Control to generate, create Data Matrix 2d barcode image in ASP.NET applications.
Must be No, a DOM element associated to a can have only one DOM element associated control
Bar Code Drawer In VS .NET
Using Barcode maker for ASP.NET Control to generate, create barcode image in ASP.NET applications.
Behavior
Generating USS Code 39 In .NET Framework
Using Barcode encoder for ASP.NET Control to generate, create Code-39 image in ASP.NET applications.
Must be Yes, a DOM element Yes, a behavior can be associated to a can have one or more accessed through an DOM element associated behaviors expando property of the behavior s name from the DOM element if the behavior was named at the time it was initialized All behaviors attached to an element can be accessed by a private _behaviors array attached to the DOM element
Encoding Identcode In VS .NET
Using Barcode creation for ASP.NET Control to generate, create Identcode image in ASP.NET applications.
These rules are enforced during the creation of a component, behavior, and control and dictate what base type your new type will inherit from Figure 32 covers the basic decision process when determining what type of new object to create based on the feature s requirements Now that we covered the basics of components, controls, and behaviors, let s tackle each type individually
Reading Code 3 Of 9 In VS .NET
Using Barcode recognizer for VS .NET Control to read, scan read, scan image in VS .NET applications.
SysComponent
Painting Data Matrix In Java
Using Barcode maker for Java Control to generate, create DataMatrix image in Java applications.
Feature Requirements
Barcode Generator In C#
Using Barcode creator for .NET Control to generate, create bar code image in .NET applications.
Is the Feature going to be associated to a DOM Element
GS1-128 Creation In Java
Using Barcode creator for Java Control to generate, create GS1 128 image in Java applications.
Component
Creating Bar Code In VB.NET
Using Barcode generator for .NET Control to generate, create bar code image in Visual Studio .NET applications.
Should the Feature be combinable with other features
Decoding Code 128 In .NET Framework
Using Barcode decoder for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
Control
Recognizing Bar Code In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
Behavior
Make GTIN - 13 In Java
Using Barcode maker for Java Control to generate, create EAN 13 image in Java applications.
Figure 32 Decision process between component, control, and behavior
Creating ANSI/AIM Code 39 In C#.NET
Using Barcode encoder for .NET framework Control to generate, create Code 39 Extended image in Visual Studio .NET applications.
SysComponent
EAN13 Drawer In .NET Framework
Using Barcode printer for VS .NET Control to generate, create GTIN - 13 image in Visual Studio .NET applications.
SysComponent is the root type of all components and provides the major-
ity of the functionality It does not inherit from another type, but does implement three interfaces: SysIDisposable, SysINotifyProperty Changed, and SysINotifyDisposing Table 32 details these three interfaces
3: Components
Table 32 Interfaces Implemented by SysComponent Interface Purpose Methods add_propertyChanged remove_propertyChanged
SysINotifyPropertyChanged Implements
property-changed noti cation event
SysINotifyDisposing
Implements disposing event Represents a disposable object
add_disposing remove_disposing dispose
SysIDisposable
SysComponent also contains ve internal members, as detailed in
Table 33
Table 33 SysComponent Members Member Name _id Purpose Type string
The unique identi er of the component Used to nd the component after it s registered with SysApplication Each component managed by SysApplication must have a unique ID Indicates whether the _id property has been set has been through its initialization routine
_idSet
boolean
_initializing Indicates whether the component
boolean
_updating
Indicates whether the component is updating Maintains a list of events and event handlers
boolean
_events
SysEventHandlerList
Besides implementing the methods required by the three interfaces, SysComponent exposes methods that allow interaction with its internal
SysComponent
members Table 34 details these methods and the methods required by the three interfaces
Table 34 SysComponent Methods Method Name beginUpdate Description Syntax compbeginUpdate();
Marks the component as updating Called during the creation of a component
endUpdate
Marks the compocompendUpdate(); nent as not updating Called during the creation of a component Executes the initialize method if the component is not initialized Executes the updated method Empty implementation Getter for the updating member
compupdated();
updated
get_isUpdating
compget_isUpdating();
initialize
Marks the component compinitialize(); as initialized Getter for the initialized member
compget_initialized();
get_initialized
dispose
Executes the compdispose(); disposing event handlers Removes the _events property from the component Unregisters the component from SysApplication
3: Components
Table 34 continued Method Name get_events Description Syntax
Getter for the events compget_events() member Getter for the ID member
compget_id();
get_id
set_id
Setter for the ID compset_id(id); member ID cannot be changed after it has been set (through this setter) or after the component has been registered with SysApplication Adds an event handler to the disposing event Removes an event handler from the disposing event Adds an event handler to the
propertyChanged compadd_disposing(handler);
add_disposing
remove_disposing
compremove_ disposing(handler);
add_propertyChanged
compadd_ propertyChanged(handler);
event
remove_propertyChanged Removes an event
handler from the
propertyChanged
compremove_ propertyChanged(handler)
event
raisePropertyChanged
Executes registered
propertyChanged
compraisePropertyChanged (propertyName);
event handlers passing in the name of the property that changed in the event arguments
SysComponent
NOTE
beginUpdate, endUpdate, and initialize
beginUpdate, endUpdate, and initialize are automatically executed
during the component creation process They are normally not executed by user-de ned code, but can be overridden to provide custom functionality
Defining New Components SysComponent is extremely useful, but directly creating instances of it is not its purpose Instead, it is intended to be used as a base class for userde ned components We can de ne a new component type using the Prototype Model we covered in 2 and registering our component to inherit from SysComponent
ErrorHandler Component
To demonstrate how to de ne a new component, we create a new error handling component The ErrorHandler component will be responsible for publishing handled and unhandled errors to an error data service
Skeleton
To start, we create the skeleton of our new component, as Listing 31 shows
Listing 31 Defining Our ErrorHandler Component
/// <reference name="MicrosoftAjaxjs"/> ErrorHandler = function() { ErrorHandlerinitializeBase(this); }; ErrorHandlerprototype = { initialize: function() { ErrorHandlercallBaseMethod(this, 'initialize'); }, dispose: function() { ErrorHandlercallBaseMethod(this, 'dispose'); } } ErrorHandlerregisterClass('ErrorHandler', SysComponent);
3: Components
Besides calling initializeBase in the constructor and registering our class to inherit from SysComponent, we overrode SysComponent s initialize and dispose methods We included these overrides in the skeleton because overriding the initialize and dispose methods is normally the rst step taken in creating a new component, and we suggest doing it right away