Building Custom Controls with ASP NET and the

Building Custom Controls with ASP. NET and the Microsoft. NET Framework ® Rames Gantanant Microsoft Regional Director, Thailand ramesg@puumsoft. co. th

What We Will Cover l l l Developing Web custom controls Creating a control designer Control rendering Event handling Developing composite controls

Session Prerequisites Basic knowledge of C# l Basic knowledge of Event. Handling in. NET l Familiarity with the. NET Framework l Understanding of object-oriented programming l Basic HTML / WYSIWYG experience l Level 200

So Why This Presentation? Benefits of designing custom controls l Code reuse l Quick page development l Make easy changes to the site through controls l

Agenda l l l Web user controls versus custom controls Creating a simple Web custom control Implementing a control designer for designtime rendering Rendering methods and how to use them Handling postback events Developing a composite control

Agenda l l l Web user controls versus custom controls Creating a simple Web custom control Implementing a control designer for designtime rendering Rendering methods and how to use them Handling postback events Developing a composite control

Web User Controls Versus Custom Controls l l Web user controls are compiled dynamically at run time Web user controls cannot be added to the Toolbox The only way to share a Web user control between applications is to put a separate copy in each application Custom controls have full visual design tool support for consumers

Creating a Simple Custom Control l Inheriting from Web. Control versus Control Consuming the control in a Web application Adding a custom property to the control

Demonstration 1 Creating a Simple Custom Control

Agenda l l l Web user controls versus custom controls Creating a simple Web custom control Implementing a control designer for designtime rendering Rendering methods and how to use them Handling postback events Developing a composite control

Creating a Simple Web Custom Control l Web. Control provides typical Web user control properties Adding the control and Web application project within the same solution helps with developing and debugging The control can be added to the toolbox and even to the global assembly cache, allowing ease of use for multiple developers

Creating a Simple Web Custom Control l Creating an icon for the control helps distinguish it when added to the toolbox

Agenda l l l Web user controls versus custom controls Creating a simple Web custom control Implementing a control designer for designtime rendering Rendering methods and how to use them Handling postback events Developing a composite control

Demonstration 2 Implementing a Control Designer for Design-Time Rendering

Implementing a Control Designer for Design-Time Rendering l l System. Design. dll provides the base class for design-time rendering Get. Design. Time. Html() overrides the default design-time rendering output Design-time and run-time HTML output are separate entities Designer class is specified in the controls attribute list

Agenda l l l Web user controls versus custom controls Creating a simple Web custom control Implementing a control designer for designtime rendering Rendering methods and how to use them Handling postback events Developing a composite control

Demonstration 3 Rendering Methods and How to Use Them

Rendering Methods and How to Use Them l l Override the Render() method when inheriting from Control Override Render. Contents() method when inheriting from Web. Control

Rendering Methods and How to Use Them l l l Default “base-element” for a control is the <span> element Specify which base-class constructor should be called when creating instances of the derived class, such as base(Html. Text. Writer. Tag. A) for an <a> element Use Add. Attributes. To. Render() method to add HTML attributes and styles to the control

Agenda l l l Web user controls versus custom controls Creating a simple Web custom control Implementing a control designer for designtime rendering Rendering methods and how to use them Handling postback events Developing a composite control

Demonstration 4 Handling Postback Events

Handling Postback Events l l IPost. Back. Event. Handler defines the method ASP. NET server controls must implement to handle postback events Define the click event Invoke delegates registered with the click event Define the method of IPost. Back. Event. Handler that raises change events

Handling Postback Events l Page. Get. Post. Back. Event. Reference() obtains a reference to a client-side script function that causes, when invoked, the server to post back to the page

Agenda l l l Web user controls versus custom controls Creating a simple Web custom control Implementing a control designer for designtime rendering Rendering methods and how to use them Developing a composite control

Demonstration 5 Developing a Composite Control

Developing a Composite Control l l INaming. Container interface identifies a container control that creates a new ID namespace within a Page object's control hierarchy (that is, it will provide a unique namespace for any server controls that it contains in the. aspx file) Ensure. Child. Controls() determines whether the server control contains child controls. If it does not, it creates child controls

Developing a Composite Control l Create. Child. Controls() notifies server controls that use composition-based implementation to create any child controls they contain in preparation for posting back or rendering

Developing a Composite Control Main Differences Between a Web User Control and a Custom Control l Minimal design-time support for authoring Authored programmatically in an objectoriented programming language that targets the common language runtime Compiled and persisted as an assembly (. dll)

Session Summary l l l Web. Control derives from Control and exposes properties common to Web user controls Adding the control and Web application project in the same solution makes it easier to debug, rebuild, and test while developing The control can be added to the toolbox and even to the global assembly cache to make it easy for multiple developers to use on different machines

Session Summary, Continued l l Composite controls are compiled and persisted as an assembly (. dll) Raise. Post. Back. Event enables a server control to process an event raised when a form is posted to the server

For More Information… l MSDN Web site at ® Ø l msdn. microsoft. com ASP. NET Ø www. asp. net

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