ASP.NET Custom Server Controls: Cute ASP.NET TextBox with Help Tips
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In my previous articles (of this series), I introduced you to how to create your own TextBox control with cool features without even deriving it from existing ASP.NET TextBox controls (including client-side JavaScript emission). In this article we will further enhance the same control with “help tips” to be displayed in a separate label (either on focus events or on mouse events).
A downloadable file for this article is available
here.
The sample downloadable solution (zip) is entirely developed using Visual Studio.NET 2003 Enterprise Architect on Windows Server 2003 Standard Edition. But, I am confident that it would work with other versions of Windows (which support .NET 1.1) as well.
Introduction
My previous articles have already shown you how to create any custom control from scratch. Now, I will not be going into the details of creating a solution, project, etc. I will just take this opportunity to explain the features available and how they have been implemented in the above downloadable VS.NET solution.
When we developed an ASP.NET product in our organization, one of our customers asked us to enhance the product with “help” wherever possible. As you know, if it is a web application, just tool tips should do the job. But they rejected our proposal. We asked them if they needed a popup. Again, the answer was NO.
They asked us to provide some type of “help tips” (always at some corner) for each and every field (during data entry) they would input. Finally, we understood that when any “server control” receives a focus (or on mouse events), some “help tips” have to be displayed in some “panel” (so that we can place the panel at any corner).
As you know, this is not really ASP.NET. We needed to add extra JavasScript “tidbits” for each and every control. As we had already completed that project, there exists no other way to accomplish this, apart from adding JavaScript for every control throughout the application. But, what if we needed to provide the same thing for a new project? The solution would be to develop our own server controls by extending the existing ones, and adding some JavaScript at the control rendering level to emit it at client-side (along with design-time support).
In this article, we develop a simple textbox with help tip support, right from scratch (even without extending from an existing textbox control in ASP.NET). I used four new methods of rendering. They are as follows:
- RenderBeginTag
- RenderContents
- RenderEndTag
- AddAttributesToRender
To be frank, all of the above methods are not really necessary for the TextBox control I developed. But, this gives me an opportunity to explain all four simultaneously. We can also implement all of our controls in a single “render” method as well. But, the above methods give much more flexibility by separating various divisions of rendering.
Next: Understanding the life cycle – Rendering methods >>
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