C＃.NET-如何从现有的Windows窗体控件继承

Question

I'm used to working in visual C++. In learning C#.NET I tend to try to find equivalent methods to how things are done in VC++.

When I have a button in C++, to get full control over it I create a class derived from CButton (the equivalent of System.Windows.Forms.Button in .NET) and then set this class as the type for my button in order to get all events and overrides routed into my code.

In C# I haven't really found an equivalent way to do this. There seems to be no way to set which class a control should be created from, and I haven't even bothered trying to replace the auto-generated code where the object is created since it is likely to be discarded the next minute.

What's the correct way of using my own class to front a user control?

EDIT: I should clarify that I'm interested in adding my custom class to the existing project. Most of the responses so far either provide non working ways of adding it to the existing project, or working ways of creating an external library with the component (DLL), but that's a bit overkill for my particular case.

Answer 1

There isn't any trick to it. Create a new .cs source file or class using Visual Studio, remember to include the proper using System.Windows.Forms statement at the top of the file, then inherit as you normally would (note: in .NET, there are no classes with the naming convention CWhatever).

Answer 2

If you derive from System.Windows.Forms.Button, for instance, your new control will be available in the toolbox. A new tab should appear at the top and will be named [Project Name] Components. You can just drag and drop it on a form.

As far as changing the type of a control already on a form, I've had success with changing the type in the designer generated code .cs file.

Here's a great article on creating custom .net controls:

The article discusses evey possible scenario, including using inheritance, and provides lots of sample code.

EDIT:

Add this to your project:

public class DerivedTextBox: System.Windows.Forms.TextBox
{
}

And then build the project. DerivedTextBox should then be available in the ToolBox.

Answer 3

You may either override the functions you need with your own code, or simply create a new user control which derives from the System.Windows.Forms.Button.

It depends on if you need to create a new control which will be used many times or if this is something you need to do for specific cases only.

Edit: Have a look at the MSDN documentation:

http://msdn.microsoft.com/en-us/library/5h0k2e6x(VS.71).aspx

Answer 4

abstract class MyClass :  Windows.Form
{
....
}


public class WindowsFormClass : MyClass
{
....
}

Similary you can create any custom class and derive it from the Control Class (Button, Textbox, Grid etc.), override its methods to add your functionality, and then create a custom object out of it. It will available to you in the toolbox and you can start using it in your project.