Steps and Events Used to Create Custom Control in C#: Windows Forms

In my previous article I have explained what is Custom Control, its types and features in brief. In this article I will write some steps to create the custom control, and will create a currency textbox control that will accept only currency type value.

Steps to create Custom control

• Open your windows forms project, and create a class. Name of class will be the control’s name, you want to create.
• Define a property, type should be respective to the value stored e.g. decimal, string, int etc.
• Override some of the required methods like onClick, onKeyPressed, onTextChanged and OnValidated in the sense of textbox, including the constructor (discussed later).
• Build the project and the control will added in to your toolbox window.

As I said that to make a custom control we have to override some required events of the base class. Here below I am writing about the methods, required to make a custom textbox.

OnKeyPress: this event occurs when user pressed a key while the respective control have focus. It passes the current value, the control have. When we override this event it has the following Syntax:

protected override void OnKeyPress(KeyPressEventArgs e)
{
//your code
}

OnValidated: Occurs when the respective control is validating. When user change the focus by using keyboard, or any other way, this validating event will occur. Following syntax will be used to override this event.

protected override void OnValidated(EventArgs e)
{
//your code
}

OnClick: Raises when the user click on the control. Contains the function is to be executed, when user click on the control. Syntax:

protected override void OnClick(EventArgs e)
{
//your code
}

OnTextChanged: Occurs when the user change the text of the control. Contains the code to be executed, when user change the text of the control. Syntax:

protected override void OnTextChanged(EventArgs e)
{
//your code
}

In the next, we will create a currency TextBox, that will only accept the currency related value like decimal, control characters.

Make your own Custom CurrencyTextBox