C# Custom Controls: Step-by-Step Guide

In C#, the basic steps for creating custom controls are as follows:

1. Create a new class that extends an existing control class, such as Control or Panel.
2. Add custom properties, methods, and events to the new class.
3. Rewrite some methods in the control class to implement custom functionality.
4. Initialize the properties and events of the controls in the constructor.
5. To repaint the control when needed, you can achieve this by overriding the OnPaint method.
6. When using custom controls, add them to a form or another container control, and configure their properties and events.

Here is an example code for a simple custom widget.

using System;
using System.Drawing;
using System.Windows.Forms;

public class MyCustomControl : Control
{
    public MyCustomControl()
    {
        this.BackColor = Color.Blue;
        this.Size = new Size(100, 100);
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);
        Graphics g = e.Graphics;
        g.FillRectangle(Brushes.Red, 0, 0, this.Width, this.Height);
    }
}

You can operate custom controls in the same way as other controls.

MyCustomControl customControl = new MyCustomControl();
customControl.Location = new Point(50, 50);
this.Controls.Add(customControl);

The above is a simple example of creating and using a custom control. In fact, more properties, methods, and events can be added based on specific requirements to achieve more complex functions.