CustomControls vs. UserControls in WPF

WPF offers 2 approaches to building your own controls: CustomControls and UserControls. In this article I'll try to list the characteristics of each approach to help you make the right choice for your project.

UserControl - composition

• Combines existing controls into a group to make them easier to reuse.
• Consists of XAML and C# code.
• Its appearance can't be changed with styles and templates.
• Derives from UserControl

This is an example of an RGB control that displays a color. The XAML combines 3 text boxes and a field that shows the color. All of the control's logic lives in the CS file.

CustomControl - extending existing controls

• Extends the functionality of existing controls.
• Consists of a code file and a default style defined in Themes/Generic.xaml.
• Can be styled in any way you like.
• The recommended approach for building a component library.

An example of a control (for picking a number) with up/down buttons. It extends a regular text box. Its appearance can easily be changed if, say, you need the buttons on the left.