user control vs custom control in c#

Custom Control	User Control
A loosely coupled control w.r.t code and UI	A tightly coupled control w.r.t code and UI
Derives from Control	Derives from UserControl
Defines UI in a ResourceDictionary	Defines UI as normal XAML
UI is skinable	Child controls are skinable
Has dynamic layout	Has static layout
UI can be changed in different projects	UI is fixed and can't have different looks in different project
Has full toolbox support, Jst drag n drop from toolbox	Can't be added to the toolbox, Jst drag n drop from sol’n explorer to page(aspx)
Defines a single control	Defines a set of controls
More flexible	Not very flexible like a Custom Control
Reusability of control (extend functionality of existing control), Designed so that it can be used by more than one application	Reusability web page, Designed for single-application scenarios
Compiled into dll	Not compiled into dll
Creation is similar to the way Web Forms pages are created; well-suited for rapid application development (RAD)	Writing involves lots of code because there is no designer support

Button, CheckBox, TextBox etc., even a UserControl is nothing but a Custom Control. You can easily load them inside a XAML page.

Custom Controls are compiled into a DLL assembly and can be reused in multiple places very easily. You have total control over the code, thus gives you more flexibility to extend the behaviour. Once you build and add a reference of the custom control in your project, you can find it in the toolbox. Thus, you will be able to drag and drop the control in your Design view and start working with it very easily.

• When you have a rapid and fixed content in your UI, use UserControl.


• When you want to separate some basic functionality of your main view to some smaller pieces with reusability, use UserControl.


• When you want to use your control in different projects and each project may want to change the look, use CustomControl.


• When you want to implement some additional functionality for a control, create a CustomControl derived from the base control.


• When you want to apply themes to your controls, use CustomControl.


• When you want to add toolbox support for your control, so that your user will be able to do drag and drop to the designer, use CustomControl.

For user control:

<%@ Register TagPrefix="UC" TagName="TestControl" Src="test.ascx" %>

For custom control:

<%@ Register TagPrefix="CC " Namespace=" CustomServerControlsLib " Assembly="CustomServerControlsLib " %>