How do the sliding buttons

Hello .. My question is

How do the sliding buttons

Such as these are

<img src="http://opengameart.org/sites/default/files/previewJoystick.png" border="0" />

<img src="http://opengameart.org/sites/default/files/preview_19.png" border="0" />

Thanks in advance ?

albrektv please give it a look at this tutorial, this should be able to help you:

Touch stick controllers

albrektv please give it a look at this tutorial, this should be able to help you:

Touch stick controllers

Thank you brother ?