Utility of android nine patch

Question

I would like to know why do we use nine-patch ? I know is to shrink or stretch images but if I want to resize an image can\'t we just do it on a dedicated image editor like

Answer 1

Nine-patch allow you to strech just a part of an image, and not the whole image. It can be useful to design for example custom buttons, EditTexts, etc...

You can lean more here: http://developer.android.com/tools/help/draw9patch.html