Android nine patch - allow only a specific area of a background drawable to stretch

Question

How does one go about creating a View that has boundaries with triangular perforations ?

I\'ve been using background drawables to achieve this so

Answer 1

Instead of using a normal image, you can generate a nine-patch png.

Use Simple Nine-patch Generator for this.

The trick is the black line on the left side. That tells Android that the png is vertically expandable along this area.

Please see this example:

Save it as a nine-patch, in the format imagename.9.png