问题是9个补丁图像作为背景

I have a list view structure, with Relative layout that uses alternating background images for odd/even elements. I'm trying to set the background drawable dynamically by calculating the position. It worked fine with the normal bitmap. But when I tried to use the ninepatch image it breaks the UI, all the elements get distorted. What am I doing wrong? Could it be how the ninepatch image is created or is there a different way to use a ninepatch image compared to a normal bitmap.I have a list view structure, with Relative lay