Android：图像设置为按钮背景是不是缩小了？

I created a button with an image set as the background through a drawable. When I run the program the image is not being centered nor shrunk to fit the button. But when you click it, the pressed image is showing properly. This was working just the other day and I have no clue what happened to change it. I created a button with an image set as the bac