Android ImageButton using transparent images

There are many irregular buttons on Android. Such as:

This time, if we want to make an irregular button, the first step is to get a transparent edge of the PNG image, and then specify to him with SRC, this time we will find that the effect has not been achieved, there is still a layer of images around the rendering. At this point also to take the second step: the need to set the background property ImageButton android:background= "#00000000", the implementation of the effect of the irregular button.