Android: Set alpha on button on click. Preferably xml only

Question

I want to introduce a 'down' style on some buttons. I've created a style, and a state list. ``` ``` The problem is that I want to be able to change just the alpha of the background when the button gets clicked (I will have variable backgrounds, so setting a sold color with alpha channel is not a solution). And I want to do this from the declarative xml only (don't want to polute my code with layout stuff). Problem is I don't know how to apply this alpha blending to the button from a xml drawable. I am pretty sure there's a way though.

Accepted Answer

I am bit late to answer this question but i just did this by changing the alpha value using View.onTouchListner

You can do this by implementing onTouch in this way

```
 @Override
public boolean onTouch(View v, MotionEvent event) {

switch (event.getAction())
    {
        case MotionEvent.ACTION_DOWN:
            v.setAlpha(0.5f);
            break;
        case MotionEvent.ACTION_UP:
            v.setAlpha(1f);
        default : 
         v.setAlpha(1f)
    }
    return false;
}
```

I guess you cant change alpha value from drawable so you will have to do this in this way only.

Android: Set alpha on button on click. Preferably xml only

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