Round button in android.. avoid presses “outside” the button?

Question

I have created/tried to create, a round button for android by using the ImageButton \"widget\". But since that type of button is treated as a square and my png-image also is

Answer 1

Try Pythagorean theorem and onTouch, simple and easy way to do it.

public boolean inCircle(MotionEvent e, int radius, int x, int y) {
    int dx = e.x - x;
    int dy = e.y - y;
    double d = Math.sqrt((dx * dx) + (dy * dy));
    if(d < radius)
        return true;
    return false;
}

the x, y is the posision of the circle, the radius is the radius, and the e is the TouchEvent you have.

@Override
public boolean onTouch(View arg0, MotionEvent arg1) {
    if(arg1.getAction() == MotionEvent.ACTION_DOWN){
           if(inCircle(arg1, radius, xCircle, yCircle){
                  //do whatever you wanna do here
                  }
            }
    return false;
}

Answer 2

I was using an ImageView as my circle button, and I needed to make some changes to @Daniel's code to make it work the way I wanted. Here's my code:

private boolean mStillDown = false;

public boolean inCircle(MotionEvent e, float radius, float x, float y) {
    float dx = e.getX() - x;
    float dy = e.getY() - y;
    double d = Math.sqrt((dx * dx) + (dy * dy));
    if(d < radius)
        return true;
    return false;
}

@Override
public boolean onTouchEvent(MotionEvent event) {

    int action = event.getAction();
    boolean inCircle = inCircle(event, getWidth()/2.0f, getWidth()/2.0f, getHeight()/2.0f);

    if(inCircle){
        if(action == MotionEvent.ACTION_DOWN || action == MotionEvent.ACTION_POINTER_DOWN){
            this.setPressed(true);
            mStillDown = true;
        }else if(action == MotionEvent.ACTION_UP || action == MotionEvent.ACTION_POINTER_UP){
            if(this.isPressed()){
                this.performClick();
                this.setPressed(false);
                mStillDown = false;
            }
        }else if(action == MotionEvent.ACTION_MOVE && mStillDown){
            this.setPressed(true);
        }
    }else{
        if(action == MotionEvent.ACTION_MOVE){
            this.setPressed(false);
        }else if(action == MotionEvent.ACTION_UP || action == MotionEvent.ACTION_POINTER_UP || action == MotionEvent.ACTION_OUTSIDE){
            mStillDown = false;
        }
    }

    return true;
}

Hopefully this is useful to someone.