Rotate button in onDraw ()

Question

I tried it like this , but it does not work. What am I doing wrong?

RotateButton sdb = (RotateButton) findViewById(R.id.slideDown); sdb.invalidate(); //rotate 

class:

 public class RotateButton extends Button { public RotateButton (Context context) { super(context); } public RotateButton (Context context, AttributeSet set) { super(context, set); } @Override protected void onDraw(Canvas canvas) { canvas.save(); Log.d("temp", "rotating"); canvas.rotate(90); super.onDraw(canvas); canvas.restore(); //requestLayout(); } }