Android: ImageView getting negative width

Android: ImageView getting negative width

I'm not sure why, but when I set the width of an imageview (called c), it
returns a negative value. ivPiano is also an imageView.
ViewTreeObserver vto = llPiano.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
llPiano.getViewTreeObserver().removeGlobalOnLayoutListener(this);
c.setTop(ivPiano.getTop());
c.setLeft(ivPiano.getLeft());
ShowMessageLong(ivPiano.getWidth());
c.getLayoutParams().width = ivPiano.getWidth();
c.getLayoutParams().height= ivPiano.getHeight();
c.bringToFront();
ShowMessageLong(c.getWidth());
}
});
ShowMessageLong() just creates and shows a toast. The first time
(ivPiano's width) shows 1200, then second one (c's width) returns -22. Any
ideas why? Thanks in advance!!