public boolean postRotate(float degrees,float px,float py){
  double radians=Math.toRadians(degrees);
  float sin=(float)Math.sin(radians);
  float cos=(float)Math.cos(radians);
  Matrix matrix=new Matrix();
  matrix.setValues(new float[]{cos,-sin,-px * cos + py * sin + px,sin,cos,-px * sin - py * cos + py,0,0,1});
  Matrix current=new Matrix();
  current.setValues(MATRIX);
  matrix.preConcat(current);
  set(matrix);
  return true;
}

public boolean postRotate ( float degrees , float px , float py ) { double radians = Math . toRadians ( degrees ) ; float sin = ( float ) Math . sin ( radians ) ; float cos = ( float ) Math . cos ( radians ) ; Matrix matrix = new Matrix ( ) ; matrix . setValues ( new float [ ] { cos , - sin , - px * cos + py * sin + px , sin , cos , - px * sin - py * cos + py , 0 , 0 , 1 } ) ; Matrix current = new Matrix ( ) ; current . setValues ( MATRIX ) ; matrix . preConcat ( current ) ; set ( matrix ) ; return true ; }
postconcats the matrix with the specified rotation . m ' = r ( degrees , px , py ) * m
