这句可以分成下列两句,基本意思是先用一系列参数生成一个StretchDIBits对象,再将其放入emf中.
StretchDIBits obj = new StretchDIBits(
              imageWriter,
              bounds,
              0,
              0,
              image.getWidth(this),
              image.getHeight(this),
              image,
              this,
              Color.black);
emf.add(obj);