如何使用ItextSharp绘制图像周围的圆

        byte[] byt = DMC_StudentImage;
        Image img = Image.GetInstance(byt);
        float width = 100f;
        float height = 100f;

        PdfContentByte content = writer.DirectContent;            
        PdfTemplate temp = content.CreateTemplate(width, height);           
        temp.Ellipse(0, 0, width, height);
        temp.Clip();
        temp.NewPath();
        temp.AddImage(img, width, 0, 0, height, 0, 0);
        Image clipped = Image.GetInstance(temp);