C# 制作PictureBox圆形头像框并从数据库中读取头像

pictureBox1.Image = Image.FromFile(@"C:\Users\Administrator\Desktop\1.png");

GraphicsPath gp = new GraphicsPath();
    gp.AddEllipse(pictureBox1.ClientRectangle);
Region region = new Region(gp);
  pictureBox1.Region = region;//赋值
 gp.Dispose();//释放资源
  region.Dispose();//释放资源

GraphicsPath gp = new GraphicsPath();

            gp.AddEllipse(pictureBox1.ClientRectangle);

            Region region = new Region(gp);

            pictureBox1.Region = region;

            gp.Dispose();

            region.Dispose();



            CheckForIllegalCrossThreadCalls = false;
            username.Text = 登录界面.jmuser;
            Thread th = new Thread(a);
            th.IsBackground = true;
            th.Start();
            us = username.Text;

            首页 form = new 首页();
            form.TopLevel = false;
            form.Parent = panel1;
            panel1.Controls.Add(form);//将子窗体载入panel            
            form.Show();

            SqlConnectionStringBuilder bu = new SqlConnectionStringBuilder();

            bu.Password = "0";
            bu.UserID = "0";
            bu.DataSource = "0-0";
            bu.InitialCatalog = "0";
            SqlConnection b = new SqlConnection(bu.ToString());
            string str = "select * from  user1  where  username ='" + 登录成功界面.us + "'";
            b.Open();

            SqlCommand c = new SqlCommand(str, b);

            SqlDataReader d = c.ExecuteReader();

            while (d.Read())
            {
                //  label2.Text = d["userid"].ToString();
                string s = d["头像"].ToString();
                byte[] imageBytes = Convert.FromBase64String(s);
                MemoryStream memoryStream = new MemoryStream(imageBytes, 0, imageBytes.Length);
                memoryStream.Write(imageBytes, 0, imageBytes.Length);
                Image image = Image.FromStream(memoryStream);
                this.pictureBox1.SizeMode = PictureBoxSizeMode.Zoom;
                this.pictureBox1.Image = image;
            }
      }