static void addWatermarkText(Graphics picture,int fontsize, string _watermarkText, string _watermarkPosition, int _width, int _height)
  {
   int[] sizes = new int[] {32, 14, 12, 10, 8, 6, 4 };
   Font crFont = null;
   SizeF crSize = new SizeF();
 
   crFont = new Font("微软雅黑", fontsize, FontStyle.Bold);
   crSize = picture.MeasureString(_watermarkText, crFont);
 
   float xpos = 0;
   float ypos = 0;
   Color color =Color.Firebrick;
 
   switch (_watermarkPosition)
   {
    case "WM_TOP_LEFT":
     xpos = ((float)_width * (float).01) + (crSize.Width / 2);
     ypos = (float)_height * (float).01;
     break;
    case "WM_TOP_RIGHT":
     xpos = ((float)_width * (float).99) - (crSize.Width / 2);
     ypos = (float)_height * (float).01;
     break;
    case "WM_BOTTOM_RIGHT":
     xpos = ((float)_width * (float).99) - (crSize.Width / 2);
     ypos = ((float)_height * (float).99) - crSize.Height;
     break;
    case "WM_BOTTOM_LEFT":
     xpos = ((float)_width * (float).01) + (crSize.Width / 2);
     ypos = ((float)_height * (float).99) - crSize.Height;
     break;
     
   }
    
   StringFormat StrFormat = new StringFormat();
   StrFormat.Alignment = StringAlignment.Center;
   SolidBrush semiTransBrush2 = new SolidBrush(Color.FromArgb(153, 0, 0, 0));//加阴影
   picture.DrawString(_watermarkText, crFont, semiTransBrush2, xpos + 1, ypos + 1, StrFormat);
 
   SolidBrush semiTransBrush = new SolidBrush(color); //添加水印
   picture.DrawString(_watermarkText, crFont, semiTransBrush, xpos, ypos, StrFormat);
 
   semiTransBrush2.Dispose();
   semiTransBrush.Dispose();
  }

static void addWatermarkText(Graphics picture,string type, int fontsize, string _watermarkText)
  {
   //1、先画矩形
   RectangleF drawRect;
   Color color;
   if (type == "Top")
   {
     drawRect = new RectangleF(73, 135, 450, 64);
     color = Color.FromArgb(255, 255, 255);
   }
   else
   {
     drawRect = new RectangleF(194, 245, 250, 39);
     color = Color.FromArgb(244, 226, 38);
   }
    
   //2、在基于矩形画水印文字
   Font crFont = null;
 
   StringFormat StrFormat = new StringFormat();
   StrFormat.Alignment = StringAlignment.Center;
 
   crFont = new Font("微软雅黑", fontsize, FontStyle.Bold);
   SolidBrush semiTransBrush = new SolidBrush(color); //添加水印
   picture.DrawString(_watermarkText, crFont, semiTransBrush, drawRect, StrFormat);
 
   semiTransBrush.Dispose();
  }