C#基于两种需求向图片添加水印

使用场景

1、也就是大家经常用的，一般是图片的4个角落，基于横纵坐标来添加。

2、在图片内基于固定位置，文字始终居中。刚开始我基于第一种场景来根据水印汉字的长度来计算坐标，后来发现方法始终不可靠。现在是先在图片固定区域(水印区域)画一个矩形，然后再矩形内添加水印汉字，并使用画刷保持文字居中。

场景一效果

场景二效果

场景一添加水印方法

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();    }

场景二添加水印方法

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();    }