C#实现给图片加水印的方法

using System;using System.Drawing;using System.Drawing.Imaging;using System.Drawing.Drawing2D;namespace Tutorial{  class WaterMark  {    [STAThread]    static void Main(string[] args)    {      //set a working directory      string WorkingDirectory = @"C:/Documents and Settings/administrator.JAZZMINE/My Documents/Projects/Tutorials/WaterMark";      //define a string of text to use as the Copyright message      string Copyright = "Copyright ?2002 - AP Photo/David Zalubowski";      //create a image object containing the photograph to watermark      Image imgPhoto = Image.FromFile(WorkingDirectory + "//watermark_photo.jpg");      int phWidth = imgPhoto.Width;      int phHeight = imgPhoto.Height;      //create a Bitmap the Size of the original photograph      Bitmap bmPhoto = new Bitmap(phWidth, phHeight, PixelFormat.Format24bppRgb);      bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution);      //load the Bitmap into a Graphics object      Graphics grPhoto = Graphics.FromImage(bmPhoto);      //create a image object containing the watermark      Image imgWatermark = new Bitmap(WorkingDirectory + "//watermark.bmp");      int wmWidth = imgWatermark.Width;      int wmHeight = imgWatermark.Height;      //------------------------------------------------------------      //Step #1 - Insert Copyright message      //------------------------------------------------------------      //Set the rendering quality for this Graphics object      grPhoto.SmoothingMode = SmoothingMode.AntiAlias;      //Draws the photo Image object at original size to the graphics object.      grPhoto.DrawImage(        imgPhoto,                // Photo Image object        new Rectangle(0, 0, phWidth, phHeight), // Rectangle structure        0,                   // x-coordinate of the portion of the source image to draw.        0,                   // y-coordinate of the portion of the source image to draw.        phWidth,                // Width of the portion of the source image to draw.        phHeight,                // Height of the portion of the source image to draw.        GraphicsUnit.Pixel);          // Units of measure      //-------------------------------------------------------      //to maximize the size of the Copyright message we will      //test multiple Font sizes to determine the largest posible      //font we can use for the width of the Photograph      //define an array of point sizes you would like to consider as possiblities      //-------------------------------------------------------      int[] sizes = new int[]{16,14,12,10,8,6,4};      Font crFont = null;      SizeF crSize = new SizeF();      //Loop through the defined sizes checking the length of the Copyright string      //If its length in pixles is less then the image width choose this Font size.      for (int i=0 ;i<7; i++)      {        //set a Font object to Arial (i)pt, Bold        crFont = new Font("arial", sizes[i], FontStyle.Bold);        //Measure the Copyright string in this Font        crSize = grPhoto.MeasureString(Copyright, crFont);        if((ushort)crSize.Width < (ushort)phWidth)          break;      }      //Since all photographs will have varying heights, determine a      //position 5% from the bottom of the image      int yPixlesFromBottom = (int)(phHeight *.05);      //Now that we have a point size use the Copyrights string height      //to determine a y-coordinate to draw the string of the photograph      float yPosFromBottom = ((phHeight - yPixlesFromBottom)-(crSize.Height/2));      //Determine its x-coordinate by calculating the center of the width of the image      float xCenterOfImg = (phWidth/2);      //Define the text layout by setting the text alignment to centered      StringFormat StrFormat = new StringFormat();      StrFormat.Alignment = StringAlignment.Center;      //define a Brush which is semi trasparent black (Alpha set to 153)      SolidBrush semiTransBrush2 = new SolidBrush(Color.FromArgb(153, 0, 0, 0));      //Draw the Copyright string      grPhoto.DrawString(Copyright, //string of text        crFont, //font        semiTransBrush2, //Brush        new PointF(xCenterOfImg+1,yPosFromBottom+1), //Position        StrFormat);      //define a Brush which is semi trasparent white (Alpha set to 153)      SolidBrush semiTransBrush = new SolidBrush(Color.FromArgb(153, 255, 255, 255));      //Draw the Copyright string a second time to create a shadow effect      //Make sure to move this text 1 pixel to the right and down 1 pixel      grPhoto.DrawString(Copyright, //string of text        crFont, //font        semiTransBrush, //Brush        new PointF(xCenterOfImg,yPosFromBottom), //Position        StrFormat); //Text alignment      //------------------------------------------------------------      //Step #2 - Insert Watermark image      //------------------------------------------------------------      //Create a Bitmap based on the previously modified photograph Bitmap      Bitmap bmWatermark = new Bitmap(bmPhoto);      bmWatermark.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution);      //Load this Bitmap into a new Graphic Object      Graphics grWatermark = Graphics.FromImage(bmWatermark);      //To achieve a transulcent watermark we will apply (2) color      //manipulations by defineing a ImageAttributes object and      //seting (2) of its properties.      ImageAttributes imageAttributes = new ImageAttributes();      //The first step in manipulating the watermark image is to replace      //the background color with one that is trasparent (Alpha=0, R=0, G=0, B=0)      //to do this we will use a Colormap and use this to define a RemapTable      ColorMap colorMap = new ColorMap();      //My watermark was defined with a background of 100% Green this will      //be the color we search for and replace with transparency      colorMap.OldColor = Color.FromArgb(255, 0, 255, 0);      colorMap.NewColor = Color.FromArgb(0, 0, 0, 0);      ColorMap[] remapTable = {colorMap};      imageAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap);      //The second color manipulation is used to change the opacity of the      //watermark. This is done by applying a 5x5 matrix that contains the      //coordinates for the RGBA space. By setting the 3rd row and 3rd column      //to 0.3f we achive a level of opacity      float[][] colorMatrixElements = {        new float[] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f},        new float[] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f},        new float[] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f},        new float[] {0.0f, 0.0f, 0.0f, 0.3f, 0.0f},        new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f}};      ColorMatrix wmColorMatrix = new ColorMatrix(colorMatrixElements);      imageAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default,        ColorAdjustType.Bitmap);      //For this example we will place the watermark in the upper right      //hand corner of the photograph. offset down 10 pixels and to the      //left 10 pixles      int xPosOfWm = ((phWidth - wmWidth)-10);      int yPosOfWm = 10;      grWatermark.DrawImage(imgWatermark,        new Rectangle(xPosOfWm,yPosOfWm,wmWidth,wmHeight), //Set the detination Position        0, // x-coordinate of the portion of the source image to draw.        0, // y-coordinate of the portion of the source image to draw.        wmWidth, // Watermark Width        wmHeight, // Watermark Height        GraphicsUnit.Pixel, // Unit of measurment        imageAttributes); //ImageAttributes Object      //Replace the original photgraphs bitmap with the new Bitmap      imgPhoto = bmWatermark;      grPhoto.Dispose();      grWatermark.Dispose();      //save new image to file system.      imgPhoto.Save(WorkingDirectory + "//watermark_final.jpg", ImageFormat.Jpeg);      imgPhoto.Dispose();      imgWatermark.Dispose();    }  }}