给图片加水印

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
public class DrawImg
{
private string WorkingDirectory = string.Empty ; //路径
private string ImageName = string.Empty; //被处理的图片
private string ImageWater = string.Empty; //水印图片
private string FontString = string.Empty; //水印文字


enum DealType{NONE,WaterImage,WaterFont,DoubleDo}; //枚举命令

private DealType dealtype;


public DrawImg()
{}

public string PublicWorkingDirectory
{
get
{
return WorkingDirectory;
}
set
{
WorkingDirectory = value;
}
}

public string PublicImageName
{
get
{
return ImageName;
}
set
{
ImageName = value;
}
}


public string PublicImageWater
{
get
{
return ImageWater;
}
set //设置了水印图片的话说明是要水印图片效果的
{
dealtype = DealType.WaterImage;
ImageWater = value;
}
}

public string PublicFontString
{
get
{
return FontString;
}
set //设置了水印文字的话说明是要水印文字效果的
{
dealtype = DealType.WaterFont;
FontString = value;
}
}



public void DealImage()
{
IsDouble();

switch( dealtype )
{
case DealType.WaterFont: WriteFont(); break;
case DealType.WaterImage: WriteImg(); break;
case DealType.DoubleDo: WriteFontAndImg(); break;
}

}

private void IsDouble()
{
if(ImageWater+""!="" && FontString+""!="")
{
dealtype = DealType.DoubleDo;
}
}

private void WriteFont()
{
//set a working directory
//string WorkingDirectory = @"C:Watermark_srcWaterPic";

//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 + ImageName);
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);

//------------------------------------------------------------
//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);

crFont = new Font("arial",sizes[i],FontStyle.Bold);

//Measure the Copyright string in this Font
crSize = grPhoto.MeasureString(FontString, 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(FontString, //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(FontString, //string of text
crFont, //font
semiTransBrush, //Brush
new PointF(xCenterOfImg,yPosFromBottom), //Position
StrFormat);

imgPhoto = bmPhoto;
grPhoto.Dispose();

//save new image to file system.
imgPhoto.Save(WorkingDirectory + ImageName + "_finally.jpg", ImageFormat.Jpeg);
imgPhoto.Dispose();

//Text alignment
}


private void WriteImg()
{
//set a working directory
//string WorkingDirectory = @"C:Watermark_srcWaterPic";

//create a image object containing the photograph to watermark
Image imgPhoto = Image.FromFile(WorkingDirectory + ImageName);
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 + ImageWater);
int wmWidth = imgWatermark.Width;
int wmHeight = imgWatermark.Height;

//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


//------------------------------------------------------------
//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 + ImageName +"_finally.jpg", ImageFormat.Jpeg);
imgPhoto.Dispose();
imgWatermark.Dispose();

}


private void WriteFontAndImg()
{

//create a image object containing the photograph to watermark
Image imgPhoto = Image.FromFile(WorkingDirectory + ImageName);
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 + ImageWater);
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(FontString, 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(FontString, //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(FontString, //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 + ImageName +"_finally.jpg", ImageFormat.Jpeg);
imgPhoto.Dispose();
imgWatermark.Dispose();


}
}


//水印图片加水印文字
// ReDrawImg img = new ReDrawImg();
// img .PublicWorkingDirectory = @"C:Watermark_srcWaterPic";
// img .PublicImageName = "watermark_photo.jpg";
// img .PublicImageWater = "watermark.bmp";
// img .PublicFontString = "清清月儿";
// img .DealImage();

//水印文字
ReDrawImg img = new ReDrawImg();
img .PublicWorkingDirectory = @"C:Watermark_srcWaterPic";
img .PublicImageName = "watermark_photo.jpg";
img .PublicFontString = @"清清月儿";
img .DealImage();


//水印图片
// ReDrawImg img = new ReDrawImg();
// img .PublicWorkingDirectory = @"C:Watermark_srcWaterPic";
// img .PublicImageName = "watermark_photo.jpg";
// img .PublicImageWater = "watermark.bmp";
// img .DealImage();


后台代码：

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
public partial class _Default : System.Web.UI.Page
{

protected void Page_Load(object sender, EventArgs e)
{

}
protected void bt_upload_Click(object sender, EventArgs e)
{
try
{
if (FileUpload1.PostedFile.FileName == "")
{
this.lb_info.Text = "请选择文件！";
}
else
{
string filepath = FileUpload1.PostedFile.FileName;
string filename = filepath.Substring(filepath.LastIndexOf("") + 1);
string serverpath1 = Server.MapPath("images/") + filename;
//string serverpath2 = Server.MapPath("images/") + System.DateTime.Now.ToString("yyy-MM-dd-hh-mm-ss") + Session.SessionID + filename;
FileUpload1.PostedFile.SaveAs(serverpath1);
//ImageThumbnail img = new ImageThumbnail(filepath);
//img.ReducedImage(0.4, serverpath2);
DrawImg img = new DrawImg();
img.PublicWorkingDirectory = Server.MapPath("images/");
img.PublicImageName = filename;
img.PublicFontString = "http://blog.csdn.net/21aspnet";
img.PublicImageWater = "yyy.jpg";
img.DealImage();
this.lb_info.Text = "上传成功！";
}
}
catch (Exception error)
{
this.lb_info.Text = "上传发生错误！原因：" + error.ToString();
}
}


}