使用gdi+在上面画文本,可以使用alphi效果.不难.
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System.Drawing.Image newImage =System.Drawing.Image.FromFile(Server.MapPath("你要加的水印"));
Bitmap bmp=new Bitmap(需要加水印的图片);
using ( Graphics g = Graphics.FromImage ( bmp ) )
{
Point ulCorner = new Point(5,5);//水印的位置
g.DrawImage(newImage,ulCorner);
g.Dispose();
}
bmp.Save(files);
上有完整的代码,自己看吧
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;namespace 水印例子
{
/// <summary>
/// Form1 的摘要说明。
/// </summary>
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.Button button1;
/// <summary>
/// 必需的设计器变量。
/// </summary>
private System.ComponentModel.Container components = null; public Form1()
{
//
// Windows 窗体设计器支持所必需的
//
InitializeComponent(); //
// TODO: 在 InitializeComponent 调用后添加任何构造函数代码
//
} /// <summary>
/// 清理所有正在使用的资源。
/// </summary>
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
} #region Windows 窗体设计器生成的代码
/// <summary>
/// 设计器支持所需的方法 - 不要使用代码编辑器修改
/// 此方法的内容。
/// </summary>
private void InitializeComponent()
{
this.button1 = new System.Windows.Forms.Button();
this.SuspendLayout();
//
// button1
//
this.button1.Location = new System.Drawing.Point(8, 24);
this.button1.Name = "button1";
this.button1.Size = new System.Drawing.Size(120, 32);
this.button1.TabIndex = 0;
this.button1.Text = "加入水印";
this.button1.Click += new System.EventHandler(this.button1_Click);
//
// Form1
//
this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
this.ClientSize = new System.Drawing.Size(136, 77);
this.Controls.Add(this.button1);
this.MaximizeBox = false;
this.MinimizeBox = false;
this.Name = "Form1";
this.Text = "Form1";
this.ResumeLayout(false); }
#endregion /// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
static void Main()
{
Application.Run(new Form1());
} private void button1_Click(object sender, System.EventArgs e)
{
//set a working directory
string WorkingDirectory = @".\"; //define a string of text to use as the Copyright message
string Copyright = "Welcome to Uncj.net 网际浪子"; //create a image object containing the photograph to water
Image imgPhoto = Image.FromFile(WorkingDirectory + "\\water_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 water
Image imgWater = new Bitmap(WorkingDirectory + "\\water.bmp");
int wmWidth = imgWater.Width;
int wmHeight = imgWater.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;
}
//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 Water image
//------------------------------------------------------------ //Create a Bitmap based on the previously modified photograph Bitmap
Bitmap bmWater = new Bitmap(bmPhoto);
bmWater.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution);
//Load this Bitmap into a new Graphic Object
Graphics grWater = Graphics.FromImage(bmWater); //To achieve a transulcent water 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 water 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 water 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
//water. 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 water 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; grWater.DrawImage(imgWater,
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, // Water Width
wmHeight, // Water Height
GraphicsUnit.Pixel, // Unit of measurment
imageAttributes); //ImageAttributes Object //Replace the original photgraphs bitmap with the new Bitmap
imgPhoto = bmWater;
grPhoto.Dispose();
grWater.Dispose(); //save new image to file system.
imgPhoto.Save(WorkingDirectory + "\\water_final.jpg", ImageFormat.Jpeg);
imgPhoto.Dispose();
imgWater.Dispose();
}
}
}