C#图片上传，加水印，自动生成缩略图源代码

using System;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
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;
using System.Text;
using System.Text.RegularExpressions;
using System.Drawing;
using System.Drawing.Imaging;
using System.Collections;
using System.ComponentModel;
namespace Legalsoft.Images
{
/// <summary>
/// News 的摘要说明
/// </summary>
public class XImage
{
public Color tBackground;
public Color tBorder;
public Color tShadow;
public int tQuality;
public string markPosition;
/// <summary>
/// 图片参数预定义
/// </summary>
static Hashtable htmimes = new Hashtable();
internal readonly string AllowExt = ".jpe|.jpeg|.jpg|.png|.tif|.tiff|.bmp|.gif";
public XImage()
{
tBackground = Color.Transparent;
tBorder = Color.Transparent;
tShadow = Color.Transparent;
tQuality = 100;
markPosition = "左下角";
#region 图片类型预定义
htmimes[".jpe"]="image/jpeg";
htmimes[".jpeg"] = "image/jpeg";
htmimes[".jpg"] = "image/jpeg";
htmimes[".png"] = "image/png";
htmimes[".tif"] = "image/tiff";
htmimes[".tiff"] = "image/tiff";
htmimes[".bmp"] = "image/bmp";
htmimes[".gif"] = "image/gif";
#endregion
}
#region 下载指定URL图片并保存
/// <summary>
/// 下载指定URL的文件并保存到指定目录
/// </summary>
/// <param name="strUrl"></param>
public void DownloadImage(string strUrl, string file)
{
System.Net.WebClient wc = new System.Net.WebClient();
wc.DownloadFile(strUrl, file);
}
#endregion
#region C#自动生成缩略图
/// <summary>
/// 按给定名字确定颜色
/// </summary>
/// <param name="name"></param>
/// <returns></returns>
public Color ToColor(string name)
{
if (name == "白色") return Color.White;
if (name == "红色") return Color.Red;
if (name == "蓝色") return Color.Blue;
if (name == "绿色") return Color.Green;
if (name == "黑色") return Color.Black;
if (name == "灰色") return Color.DarkGray;
if (name == "黄色") return Color.Yellow;
if (name == "紫色") return Color.Cyan;
if (name == "无色") return Color.Transparent;
return Color.Transparent;
}
/// <summary>
/// 按名字设置各种颜色，可以自行扩充:)
/// </summary>
/// <param name="name"></param>
/// <returns></returns>
public int ToQuality(string name)
{
return Int32.Parse(name.Replace("%", ""));
}
/// <summary>
/// 获取图像编码解码器的所有相关信息
/// </summary>
/// <param name="mimeType">包含编码解码器的多用途网际邮件扩充协议 (MIME) 类型的字符串</param>
/// <returns>返回图像编码解码器的所有相关信息</returns>
private static ImageCodecInfo GetCodecInfo(string mimeType)
{
ImageCodecInfo[] CodecInfo = ImageCodecInfo.GetImageEncoders();
foreach (ImageCodecInfo ici in CodecInfo)
{
if (ici.MimeType == mimeType) return ici;
}
return null;
}
/// <summary>
/// 检测扩展名的有效性
/// </summary>
/// <param name="sExt">文件名扩展名</param>
/// <returns>如果扩展名有效,返回true,否则返回false.</returns>
private bool CheckValidExt(string sExt)
{
bool flag = false;
string[] aExt = AllowExt.Split("|");
foreach (string filetype in aExt)
{
if (filetype.ToLower() == sExt)
{
flag = true;
break;
}
}
return flag;
}
/// <summary>
/// 保存图片
/// </summary>
/// <param name="image">Image 对象</param>
/// <param name="savePath">保存路径</param>
/// <param name="ici">指定格式的编解码参数</param>
private void SaveImage(System.Drawing.Image image, string savePath, ImageCodecInfo ici)
{
//设置 原图片 对象的 EncoderParameters 对象
EncoderParameters parameters = new EncoderParameters(1);
parameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, ((long)tQuality));
image.Save(savePath, ici, parameters);
parameters.Dispose();
}
/// <summary>
/// 生成缩略图
/// </summary>
/// <param name="sourceImagePath">原图片路径(相对路径)</param>
/// <param name="thumbnailImagePath">生成的缩略图路径,如果为空则保存为原图片路径(相对路径)</param>
/// <param name="thumbnailImageWidth">缩略图的宽度（高度与按源图片比例自动生成）</param>
public void ToThumbnail(string sourceImagePath, string thumbnailImagePath, int thumbnailImageWidth, int thumbnailImageHeight )
{
// 1.先检查图片格式等信息
string ThumbnailImagePath = thumbnailImagePath;
string SourceImagePath = sourceImagePath;
string sExt = SourceImagePath.Substring(SourceImagePath.LastIndexOf(".")).ToLower();
if (SourceImagePath.ToString() == System.String.Empty)
{
throw new NullReferenceException("SourceImagePath is null!");
}
if (!CheckValidExt(sExt))
{
throw new ArgumentException("原图片文件格式不正确,支持的格式有[ " + AllowExt + " ]", "SourceImagePath");
}
// 从原图片创建 Image 对象
System.Drawing.Image image = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(SourceImagePath));
// 2.计算图片的位置、尺寸等信息
int tWidth, tHeight, tLeft, tTop;
double fScale = (double)thumbnailImageHeight / (double)thumbnailImageWidth; // 高度宽度比
if (((double)image.Width * fScale) > (double)image.Height) // 如果原图比较宽
{
tWidth = thumbnailImageWidth;
tHeight = (int)((double)image.Height * (double)tWidth / (double)image.Width);
tLeft = 0;
tTop = (thumbnailImageHeight-tHeight)/2;
}
else
{
tHeight = thumbnailImageHeight;
tWidth = (int)((double)image.Width * (double)tHeight / (double)image.Height);
tLeft = (thumbnailImageWidth-tWidth)/2;
tTop = 0;
}
if (tLeft < 0) tLeft = 0;
if (tTop < 0) tTop = 0;
if (tBorder != Color.Transparent)
{
tWidth -= 2;
tHeight -= 2;
tLeft++;
tTop++;
}
if (tShadow != Color.Transparent)
{
tWidth -= 1;
tHeight -= 1;
}
//用指定的大小和格式初始化 Bitmap 类的新实例
//Bitmap bitmap = new Bitmap(ThumbnailImageWidth, num, PixelFormat.Format32bppArgb);
Bitmap bitmap = new Bitmap(thumbnailImageWidth, thumbnailImageHeight, PixelFormat.Format32bppArgb);
//从指定的 Image 对象创建新 Graphics 对象
Graphics graphics = Graphics.FromImage(bitmap);
//清除整个绘图面并以透明背景色填充
if (tBackground != Color.Transparent)
{
graphics.Clear(tBackground);
}
else
{
graphics.Clear(Color.Transparent);
}
// 添加阴影
if (tShadow != Color.Transparent)
{
Pen shPen = new Pen(tShadow);
graphics.DrawLine(shPen, new Point(1, thumbnailImageHeight-1), new Point(thumbnailImageWidth-1, thumbnailImageHeight-1));
graphics.DrawLine(shPen, new Point(thumbnailImageWidth-1, 1), new Point(thumbnailImageWidth-1, thumbnailImageHeight-1));
}
// 添加边框
if (tBorder != Color.Transparent)
{
Pen bdPen = new Pen(tBorder);
if (tShadow != Color.Transparent)
{
graphics.DrawRectangle(bdPen, new Rectangle(0, 0, thumbnailImageWidth-2, thumbnailImageHeight-2));
}
else
{
graphics.DrawRectangle(bdPen, new Rectangle(0, 0, thumbnailImageWidth-1, thumbnailImageHeight-1));
}
}
//在指定位置并且按指定大小绘制 原图片 对象
graphics.DrawImage(image, new Rectangle(tLeft, tTop, tWidth, tHeight));
image.Dispose();
try
{
//将此 原图片 以指定格式并用指定的编解码参数保存到指定文件
string savepath = (ThumbnailImagePath == null ? SourceImagePath : ThumbnailImagePath);
SaveImage(bitmap, HttpContext.Current.Server.MapPath(savepath), GetCodecInfo((string)htmimes[sExt]));
}
catch (System.Exception e)
{
throw e;
}
finally
{
bitmap.Dispose();
graphics.Dispose();
}
}
#endregion
#region C#给图片添加水印
public void Mark(string sourceImagePath, string markString)
{
// 1.先检查图片格式等信息
string markImagePath = sourceImagePath;
string SourceImagePath = sourceImagePath;
string sExt = SourceImagePath.Substring(SourceImagePath.LastIndexOf(".")).ToLower();
if (SourceImagePath.ToString() == System.String.Empty)
{
throw new NullReferenceException("SourceImagePath is null!");
}
if (!CheckValidExt(sExt))
{
throw new ArgumentException("原图片文件格式不正确,支持的格式有[ " + AllowExt + " ]", "SourceImagePath");
}
// 从原图片创建 Image 对象
System.Drawing.Image image = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(SourceImagePath));
//用指定的大小和格式初始化 Bitmap 类的新实例
Bitmap bitmap = new Bitmap(image.Width, image.Height, PixelFormat.Format32bppArgb);
//从指定的 Image 对象创建新 Graphics 对象
Graphics graphics = Graphics.FromImage(bitmap);
//在指定位置并且按指定大小绘制 原图片 对象
graphics.DrawImage(image, new Rectangle(0, 0, image.Width, image.Height));
#region 绘制水印
// 设置水印字体
int fHeight = image.Height/5;
if(fHeight>16) fHeight = 16;
Font drawFont = new Font("Arial", fHeight);
// 设置水印文字位置，默认为左下角
float x = 4;
float y = image.Height - drawFont.Height - 4;
if (markPosition == "左上角")
{
y = 4;
}
if (markPosition == "右上角")
{
x = image.Width - markString.Length * fHeight / 2 - fHeight;
y = 4;
}
if (markPosition == "右下角")
{
x = image.Width - markString.Length * fHeight / 2 - fHeight;
}
if (markPosition == "图片中间")
{
x = image.Width / 2 - markString.Length * fHeight / 2;
y = image.Height / 2 - fHeight / 2;
}
StringFormat drawFormat = new StringFormat();
drawFormat.FormatFlags = StringFormatFlags.NoWrap;
// 设置水印文字颜色，先绘制一个黑色字作为阴影，再绘制白色字，这样比较显眼；
SolidBrush drawBrush = new SolidBrush(Color.Black);
graphics.DrawString(markString, drawFont, drawBrush, x, y, drawFormat);
drawBrush.Color = Color.White;
graphics.DrawString(markString, drawFont, drawBrush, x-1, y-1, drawFormat);
#endregion
image.Dispose();
try
{
//将此 原图片 以指定格式并用指定的编解码参数保存到指定文件
string savepath = SourceImagePath;
SaveImage(bitmap, HttpContext.Current.Server.MapPath(savepath), GetCodecInfo((string)htmimes[sExt]));
}
catch (System.Exception e)
{
throw e;
}
finally
{
bitmap.Dispose();
graphics.Dispose();
}
}
#endregion
}
}

经过测试的超强C#图片上传，加水印，自动生成缩略图源代码。可以指定水印位置、文字；可以设置缩略图背景颜色，边框及其颜色，阴影及其颜色；可以指定缩略图质量；支持GIF,JPEG,JPG,PNG,BMP,TIFF等多种格式图片文件。