ASP.NET 2.0上传图片生成缩略图类
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
/// <summary>
/// 图片处理类
/// 1、生成缩略图片或按照比例改变图片的大小和画质
/// 2、将生成的缩略图放到指定的目录下
/// </summary>
public class ImageClass
{
public Image ResourceImage;
private int ImageWidth;
private int ImageHeight;
public string ErrMessage;
/// <summary>
/// 类的构造函数
/// </summary>
/// <param name="ImageFileName">图片文件的全路径名称</param>
public ImageClass()
{
}
public bool ThumbnailCallback()
{
return false;
}
/// <summary>
/// 生成缩略图重载方法1，返回缩略图的Image对象
/// </summary>
/// <param name="Width">缩略图的宽度</param>
/// <param name="Height">缩略图的高度</param>
/// <returns>缩略图的Image对象</returns>
public Image GetReducedImage(int Width, int Height)
{
try
{
Image ReducedImage;
Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback);
ReducedImage = ResourceImage.GetThumbnailImage(Width, Height, callb, IntPtr.Zero);
return ReducedImage;
}
catch (Exception e)
{
ErrMessage = e.Message;
return null;
}
}
/// <summary>
/// 生成缩略图重载方法2，将缩略图文件保存到指定的路径
/// </summary>
/// <param name="Width">缩略图的宽度</param>
/// <param name="Height">缩略图的高度</param>
/// <param name="targetFilePath">缩略图保存的全文件名，(带路径)，参数格式：D:\Images\filename.jpg</param>
/// <returns>成功返回true，否则返回false</returns>
public bool GetReducedImage(int Width, int Height,string ImageFileName, string targetFilePath)
{
Image ReducedImage = Image.FromFile(ImageFileName);
//新建一个bmp图片
System.Drawing.Image bitmap = new System.Drawing.Bitmap(Width, Height);
//新建一个画板
Graphics g = System.Drawing.Graphics.FromImage(bitmap);
//设置高质量插值法
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
//设置高质量,低速度呈现平滑程度
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//清空画布并以透明背景色填充
g.Clear(Color.Transparent);
//在指定位置并且按指定大小绘制原图片的指定部分
g.DrawImage(ReducedImage, new Rectangle(0, 0, Width, Height),
new Rectangle(0, 0, ReducedImage.Width, ReducedImage.Height),
GraphicsUnit.Pixel);
try
{
//以jpg格式保存缩略图
bitmap.Save(targetFilePath, System.Drawing.Imaging.ImageFormat.Jpeg);
return true;
}
catch (System.Exception e)
{
throw e;
}
finally
{
ReducedImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}
/// <summary>
/// 生成缩略图重载方法3，返回缩略图的Image对象
/// </summary>
/// <param name="Percent">缩略图的宽度百分比 如：需要百分之80，就填0.8</param>
/// <returns>缩略图的Image对象</returns>
public Image GetReducedImage(double Percent)
{
try
{
Image ReducedImage;
Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback);
ImageWidth = Convert.ToInt32(ResourceImage.Width * Percent);
ImageHeight = Convert.ToInt32(ResourceImage.Width * Percent);
ReducedImage = ResourceImage.GetThumbnailImage(ImageWidth, ImageHeight, callb, IntPtr.Zero);
return ReducedImage;
}
catch (Exception e)
{
ErrMessage = e.Message;
return null;
}
}
/// <summary>
/// 生成缩略图重载方法4，返回缩略图的Image对象
/// </summary>
/// <param name="Percent">缩略图的宽度百分比 如：需要百分之80，就填0.8</param>
/// <param name="targetFilePath">缩略图保存的全文件名，(带路径)，参数格式：D:\Images\filename.jpg</param>
/// <returns>成功返回true,否则返回false</returns>
public bool GetReducedImage(double Percent, string targetFilePath)
{
try
{
Image ReducedImage;
Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback);
ImageWidth = Convert.ToInt32(ResourceImage.Width * Percent);
ImageHeight = Convert.ToInt32(ResourceImage.Width * Percent);
ReducedImage = ResourceImage.GetThumbnailImage(ImageWidth, ImageHeight, callb, IntPtr.Zero);
ReducedImage.Save(@targetFilePath, ImageFormat.Jpeg);
ReducedImage.Dispose();
return true;
}
catch (Exception e)
{
ErrMessage = e.Message;
return false;
}
}
}
使用办法其中strBigImage代表了全路径以及文件名的要缩略图片地址,strThumbImage表示全路径以及文件名的生成文件名
ImageClass imgclass =new ImageClass();
imgclass.GetReducedImage(180,180,strBigImage,strThumbImage);
