图片缩放处理-优快云博客

本文介绍了一个用于生成图片缩略图的C#类，该类能够根据指定尺寸调整原图大小并保存为多种格式，包括JPEG、GIF和PNG等。

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Code
using System;
using System.Data;
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.Drawing;
using System.Drawing.Imaging;
using System.IO;
/// <summary>
/// ImageClass 的摘要说明
/// </summary>
namespace ImageClass
{
public class ImageClass
    {
public bool ThumbnailCallback()
        {
return false;
        }
public  void ShowThumbnail(string oldfile, string newfile,int white,int height)
        {
            System.Drawing.Image image = System.Drawing.Image.FromFile(oldfile);
//获取原图高度和宽度
            int oldh = image.Height;
int oldw = image.Width;
int neww, newh;
            neww = white; newh = height;   //直接设定新图的高宽,,

try
            {
                System.Drawing.Image.GetThumbnailImageAbort callb = new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback);
                System.Drawing.Image bt = new System.Drawing.Bitmap(neww, newh);
                System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bt);
                gr.Clear(Color.White);
                gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                gr.DrawImage(image, new Rectangle(0, 0, neww, newh), 0, 0, oldw, oldh, GraphicsUnit.Pixel);
switch (oldfile.Substring(oldfile.Length - 3).ToUpper())
                {
case "JPG":
                        bt.Save(newfile, ImageFormat.Jpeg);
break;
case "GIF":
                        bt.Save(newfile, ImageFormat.Gif);
break;
case "PNG":
                        bt.Save(newfile, ImageFormat.Png);
break;
default:
                        bt.Save(newfile, ImageFormat.Jpeg);
break;
                }
                gr.Dispose();
                bt.Dispose();
                image.Dispose();
            }
catch { }

        }
    }
}