在ASP.NET中上傳圖片並生成縮略圖，可以參照下列代碼：
private void btnUploadPicture_Click(object sender, System.EventArgs e)
{
//檢查上傳文件的格式是否有效
if(this.UploadFile.PostedFile.ContentType.ToLower().IndexOf("image") < 0)
{
Response.Write("上傳圖片格式無效！");
return;
}
//生成原圖
Byte[] oFileByte = new byte[this.UploadFile.PostedFile.ContentLength];
System.IO.Stream oStream = this.UploadFile.PostedFile.InputStream;
System.Drawing.Image oImage = System.Drawing.Image.FromStream(oStream);
int oWidth = oImage.Width; //原圖寬度
int oHeight = oImage.Height; //原圖高度
int tWidth = 100; //設置縮略圖初始寬度
int tHeight = 100; //設置縮略圖初始高度
//按比例計算出縮略圖的寬度和高度
if(oWidth >= oHeight)
{
tHeight = (int)Math.Floor(Convert.ToDouble(oHeight) * (Convert.ToDouble(tWidth)
/ Convert.ToDouble(oWidth)));
}
else
{
tWidth = (int)Math.Floor(Convert.ToDouble(oWidth) * (Convert.ToDouble(tHeight)
/ Convert.ToDouble(oHeight)));
}
//生成縮略原圖
Bitmap tImage = new Bitmap(tWidth,tHeight);
Graphics g = Graphics.FromImage(tImage);
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
//設置高質量插值法
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//設置高質量,低速度呈現平滑程度
g.Clear(Color.Transparent); //清空畫布並以透明背景色填充
g.DrawImage(oImage,new Rectangle(0,0,tWidth,tHeight),
new Rectangle(0,0,oWidth,oHeight),GraphicsUnit.Pixel);
string oFullName = Server.MapPath(".") + "/" + "o" +
DateTime.Now.ToShortDateString().Replace("-","") + DateTime.Now.Hour.ToString()
+ DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString()
+ DateTime.Now.Millisecond.ToString() + ".jpg"; //保存原圖的物理路徑
string tFullName = Server.MapPath(".") + "/" + "t" +
DateTime.Now.ToShortDateString().Replace("-","") + DateTime.Now.Hour.ToString()
+ DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString()
+ DateTime.Now.Millisecond.ToString() + ".jpg"; //保存縮略圖的物理路徑
try
{
//以JPG格式保存圖片
oImage.Save(oFullName,System.Drawing.Imaging.ImageFormat.Jpeg);
tImage.Save(tFullName,System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch(Exception ex)
{
throw ex;
}
finally
{
//釋放資源
oImage.Dispose();
g.Dispose();
tImage.Dispose();
}
}
