[转].net 缩略图方法

本文转自：http://www.cnblogs.com/promic/archive/2010/04/21/1717190.html

private static string strConnect = System.Configuration.ConfigurationManager.AppSettings["connStr"];

    //上传图像

    protected void btnUpload_Click(object sender, EventArgs e)

    {

        ……

        string imgType;

        string fullFileName = this.txtPath.PostedFile.FileName;

        imgType = fullFileName.Substring(fullFileName.LastIndexOf(".") + 1).ToLower();

        string UserDirectory = Session["UserID"].ToString();//用户ID为所创建文件夹的名字

        string UserPath = Server.MapPath("UpLoad").ToString() + "\\" + UserDirectory;

        //如果文件夹不存在则创建

        if (!Directory.Exists(UserPath))

        {

            Directory.CreateDirectory(UserPath);

        }

        string originalImagePath = UserPath + "\\" + "Original";

        if(!Directory.Exists(originalImagePath))

        {

            Directory.CreateDirectory(originalImagePath);

        }

        string thumbnailPath = UserPath + "\\" + "Thumbnail";

        if (!Directory.Exists(thumbnailPath))

        {

            Directory.CreateDirectory(thumbnailPath);

        }

        // 获取上传图像的文件名

        string fileName = txtName.Text;

        ……

            if (imgType=="jpg"||imgType=="jpeg"||imgType=="bmp"||imgType=="png"||imgType=="icon")

            {

                try

                {

                    //生成原图

                    byte[] oFileByte = new byte[this.txtPath.PostedFile.ContentLength];

                    Stream oStream = this.txtPath.PostedFile.InputStream;

                    System.Drawing.Image oImage = System.Drawing.Image.FromStream(oStream);

                    int oWidth = oImage.Width;//原图宽度

                    int oHeight = oImage.Height;//原图高度

                    int tWidth = 100;//设置缩略图初始宽度

                    int tHeight = 100;//设置缩略图初始宽度

//按比例计算出缩略图的宽度和高度

                    if (oWidth >= oHeight)

                    {

                        tHeight = (int)Math.Floor(Convert.ToDouble(oHeight) * (Convert.ToDouble(tWidth) / Convert.ToDouble(oHeight)));

                    }

                    else

                    {

                        tWidth = (int)Math.Floor(Convert.ToDouble(oWidth) * (Convert.ToDouble(tHeight) / Convert.ToDouble(oHeight)));

                    }
//生成缩略图

                    Bitmap tImage = new Bitmap(tWidth,tHeight);

                    Graphics g = Graphics.FromImage(tImage);

                    g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;//设置高质量插值法

                    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;//设置高质量，低速度呈现平滑程度

                    g.Clear(Color.Transparent);//清空画布并以透明背景色填充

                    g.DrawImage(oImage, new Rectangle(0, 0, tWidth, tHeight), new Rectangle(0, 0, oWidth, oHeight), GraphicsUnit.Pixel);
//this.txtPath.PostedFile.SaveAs(originalImagePath + "\\" + fileName + "." + imgType);

                    //string originalImageUrl = "UpLoad/" + UserDirectory + "/" + "Orginal/"+fileName + ".jpg" ;//得到服务端原图片的虚拟路径

                    // string thumbnailImageUrl = "UpLoad/" + UserDirectory + "/" + "Thumbnail/" + fileName + ".jpg";//得到服务端原图片的虚拟路径

                    //以JPG格式保存图像

                    //oImage.Save(originalImageUrl, System.Drawing.Imaging.ImageFormat.Jpeg);/*看看这里这两个保存方式有没有问题*/

                  //   tImage.Save(thumbnailImageUrl, System.Drawing.Imaging.ImageFormat.Jpeg);

                    string oPath = originalImagePath + "\\" + fileName + ".jpg";

                    string tPath = thumbnailPath + "\\" + fileName + ".jpg";

                    //以JPG格式保存图像

                    oImage.Save(oPath, System.Drawing.Imaging.ImageFormat.Jpeg);

                    tImage.Save(tPath, System.Drawing.Imaging.ImageFormat.Jpeg);
lblMessage.Visible = true;

                    lblMessage.Text = "图像上传成功！";

                    txtName.Text = "";

                    txtDescription.Text = "";

                    //释放资源

                    oImage.Dispose();

                    g.Dispose();

                    tImage.Dispose();

                }

                catch (Exception ex)

                {

                    lblMessage.Visible = true;

                    lblMessage.Text = "由于网络原因，上载文件错误 " + ex.Message;

                }

            }

            else

            {

                Response.Write("<script language=‘javascript‘>alert(‘你选择的图像格式错误！‘);</script>");

                lblMessage.Visible = false;

            }

}

[转].net 缩略图方法