感谢简易机场和AlienCoder提供的答复。 我已经找到了对我自己的询问的答复。

我们需要利用溪流将双向数据转换成我sql数据库。 以后的制图图书馆应当用来装载溪流。 与此同时,我们需要根据我们的需要来改变形象。

           protected void Page_Load(object sender, EventArgs e){      

            //Create connection to mysql database.
            MySqlConnection conn = new MySqlConnection(db);
            conn.Open();
            string s;
            s = Session["t"].ToString();

            string commantext = "select img_id,img_file,img_type,img_name from image where img_name= "+s+" ";

           MySqlCommand cmd = new MySqlCommand(commantext,conn);
            cmd.Parameters.Add("?img_id", MySqlDbType.Int32).Value = s;

           //create datatable. GetData is a method to fetch the data.
           DataTable dt = GetData(cmd);

           //Get data from database to bytes.
           Byte[] bytes = (Byte[])dt.Rows[0]["img_file"];

           //Defining the size to display data.
           int outputSize = 100;


                if (bytes.Length > 0)
                {

                    // Open a stream for the image and write the bytes into it
                    System.IO.MemoryStream stream = new System.IO.MemoryStream(bytes, true);
                    stream.Write(bytes, 0, bytes.Length);
                    Bitmap bmp = new Bitmap(stream);
                    Size new_size = new Size();

                    //resize based on the longer dimension

                    if (bmp.Width > bmp.Height)
                    {
                        new_size.Width = outputSize;
                        new_size.Height = (int)(((double)outputSize / (double)bmp.Width) * (double)bmp.Height);

                    }
                    else
                    {
                        new_size.Width = (int)(((double)outputSize / (double)bmp.Height) * (double)bmp.Width);                            
                        new_size.Height = outputSize;

                    }
                    Bitmap bitmap = new Bitmap(new_size.Width, new_size.Height, bmp.PixelFormat);
                    Graphics new_g = Graphics.FromImage(bitmap);
                    new_g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                    new_g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                    new_g.DrawImage(bmp, -1, -1, bitmap.Width + 1, bitmap.Height + 1);
                    bmp.Dispose();
                    bitmap.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
                    bitmap.Dispose();
                    new_g.Dispose();
                    stream.Close();
                }
             }

private DataTable GetData(MySqlCommand cmd)
{

    DataTable dt = new DataTable();
    //String strConnString = System.Configuration.ConfigurationManager    .ConnectionStrings["conString"].ConnectionString;

    MySqlConnection con = new MySqlConnection(db);
    MySqlDataAdapter sda = new MySqlDataAdapter();
    cmd.CommandType = CommandType.Text;
    cmd.Connection = con;

    try
    {
        con.Open();
        sda.SelectCommand = cmd;
        sda.Fill(dt);
        return dt;
    }

    catch
    {            return null;
    }

    finally
    {   con.Close();
        sda.Dispose();
        con.Dispose();
    }
}
}

1. I would resize the images on the page being used to display them. Where are they being displayed?

或

2. I would resize the images at the time they are saved

假设你的唯一挑战是只扩大图像(无论是在上载之前还是当检索时)。

指出有许多办法......

public static Size getScaledDimensions( Image img, Int32 maxW, Int32 maxH)
{

    //check if image is already within desired dimensions
    if (img.Height <= maxH & img.Width <= maxW)
    {
        Size orgsize = new Size(img.Width, img.Height);
        return orgsize; // no need to rescale
    }
    else //proceed with rescaling
    {

        int finalH;
        int finalW;

        //use height/width ratio to determine our new dimensions

        double hwRatio = (double)img.Height / (double)img.Width;


             int newW = (int) (maxH/ hwRatio);
            int newH = (int) (hwRatio * maxW);

           //make sure we scale the right dimension
            if (newW <= maxW) // scale width
            {
                finalH = maxH;
                finalW = newW;
            }
            else
            { // scale height
                finalH = newH;
                finalW = maxW;
            }//end if
        Size newsize = new Size(finalW, finalH);

        return newsize;

    }