Asp.Net uploads pictures and generates thumbnails

front end

<body>
    <form id="sheet" runat="server">
    <div>
        <asp:FileUpload ID="UpFile" runat="server" />
         <asp:Button ID="btnUpLoad" runat="server"
            Text="UpLoad And Create Small Picture" οnclick="btnUpLoad_Click" />
        <br />
        Your Small Picture Is:<br />
        <asp:Image ID="imgShow" runat="server" />
    </div>
    </form>
</body>

code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        imgShow.Visible = false;
    }
    protected void btnUpLoad_Click(object sender, EventArgs e)
    {
        string filePath = UpFile.PostedFile.FileName;
        string fileName = filePath.Substring(filePath.LastIndexOf("//") + 1);
        string flag = filePath.Substring(filePath.LastIndexOf(".") + 1);
        flag = flag.ToLower();
        if (flag != "jpg" && flag != "bmp" && flag != "gif")
        {
            Response.Write("<script>alert('你选择的不是图片文件！');</script>");
        }
        else
        {
            string savepath = Server.MapPath("UpLoadFiles/") + string.Format("{0:yyyyMMddHHmmss}", DateTime.Now) + "." + flag;
            UpFile.PostedFile.SaveAs(savepath);

            System.Drawing.Image originalImage = System.Drawing.Image.FromFile(savepath);
            int x = 0;
            int y = 0;
            int ow = originalImage.Width;
            int oh = originalImage.Height;

int width = 640;
int height = 512;

            System.Drawing.Image bitmap = new System.Drawing.Bitmap(width,height);
            Graphics g = System.Drawing.Graphics.FromImage(bitmap);
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            g.Clear(Color.Transparent);
            g.DrawImage(originalImage, new Rectangle(0, 0, width, height), new Rectangle(x, y, ow, oh), GraphicsUnit.Pixel);
            try
            {
                string NewSaveName = Server.MapPath("UpLoadFiles/") + string.Format("{0:yyyyMMddHHmmss}", DateTime.Now) + ".jpg";
                bitmap.Save(NewSaveName, System.Drawing.Imaging.ImageFormat.Jpeg);
                imgShow.Visible = true;
                imgShow.ImageUrl = NewSaveName;
            }
            catch (System.Exception ex)
            {                 throw ex;             }             finally             {                 originalImage.Dispose();                 bitmap.Dispose();                 g.Dispose();             }         }     } } work There is no time to adjust, and there is no proportional scaling of the picture. You need to optimize it yourself.

Asp.Net uploads pictures and generates thumbnails

Guess you like