Asp. NET to upload pictures and generate thumbnails of the method _ practical skills

The example in this article describes how asp.net implements uploading pictures and generating thumbnails. Share to everyone for your reference, specific as follows:

protected void Bt_upload_click (object sender, EventArgs e) {//check that the format of the uploaded file is valid if (this. UploadFile.PostedFile.ContentType.ToLower (). IndexOf ("image") < 0) {Response.Write ("Upload picture format is not valid!")
   ");
  Return }//Generate original 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; Original artwork width int oheight = oimage.height; Original height int twidth = 100; Set the initial width of the thumbnail int theight = 100;  Set thumbnail initial height//proportionally calculate the width and height of the thumbnail 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)
  ));
  ///Generate thumbnail artwork Bitmap timage = new Bitmap (twidth, theight);
  Graphics g = graphics.fromimage (timage); G.interpolationmode = System.Drawing.Drawing2D.InterpolationMode.High; Set high quality interpolation method G.smoothingmode = system.drawing.drawing2d.smoothingmode.highquality;//Set high quality, low speed rendering smoothness degree g.clear ( Color.transparent); Empty the canvas and fill the g.drawimage with a transparent background color (oimage, new Rectangle (0, 0, Twidth, theight), new Rectangle (0, 0, Owidth, oheight), Graphic
  Sunit.pixel); String ofullname = Server.MapPath (".") + "/image/" + "O" + DateTime.Now.ToShortDateString (). Replace ("-", "") + DateTime.Now.Hour.ToString () + DateTime.Now.Minute.ToString () + DateTime.Now.Second.ToString () + DateTime.Now.Millisecond.ToString () + ". jpg"; Save the physical path to the original image string tfullname = Server.MapPath (".") + "/image/" + "T" + DateTime.Now.ToShortDateString (). Replace ("-", "") + DateTime.Now.Hour.ToString () + DateTime.Now.Minute.ToString () + DateTime.Now.Second.ToString () + DateTime.Now.Millisecond.ToString () + ". jpg";
   Save the physical path of the thumbnail try {//Save the picture in JPG format oimage.save (ofullname, System.Drawing.Imaging.ImageFormat.Jpeg); Timage.save (Tfullname, System.Drawing.ImaGing.
  IMAGEFORMAT.JPEG);
  catch (Exception ex) {throw ex;
   finally {//release resource oimage.dispose ();
   G.dispose ();
  Timage.dispose ();

 }
 }
}

Here's another way to improve:

#region Upload a picture and generate thumbnails///<summary>///upload images generate thumbnails///</summary>///<param name= "Originalimagepath" > Photo Source Road Diameter </param>///<param name= "Thumbnailpath" > Thumbnail path (physical path) </param>///<param name= "width" > thumbnail width </param>///<param name= "height" > Thumbnail height </param>///<param name= "mode" > How to Generate Thumbnails </param > public static void Makethumbnail (String originalimagepath, string thumbnailpath, int width, int height, string mode)
  {//Get the source picture from the path file System.Drawing.Image originalimage = System.Drawing.Image.FromFile (Originalimagepath);
  int towidth = width;
  int toheight = height;
   int x = 0;
  int y = 0; Gets the width of the picture int ow = image.
  Width; Gets the height of the picture int oh = image.
  Height;
    How to generate thumbnails switch (mode) {case ' HW ': break;
    Case "W"://specified width high proportionally toheight = Originalimage.height * width/originalimage.width;
    Break
    Case "H"://The height of the specified picture is proportional towidth = originalimage.width * height/originalimage.height;
  Break  Case "cut"://If the reduction mode is not deformed if (double) originalimage.width/(double) originalimage.height > (double) towidth/(Do
     uble) toheight) {oh = Originalimage.height;
     The width of the thumbnail picture ow = originalimage.height * towidth/toheight;
     y = 0;
    x = (Originalimage.width-ow)/2;
     else {ow = Originalimage.width;
     The height of the thumbnail picture Oh = originalimage.width * toheight/towidth;
     x = 0;
    Y (Originalimage.height-oh)/2;
    } break;
   Default:break;
  //Create a new bmp picture Bitmap Bitmap = new Bitmap (towidth, toheight);
  Create a new canvas to bitmap width as the size of the canvas Graphics g = graphics.fromimage (bitmap);
  Setting high quality interpolation method g.interpolationmode = Interpolationmode.high;
  With high quality low speed present G.smoothingmode = smoothingmode.highquality;
   Empty the canvas to fill the g.clear (color.transparent) with a white background color; Draws the specified portion of the original picture at the specified location g.drawimage (originalimage,new Rectangle (towidth,toheight), New Rectangle (X,y,ow,oh),
   GraphicsUnit.Pixel); try {//save thumbnail bitmap in jpg format. Save (tHUMBNAILPATH,SYSTEM.DRAWING.IMAGING.IMAGEFORMAT.JPEG);
   catch (Exception ex) {throw ex;
    finally {//release resource originalimage.dispose (); Bitmap.
    Dispose ();
   G.dispose ();

 }} #endregion

I hope this article will help you with ASP.net programming.