Asp. Net uploads images and generates high-definition thumbnails

Asp. Net uploads images and generates high-definition thumbnails

Not very complex. Write it down. The purpose is only to achieve it, but not to follow the standards carefully. See the code that already exists on the Internet.

Using System. Drawing;

Page,

Click Submit:

The Code is as follows:

HttpPostedFile hpf = UploadImage. PostedFile; // Get the file name (excluding the path) String Filename = Path. GetFileName (hpf. FileName); // original Modification If (hpf. FileName. Length <1) { Response. Write ("select the image file you want to upload "); Return; } If (hpf. ContentType! = "Image/jpeg" & hpf. ContentType! = "Image/gif") // original Modification { Response. Write ("only files of the gif jpg type can be uploaded "); Return; } Else { System. Text. StringBuilder sb = new System. Text. StringBuilder (); Sb. Append (DateTime. Now. Year. ToString ()); Sb. Append (DateTime. Now. Month. ToString ()); Sb. Append (DateTime. Now. Day. ToString ()); Sb. Append (DateTime. Now. Hour. ToString ()); Sb. Append (DateTime. Now. Minute. ToString ()); Sb. Append (DateTime. Now. Second. ToString ()); If (Filename. ToLower (). EndsWith ("gif ")) { Sb. Append (". gif "); } Else if (Filename. ToLower (). EndsWith ("jpg ")) { Sb. Append (". jpg "); } Else if (Filename. ToLower (). EndsWith ("jpeg ")) { Sb. Append (". jpeg "); } Filename = sb. ToString (); } // Save the image to the server Try { Hpf. SaveAs (Server. MapPath ("Album \") + Filename); // modify it by yourself! } Catch (Exception ee) { Response. Write ("Image Upload Failed, cause" + ee. Message ); Return; } // Generate a thumbnail // Original image name String originalFilename = hpf. FileName; // Generated high-quality image name String strFile = Server. MapPath ("Album \ Small _") + Filename; // Obtain an image object from a file System. Drawing. Image image = System. Drawing. Image. FromStream (hpf. InputStream, true ); Double Width = Double. Parse (TextBox1.Text. Trim ()); Double Height = Double. Parse (TextBox2.Text. Trim ()); System. Double NewWidth, NewHeight; If (image. Width> image. Height) { NewWidth = Width; NewHeight = image. Height * (NewWidth/image. Width ); } Else { NewHeight = Height; NewWidth = (NewHeight/image. Height) * image. Width; } If (NewWidth> Width) { NewWidth = Width; } If (NewHeight> Height) { NewHeight = Height; } System. Drawing. Size size = new Size (int) NewWidth, (int) NewHeight); // image Size System. Drawing. Image bitmap = new System. Drawing. Bitmap (size. Width, size. Height); // create a bmp Image System. Drawing. Graphics graphics = System. Drawing. Graphics. FromImage (bitmap); // create a Drawing board Graphics. InterpolationMode = System. Drawing. Drawing2D. InterpolationMode. High; // set the High quality interpolation method. Graphics. SmoothingMode = System. Drawing. Drawing2D. SmoothingMode. HighQuality; // set high quality and smooth Low Speed Graphics. Clear (Color. White); // Clear the canvas // Draw a picture at a specified position Graphics. DrawImage (image, new System. Drawing. Rectangle (0, 0, bitmap. Width, bitmap. Height ), New System. Drawing. Rectangle (0, 0, image. Width, image. Height ), System. Drawing. GraphicsUnit. Pixel ); // Text watermark System. Drawing. Graphics textGraphics = System. Drawing. Graphics. FromImage (bitmap ); System. Drawing. Font font = new Font ("", 10 ); System. Drawing. Brush brush = new SolidBrush (Color. Black ); TextGraphics. DrawString (TextBox3.Text. Trim (), font, brush, 10, 10 ); TextGraphics. Dispose (); /// Image Watermark // System. Drawing. Image copyImage = System. Drawing. Image. FromFile (System. Web. HttpContext. Current. Server. MapPath ("pic/1.gif ")); // Graphics a = Graphics. FromImage (bitmap ); //. DrawImage (copyImage, new Rectangle (bitmap. width-copyImage.Width, bitmap. height-copyImage.Height, copyImage. width, copyImage. height), 0, 0, copyImage. width, copyImage. height, GraphicsUnit. pixel ); // CopyImage. Dispose (); // A. Dispose (); // CopyImage. Dispose (); // Save the thumbnail Try { Bitmap. Save (strFile, System. Drawing. Imaging. ImageFormat. Jpeg ); } Catch (Exception ex) { Response. Write ("failed to save the thumbnail:" + ex. Message ); } Graphics. Dispose (); Image. Dispose (); Bitmap. Dispose ();

The entire implementation process is shown in the figure below:

Browse the page and select an image:

After you click submit, the image and thumbnail are generated in the target Folder:

We can see that the text watermark in the thumbnail has been generated:

So far, the entire function has been implemented.