Thumbnails in ASP.NET
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Previously, the thumbnail on the page must be used to use a third party component. Now, with .NET, thumbnails can be easily implemented. Below is an example of achieving thumbnails.
View example code as follows: thumbnail.aspx <% @ page language = "vb" autoeventwireup = "false" codebehind = "thumbnail.aspx.vb" inherits = "aspxweb.thumbnail"%>
Easily implement thumbnail in ASP.NET </ title> <meta content =" Microsoft Visual Studio.net 7.0 "Name =" Generator " > <meta content = "Visual Basic 7.0" name = "CODE_LANGUAGE"> <meta content = "JavaScript" name = "vs_defaultClientScript"> <meta content = "http://schemas.microsoft.com/intellisense/ie5" name = "vs_targetschema"> </ head> <body ms_positioning = "gridLayout"> <ask: label id = "label1" runat = "server"> </ ask: label> <form id = "form1" method = "post" runat = "server" enctype = "multipart / form-data"> <INPUT type = "file" name = "file" width = "600"> <br> <br> <asp: Button id = "Button1" runat = " server "> </ asp: Button> </ form> </ body> </ HTML> after the code: Thumbnail.aspx.vb Imports System Imports System.Web Imports System.Drawing Imports System.IO Imports System.Drawing.Imaging Public Class thumbnail inherits system.Web.ui.page protected w ithEvents Label1 As System.Web.UI.WebControls.Label Protected WithEvents Button1 As System.Web.UI.WebControls.Button #Region "Web Form Designer Generated Code" 'This call is required by the Web Form Designer. <System.Diagnostics. DebuggersteptHrough ()></p>
<p>Private Sub InitializeComponent () End Sub Private Sub Page_Init (ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init 'CODEGEN: This method call is required by the Web Form Designer' Do not modify it using the code Editor. InitializeComponent () End Sub #end (Byval e AS System.Object, byval e as system.eventargs) Handles mybase.load label1.text = "<h3> Easily implement thumbnails in ASP.NET < / h3> "Button1.Text =" upload and display thumbnail "End Sub Private Sub Button1_Click (ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click Dim MyFileColl As HttpFileCollection = HttpContext.Current.Request.Files Dim MyPostedFile As httppostedfile = myfilecoll.Item (0) if lcase (MyPostedFile.contentType.tostring ()). Indexof ("Image" <0 Then Response.write ("invalid graphics format.</p>
<p>") Exit Sub End If GetThumbNail (MyPostedFile.FileName, 100, 100, MyPostedFile.ContentType.ToString (), _ False, MyPostedFile.InputStream) End Sub Private Function GetImageType (ByVal strContentType) As System.Drawing.Imaging.ImageFormat Select Case (strContentType.ToString (). ToLower ()) Case "image / pjpeg" GetImageType = System.Drawing.Imaging.ImageFormat.Jpeg Case "image / gif" GetImageType = System.Drawing.Imaging.ImageFormat.Gif Case "image / bmp "GetImageType = System.Drawing.Imaging.ImageFormat.Bmp Case" image / tiff "GetImageType = System.Drawing.Imaging.ImageFormat.Tiff Case" image / x-icon "GetImageType = System.Drawing.Imaging.ImageFormat.Icon Case" image / x-png "GetImageType = System.Drawing.Imaging.ImageFormat.Png Case" image / x-emf "GetImageType = System.Drawing.Imaging.ImageFormat.Emf Case" image / x-exif "GetImageType = System.Drawing. Imaging.Imageformat.exif Case "Image / X-WMF" getimageType = system.drawing.imaging.imageformat.wmf case else getimageType = system.drawing.Image.imageforma t.MemoryBmp End Select End Function Private Sub GetThumbNail (ByVal strFileName, ByVal iWidth, ByVal iheight, ByVal strContentType, _ ByVal blnGetFromFile, ByVal ImgStream) Dim oImg As Image If blnGetFromFile Then oImg = oImg.FromFile (strFileName) Else oImg = oImg. FromStream (ImgStream) End If oImg = oImg.GetThumbnailImage (iWidth, iheight, Nothing, (New IntPtr ()). Zero) Dim strGuid As String = (New Guid ()). NewGuid (). ToString (). ToUpper () Dim strfileext as string = strfilename.substring (Strfilename.lastIndexof (".") 'Save to local' oimg.save (Server.Mappath ("Images") "/" </p>
<p>strGuid strFileExt, GetImageType (strContentType)) 'direct output file url' Response.Redirect ( "images /" strGuid strFileExt) 'displayed on the screen less Response.ContentType = strContentType Dim MemStream As New MemoryStream ()' Note: This If you use Oimg.Save (response.outputstream, GetImageType (strContentType)) 'to different formats, such as PNG format. oImg.Save (MemStream, GetImageType (strContentType)) MemStream.WriteTo (Response.OutputStream) End Sub End Class C # using System; using System.Collections; using System.ComponentModel; using System.Data; using System.Drawing; using System. Web; using System.Web.SessionState; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.HtmlControls; using System.IO; using System.Drawing.Imaging; namespace eMeng.Exam {/// <Summary> /// thumbnail's summary description. /// </ summary> public class Thumbnail: System.Web.UI.Page {protected System.Web.UI.WebControls.Label Label1; protected System.Web.UI.WebControls.Button Button1; private void Page_Load (object sender, System.Eventargs e) {// Place user code here to initialize page label1.text = "<h3> Easily implement thumbnail </ h3>"; button1.text = "in ASP.NET "} #Region Web Form Designer Generated Code Override Protected Void OnInit (Eventargs E) {// // Codegen: This call is required for the ASP.NET Web Form Designer. // InitializeComponent (); base.onit (e);} /// <summary> /// Designer Supports the required method - Do not use the code editor to modify the // / this method.</p>
<p>/// </ summary> private void InitializeComponent () {this.Button1.Click = new System.EventHandler (this.Button1_Click); this.Load = new System.EventHandler (this.Page_Load);} #endregion private void Button1_Click (object sender, System.EventArgs e) {HttpFileCollection MyFileColl = HttpContext.Current.Request.Files; HttpPostedFile MyPostedFile = MyFileColl [0];.. if (MyPostedFile.ContentType.ToString () ToLower () IndexOf ( "image") <0) {response.write ("invalid graphics format.</p>
<p>"); Return;} GetThumbNail (MyPostedFile.FileName, 100, 100, MyPostedFile.ContentType.ToString (), false, MyPostedFile.InputStream);} private System.Drawing.Imaging.ImageFormat GetImageType (object strContentType) {if ((strContentType .Tostring (). TOLOWER ()) == "image / pjpeg") {return system.drawing.imaging.imageformat.jpeg;} else f ((StrContentType.toString (). TOLOWER ()) == "image / gif ") {Return System.drawing.Imaging.ImageFormat.gif;} else f (). TOLOWER ()) ==" image / bmp ") {return system.drawing.image.imageformat.bmp;} ELSE IF ((StrContentType.toString (). TOLOWER ()) == "Image / Tiff") {Return System.drawing.Imaging.imageFormat.tiff;} else IF ((StrContentType.toString (). Tool! ()) = = "image / x-icon") {return system.drawing.imaging.imageformat.icon;} else f (). TOLOWER ()) == "image / x-png") {Return System. Drawing.Image.ImageFormat.png;} else IF ((strcontenttype.tostring (). TOLOWER ()) == "image / x-emf") {return system.drawing.Image .} Else IF ((strconteTtype.tostring (). TOLOWER ()) == "image / x-exif") {return system.drawing.imaging.imageformat.exif;} else f ((strContentType.tostring) () .ToLower ()) == "image / x-wmf") {return System.Drawing.Imaging.ImageFormat.Wmf;} else {return System.Drawing.Imaging.ImageFormat.MemoryBmp;}} private void getThumbNail (string strFileName, int iWidth, int iheight, string strContentType, bool blnGetFromFile, System.IO.Stream ImgStream) {System.Drawing.Image oImg; if (blnGetFromFile) {oImg = System.Drawing.Image.FromFile (strFileName);} else { Oimg =</p></div><div class="text-center mt-3 text-grey">
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