questo è un altro esempio
codice:
<%@ Page Language="VB" AutoEventWireup="false" CodeFile="a.aspx.vb" Inherits="prove_a" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<h3>esempio</h3>
<asp:PlaceHolder ID="PlaceHolder1" runat="server" EnableViewState="false"></asp:PlaceHolder>
</div>
</form>
</body>
</html>
codice:
Option Strict On
Partial Class prove_a
Inherits System.Web.UI.Page
Protected Sub Page_Load(sender As Object, e As System.EventArgs) Handles Me.Load
Dim immagine As String = Me.Request.QueryString("immagine")
If immagine = "1" Then
ReturnImage()
End If
Dim img As New WebControls.Image()
img.ImageUrl = "?immagine=1"
Me.PlaceHolder1.Controls.Clear()
Me.PlaceHolder1.Controls.Add(img)
End Sub
Private Sub ReturnImage()
Dim redPen As New Pen(Color.Red, 3)
Dim brush As New System.Drawing.Drawing2D.HatchBrush(Drawing2D.HatchStyle.Cross, Color.Red, Color.Yellow)
Dim curBitmap As New Bitmap(200, 200)
Dim g As Graphics = Graphics.FromImage(curBitmap)
g.FillRectangle(brush, 50, 50, 100, 100)
g.DrawLine(Pens.WhiteSmoke, 10, 10, 180, 10)
g.DrawLine(Pens.White, 10, 10, 10, 180)
Response.ContentType = "image/gif"
curBitmap.Save(Response.OutputStream, Imaging.ImageFormat.Gif)
curBitmap.Dispose()
g.Dispose()
brush.Dispose()
redPen.Dispose()
Response.End()
End Sub
End Class
è funzionante