showimagevb.aspx.vb

Telerik是很大的第三方软件制造商

Imports System
Imports System.Collections
Imports System.ComponentModel
Imports System.Data
Imports System.Data.OleDb
Imports System.Drawing
Imports System.Web
Imports System.Web.SessionState
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.HtmlControls
Imports System.IO



Namespace Telerik.EditorExamplesVBNET.Editor.Examples.DBImages

    Public Class ShowImage
        Inherits System.Web.UI.Page

        Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
            'Get the file information from the database
            Dim conn As New OleDbConnection(DefaultVB.ConnectionString)
            conn.Open()
            If Request.QueryString("file") Is Nothing Then
                WriteImage(GetEmptyImage())
                Return
            End If

            Dim query As String = "SELECT {0} FROM Images WHERE FileName = '" + Request.QueryString("file").Replace("'", "''") + "'"

            'Check if to get the thumbnail of a file, or to get the full file
            If Not (Request.QueryString("type") Is Nothing) AndAlso Request.QueryString("type") = "thumb" Then
                query = String.Format(query, "Thumbnail")
            Else
                query = String.Format(query, "FullImage")
            End If

            'Get the image and display it
            Dim command As New OleDbCommand(query, conn)
            Dim reader As OleDbDataReader = command.ExecuteReader()
            If reader.Read() Then
                WriteImage(CType(reader(0), Byte()))
            Else
                'There was not such an image, so display the no_image image
                WriteImage(GetEmptyImage())
            End If
        End Sub 'Page_Load


        '/ <summary>
        '/ Flushes a byte array to the output stream
        '/ </summary>
        '/ <param name="image"></param>
        Private Sub WriteImage(ByVal image() As Byte)
            Response.Buffer = True
            Response.Clear()
            Response.ContentType = "image/gif"
            Response.AddHeader("content-disposition", "attachment; filename=" + Request.QueryString("FileName"))
            Response.BinaryWrite(image)
            Response.Flush()
            Response.End()
        End Sub 'WriteImage


        '/ <summary>
        '/ Creates an empty bitmap image and returns it as an array of bytes
        '/ </summary>
        '/ <returns></returns>
        Private Function GetEmptyImage() As Byte()
            Dim height As Integer = DefaultVB.ThumbsHeight
            Dim width As Integer = DefaultVB.ThumbsWidth
            Dim empty As New Bitmap(width, height)
            Dim ms As New MemoryStream
            empty.Save(ms, System.Drawing.Imaging.ImageFormat.Gif)
            Return ms.ToArray()
        End Function 'GetEmptyImage

#Region "Web Form Designer generated code"

        Protected Overrides Sub OnInit(ByVal e As EventArgs)
            InitializeComponent()
            MyBase.OnInit(e)
        End Sub 'OnInit


        Private Sub InitializeComponent()

        End Sub 'InitializeComponent

#End Region
    End Class 'ShowImage
End Namespace 'DBImages