-
August 20th, 2010, 08:32 AM
#1
Problem in saving image to database from picturebox. VB.Net 2008. Framework 3.5.
Hi there,
I have a form containing a listbox showing a list of image names. It's bound
to the database table. When an image name is clicked it shows the image and
imagename in a picturebox and textbox respectively. When no image is selected
in the listbox, a new record can be inserted by browsing a new image in the
picturebox by an openfiledialog, writing the imagename in the textbox and
pressing the OK button. When an image is already selected, the record can be
updated by pressing the same OK button. The data is saved into MSSQL Server
2005. Corresponding table fields are Keycode int autono,
logoname nvarchar(50), logo image.
Now the problem, when I insert a new data with an image everything goes fine
but whenever I try to update an existing data with an image it throws an
exception- 'A generic error occurred in GDI+.' at the following line-
'pic.Image.Save(ms, pic.Image.RawFormat)'. Surprisingly when I update an
existing data without any image in the picturebox no exception is generated.
I have crossed checked it and seems that the problem is just at one point-
'Updating the image from the picturebox'.
I'm almost done all throughout but stuck to this particular point. Please help. Regards.
My code to insert/update the data by OK button and to populate it by listbox
doubleclick follows:
Code:
Private ms As MemoryStream
Private arrImage() As Byte
Private conn As SqlConnection
Private cmd As SqlCommand
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'Method to bind listbox.
BindListBox(lst, "Select Keycode,LogoName from tbltest", "Logoname", "keycode")
Tag = "Insert"
End Sub
Private Sub lst_DoubleClick(ByVal sender As Object, ByVal e As System.EventArgs) Handles lst.DoubleClick
Dim dr As SqlDataReader
dr = CreateReader("Select LogoName,logo from tblTest where keycode=" & lst.SelectedValue)
If dr.Read Then
txtLogoName.Text = vbNullString & dr("Logoname")
If Not IsDBNull(dr("Logo")) Then
arrImage = CType(dr("Logo"), Byte())
ms = New MemoryStream(arrImage)
pic.Image = Image.FromStream(ms)
ms.Close()
Else
pic.Image = Nothing
pic.Invalidate()
End If
Tag = "Update"
End If
dr.Close()
closeconnection()
arrImage = Nothing
ms = Nothing
End Sub
Private Sub btnOk_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOk.Click
Dim com As SqlCommand
Dim strSql As String
If Tag = "Insert" Then
strSql = "Insert into tbltest (logoname,logo) values ('" & Trim(txtLogoName.Text) & "',@Logo)"
Else
strSql = "Update tbltest set logoname='" & Trim(txtLogoName.Text) & "',Logo=@Logo Where keycode=" & lst.SelectedValue
End If
com = CreateCommand(strSql)
com.Parameters.Add(New SqlParameter("@Logo", SqlDbType.Image))
If Not pic.Image Is Nothing Then
ms = New MemoryStream()
pic.Image.Save(ms, pic.Image.RawFormat)
arrImage = ms.GetBuffer
ms.Close()
com.Parameters("@Logo").Value = arrImage
Else
com.Parameters("@Logo").Value = DBNull.Value
End If
If com.ExecuteNonQuery = 1 Then
closeconnection()
BindListBox(lst, "Select Keycode,LogoName from tbltest", "Logoname", "keycode")
pic.Image = Nothing
pic.Invalidate()
txtLogoName.Clear()
Tag = "Insert"
End If
arrImage = Nothing
ms = Nothing
strSql = Nothing
End Sub
Private Sub btnBrowse_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnBrowse.Click
With dlg
.Filter = "All Files|*.*|Bitmap|*.bmp|GIF|*.gif|Icon|*.ico|JPEG|*.jpg|PNG|*.png"
.FilterIndex = 5
End With
If dlg.ShowDialog() = DialogResult.OK Then pic.Image = Image.FromFile(dlg.FileName)
End Sub
Public Sub setconnection()
Try
conn = New SqlConnection("Data Source=MyServer;Initial Catalog=TestDB;User Id=sa;Password=;")
conn.Open()
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
Public Sub closeconnection()
conn.Close()
End Sub
Public Function CreateCommand(ByVal query As String) As SqlCommand
setconnection()
Dim command As New SqlCommand(query, conn)
Return command
End Function
Public Function CreateReader(ByVal query As String) As SqlDataReader
Dim reader As SqlDataReader
setconnection()
cmd = CreateCommand(query)
reader = cmd.ExecuteReader()
Return reader
End Function
-
August 20th, 2010, 11:32 AM
#2
Re: Problem in saving image to database from picturebox. VB.Net 2008. Framework 3.5.
If there's an image in there, just DELETE it before replacing it. Let the user know, though.
-
August 21st, 2010, 07:21 AM
#3
Re: Problem in saving image to database from picturebox. VB.Net 2008. Framework 3.5.
I have found the root of the problem but still couldn't get any solution. When we save the image using this line- 'pic.Image.Save(ms, pic.Image.RawFormat)' the image needs to be in its original format for the RawFormat() method to work properly. So when we click the Browse button, it's browsing an image into the picturebox in its original format. But when we
retrieve the image from the database using arrays and streams, though we can view it but it's not in its original format and hence the above mentioned line in btnOk is throwing the exception.
That's exactly the point and that's why inserting a new image is ok, update with a different image is ok but update with the same image is crashing. I think the key to solve it is while retrieving the image from the database if we can somehow convert it to its original format or some format that's recognizable by the RawFormat() method and then show it in the picturebox. In that way when we press btnOk for update, RawFormat() will get the original format of the picture and save it properly.
I don't know how to do it practically or if there's some workaround. Can anybody make a solution out of this? Please assess on this topic and give your views. Regards.
-
August 21st, 2010, 12:14 PM
#4
Re: Problem in saving image to database from picturebox. VB.Net 2008. Framework 3.5.
Something like this?
Code:
' Imports System.IO;
' Imports System.Drawing.Imaging;
Using ms As New MemoryStream()
Me.pictureBox1.Image.Save(ms, ImageFormat.MemoryBmp)
Dim imgBytes As [Byte]() = ms.GetBuffer()
End Using
Posting Permissions
- You may not post new threads
- You may not post replies
- You may not post attachments
- You may not edit your posts
-
Forum Rules
|
Click Here to Expand Forum to Full Width
|