{Resolved} - Killing images ... file disposal - access probs?

[illskills]

i have this code below to remove dynamically created image boxes from a form and then kill the file and refresh the image list and repopulate image boxs but its not working .... keeps telling me that the files are open/readonly

is there a quick way to close these images ?

many thanks
illskills

Dim sCurrFile As String
        sCurrFile = cmbDesigns.Text
        If sCurrFile.Trim = "" Then
            Exit Sub
        End If
 
        If MessageBox.Show("Remove from gallery?", "Remove image.", MessageBoxButtons.OKCancel, MessageBoxIcon.Exclamation) = DialogResult.OK Then
            Dim i As Integer = 0
removeanother:
            For i = 0 To Me.Controls.Count - 1
                If Me.Controls(i).GetType.ToString = "System.Windows.Forms.PictureBox" Then
                    If Me.Controls(i).Name <> "pbPreview1" Then
                        If Me.Controls(i).Name <> "pbPrevTes" Then
                            Dim oControl As PictureBox
                            oControl = CType(Me.Controls(i), PictureBox)
                            oControl.Image = Nothing
                            Me.Controls.Remove(oControl)
                            GoTo removeanother
                        End If
                    End If
                End If
            Next i
            pbPreview1.Image = Nothing
            pbPrevTes.Image = Nothing
 
            On Error Resume Next
            Kill(Application.StartupPath & "\Gallery\KeyPatterns\" & sCurrFile.Trim)
            On Error GoTo 0
 
            Dim sFirstFile As String = ""
            sFirstFile = PopulateItems()
            cmbDesigns.Text = sFirstFile
            If sFirstFile <> "" Then
                Dim oBMP As New Bitmap(Application.StartupPath & "\Gallery\KeyPatterns\" & Trim(sFirstFile))
                'oBMP = ResizeImage(oBMP, 320, 600)
                UpdateImage(oBMP)
            End If
        End If

[gigemboy]

Well I don't like how you are using the goto statements, and not sure if that is even removing everything it should, try something like this:

Dim MyRemoveList As New ArrayList 'list to hold the controls that need to be removed
        For Each ctrl As Control In Me.Controls
            If TypeOf ctrl Is PictureBox Then
                If ctrl.Name <> "pbPreview1" Or ctrl.Name <> "pbPrevTes" Then
                    MyRemoveList.Add(ctrl) 'adds the control to the list
                End If
            End If
        Next
        For Each ctrl As Control In MyRemoveList
            Me.Controls.Remove(ctrl) 'removes all of the controls in the list from the form
        Next
 
'and the above should replace your code below...
Dim i As Integer = 0
removeanother:
            For i = 0 To Me.Controls.Count - 1
                If Me.Controls(i).GetType.ToString = "System.Windows.Forms.PictureBox" Then
                    If Me.Controls(i).Name <> "pbPreview1" Then
                        If Me.Controls(i).Name <> "pbPrevTes" Then
                            Dim oControl As PictureBox
                            oControl = CType(Me.Controls(i), PictureBox)
                            oControl.Image = Nothing
                            Me.Controls.Remove(oControl)
                            GoTo removeanother
                        End If
                    End If
                End If
            Next i

I think you were having the same problem I was in testing it when removing a control, it messes up the remove loop because all the control indexes change, which is why I think you did the goto, in order to do it again for all the controls it missed. So the above code makes a list of controls from the controls that need to be removed, then removes them after the list is made...

Not sure if this will effect anything in the program, but it could if your controls actually arent being removed like they should be.

I also dont like the Kill command... you should not have to use it at all...

[jmcilhinney]

Setting the Image property of a PictureBox to Nothing merely removes the displayed Image object from the PictureBox, but the Image object still exists, thus locking the file. Here's a quote from the help topic for the Bitmap constructor you are using:

The file remains locked until the Bitmap object is disposed.

This means that you have to call the Dispose method of the Bitmap object, which you can do via the Image property of the PictureBox, i.e.:

oControl.Image.Dispose()

A few notes on your code.
1. I strongly suggest that you learn to use structured exception handling (SEH), i.e. Try...Catch...Finally...End Try blocks. On Error Resume Next should not be used in VB.NET.
2. You should try to avoid using GoTo statements if at all possible. There are very few places where GoTo statements are necessary and your "GoTo removeanother" is very BAD programming. What you are doing is restarting the loop every time you remove a PictureBox, thus examining all the controls you've just looked at again. If you had 100 controls and the last 10 were PictureBoxes, your code would examine the first 90 controls 10 times each. What you should be doing is reversing your loop, i.e.

For i = Me.Controls.Count - 1 To 0 Step -1

and get rid of that GoTo altogether. When ever you want to remove items froma collection in a loop you should always work backwards, so that those items yet to be examined do not have their indices affected by removing an item.

[gigemboy]

When ever you want to remove items froma collection in a loop you should always work backwards, so that those items yet to be examined do not have their indices affected by removing an item.

Just now learned that myself

***EDIT - and for IllSkill - we aren't "picking" on you, just showing better ways of doing it I was coding like that not too long ago, until joining this forum. I can't tell you how much I've learned in just a few months of reading the posts on here. Keep up the work, and keep reading this forum

[illskills]

nice one people .... im sorry bout the goto statements ... will re examin the code and get back to you with a result []

thanks again
illskills

[illskills]

should increase the speed of my preview redraw n e ways

[illskills]

here's the code i added btw

Dim sCurrFile As String
        sCurrFile = cmbDesigns.Text
        If sCurrFile.Trim = "" Then
            Exit Sub
        End If
 
        If MessageBox.Show("Remove from gallery?", "Remove image.", MessageBoxButtons.OKCancel, MessageBoxIcon.Exclamation) = DialogResult.OK Then
            Dim MyRemoveList As New ArrayList 'list to hold the controls that need to be removed
            Dim i As Integer = 0
            For Each ctrl As Control In Me.Controls
                If TypeOf ctrl Is PictureBox Then
                    If ctrl.Name <> "pbPreview1" Then
                        If ctrl.Name <> "pbPrevTes" Then
                            MyRemoveList.Add(ctrl) 'adds the control to the list
                        End If
                    End If
                End If
            Next
            For Each ctrl As Control In MyRemoveList
                Dim MyPb As PictureBox
                MyPb = ctrl
                MyPb.Image.Dispose()
                MyPb.Image = Nothing
                Me.Controls.Remove(ctrl) 'removes all of the controls in the list from the form
            Next
            pbPreview1.Image.Dispose()
            pbPrevTes.Image.Dispose()
            pbPreview1.Image = Nothing
            pbPrevTes.Image = Nothing
 
 
            On Error Resume Next
            Kill(Application.StartupPath & "\Gallery\KeyPatterns\" & sCurrFile.Trim)
            On Error GoTo 0
 
            Dim sFirstFile As String = ""
            sFirstFile = PopulateItems()
            cmbDesigns.Text = sFirstFile
            If sFirstFile <> "" Then
                If Dir(Application.StartupPath & "\Gallery\KeyPatterns\" & Trim(cmbDesigns.Text)) = "" Then Exit Sub
                Dim oBMP As New Bitmap(Application.StartupPath & "\Gallery\KeyPatterns\" & Trim(sFirstFile))
                UpdateImage(oBMP)
            End If

all working now anyways many thanks .... will replace code at the bottom when i get chance

[jmcilhinney]

I don't quite understand why you would choose to use two loops to do something that I gave you a perfectly good solution to that uses a single loop:

Dim ctl As Control
 
For i As Integer = Me.Controls.Count - 1 To 0 Step -1
    ctl = Me.Controls(i)
 
    If TypeOf ctl Is PictureBox AndAlso ctl.Name <> "pbPreview1" AndAlso ctl.Name <> "pbPrevTes" Then
        DirectCast(ctl, PictureBox).Image.Dispose()
        Me.Controls.Remove(ctl)
    End If
Next i

Setting the Image property of the PictureBoxes being removed does nothing useful. You only need to cast the Control to a PictureBox in order to access its Image property once to Dispose it. I also suggest using the IO.File.Delete method instead of Kill.

[illskills]

thanks jm ... ill add the above function mate

once again cheers for the know how

how does the io.file.delete() cmd differ from kill ?

and whats the correct syntax ?

[jmcilhinney]

The correct syntax is whatever it says in the help/MSDN:

Kill
IO.File.Delete

Kill is useful as it can accept wildcards, but for a specific file I'd always use File.Delete as Kill will call File.Delete anyway. Also, File.Delete does not throw an exception if the file does not exist, while Kill does.

[illskills]

ahhhhh ncie one