Visual Basic

Dave Kreskowiak14-Sep-18 6:34

Dave Kreskowiak

14-Sep-18 6:34

You're going to have to go back to the person who wrote that code and ask him/her. I don't have the time to dig into this.

An unbalanced stack is usually caused by parameter types being declared and passed incorrectly from what Windows expects. Specifically, the problem is going to be rooted in this line:

VB.NET

<DllImport("shell32.dll", CharSet:=CharSet.Unicode, PreserveSig:=False)>
Public Function SHCreateItemFromParsingName(
 <MarshalAs(UnmanagedType.LPWStr)> ByVal pszPath As String,
 ByVal pbc As IntPtr,
 <MarshalAs(UnmanagedType.LPStruct)> ByVal riid As Guid,
 <MarshalAs(UnmanagedType.Interface, IidParameterIndex:=2)> ByRef ppv As IShellItem) As Integer
End Function

Asking questions is a skill
CodeProject Forum Guidelines
Google: C# How to debug code
Seriously, go read these articles.

Dave Kreskowiak

Eddy Vluggen14-Sep-18 23:32

14-Sep-18 23:32

pinvoke.net: SHCreateItemFromParsingName (shell32)[^]

The example there does not have the "As Integer" part at the end of the declaration.

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

Richard Deeming18-Sep-18 3:38

18-Sep-18 3:38

That looks like a mistake - the official documentation says it returns an HRESULT:
SHCreateItemFromParsingName function | Microsoft Docs[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Eddy Vluggen18-Sep-18 5:05

Open / Display SVG images within Visual Basic 6

18-Sep-18 5:05

Good catch Smile | :)

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

davesmithmiap13-Sep-18 1:19

davesmithmiap

13-Sep-18 1:19

Hi
I am trying to find a way of displaying SVG within Visual Basic 6, you could at one point use Adobe Viewer 3 - but not longer.

I have managed to self create a HTML page, launch the assocaited web browser to show it, then i capture the screen - however the screen is captured but without the image being shown on it, yet the image is on the web page, if i do a normal screen capture - i can get the image.

All i am actually looking to do is to show the svg image within our vb application - which sadly it is written in vb6 and is far too big to change over.

I have looked into the SVG and in theroy could write an XML parser to read in and display but it makes sense to use the inbuilt browser control as they get updated.

Any suggestions ?

Re: Open / Display SVG images within Visual Basic 6

Richard Deeming13-Sep-18 2:33

Re: Open / Display SVG images within Visual Basic 6

13-Sep-18 2:33

The web browser control uses Internet Explorer. By default, it's stuck in IE7 mode unless you change the registry on every computer that runs your application:
Web Browser Control & Specifying the IE Version - Rick Strahl's Web Log[^]

IE didn't add support for SVG until v8:
Can I use... Support tables for HTML5, CSS3, etc[^] (Click "Show all" to see the old versions.)

Even if you can force the control to use the latest rendering mode, you may still need some workarounds for the bugs:
Test Scaling Of SVG Images In Fluid Layouts[^]

Do you need to resize the SVG image? If not, it would make more sense to convert it to an image format that VB6 supports.

NB: VB6 has been "dead" for almost two decades now. Whilst the application will still work, you'll struggle to support any new API or technology created in this millennium, and you'll find it increasingly difficult to get help for any issues. It may be time to re-evaluate the "too big to change" decision. Smile | :)

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Member 1396504228-Sep-18 3:15

Member 13965042

28-Sep-18 3:15

Hi,
support for *.svg-files is quite limited on Windows operating systems. So while I would normally advise to keep your vb6 code free of dependencies, in this case it is not possible to do without. However, since you are using a "real" programming language such as vb6 Big Grin | :-D

, you're in luck:
Have a look at Avax Vector ActiveX (OCX)
This library will add a lot more than just *.svg support and you'll find proper vb6 example code on the page - so you should be up and running within an hour.

Another approach, depending on how much effort you want to invest, would be to use the vbRichClient-Framework which uses cairo as a forms rendering engine: *.svg loading and saving is build right in and vbRichClient.dll is a rather well-performing and light-weight library - and since you'll have to distribute vbrun.dll anyway...

Btw. I wouldn't pay any notice to people trying to get you to "migrate" you to a "up-to-date platform". Chances are, these folks have never used vb6 anyway - and thus don't know how it has envolved in the last 20 years. As long as Windows is based mostly on COM, any managed code will look very poor indeed when compared to vb6.

Re: Open / Display SVG images within Visual Basic 6

Richard Deeming28-Sep-18 4:38

Re: Open / Display SVG images within Visual Basic 6

28-Sep-18 4:38

Linking to commercial products is spam, and will not be tolerated. Your "Avax Vector ActiveX" library costs $380.

wrote:
Chances are, these folks have never used vb6 anyway - and thus don't know how it has envolved in the last 20 years.

You know what they say about assumptions. Lots of us have suffered through using VB6 back when it was an active language. And it has been officially dead for almost 20 years, so it won't have "evolved" much. D'Oh! | :doh:

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Darrell Hagan 202113-Jun-21 12:53

Darrell Hagan 2021

13-Jun-21 12:53

Phooey. VB6 was and still is by far a better programming tool than any of that bloated and messy .NET crap.....

Could someone explain why For Each and For Next loops behave differently with lists?

MattiasW768-Sep-18 14:13

Re: Could someone explain why For Each and For Next loops behave differently with lists?

8-Sep-18 14:13

Hi everyone.
I think this might be my first post here. I rarely post questions, normally I like to search for my answers but this I thought I try to ask here.

Anyway, I noticed something that I found strange while using lists and For loops.

I'm pasting an example code here:
What it does is trying to scale rectangles saved within a list using loops.

Sub TestForLoop()
    ' Declare a list of rectangles and add 2 rectangles to it
    Dim lstRectangles As New List(Of Rectangle)
    lstRectangles.Add(New Rectangle(100, 200, 1000, 2000))
    lstRectangles.Add(New Rectangle(500, 700, 1500, 2000))

    ' This is the number used to scale the rectangle
    Dim gScale As Single = 0.1

    ' Before doing changes, write the rectangles dimensions to debug window.
    ShowRectDimensions("Before scaling:               ", lstRectangles)
    Debug.WriteLine("")

    ' Jump thru the elements, update and scale each rectangles dimensions. 
    For Each rect As Rectangle In lstRectangles
        With rect
            rect = New Rectangle(CInt(.Left * gScale), CInt(.Top * gScale),
                                 CInt(.Width * gScale), CInt(.Height * gScale))
            ' Write the changes to debug window while looping thru the list.
            Debug.WriteLine("Result inside For Each Loop:  {0}x{1},{2}x{3}", .Left, .Top, .Width, .Height)
        End With
    Next

    ' After the loop, write the rectangles dimensions to debug window once again.
    ShowRectDimensions("Result outside For Each Loop: ", lstRectangles)
    Debug.WriteLine("")


    ' Go thru the list, update and scale each rectangles dimension. 
    For i As Integer = 0 To lstRectangles.Count - 1
        With lstRectangles(i)
            lstRectangles(i) = New Rectangle(CInt(.Left * gScale), CInt(.Top * gScale),
                                             CInt(.Width * gScale), CInt(.Height * gScale))
            ' Write the changes to debug window while looping thru the list.
            Debug.WriteLine("Result inside For Next Loop:  {0}x{1},{2}x{3}", .Left, .Top, .Width, .Height)
        End With
    Next

    ' After the loop, write the rectangles dimensions to debug window once again.
    ShowRectDimensions("Result outside For Next Loop: ", lstRectangles)
    Debug.WriteLine("")
End Sub

' Created this sub to save some repetition. It writes the dimensions of the rectangles in a list.
Private Sub ShowRectDimensions(sText As String, lstRectangles As List(Of Rectangle))
    For Each rect As Rectangle In lstRectangles
        With rect
            Debug.WriteLine("{0}{1}x{2},{3}x{4}", sText, CStr(.Left), CStr(.Top), CStr(.Width), CStr(.Height))
        End With
    Next
End Sub

This produces this result in the debug window:

Before scaling:               100x200,1000x2000
Before scaling:               500x700,1500x2000

Result inside For Each Loop:  10x20,100x200
Result inside For Each Loop:  50x70,150x200
Result outside For Each Loop: 100x200,1000x2000
Result outside For Each Loop: 500x700,1500x2000

Result inside For Next Loop:  100x200,1000x2000
Result inside For Next Loop:  500x700,1500x2000
Result outside For Next Loop: 10x20,100x200
Result outside For Next Loop: 50x70,150x200

As you can see, while being on the inside of a for each loop the changes to the elements is readable and reusable. But when getting on the outside it is clear that none of the changes got saved back to the list.

However, when using the traditional For Next loop, no changes can be seen to the list until you get to the outside. This is the opposite behaviour. Confused | :confused:

This just feels weird and forces me to copy the value when I want to do more advanced calculations and the write it back to the item after. And as far as I can see the Inumerable loop seems worthless when wanting to write data back..

Am I doing something wrong or is there a logic to this?

[Edited a typo..]

modified 9-Sep-18 7:09am.

Eddy Vluggen8-Sep-18 23:51

Re: Could someone explain why For Each and For Next loops behave differently with lists?

8-Sep-18 23:51

MSDN[^] states:
The Current property of the enumerator object is ReadOnly, and it returns a local copy of each collection element. This means that you cannot modify the elements themselves in a For Each...Next loop. Any modification you make affects only the local copy from Current and isn't reflected back into the underlying collection. However, if an element is a reference type, you can modify the members of the instance to which it points.

Imagine a for-next to make a copy of the list; if you have reference-type objects in there (objects), then you can modify the properties of the object (only the pointer to object is readonly, not its properties). That doesn't work for value-types.

Use an object instead of a Rectangle, and things will work as you expected. If you want to keep using Rectangle (which is cheaper in terms of resource-usage) you'd limit yourself to For..Next loops.

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

MattiasW769-Sep-18 1:04

Re: Could someone explain why For Each and For Next loops behave differently with lists?

9-Sep-18 1:04

Oh great..

I fell for the byval mistake... again. D'Oh! | :doh:

Of course that's why the elements was a copy. I was so sure this had worked before but obviously with reference objects.

Thank's for pointing this out, Eddy! Thumbs Up | :thumbsup:

I should have realised this but when it failed me I just switched to a For..Next loop and ran into the next problem.
Changes to the lists elements is not visible until you exit the loop.

Dare I ask why this is?

Eddy Vluggen9-Sep-18 2:11

Re: Could someone explain why For Each and For Next loops behave differently with lists?

9-Sep-18 2:11

MattiasW76 wrote:
Dare I ask why this is?

Asking is always good, but in this case I don't know the answer. Does the same happen if you use an array instead of a list?

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

MattiasW7620-Sep-18 9:09

Re: Could someone explain why For Each and For Next loops behave differently with lists?

20-Sep-18 9:09

Using an array fixed this behaviour. Reason seems to be using the With Statement as Dave Kreskowiak said. If I take that away the list and array behaves the same.

Thank you again for helping.

Dave Kreskowiak9-Sep-18 4:54

Dave Kreskowiak

9-Sep-18 4:54

The problem is that you're using the With statement.

With gets you a reference to an object instance. If you try to replace that object instance with a new one, like you're doing in your For loops, the With is still looking at the original object instance, NOT THE NEW ONE.

Remove the With statements and fully qualify all of your object property references and watch what happens:

VB.NET

    Sub TestForLoop()
        ' Declare a list of rectangles and add 2 rectangles to it
        Dim lstRectangles As New List(Of Rectangle)
        lstRectangles.Add(New Rectangle(100, 200, 1000, 2000))
        lstRectangles.Add(New Rectangle(500, 700, 1500, 2000))

        ' This is the number used to scale the rectangle
        Dim gScale As Single = 0.1

        ' Before doing changes, write the rectangles dimensions to debug window.
        ShowRectDimensions("Before scaling:               ", lstRectangles)
        Debug.WriteLine("")

        ' Jump thru the elements, update and scale each rectangles dimensions. 
        For Each rect As Rectangle In lstRectangles
            rect = New Rectangle(CInt(rect.Left * gScale), CInt(rect.Top * gScale),
                                 CInt(rect.Width * gScale), CInt(rect.Height * gScale))
            ' Write the changes to debug window while looping thru the list.
            Debug.WriteLine("Result inside For Each Loop:  {0}x{1},{2}x{3}", rect.Left, rect.Top, rect.Width, rect.Height)
        Next

        ' After the loop, write the rectangles dimensions to debug window once again.
        ShowRectDimensions("Result outside For Each Loop: ", lstRectangles)
        Debug.WriteLine("")


        ' Go thru the list, update and scale each rectangles dimension. 
        For i As Integer = 0 To lstRectangles.Count - 1
            Dim rect As Rectangle = lstRectangles(i)
            lstRectangles(i) = New Rectangle(CInt(rect.Left * gScale), CInt(rect.Top * gScale),
                                                 CInt(rect.Width * gScale), CInt(rect.Height * gScale))
            ' Write the changes to debug window while looping thru the list.
            Debug.WriteLine("Result inside For Next Loop:  {0}x{1},{2}x{3}", lstRectangles(i).Left, lstRectangles(i).Top, lstRectangles(i).Width, lstRectangles(i).Height)
        Next

        ' After the loop, write the rectangles dimensions to debug window once again.
        ShowRectDimensions("Result outside For Next Loop: ", lstRectangles)
        Debug.WriteLine("")
    End Sub

    ' Created this sub to save some repetition. It writes the dimensions of the rectangles in a list.
    Private Sub ShowRectDimensions(sText As String, ByRef lstRectangles As List(Of Rectangle))
        For i As Integer = 0 To lstRectangles.Count - 1
            With lstRectangles(i)
                Debug.WriteLine("{0}{1}x{2},{3}x{4}", sText, CStr(.Left), CStr(.Top), CStr(.Width), CStr(.Height))
            End With
        Next
    End Sub

Asking questions is a skill
CodeProject Forum Guidelines
Google: C# How to debug code
Seriously, go read these articles.

Dave Kreskowiak

Re: Could someone explain why For Each and For Next loops behave differently with lists?

MattiasW7627-Sep-18 2:59

Adding Custom TabPage to TabControl: Closed

27-Sep-18 2:59

Wanted to prove this but being a Father and Husband I'm unable to control my spare time.

However, If anyone is interested I did this little code to test this:

Sub TestForLoop()

    ' Declare a list of rectangles and add 3 rectangles to it
    Dim lstRectangles As New List(Of Rectangle)
    lstRectangles.Add(New Rectangle(100, 200, 1000, 2000))
    lstRectangles.Add(New Rectangle(500, 150, 500, 200))
    lstRectangles.Add(New Rectangle(500, 700, 1500, 2000))

    Dim pre, n As Integer


    Debug.WriteLine(vbCrLf & "Inside Loop:")

    ' I'm skipping the first rectangle to avoid division with zero.
    For i As Integer = 1 To lstRectangles.Count - 1
        With lstRectangles(i)

            ' Do a change to the rectangle within the with-block.
            lstRectangles(i) = New Rectangle(.Left + 10, .Top, .Width, .Height)

            ' Show Change.
            Debug.WriteLine("Rectangle " & i)
            Debug.WriteLine("    1st result, Direct Call: {0}  -  With-block: {1}  -  (Added:
                           10)", lstRectangles(i).Left, .Left)

            ' Do calculations based on values from previous rectangles.
            n = lstRectangles(i - 1).Left / i

            ' Do a new change to the rectangle based on calulations and still within the same with-block.
            lstRectangles(i) = New Rectangle(.Left + n, .Top, .Width, .Height)

            ' Show new change.
            Debug.WriteLine("New result, Direct Call: {0}  -  With-block: {1}  -  (Added:
                           {2})", lstRectangles(i).Left, .Left, n)
        End With
    Next

    Debug.WriteLine(vbCrLf & "Outside Loop:")

    For i As Integer = 1 To lstRectangles.Count - 1
        With lstRectangles(i)
            Debug.WriteLine("Result: ({0}x{1}, {2}x{3})", .Left, .Top, .Width, .Height)
        End With
    Next

End Sub

This produced this result:

Inside Loop:
Rectangle 1
  1st result, Direct Call: 510  -  With-block: 500  -  (Added: 10)
  New result, Direct Call: 600  -  With-block: 500  -  (Added: 100)
Rectangle 2
  1st result, Direct Call: 510  -  With-block: 500  -  (Added: 10)
  New result, Direct Call: 800  -  With-block: 500  -  (Added: 300)

Outside Loop:
Result: (600x150, 500x200)
Result: (800x700, 1500x2000)

The result should have been 610 and 815. The added 10s disappears. This shows that the with-block reports the same value to both calculations even though there has been a change between them. However all direct calls give the updated value.

Thank you for clearing this out Dave.

mo14927-Sep-18 11:12

mo1492

7-Sep-18 11:12

I don't know what happened to cause this issue. I recreated the project and
the problem went away.

Hello, I'm trying to figure out how to add a custom TabPage to a TabControl.
After searching around I found this sample code of a custom TabControl which supports
my custom XmlTabPage that works as far as adding the page through the Designer but for some reason I get errors after adding the control.

In my Form:
Private Sub InitializeComponent()
Me.CustomTabControl1 = New XmlEditor.CustomTabControl
Me.XmlDataTabPage = New XmlEditor.XmlTabPage
end sub
Friend WithEvents CustomTabControl1 As XmlEditor.CustomTabControl
Friend WithEvents XmlDataTabPage As XmlEditor.XmlTabPage

'The error is that these controls are not defined. ' for the code
New XmlEditor.CustomTabControl and New XmlEditor.XmlTabPage as well
as the Friend declarations.

This code is inserted by the Designer.
These controls are part of the main project.
I can add the prefix 'Global.'XmlEditor.CustomTabControl to both controls and it
works but the next time I use the Designer, it writes the old code.

Can someone help? Below is the partial CustomTabControl code.
Thank you.

Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.drawing.Design
<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Partial Class CustomTabControl
Inherits System.Windows.Forms.TabControl

<System.ComponentModel.Editor(GetType(TabPageCollectionEditor), GetType(UITypeEditor))> _
Public Shadows ReadOnly Property TabPages() As TabPageCollection
Get
Return MyBase.TabPages
End Get
End Property

'UserControl overrides dispose to clean up the component list.
<System.Diagnostics.DebuggerNonUserCode()> _
Protected Overrides Sub Dispose(ByVal disposing As Boolean)
Try
If disposing AndAlso components IsNot Nothing Then
components.Dispose()
End If
Finally
MyBase.Dispose(disposing)
End Try
End Sub

'Required by the Windows Form Designer
Private components As System.ComponentModel.IContainer

'NOTE: The following procedure is required by the Windows Form Designer
'It can be modified using the Windows Form Designer.
'Do not modify it using the code editor.
<System.Diagnostics.DebuggerStepThrough()> _
Private Sub InitializeComponent()
components = New System.ComponentModel.Container()
End Sub

Public Class TabPageCollectionEditor
Inherits System.ComponentModel.Design.CollectionEditor

Public Sub New(ByVal type As Type)
MyBase.New(type)
End Sub

Protected Overrides Function CreateCollectionItemType() As System.Type
Return GetType(TabPage)
End Function

Protected Overrides Function CreateNewItemTypes() As System.Type()
Return New Type() {GetType(TabPage), GetType(XmlTabPage)}
End Function

End Class

End Class

-- modified 9-Sep-18 19:09pm.

How to declare Crypto?

Member 139535037-Sep-18 6:04

Member 13953503

7-Sep-18 6:04

Hello

In the following line of code

Dim hashedPassword = Crypto.HashPassword(password)

what would crypto be declared as, please? Most examples in tutorials refer to CryptoStream. The full code is

Public Sub CreateAccount(ByVal username As String, ByVal password As String)
        Dim hashedPassword = Crypto.HashPassword(password)
        CreateAccountInDatabase(username, hashedPassword)
    End Sub

    Private Sub CreateAccountInDatabase(username As String, hashedPassword As Object)
        Throw New NotImplementedException()
    End Sub

    Private Sub CreateAccount(ByVal username As String, ByVal password As String, ByVal email As String)
        Using connection As New OleDbConnection("connectionString")

            Dim Sql As String = "INSERT INTO university (username,strEmail,hashed) VALUES (@username,@strEmail,@hashed)"

            Dim cmd As New OleDbCommand(Sql)
            cmd.Connection = connection

            cmd.Parameters.AddWithValue("@username", username)
            cmd.Parameters.AddWithValue("@strEmail", email)
            Dim hashedPassword = Crypto.HashPassword(password)
            cmd.Parameters.AddWithValue("@hashed", hashedPassword)
            connection.Open()
            cmd.ExecuteNonQuery()

        End Using
    End Sub

    Private Sub BtnReg_Click(sender As Object, e As EventArgs) Handles BtnReg.Click
                CreateAccount(username.Text, password.Text, strEmail.Text)

        End Sub

Advice appreciated.

Re: How to declare Crypto?

Richard Deeming7-Sep-18 7:46