Problem with Textbox control Array - Xtreme Visual Basic Talk

07-09-2012, 07:02 AM

ferion

Newcomer

Join Date: Jun 2012

Posts: 14

Problem with Textbox control Array

Heyy.

What I'm trying to do is create a textbox control array at runtime, but I don't get it to work.

Here is the code:

Code:

Dim lyricsbox() As TextBox

Private Sub Form_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim width As Integer = Me.Width
        Dim numberoftxtboxes As Integer = width / 600
        Dim i As Integer = 0
        Do While i < numberoftxtboxes
            ReDim lyricsbox(i)
            lyricsbox(i) = New TextBox
            lyricsbox(i).Size = New Size(600, Me.Height - 135)
            lyricsbox(i).Visible = True
            lyricsbox(i).Parent = Me
            lyricsbox(i).Multiline = True
            lyricsbox(i).BringToFront()
            lyricsbox(i).Text = ""
            If i = numberoftxtboxes - 1 Then
                lyricsbox(i).ScrollBars = ScrollBars.Vertical
            End If

            If i = 0 Then
                lyricsbox(i).Location = New Point((Me.Width - numberoftxtboxes * 600 - (numberoftxtboxes - 1) * 10) / 2, 60)
            Else
                lyricsbox(i).Location = New Point((Me.Width - numberoftxtboxes * 600 - (numberoftxtboxes - 1) * 10) / 2 + i * 600 + i * 10, 60)
            End If
            i += 1
        Loop
End Sub

This code results in that all the controls are "Nothing" but the last one. At runtime I can check the members of the control array:

When 2 controls should be created:
(0) Nothing
(1) {Text = ""}

When 3 controls should be created:
(0) Nothing
(1) Nothing
(2) {Text = ""}

What have I done wrong?
Thank you in advance

07-09-2012, 07:48 AM

DrPunk

Senior Contributor

* Expert *

Join Date: Apr 2003

Location: Never where I want to be

Posts: 1,278

You don't really need to bother with an array to store the controls in. The form itself will kinda act like the array that you'll add controls in.

Although you shouldn't really go messing about with it, this is one of the times when it's worth looking at the Form's Designer.vb file to see what code VB generates to add controls to a form. You can then copy that code yourself for adding your own controls.

So, for example, start a new windows application project and add a textbox to the form. Over on the Solution Explorer, look for the button at the top that's Show All Files and click it. Your form should get an expandable plus sign next to it. Expand it and you should see the Form1.Designer.vb file. Open that file and you'll see the code that VB has automatically created for adding the textbox you added to the form. It should look similar to...

Code:

<System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.TextBox1 = New System.Windows.Forms.TextBox
        Me.SuspendLayout()
        '
        'TextBox1
        '
        Me.TextBox1.Location = New System.Drawing.Point(13, 13)
        Me.TextBox1.Name = "TextBox1"
        Me.TextBox1.Size = New System.Drawing.Size(100, 20)
        Me.TextBox1.TabIndex = 0
        '
        'Form1
        '
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.ClientSize = New System.Drawing.Size(284, 262)
        Me.Controls.Add(Me.TextBox1)
        Me.Name = "Form1"
        Me.Text = "Form1"
        Me.ResumeLayout(False)
        Me.PerformLayout()

    End Sub
    Friend WithEvents TextBox1 As System.Windows.Forms.TextBox

The important part from that code that you're missing in your code is the Me.Controls.Add(Me.TextBox1) that actually adds the control to the form.

So, scrapping the array that's not needed, the code that should do what you're trying to do would be...

Code:

Private Sub Form_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim width As Integer = Me.Width
        Dim numberoftxtboxes As Integer = width / 600
        Dim i As Integer = 0

        Dim txt As TextBox ' You only need one object that will keep getting recreated for new textboxes.

        Do While i < numberoftxtboxes

            txt = New TextBox

            ' You should probably give the control a name
            txt.Name = "Textbox" & i.ToString

            txt.Size = New Size(600, Me.Height - 135)
            txt.Visible = True
            txt.Parent = Me
            txt.Multiline = True
            txt.BringToFront()
            txt.Text = ""
            If i = numberoftxtboxes - 1 Then
                txt.ScrollBars = ScrollBars.Vertical
            End If

            If i = 0 Then
                txt.Location = New Point((Me.Width - numberoftxtboxes * 600 - (numberoftxtboxes - 1) * 10) / 2, 60)
            Else
                txt.Location = New Point((Me.Width - numberoftxtboxes * 600 - (numberoftxtboxes - 1) * 10) / 2 + i * 600 + i * 10, 60)
            End If

            me.controls.add(txt)

            i += 1
        Loop
End Sub

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