在运行时编辑多行文本框时出现问题 vb.net

Question

I am a college student without much vb.net experience and need some help on a personal project. I am trying to increase the height of a multiline textbox control so I can insert multiple lines during runtime. I want to go to a new line in my textbox after I hit enter. Also, simultaneously I am trying to generate a combobox next to each textbox line created by hitting enter. Here is the code I have so far:

Private Sub ThisTextBox_keypress(ByVal sender As System.Object, ByVal e As KeyPressEventArgs) Handles ThisTextBox.KeyPress

    Dim TextboxLine As String() = ThisTextBox.Text.Split(vbNewLine)
    Dim Linecount As Integer = TextboxLine.Count
    If e.KeyChar = Chr(Keys.Enter) Then
       Me.ThisTextBox.Height = TextRenderer.MeasureText(" ", Me.ThisTextBox.Font).Height * _ Linecount 
       For Each Item In TextboxLine
            Dim newCombobox = New ComboBox()
            Me.Controls.Add(newCombobox)
            newCombobox.Items.Insert(0, "Item 1")
            newCombobox.Items.Insert(1, "Item 2")
            newCombobox.Items.Insert(2, "Item 3")
            newCombobox.Items.Insert(3, "Item 4")

            newCombobox.Location = New System.Drawing.Point(108, 69+=27)
            newCombobox.Size = New System.Drawing.Size(92, 21)

        Next
    End If


End Sub

The problem is the textbox increases its height with each character I type into it, and when I hit enter, the control height increases in weird increments that cannot be related to the text font * number of lines. Also, my code may be way off on how to create a combobox during runtime and set it to a specific location, but hopefully you are able to see what I am trying to do. Thanks in advance.

Answer 1

Interesting question.

The following code almost achieves what you want, however placing a combobox next to each text line causes problems because there isn't enough space to make the combobox tall enough.

Private Sub ThisTextBox_keypress(ByVal sender As System.Object, ByVal e As KeyPressEventArgs) Handles ThisTextBox.KeyPress
    Static previousLineCount = 0
    Dim LineCount As Integer = ThisTextBox.Lines.Count
    If LineCount > previousLineCount Then

        Dim lineHeight As Integer = TextRenderer.MeasureText(" ", Me.ThisTextBox.Font).Height
        ThisTextBox.Height = lineHeight * LineCount + 10
        For Each Item In ThisTextBox.Lines
            Dim newCombobox = New ComboBox()
            Me.Controls.Add(newCombobox)
            newCombobox.Items.Insert(0, "Item 1")
            newCombobox.Items.Insert(1, "Item 2")
            newCombobox.Items.Insert(2, "Item 3")
            newCombobox.Items.Insert(3, "Item 4")

            newCombobox.Location = New System.Drawing.Point(ThisTextBox.Left + ThisTextBox.Width, ThisTextBox.Top + (LineCount) * lineHeight - 12)
            newCombobox.Size = New System.Drawing.Size(92, lineHeight)

        Next
    End If
End Sub

I'm not aware of a way to change the height of a combobox control (someone else here might know if you can) but it's going to look funny anyway.

You might also look into using a RichTextBox control and changing the line spacing.

Hopefully the code above helps to get you started anyway.