How to implement fancy scroll bar for multiline textbox?
See the question and my original answer on StackOverflowIf the fancy scroll bar can be implemented as another control (your image actually looks like that), here is the code of a ListBox that supports custom scrolling:
Imports System.Runtime.InteropServices
Public Class CustomScrollListBox
Inherits ListBox
Public Sub Scroll(ByVal percentage As Single)
If (percentage < 0.0!) Then
Throw New ArgumentException(Nothing, "percentage")
End If
' Sends the scroll / set position Windows message
Const WM_VSCROLL As Integer = &H115
Const SB_THUMBPOSITION As Integer = 4
Dim wp As Integer = CInt(((percentage * MyBase.Items.Count) * 65536.0!)) + SB_THUMBPOSITION
CustomScrollListBox.SendMessage(MyBase.Handle, WM_VSCROLL, New IntPtr(wp), IntPtr.Zero)
End Sub
<DllImport("user32.dll")> _
Private Shared Function SendMessage(ByVal hWnd As IntPtr, ByVal msg As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As IntPtr
End Function
Protected Overrides ReadOnly Property CreateParams() As CreateParams
Get
' Removes the vertical scroll window style
Dim p As CreateParams = MyBase.CreateParams
Const WS_VSCROLL As Integer = &H200000
p.Style = (p.Style And -WS_VSCROLL)
Return p
End Get
End Property
End Class
And here is a sample form that uses it. I have implemented the custom scroller as a standard Trackbar (trackBar1) for the example:
Public Class Form1
Private trackBar As TrackBar
Private listBox As CustomScrollListBox
Protected Overrides Sub OnLoad(ByVal e As System.EventArgs)
' initialize some listbox props
listBox = New CustomScrollListBox
listBox.Location = New Point(&H19, 210)
listBox.Name = "listBox2"
listBox.Size = New Size((&H17D - Me.TrackBar1.Width), &HAD)
listBox.TabIndex = 1
MyBase.Controls.Add(listBox)
' add some items
Dim i As Integer
For i = 0 To 100 - 1
listBox.Items.Add(("item" & i))
Next i
End Sub
Private Sub TrackBar1_Scroll(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TrackBar1.Scroll
' compute trackbar's position as a percentage
listBox.Scroll(CSng(TrackBar1.Maximum - TrackBar1.Value) / TrackBar1.Maximum - TrackBar1.Minimum)
End Sub
End Class