B4J Code Snippet [B4J] (Crow Up/Down every 25%) - Scrollbar in a TableView

Sub Process_Globals
    Public tbvSearch As TableView

    #Region ScrollPane Position
    Public VerticalScrollBar As JavaObject
    Public pnPosition As Pane
    Public btnVTPosition As B4XView
    Public btnVBPosition As B4XView
    Type MyScrollPane (MinValue As Double, MaxValue As Double, SetValue As Double)
    Public msp As MyScrollPane
    #End Region
    ....
End Sub

Sub AppStart (Form1 As Form, Args() As String)
    msp.Initialize
    VerticalScrollBar = FindVerticalScrollBar(tbvSearch)
    ....
End Sub

Sub MainForm_Resize (Width As Double, Height As Double)
    CallSubDelayed(Me, "VisiblePosition") '
    ....
End Sub

#Region Scroll-Bar Position H&V in TableView

'Scroll UP (crow up every 25%)
Private Sub btnVBPosition_Click
    If tbvSearch.Items.Size = 0 Then Return

    msp.MinValue = VerticalScrollBar.RunMethod("getMin", Null)
    msp.MaxValue = VerticalScrollBar.RunMethod("getMax", Null)

    If msp.SetValue > 0.75 And msp.SetValue <= 1.0 Then
        msp.SetValue = 0.75
    Else If msp.SetValue > 0.50 And msp.SetValue <= 0.75 Then
        msp.SetValue = (msp.MinValue + msp.MaxValue) / 2 '0.50
    Else If msp.SetValue > 0.25 And msp.SetValue <= 0.50 Then
        msp.SetValue = (msp.MinValue + msp.MaxValue) / 4 '0.25
    Else If msp.SetValue > 0.0 And msp.SetValue <= 0.25 Then
        msp.SetValue = 0.00
    End If
    VerticalScrollBar.RunMethod("setValue", Array(msp.SetValue))
    If SelectedRow >= 0 Then
        tbvSearch.RequestFocus
        tbvSearch.SelectedRow = SelectedRow
        tbvSearch.SelectCell(SelectedRow,2)
    End If
End Sub

'Scroll DN (crow down every 25%)
Private Sub btnVTPosition_Click
    If tbvSearch.Items.Size = 0 Then Return
 
    msp.MinValue = VerticalScrollBar.RunMethod("getMin", Null)
    msp.MaxValue = VerticalScrollBar.RunMethod("getMax", Null)

    If msp.SetValue >= 0.0 And msp.SetValue < 0.25 Then
        msp.SetValue = (msp.MinValue + msp.MaxValue) / 4 '0.25
    Else If msp.SetValue >= 0.25 And msp.SetValue < 0.50 Then
        msp.SetValue = (msp.MinValue + msp.MaxValue) / 2 '0.50
    Else If msp.SetValue >= 0.50 And msp.SetValue < 0.75 Then
        msp.SetValue = 0.75
    Else If msp.SetValue >= 0.75 And msp.SetValue < 1.0 Then
        msp.SetValue = 1.00
    End If
    VerticalScrollBar.RunMethod("setValue", Array(msp.SetValue))
    If SelectedRow >= 0 Then
        tbvSearch.RequestFocus
        tbvSearch.SelectedRow = SelectedRow
        tbvSearch.SelectCell(SelectedRow,2)
    End If
End Sub

Private Sub FindVerticalScrollBar (tv As TableView) As JavaObject
    Dim jo As JavaObject = tv
    Dim bars() As Object = jo.RunMethodJO("lookupAll", Array(".scroll-bar")).RunMethod("toArray", Null)
    For Each baro As JavaObject In bars
        Dim orientation As String = baro.RunMethod("getOrientation", Null)
        If orientation = "VERTICAL" Then
            Return baro
        End If
    Next
    Return Null
End Sub

Private Sub ScrollChangedEvent
    Dim jo As JavaObject
    jo = tbvSearch
    Dim nodes() As Object
    nodes = jo.RunMethodJO("lookupAll",Array(".scroll-bar")).RunMethod("toArray",Null)
    Dim TableViewScrollBar As JavaObject
 
    For Each sb As Object In nodes
        Dim sbJO As JavaObject
        sbJO = sb
        Dim orientation As String = sbJO.RunMethod("getOrientation", Null)
        If orientation = "VERTICAL" Then
            TableViewScrollBar = sbJO
        End If
    Next
 
    Dim r As Reflector
    r.Target = TableViewScrollBar
    r.AddChangeListener("tbvSearch_ScrollPosition","valueProperty")
End Sub

Private Sub tbvSearch_ScrollPosition_Changed (OldVal As Object, NewVal As Object)
    btnVBPosition.Visible = IIf(NewVal.As(Double) = 0.0, False, True)
    btnVTPosition.Visible = IIf(NewVal.As(Double) = 1.0, False, True)
End Sub

Private Sub VisiblePosition
    Dim jo As JavaObject = tbvSearch
    Dim bars() As Object = jo.RunMethodJO("lookupAll", Array(".scroll-bar")).RunMethod("toArray", Null)
 
    For Each node As Node In bars
        If GetType(node) = "com.sun.javafx.scene.control.skin.VirtualScrollBar" Or GetType(node) = "javafx.scene.control.ScrollBar" Then
            Dim SB As JavaObject = node
            Dim BarOrientation As String = SB.RunMethodJO("getOrientation",Null).RunMethod("toString",Null)
            If BarOrientation = "VERTICAL" Then
                ' Delete or Restore UP/DN buttons View (when the bar is visible or not)
                pnPosition.Visible = node.Visible
            End If
        End If
    Next
    If pnPosition.Visible Then ScrollChangedEvent
End Sub

#End Region