Custom Editor - display scroll bar

Hi Michael,

Thank you for your message. To implement a scrolling functionality to your custom editor is not a trivial task. So, an easier way to resolve this issue is to use our RichEditControl. It can also show HTML text and provide the scroll bars feature by default.

I would like to note that the text for a RichEditControl in this case must have HTML mark up format.

If you wish to limit the CardView in-place editor height, we suggest that you use the RepositoryItemRichTextEdit.MaxHeight property.

I hope this information will be helpful to you. Feel free to contact us if you have any further difficulty. We are happy to help you at any time.

Updated by Yulia 15.08.2012 18:30

To implement a scrollbar in your custom editor, add the VScrollBar control to the editor's Controls property. Handle the VScrollBar.ValueChanged event and override the custom BaseEditPainter.DrawContent method in the following manner:

	
[VB.NET]
Public Sub New()
        _scrollBar = New VScrollBar()
        _scrollBar.Dock = DockStyle.Right
        AddHandler _scrollBar.ValueChanged, AddressOf vScroller_ValueChanged
        Me.Controls.Add(_scrollBar)
    End Sub

    Private Sub vScroller_ValueChanged(ByVal sender As Object, ByVal e As EventArgs)
        Dim vScroller As VScrollBar = TryCast(sender, VScrollBar)
        TryCast(Me.Painter, HtmlLabelPainter).ScrollBarValue = vScroller.Value
        Me.Refresh()
    End Sub

    Protected Overrides Sub DrawContent(ByVal info As ControlGraphicsInfoArgs)
        Dim rect As New Rectangle(info.ViewInfo.ContentRect.X, info.ViewInfo.ContentRect.Y - _scrollBarValue, info.ViewInfo.ContentRect.Width, info.ViewInfo.ContentRect.Height)
        info.Graphics.FillRectangle(info.ViewInfo.PaintAppearance.GetBackBrush(info.Cache), info.ViewInfo.ContentRect)
        Dim viewInfo As HtmlLabelViewInfo = TryCast(info.ViewInfo, HtmlLabelViewInfo)
        Dim item As RepositoryItemHtmlLabel = TryCast(viewInfo.Item, RepositoryItemHtmlLabel)
        If item.AllowHtmlString Then
            rect.Height = 0
            Dim _stringInfo As StringInfo = RepositoryItemHtmlLabel.CalculateStringInfo(info.Graphics, viewInfo.PaintAppearance, viewInfo.DisplayText, rect)
            StringPainter.Default.DrawString(info.Cache, _stringInfo)
        Else
            info.Cache.DrawString(viewInfo.DisplayText, viewInfo.PaintAppearance.Font, viewInfo.PaintAppearance.GetForeBrush(info.Cache), viewInfo.ContentRect, viewInfo.PaintAppearance.GetStringFormat())
        End If

    End Sub

To specify the upper limit of values in the scrollable range, use the VScrollBar.Maximum property. We suggest that you override the OnEditValueChanged method to calculate the VScrollBar.Maximum property value. Here is a sample code snippet that illustrates this task:

	
[VB.NET]
Protected Overrides Sub OnEditValueChanged()
        MyBase.OnEditValueChanged()

        Dim rect As New Rectangle(0, 0, Width - _scrollBar.Width, 0)
        Try
            TryCast(Me.Painter, HtmlLabelPainter).ScrollBarValue = 0
            Dim _stringInfo As StringInfo = RepositoryItemHtmlLabel.CalculateStringInfo(Me.ViewInfo.GInfo.AddGraphics(Nothing), Me.ViewInfo.PaintAppearance, Me.ViewInfo.DisplayText, rect) ' ContentRect)
            Dim result = _stringInfo.Bounds.Height - Me.ViewInfo.Bounds.Height
            _scrollBar.Maximum = result + _scrollBar.LargeChange - 1
        Finally
            Me.ViewInfo.GInfo.ReleaseGraphics()
        End Try

    End Sub

In addition, I have created and attached a sample project illustrating this task.