Assembly: System.Design (in system.design.dll)
The section contains two code examples. The first code example demonstrates how to derive a class from the TableDesigner class. The second code example demonstrates how to display the StyledTable class at design time.
The following code example demonstrates how to create a designer class named StyledTableDesigner, which is derived from the TableDesigner class, and is used to display two cells at design time for a class that is derived from the Table class.
' Create a class, named StyledTableDesigner, ' that derives from the TableDesigner class. ' This class displays a class named StyledTable ' at design time. Public Class StyledTableDesigner Inherits TableDesigner ' Override the GetDesignTimeHtml method to display ' placeholder text at design time for the ' rows and cells of the StyledTable class. Public Overrides Function GetDesignTimeHtml() As String Dim sTable As StyledTable = CType(Component, StyledTable) Dim designTimeHTML As String Dim rows As TableRowCollection = sTable.Rows Dim cellsWithDummyContents As ArrayList = Nothing Dim emptyTable As Boolean = rows.Count = 0 Dim emptyRows As Boolean = False Dim counter As Integer = 1 Dim numcells As Integer = 2 Try ' Create two cells to display ' in a row at design time. If emptyTable Then Dim row As TableRow = New TableRow() rows.Add(row) Dim i As Integer For i = 0 To numcells - 1 Dim c As TableCell = New TableCell() c.Text = "Cell #" & counter.ToString() counter += 1 rows(0).Cells.Add(c) Next i Else emptyRows = True Dim j As Integer For j = 0 To rows.Count - 1 If rows(j).Cells.Count <> 0 Then emptyRows = False Exit For End If Next j If emptyRows = True Then Dim k As Integer For k = 0 To numcells - 1 Dim c As TableCell = New TableCell() c.Text = "Cell #" & counter.ToString() counter += 1 rows(0).Cells.Add(c) Next k End If End If If emptyTable = False Then ' If the rows and cells were defined by the user, but the ' cells remain empty this code defines a string to display ' in them at design time. Dim row As TableRow For Each row In rows Dim c As TableCell For Each c In row.Cells If ((c.Text.Length = 0) AndAlso (c.HasControls() = False)) Then If cellsWithDummyContents Is Nothing Then cellsWithDummyContents = New ArrayList() End If cellsWithDummyContents.Add(c) c.Text = "Cell #" & counter.ToString() counter += 1 End If Next c Next row End If ' Retrieve the design-time HTML for the StyledTable class. designTimeHTML = MyBase.GetDesignTimeHtml() Finally ' If the StyledTable was empty before the dummy text was added, ' restore it to that state. If emptyTable Then rows.Clear() Else ' Clear the cells that were empty before the dummy text ' was added. If Not (cellsWithDummyContents Is Nothing) Then Dim c As TableCell For Each c In cellsWithDummyContents c.Text = [String].Empty Next c End If If emptyRows Then rows(0).Cells.Clear() End If End If End Try Return designTimeHTML End Function End Class
The following code example uses the DesignerAttribute to associate the StyledTableDesigner class with the StyledTable class so that it can be displayed at design time.
' Create a class that uses the StyledTableDesigner ' class to display its contents at design time. <Designer("Examples.AspNet.Design.StyledTableDesigner", "TableDesigner")> _ Public Class StyledTable Inherits Table Private tableStyle As Style = New Style() Public Sub New() tableStyle.BackColor = Color.LightBlue tableStyle.BorderColor = Color.Black CellSpacing = 4 CellPadding = 0 GridLines = GridLines.None BorderWidth = Unit.Point(1) Width = Unit.Percentage(100) Height = Unit.Percentage(100) End Sub End Class