Imports System.Runtime.CompilerServices
''' <summary>
''' Provides extension methods for a <see cref="TabControl"/> control.
''' </summary>
<HideModuleName>
Public Module TabControlExtensions
''' <summary>
''' Collection used to store tab pages whose tab header need to remain disabled on a <see cref="TabControl"/>.
''' <para></para>
''' This collection depends on <see cref="TabControlExtensions.DisableOrEnableTabs_Internal"/> method.
''' </summary>
Private disabledTabs As HashSet(Of TabPage)
''' <summary>
''' Collection used to store tab controls whose its <see cref="TabControl.Selecting"/> event
''' has been associated to <see cref="TabControlExtensions.disableTabPageHandler"/>.
''' <para></para>
''' This collection depends on <see cref="TabControlExtensions.DisableOrEnableTabs_Internal"/> method.
''' </summary>
Private tabHandlerAddedControls As HashSet(Of TabControl)
''' <summary>
''' A <see cref="TabControlCancelEventHandler"/> delegate used for disabling tabs on a <see cref="TabControl"/>.
''' <para></para>
''' This handler depends on <see cref="TabControlExtensions.DisableOrEnableTabs_Internal"/> method.
''' </summary>
Private tabDisablerHandler As TabControlCancelEventHandler
''' <summary>
''' Disables one or multiple <see cref="TabPage"/>,
''' making the tabs unselectable in the source <see cref="TabControl"/>.
''' </summary>
'''
''' <param name="tabControl">
''' The source <see cref="TabControl"/>.
''' </param>
'''
''' <param name="tabPages">
''' An Array of <see cref="TabPage"/> to disable.
''' </param>
<Extension>
<DebuggerStepThrough>
Public Sub DisableTabs(tabControl As TabControl, ParamArray tabPages As TabPage())
TabControlExtensions.DisableOrEnableTabs_Internal(tabControl, enabled:=False, tabPages)
End Sub
''' <summary>
''' Enables one or multiple <see cref="TabPage"/> that were previously
''' disabled by a call to <see cref="TabControlExtensions.DisableTabPages"/> method,
''' making the tabs selectable again in the source <see cref="TabControl"/>.
''' </summary>
'''
''' <param name="tabControl">
''' The source <see cref="TabControl"/>.
''' </param>
'''
''' <param name="tabPages">
''' An Array of <see cref="TabPage"/> to enable.
''' </param>
<Extension>
<DebuggerStepThrough>
Public Sub EnableTabs(tabControl As TabControl, ParamArray tabPages As TabPage())
TabControlExtensions.DisableOrEnableTabs_Internal(tabControl, enabled:=True, tabPages)
End Sub
''' <summary>
''' *** FOR INTERNAL USE ONLY ***
''' <para></para>
''' Disables or enables one or multiple <see cref="TabPage"/>,
''' denying or allowing their tab selection in the source <see cref="TabControl"/>.
''' </summary>
'''
''' <param name="tabControl">
''' The source <see cref="TabControl"/>.
''' </param>
'''
''' <param name="enabled">
''' If <see langword="False"/>, disables the tab pages and make them unselectable in the source <see cref="TabControl"/>;
''' otherwise, enable the tab pages and allows to be selected in the source <see cref="TabControl"/>.
''' </param>
'''
''' <param name="tabPages">
''' An Array of the tab pages to disable or enable.
''' </param>
<DebuggerStepThrough>
Private Sub DisableOrEnableTabs_Internal(tabControl As TabControl, enabled As Boolean, ParamArray tabPages As TabPage())
If tabControl Is Nothing Then
Throw New ArgumentNullException(paramName:=NameOf(tabControl))
End If
If tabPages Is Nothing Then
Throw New ArgumentNullException(paramName:=NameOf(tabPages))
End If
' Initialize collections.
If TabControlExtensions.disabledTabs Is Nothing Then
TabControlExtensions.disabledTabs = New HashSet(Of TabPage)
End If
If TabControlExtensions.tabHandlerAddedControls Is Nothing Then
TabControlExtensions.tabHandlerAddedControls = New HashSet(Of TabControl)
End If
' Initialize handler.
If TabControlExtensions.tabDisablerHandler Is Nothing Then
TabControlExtensions.tabDisablerHandler =
Sub(sender As Object, e As TabControlCancelEventArgs)
If e.TabPageIndex < 0 Then
Exit Sub
End If
Select Case e.Action
Case TabControlAction.Selecting, TabControlAction.Selected
e.Cancel = TabControlExtensions.disabledTabs.Contains(e.TabPage)
Case Else
Exit Sub
End Select
End Sub
End If
For Each tabPage As TabPage In tabPages
If tabPage Is Nothing Then
Throw New NullReferenceException($"{NameOf(tabPage)} object is null.")
End If
' Disable or enable the tab page.
tabPage.Enabled = enabled
If Not enabled Then ' Disable the tab header.
Dim success As Boolean = disabledTabs.Add(tabPage)
If success AndAlso Not TabControlExtensions.tabHandlerAddedControls.Contains(tabControl) Then
AddHandler tabControl.Selecting, TabControlExtensions.tabDisablerHandler
TabControlExtensions.tabHandlerAddedControls.Add(tabControl)
End If
Else ' Enable the tab header.
Dim success As Boolean = disabledTabs.Remove(tabPage)
If success AndAlso TabControlExtensions.tabHandlerAddedControls.Contains(tabControl) AndAlso
Not TabControlExtensions.disabledTabs.Any() Then
RemoveHandler tabControl.Selecting, TabControlExtensions.tabDisablerHandler
TabControlExtensions.tabHandlerAddedControls.Remove(tabControl)
End If
End If
Next tabPage
End Sub
End Module
en el foro, je!.