问题
As opposed to the TextBox control which use CrLf line endings the RichTextBox control use Lf line endings. I don't want that. I need consistency. I need a RichTextBox control whom use CrLf line endings.
I opened the control in reflector and noticed that the getter of the Text property calls the following function:
Private Function StreamOut(ByVal flags As Integer) As String
'...
Me.StreamOut(data, flags, False)
'...
End Function
Which ends up calling:
Private Sub StreamOut(ByVal data As Stream, ByVal flags As Integer, ByVal includeCrLfs As Boolean)
'...
Dim es As New EDITSTREAM
'...
ElseIf includeCrLfs Then
num = (num Or &H20)
Else
'...
es.dwCookie = DirectCast(num, IntPtr)
'...
End Sub
And as you can see, the includeCrLfs parameter will always be False.
So I subclassed the control and intercepted the EM_STREAMOUT message. The LParam of this message contains the pointer to the EDITSTREAM structure. I appended the &H20 flag as seen in the function above, but this didn't work. The Text property started to return an empty string. I believe that I might have to remove/append other flags, but I have no clue as to which flags. Also, MSDN do not provide any hints other than application-defined value.
dwCookie
Specifies an application-defined value that the rich edit control passes to the EditStreamCallback callback function specified by the pfnCallback member.
Here's my subclassed control:
Public Class UIRichTextBox
Inherits System.Windows.Forms.RichTextBox
Private Sub EmStreamOut(ByRef m As Message)
Dim es As New EDITSTREAM
es = DirectCast(Marshal.PtrToStructure(m.LParam, GetType(EDITSTREAM)), EDITSTREAM)
If (IntPtr.Size = 4) Then
Dim cookie As Int32 = es.dwCookie.ToInt32()
'cookie = (cookie Or &H20I) '<- Didn't work
es.dwCookie = New IntPtr(cookie)
Else
Dim cookie As Int64 = es.dwCookie.ToInt64()
'cookie = (cookie Or &H20L) '<- Didn't work
es.dwCookie = New IntPtr(cookie)
End If
Marshal.StructureToPtr(es, m.LParam, True)
MyBase.WndProc(m)
End Sub
Protected Overrides Sub WndProc(ByRef m As Message)
Select Case m.Msg
Case EM_STREAMOUT
Me.EmStreamOut(m)
Exit Select
Case Else
MyBase.WndProc(m)
Exit Select
End Select
End Sub
Private Const EM_STREAMOUT As Integer = &H44A
Private Delegate Function EDITSTREAMCALLBACK(ByVal dwCookie As IntPtr, ByVal buf As IntPtr, ByVal cb As Integer, <Out()> ByRef transferred As Integer) As Integer
<StructLayout(LayoutKind.Sequential)> _
Private Class EDITSTREAM
Public dwCookie As IntPtr = IntPtr.Zero
Public dwError As Integer
Public pfnCallback As EDITSTREAMCALLBACK
End Class
End Class
Update
So it turns out that the flags are not undocumented at all. They are part of the EM_GETEDITSTYLE and EM_SETEDITSTYLE messages. But as you can see, the flag is obsolete.
SES_USECRLF Obsolete. Do not use.
So I guess I'm back at square one overriding the text property.
Public Overrides Property Text() As String
Get
Dim value As String = MyBase.Text
If (Not value Is Nothing) Then
value = value.Replace(ChrW(13), "")
value = value.Replace(ChrW(10), Environment.NewLine)
End If
Return value
End Get
Set(value As String)
MyBase.Text = value
End Set
End Property
回答1:
So I managed to create a working solution using reflection. I'm sure there must be a good reason as to why SES_USECRLF is obsolete, so proceed with caution.
Public Class UIRichTextBox
Inherits System.Windows.Forms.RichTextBox
Shared Sub New()
UIRichTextBox.InternalEditStream = GetType(System.Windows.Forms.RichTextBox).GetField("editStream", (BindingFlags.NonPublic Or BindingFlags.Instance))
UIRichTextBox.InternalStreamIn = GetType(System.Windows.Forms.RichTextBox).GetMethod("StreamIn", (BindingFlags.NonPublic Or BindingFlags.Instance), Nothing, New Type() {GetType(System.IO.Stream), GetType(System.Int32)}, Nothing)
UIRichTextBox.InternalStreamOut = GetType(System.Windows.Forms.RichTextBox).GetMethod("StreamOut", (BindingFlags.NonPublic Or BindingFlags.Instance), Nothing, New Type() {GetType(System.IO.Stream), GetType(System.Int32), GetType(System.Boolean)}, Nothing)
End Sub
Public Sub New()
Me.m_includeCrLfs = True
End Sub
<DefaultValue(True), Category("Behavior")> _
Public Property IncludeCrLfs() As Boolean
Get
Return Me.m_includeCrLfs
End Get
Set(value As Boolean)
If (value <> Me.m_includeCrLfs) Then
Me.m_includeCrLfs = value
Me.RecreateHandle()
End If
End Set
End Property
Public Overrides Property [Text]() As String
Get
Dim value As String = Nothing
If (Me.StreamOut(&H11, value)) Then
Return value
End If
Return MyBase.[Text]
End Get
Set(ByVal value As String)
If (Not Me.StreamIn(value, &H11)) Then
MyBase.[Text] = value
End If
End Set
End Property
Private Function StreamIn(ByVal str As String, ByVal flags As Integer) As Boolean
If (((Me.IsHandleCreated AndAlso ((Not Me.IsDisposed) AndAlso (Not Me.Disposing))) AndAlso ((Not str Is Nothing) AndAlso (str.Length > 0))) AndAlso ((Not UIRichTextBox.InternalEditStream Is Nothing) AndAlso (Not UIRichTextBox.InternalStreamIn Is Nothing))) Then
Dim bytes As Byte()
Dim index As Integer = str.IndexOf(ChrW(0))
If (index <> -1) Then
str = str.Substring(0, index)
End If
If ((flags And &H10) <> 0) Then
bytes = Encoding.Unicode.GetBytes(str)
Else
bytes = Encoding.Default.GetBytes(str)
End If
Dim data As New System.IO.MemoryStream()
UIRichTextBox.InternalEditStream.SetValue(Me, data)
data.Write(bytes, 0, bytes.Length)
data.Position = 0
UIRichTextBox.InternalStreamIn.Invoke(Me, New Object() {data, flags})
Return True
End If
Return False
End Function
Private Function StreamOut(ByVal flags As Integer, ByRef result As String) As Boolean
If ((Me.IsHandleCreated AndAlso ((Not Me.IsDisposed) AndAlso (Not Me.Disposing))) AndAlso (Not UIRichTextBox.InternalStreamOut Is Nothing)) Then
Dim data As New System.IO.MemoryStream()
UIRichTextBox.InternalStreamOut.Invoke(Me, New Object() {data, flags, Me.m_includeCrLfs})
data.Position = 0
Dim length As Integer = CInt(data.Length)
Dim str As String = String.Empty
If (length > 0) Then
Dim buffer As Byte() = New Byte(length - 1) {}
data.Read(buffer, 0, length)
If ((flags And &H10) <> 0) Then
str = Encoding.Unicode.GetString(buffer, 0, buffer.Length)
Else
str = Encoding.Default.GetString(buffer, 0, buffer.Length)
End If
If ((Not String.IsNullOrEmpty(str)) AndAlso (str.Chars((str.Length - 1)) = ChrW(0))) Then
str = str.Substring(0, (str.Length - 1))
End If
End If
result = str
Return True
End If
Return False
End Function
Private Shared ReadOnly InternalEditStream As FieldInfo
Private Shared ReadOnly InternalStreamIn As MethodInfo
Private Shared ReadOnly InternalStreamOut As MethodInfo
Private m_includeCrLfs As Boolean
End Class
来源：https://stackoverflow.com/questions/24082742/how-to-change-richtextbox-line-endings-from-lf-to-crlf