将文件加载到 RichTextBox 时，某些超链接不会触发 LinkClicked 事件
Some hyperlinks don't trigger the LinkClicked event when loading a file into RichTextBox
在 .net 4.7 中的一个简单 Windows 表单应用程序中，我的表单上只有一个 RichTextBox。我正在从本地加载一个在 MS Word 2016 中创建的 *.rtf 文件。hyperlinks 已在 Word 中设置。问题是在应用程序中单击 hyperlink 时并非所有 link 都会触发 LinkClicked 事件。
行为如下：
如果 hyperlink 后跟足够多的字符（这会有所不同），它将由 LinkClicked 事件触发。如果我删除 hyperlink 后面的字符，它不会触发事件。
更新
经过测试，最后一个URL后需要插入的字符数等于正在加载的*.rtf文件中所有URL字符的总和。
我不能post一张图，括号里的字是hyperlink
无效：
[点击此处]了解更多信息。
{\rtf1\ansi\ansicpg1252\deff0\nouicompat\deflang4105{\fonttbl{\f0\fnil\fcharset0 Calibri;}}
{\*\generator Riched20 10.0.17134}\viewkind4\uc1
{\field{\*\fldinst { HYPERLINK "http://www.google.com" }}{\fldrslt {Click here}}}
\pard\sa200\sl276\slmult1\f0\fs22\lang9 for more information.\par
}
作品：
[点击这里查看更多信息。 Lorem 假和
{\rtf1\ansi\ansicpg1252\deff0\nouicompat\deflang4105{\fonttbl{\f0\fnil\fcharset0 Calibri;}}
{\*\generator Riched20 10.0.17134}\viewkind4\uc1
{\field{\*\fldinst { HYPERLINK "http://www.google.com" }}{\fldrslt {Click here}}}
\pard\sa200\sl276\slmult1\f0\fs22\lang9 for more information. Lorem ipsum\par
}
link 工作所需的字符数在大约 20 到大约 100 个字符之间变化。
我创建了一个小项目以确保问题不是源于主项目中的其他任何地方。该项目仅包含一个 RichTextBox。我已将 DetectUrls 设置为 True，这没有任何区别。我还尝试在 Google 文档中创建 *.rtf 文件以检查 Word 版本是否可能是问题所在。我还使用 WordPad 进行了测试，包括在 Notepad++ 中手动输入 URLs。 .Net Framework 4.6 中没有出现此问题，但我有使用 .Net 4.7 的要求。如果我动态添加 link，问题也不会发生，但我不能按照我的要求这样做。
Public Sub Form1_Load(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles MyBase.Load
Dim LoadFileName As Object
LoadFileName = "C:\Users\anononym\source\repos\WindowsApp1\Test.rtf"
RichTextBox1.LoadFile(LoadFileName, RichTextBoxStreamType.RichText)
End Sub
Private Sub RichTextBox_LinkClicked(sender As Object, e As LinkClickedEventArgs) Handles RichTextBox1.LinkClicked
System.Diagnostics.Process.Start(e.LinkText)
End Sub
预期的结果是hyperlink在所有情况下都重定向到Word中设置的网站，我使用www.google.com进行测试
从.Net 4.7开始，RichTextBox使用RichEdit50控件；以前的版本使用 RichEdit20 控件。我不知道控件版本之间对超链接的处理差异的原因，但显然存在一些差异。
A work-around 是配置您的 .Net 4.7 应用程序以使用较旧的控件。这是通过将以下内容添加到您的 App.config 文件来完成的。
<runtime>
<AppContextSwitchOverrides value="Switch.System.Windows.Forms.DoNotLoadLatestRichEditControl=true" />
</runtime>
编辑：
问题的根源似乎是原始 RichTextBox.CharRangeToString Method 中的黑客攻击。
//Windows bug: 64-bit windows returns a bad range for us. VSWhidbey 504502.
//Putting in a hack to avoid an unhandled exception.
if (c.cpMax > Text.Length || c.cpMax-c.cpMin <= 0) {
return string.Empty;
}
当使用 Friendly Name Hyperlinks available in the RichEdit50 control, the RichTextBox.Text.Length property can be less than the c.cpMax value as the link is not included in the returned property value. This causes the method to return String.Empty to the calling RichTextBox.EnLinkMsgHandler Method 时，如果返回 Empty.String 则不会引发 LickClicked 事件。
case NativeMethods.WM_LBUTTONDOWN:
string linktext = CharRangeToString(enlink.charrange);
if (!string.IsNullOrEmpty(linktext))
{
OnLinkClicked(new LinkClickedEventArgs(linktext));
}
m.Result = (IntPtr)1;
return;
为了处理这个bug，下面定义了一个自定义的RichTextBoxclass来修改CharRangeToString方法的逻辑。在 WndProc 过程中调用此修改后的逻辑以绕过默认逻辑。
Imports System.Runtime.InteropServices
Imports WindowsApp2.NativeMthods ' *** change WindowsApp2 to match your project
Public Class RichTextBoxFixedForFriendlyLinks : Inherits RichTextBox
Friend Function ConvertFromENLINK64(es64 As ENLINK64) As ENLINK
' Note: the RichTextBox.ConvertFromENLINK64 method is written using C# unsafe code
' this is version uses a GCHandle to pin the byte array so that
' the same Marshal.Read_Xyz methods can be used
Dim es As New ENLINK()
Dim hndl As GCHandle
Try
hndl = GCHandle.Alloc(es64.contents, GCHandleType.Pinned)
Dim es64p As IntPtr = hndl.AddrOfPinnedObject
es.nmhdr = New NMHDR()
es.charrange = New CHARRANGE()
es.nmhdr.hwndFrom = Marshal.ReadIntPtr(es64p)
es.nmhdr.idFrom = Marshal.ReadIntPtr(es64p + 8)
es.nmhdr.code = Marshal.ReadInt32(es64p + 16)
es.msg = Marshal.ReadInt32(es64p + 24)
es.wParam = Marshal.ReadIntPtr(es64p + 28)
es.lParam = Marshal.ReadIntPtr(es64p + 36)
es.charrange.cpMin = Marshal.ReadInt32(es64p + 44)
es.charrange.cpMax = Marshal.ReadInt32(es64p + 48)
Finally
hndl.Free()
End Try
Return es
End Function
Protected Overrides Sub WndProc(ByRef m As Message)
If m.Msg = WM_ReflectNotify Then
Dim hdr As NMHDR = CType(m.GetLParam(GetType(NMHDR)), NMHDR)
If hdr.code = EN_Link Then
Dim lnk As ENLINK
If IntPtr.Size = 4 Then
lnk = CType(m.GetLParam(GetType(ENLINK)), ENLINK)
Else
lnk = ConvertFromENLINK64(CType(m.GetLParam(GetType(ENLINK64)), ENLINK64))
End If
If lnk.msg = WM_LBUTTONDOWN Then
Dim linkUrl As String = CharRangeToString(lnk.charrange)
' Still check if linkUrl is not empty
If Not String.IsNullOrEmpty(linkUrl) Then
OnLinkClicked(New LinkClickedEventArgs(linkUrl))
End If
m.Result = New IntPtr(1)
Exit Sub
End If
End If
End If
MyBase.WndProc(m)
End Sub
Private Function CharRangeToString(ByVal c As CHARRANGE) As String
Dim ret As String = String.Empty
Dim txrg As New TEXTRANGE With {.chrg = c}
''Windows bug: 64-bit windows returns a bad range for us. VSWhidbey 504502.
''Putting in a hack to avoid an unhandled exception.
'If c.cpMax > Text.Length OrElse c.cpMax - c.cpMin <= 0 Then
' Return String.Empty
'End If
' *********
' c.cpMax can be greater than Text.Length if using friendly links
' with RichEdit50. so that check is not valid.
' instead of the hack above, first check that the number of characters is positive
' and then use the result of sending EM_GETTEXTRANGE to handle the
' possibilty of Text.Length < c.cpMax
' *********
Dim numCharacters As Int32 = (c.cpMax - c.cpMin) + 1 ' +1 for null termination
If numCharacters > 0 Then
Dim charBuffer As CharBuffer
charBuffer = CharBuffer.CreateBuffer(numCharacters)
Dim unmanagedBuffer As IntPtr
Try
unmanagedBuffer = charBuffer.AllocCoTaskMem()
If unmanagedBuffer = IntPtr.Zero Then
Throw New OutOfMemoryException()
End If
txrg.lpstrText = unmanagedBuffer
Dim len As Int32 = CInt(SendMessage(New HandleRef(Me, Handle), EM_GETTEXTRANGE, 0, txrg))
If len > 0 Then
charBuffer.PutCoTaskMem(unmanagedBuffer)
ret = charBuffer.GetString()
End If
Finally
If txrg.lpstrText <> IntPtr.Zero Then
Marshal.FreeCoTaskMem(unmanagedBuffer)
End If
End Try
End If
Return ret
End Function
End Class
虽然上面的代码不是那么重要，但它需要一些 methods/structures 来自不可公开访问的基础实现。下面介绍了这些方法的 VB 版本。大多数是从原始 C# 源代码直接转换而来。
Imports System.Runtime.InteropServices
Imports System.Text
Public Class NativeMthods
Friend Const EN_Link As Int32 = &H70B
Friend Const WM_NOTIFY As Int32 = &H4E
Friend Const WM_User As Int32 = &H400
Friend Const WM_REFLECT As Int32 = WM_User + &H1C00
Friend Const WM_ReflectNotify As Int32 = WM_REFLECT Or WM_NOTIFY
Friend Const WM_LBUTTONDOWN As Int32 = &H201
Friend Const EM_GETTEXTRANGE As Int32 = WM_User + 75
Public Structure NMHDR
Public hwndFrom As IntPtr
Public idFrom As IntPtr 'This is declared as UINT_PTR in winuser.h
Public code As Int32
End Structure
<StructLayout(LayoutKind.Sequential)>
Public Class ENLINK
Public nmhdr As NMHDR
Public msg As Int32 = 0
Public wParam As IntPtr = IntPtr.Zero
Public lParam As IntPtr = IntPtr.Zero
Public charrange As CHARRANGE = Nothing
End Class
<StructLayout(LayoutKind.Sequential)>
Public Class ENLINK64
<MarshalAs(UnmanagedType.ByValArray, SizeConst:=56)>
Public contents(0 To 55) As Byte
End Class
<StructLayout(LayoutKind.Sequential)>
Public Class CHARRANGE
Public cpMin As Int32
Public cpMax As Int32
End Class
<StructLayout(LayoutKind.Sequential)>
Public Class TEXTRANGE
Public chrg As CHARRANGE
Public lpstrText As IntPtr ' allocated by caller, zero terminated by RichEdit
End Class
Public MustInherit Class CharBuffer
Public Shared Function CreateBuffer(ByVal size As Int32) As CharBuffer
If Marshal.SystemDefaultCharSize = 1 Then
Return New AnsiCharBuffer(size)
End If
Return New UnicodeCharBuffer(size)
End Function
Public MustOverride Function AllocCoTaskMem() As IntPtr
Public MustOverride Function GetString() As String
Public MustOverride Sub PutCoTaskMem(ByVal ptr As IntPtr)
Public MustOverride Sub PutString(ByVal s As String)
End Class
Public Class AnsiCharBuffer : Inherits CharBuffer
Friend buffer() As Byte
Friend offset As Int32
Public Sub New(ByVal size As Int32)
buffer = New Byte(0 To size - 1) {}
End Sub
Public Overrides Function AllocCoTaskMem() As IntPtr
Dim result As IntPtr = Marshal.AllocCoTaskMem(buffer.Length)
Marshal.Copy(buffer, 0, result, buffer.Length)
Return result
End Function
Public Overrides Function GetString() As String
Dim i As Int32 = offset
Do While i < buffer.Length AndAlso buffer(i) <> 0
i += 1
Loop
Dim result As String = Encoding.Default.GetString(buffer, offset, i - offset)
If i < buffer.Length Then
i += 1
End If
offset = i
Return result
End Function
Public Overrides Sub PutCoTaskMem(ByVal ptr As IntPtr)
Marshal.Copy(ptr, buffer, 0, buffer.Length)
offset = 0
End Sub
Public Overrides Sub PutString(ByVal s As String)
Dim bytes() As Byte = Encoding.Default.GetBytes(s)
Dim count As Int32 = Math.Min(bytes.Length, buffer.Length - offset)
Array.Copy(bytes, 0, buffer, offset, count)
offset += count
If offset < buffer.Length Then
buffer(offset) = 0
offset += 1
End If
End Sub
End Class
Public Class UnicodeCharBuffer : Inherits CharBuffer
Friend buffer() As Char
Friend offset As Int32
Public Sub New(ByVal size As Int32)
buffer = New Char(size - 1) {}
End Sub
Public Overrides Function AllocCoTaskMem() As IntPtr
Dim result As IntPtr = Marshal.AllocCoTaskMem(buffer.Length * 2)
Marshal.Copy(buffer, 0, result, buffer.Length)
Return result
End Function
Public Overrides Function GetString() As String
Dim i As Int32 = offset
Do While i < buffer.Length AndAlso AscW(buffer(i)) <> 0
i += 1
Loop
Dim result As New String(buffer, offset, i - offset)
If i < buffer.Length Then
i += 1
End If
offset = i
Return result
End Function
Public Overrides Sub PutCoTaskMem(ByVal ptr As IntPtr)
Marshal.Copy(ptr, buffer, 0, buffer.Length)
offset = 0
End Sub
Public Overrides Sub PutString(ByVal s As String)
Dim count As Int32 = Math.Min(s.Length, buffer.Length - offset)
s.CopyTo(0, buffer, offset, count)
offset += count
If offset < buffer.Length Then
buffer(offset) = ChrW(0)
offset += 1
End If
End Sub
End Class
<DllImport("user32.dll", CharSet:=CharSet.Auto)>
Public Shared Function SendMessage(ByVal hWnd As HandleRef, ByVal msg As Int32, ByVal wParam As Int32, ByVal lParam As TEXTRANGE) As IntPtr
End Function
End Class
将这些 class 添加到我们的项目中并执行构建。 RichTextBoxFixedForFriendlyLinks 应该在工具箱中可用。您可以在通常使用 RichTextBox 控件的地方使用它。
编辑 2：
此问题已在 MS 开发人员社区上发布为：WinForm RichTextBox LinkClicked event fails to fire when control loaded with RTF containing a friendly name hyperlink
这是 @TnTinMn 的 VB 实现的 C# 转换，它对我有用。感谢 https://github.com/icsharpcode/CodeConverter 完成大部分转换。
显然，根据需要更改下面的命名空间。再次感谢@TnTinMn。
RichTextBoxFixedForFriendlyLinks.cs
using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using static TestRtf.NativeMthods;
namespace TestRtf
{
public partial class RichTextBoxFixedForFriendlyLinks : RichTextBox
{
internal ENLINK ConvertFromENLINK64(ENLINK64 es64)
{
// Note: the RichTextBox.ConvertFromENLINK64 method is written using C# unsafe code
// this is version uses a GCHandle to pin the byte array so that
// the same Marshal.Read_Xyz methods can be used
var es = new ENLINK();
GCHandle? hndl = null;
try
{
hndl = GCHandle.Alloc(es64.contents, GCHandleType.Pinned);
var es64p = hndl.Value.AddrOfPinnedObject();
es.nmhdr = new NMHDR();
es.charrange = new CHARRANGE();
es.nmhdr.hwndFrom = Marshal.ReadIntPtr(es64p);
es.nmhdr.idFrom = Marshal.ReadIntPtr(es64p + 8);
es.nmhdr.code = Marshal.ReadInt32(es64p + 16);
es.msg = Marshal.ReadInt32(es64p + 24);
es.wParam = Marshal.ReadIntPtr(es64p + 28);
es.lParam = Marshal.ReadIntPtr(es64p + 36);
es.charrange.cpMin = Marshal.ReadInt32(es64p + 44);
es.charrange.cpMax = Marshal.ReadInt32(es64p + 48);
}
finally
{
if (hndl.HasValue)
hndl.Value.Free();
}
return es;
}
protected override void WndProc(ref Message m)
{
if (m.Msg == WM_ReflectNotify)
{
NMHDR hdr = (NMHDR)m.GetLParam(typeof(NMHDR));
if (hdr.code == EN_Link)
{
ENLINK lnk;
if (IntPtr.Size == 4)
{
lnk = (ENLINK)m.GetLParam(typeof(ENLINK));
}
else
{
lnk = ConvertFromENLINK64((ENLINK64)m.GetLParam(typeof(ENLINK64)));
}
if (lnk.msg == WM_LBUTTONDOWN)
{
string linkUrl = CharRangeToString(lnk.charrange);
// Still check if linkUrl is not empty
if (!string.IsNullOrEmpty(linkUrl))
{
OnLinkClicked(new LinkClickedEventArgs(linkUrl));
}
m.Result = new IntPtr(1);
return;
}
}
}
base.WndProc(ref m);
}
private string CharRangeToString(CHARRANGE c)
{
string ret = string.Empty;
var txrg = new TEXTRANGE() { chrg = c };
// 'Windows bug: 64-bit windows returns a bad range for us. VSWhidbey 504502.
// 'Putting in a hack to avoid an unhandled exception.
// If c.cpMax > Text.Length OrElse c.cpMax - c.cpMin <= 0 Then
// Return String.Empty
// End If
// *********
// c.cpMax can be greater than Text.Length if using friendly links
// with RichEdit50. so that check is not valid.
// instead of the hack above, first check that the number of characters is positive
// and then use the result of sending EM_GETTEXTRANGE to handle the
// possibilty of Text.Length < c.cpMax
// *********
int numCharacters = c.cpMax - c.cpMin + 1; // +1 for null termination
if (numCharacters > 0)
{
var charBuffer = default(CharBuffer);
charBuffer = CharBuffer.CreateBuffer(numCharacters);
IntPtr unmanagedBuffer = IntPtr.Zero;
try
{
unmanagedBuffer = charBuffer.AllocCoTaskMem();
if (unmanagedBuffer == IntPtr.Zero)
{
throw new OutOfMemoryException();
}
txrg.lpstrText = unmanagedBuffer;
IntPtr len = SendMessage(new HandleRef(this, Handle), EM_GETTEXTRANGE, 0, txrg);
if (len != IntPtr.Zero)
{
charBuffer.PutCoTaskMem(unmanagedBuffer);
ret = charBuffer.GetString();
}
}
finally
{
if (txrg.lpstrText != IntPtr.Zero)
{
Marshal.FreeCoTaskMem(unmanagedBuffer);
}
}
}
return ret;
}
}
}
NativeMthods.cs:
using System;
using System.Runtime.InteropServices;
using System.Text;
namespace TestRtf
{
public partial class NativeMthods
{
internal const int EN_Link = 0x70B;
internal const int WM_NOTIFY = 0x4E;
internal const int WM_User = 0x400;
internal const int WM_REFLECT = WM_User + 0x1C00;
internal const int WM_ReflectNotify = WM_REFLECT | WM_NOTIFY;
internal const int WM_LBUTTONDOWN = 0x201;
internal const int EM_GETTEXTRANGE = WM_User + 75;
public partial struct NMHDR
{
public IntPtr hwndFrom;
public IntPtr idFrom; // This is declared as UINT_PTR in winuser.h
public int code;
}
[StructLayout(LayoutKind.Sequential)]
public partial class ENLINK
{
public NMHDR nmhdr;
public int msg = 0;
public IntPtr wParam = IntPtr.Zero;
public IntPtr lParam = IntPtr.Zero;
public CHARRANGE charrange = null;
}
[StructLayout(LayoutKind.Sequential)]
public partial class ENLINK64
{
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 56)]
public byte[] contents = new byte[56];
}
[StructLayout(LayoutKind.Sequential)]
public partial class CHARRANGE
{
public int cpMin;
public int cpMax;
}
[StructLayout(LayoutKind.Sequential)]
public partial class TEXTRANGE
{
public CHARRANGE chrg;
public IntPtr lpstrText; // allocated by caller, zero terminated by RichEdit
}
public abstract partial class CharBuffer
{
public static CharBuffer CreateBuffer(int size)
{
if (Marshal.SystemDefaultCharSize == 1)
{
return new AnsiCharBuffer(size);
}
return new UnicodeCharBuffer(size);
}
public abstract IntPtr AllocCoTaskMem();
public abstract string GetString();
public abstract void PutCoTaskMem(IntPtr ptr);
public abstract void PutString(string s);
}
public partial class AnsiCharBuffer : CharBuffer
{
internal byte[] buffer;
internal int offset;
public AnsiCharBuffer(int size)
{
buffer = new byte[size];
}
public override IntPtr AllocCoTaskMem()
{
var result = Marshal.AllocCoTaskMem(buffer.Length);
Marshal.Copy(buffer, 0, result, buffer.Length);
return result;
}
public override string GetString()
{
int i = offset;
while (i < buffer.Length && buffer[i] != 0)
i += 1;
string result = Encoding.Default.GetString(buffer, offset, i - offset);
if (i < buffer.Length)
{
i += 1;
}
offset = i;
return result;
}
public override void PutCoTaskMem(IntPtr ptr)
{
Marshal.Copy(ptr, buffer, 0, buffer.Length);
offset = 0;
}
public override void PutString(string s)
{
var bytes = Encoding.Default.GetBytes(s);
int count = Math.Min(bytes.Length, buffer.Length - offset);
Array.Copy(bytes, 0, buffer, offset, count);
offset += count;
if (offset < buffer.Length)
{
buffer[offset] = 0;
offset += 1;
}
}
}
public partial class UnicodeCharBuffer : CharBuffer
{
internal char[] buffer;
internal int offset;
public UnicodeCharBuffer(int size)
{
buffer = new char[size];
}
public override IntPtr AllocCoTaskMem()
{
var result = Marshal.AllocCoTaskMem(buffer.Length * 2);
Marshal.Copy(buffer, 0, result, buffer.Length);
return result;
}
public override string GetString()
{
int i = offset;
while (i < buffer.Length && buffer[i] != 0)
i += 1;
string result = new string(buffer, offset, i - offset);
if (i < buffer.Length)
{
i += 1;
}
offset = i;
return result;
}
public override void PutCoTaskMem(IntPtr ptr)
{
Marshal.Copy(ptr, buffer, 0, buffer.Length);
offset = 0;
}
public override void PutString(string s)
{
int count = Math.Min(s.Length, buffer.Length - offset);
s.CopyTo(0, buffer, offset, count);
offset += count;
if (offset < buffer.Length)
{
buffer[offset] = '[=11=]';
offset += 1;
}
}
}
[DllImport("user32.dll", CharSet = CharSet.Auto)]
public static extern IntPtr SendMessage(HandleRef hWnd, int msg, int wParam, TEXTRANGE lParam);
}
}
在 .net 4.7 中的一个简单 Windows 表单应用程序中，我的表单上只有一个 RichTextBox。我正在从本地加载一个在 MS Word 2016 中创建的 *.rtf 文件。hyperlinks 已在 Word 中设置。问题是在应用程序中单击 hyperlink 时并非所有 link 都会触发 LinkClicked 事件。
行为如下： 如果 hyperlink 后跟足够多的字符（这会有所不同），它将由 LinkClicked 事件触发。如果我删除 hyperlink 后面的字符，它不会触发事件。
更新 经过测试，最后一个URL后需要插入的字符数等于正在加载的*.rtf文件中所有URL字符的总和。
我不能post一张图，括号里的字是hyperlink
无效： [点击此处]了解更多信息。
{\rtf1\ansi\ansicpg1252\deff0\nouicompat\deflang4105{\fonttbl{\f0\fnil\fcharset0 Calibri;}}
{\*\generator Riched20 10.0.17134}\viewkind4\uc1
{\field{\*\fldinst { HYPERLINK "http://www.google.com" }}{\fldrslt {Click here}}}
\pard\sa200\sl276\slmult1\f0\fs22\lang9 for more information.\par
}
作品： [点击这里查看更多信息。 Lorem 假和
{\rtf1\ansi\ansicpg1252\deff0\nouicompat\deflang4105{\fonttbl{\f0\fnil\fcharset0 Calibri;}}
{\*\generator Riched20 10.0.17134}\viewkind4\uc1
{\field{\*\fldinst { HYPERLINK "http://www.google.com" }}{\fldrslt {Click here}}}
\pard\sa200\sl276\slmult1\f0\fs22\lang9 for more information. Lorem ipsum\par
}
link 工作所需的字符数在大约 20 到大约 100 个字符之间变化。
我创建了一个小项目以确保问题不是源于主项目中的其他任何地方。该项目仅包含一个 RichTextBox。我已将 DetectUrls 设置为 True，这没有任何区别。我还尝试在 Google 文档中创建 *.rtf 文件以检查 Word 版本是否可能是问题所在。我还使用 WordPad 进行了测试，包括在 Notepad++ 中手动输入 URLs。 .Net Framework 4.6 中没有出现此问题，但我有使用 .Net 4.7 的要求。如果我动态添加 link，问题也不会发生，但我不能按照我的要求这样做。
Public Sub Form1_Load(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles MyBase.Load
Dim LoadFileName As Object
LoadFileName = "C:\Users\anononym\source\repos\WindowsApp1\Test.rtf"
RichTextBox1.LoadFile(LoadFileName, RichTextBoxStreamType.RichText)
End Sub
Private Sub RichTextBox_LinkClicked(sender As Object, e As LinkClickedEventArgs) Handles RichTextBox1.LinkClicked
System.Diagnostics.Process.Start(e.LinkText)
End Sub
预期的结果是hyperlink在所有情况下都重定向到Word中设置的网站，我使用www.google.com进行测试
从.Net 4.7开始，RichTextBox使用RichEdit50控件；以前的版本使用 RichEdit20 控件。我不知道控件版本之间对超链接的处理差异的原因，但显然存在一些差异。
A work-around 是配置您的 .Net 4.7 应用程序以使用较旧的控件。这是通过将以下内容添加到您的 App.config 文件来完成的。
<runtime>
<AppContextSwitchOverrides value="Switch.System.Windows.Forms.DoNotLoadLatestRichEditControl=true" />
</runtime>
编辑：
问题的根源似乎是原始 RichTextBox.CharRangeToString Method 中的黑客攻击。
//Windows bug: 64-bit windows returns a bad range for us. VSWhidbey 504502.
//Putting in a hack to avoid an unhandled exception.
if (c.cpMax > Text.Length || c.cpMax-c.cpMin <= 0) {
return string.Empty;
}
当使用 Friendly Name Hyperlinks available in the RichEdit50 control, the RichTextBox.Text.Length property can be less than the c.cpMax value as the link is not included in the returned property value. This causes the method to return String.Empty to the calling RichTextBox.EnLinkMsgHandler Method 时，如果返回 Empty.String 则不会引发 LickClicked 事件。
case NativeMethods.WM_LBUTTONDOWN:
string linktext = CharRangeToString(enlink.charrange);
if (!string.IsNullOrEmpty(linktext))
{
OnLinkClicked(new LinkClickedEventArgs(linktext));
}
m.Result = (IntPtr)1;
return;
为了处理这个bug，下面定义了一个自定义的RichTextBoxclass来修改CharRangeToString方法的逻辑。在 WndProc 过程中调用此修改后的逻辑以绕过默认逻辑。
Imports System.Runtime.InteropServices
Imports WindowsApp2.NativeMthods ' *** change WindowsApp2 to match your project
Public Class RichTextBoxFixedForFriendlyLinks : Inherits RichTextBox
Friend Function ConvertFromENLINK64(es64 As ENLINK64) As ENLINK
' Note: the RichTextBox.ConvertFromENLINK64 method is written using C# unsafe code
' this is version uses a GCHandle to pin the byte array so that
' the same Marshal.Read_Xyz methods can be used
Dim es As New ENLINK()
Dim hndl As GCHandle
Try
hndl = GCHandle.Alloc(es64.contents, GCHandleType.Pinned)
Dim es64p As IntPtr = hndl.AddrOfPinnedObject
es.nmhdr = New NMHDR()
es.charrange = New CHARRANGE()
es.nmhdr.hwndFrom = Marshal.ReadIntPtr(es64p)
es.nmhdr.idFrom = Marshal.ReadIntPtr(es64p + 8)
es.nmhdr.code = Marshal.ReadInt32(es64p + 16)
es.msg = Marshal.ReadInt32(es64p + 24)
es.wParam = Marshal.ReadIntPtr(es64p + 28)
es.lParam = Marshal.ReadIntPtr(es64p + 36)
es.charrange.cpMin = Marshal.ReadInt32(es64p + 44)
es.charrange.cpMax = Marshal.ReadInt32(es64p + 48)
Finally
hndl.Free()
End Try
Return es
End Function
Protected Overrides Sub WndProc(ByRef m As Message)
If m.Msg = WM_ReflectNotify Then
Dim hdr As NMHDR = CType(m.GetLParam(GetType(NMHDR)), NMHDR)
If hdr.code = EN_Link Then
Dim lnk As ENLINK
If IntPtr.Size = 4 Then
lnk = CType(m.GetLParam(GetType(ENLINK)), ENLINK)
Else
lnk = ConvertFromENLINK64(CType(m.GetLParam(GetType(ENLINK64)), ENLINK64))
End If
If lnk.msg = WM_LBUTTONDOWN Then
Dim linkUrl As String = CharRangeToString(lnk.charrange)
' Still check if linkUrl is not empty
If Not String.IsNullOrEmpty(linkUrl) Then
OnLinkClicked(New LinkClickedEventArgs(linkUrl))
End If
m.Result = New IntPtr(1)
Exit Sub
End If
End If
End If
MyBase.WndProc(m)
End Sub
Private Function CharRangeToString(ByVal c As CHARRANGE) As String
Dim ret As String = String.Empty
Dim txrg As New TEXTRANGE With {.chrg = c}
''Windows bug: 64-bit windows returns a bad range for us. VSWhidbey 504502.
''Putting in a hack to avoid an unhandled exception.
'If c.cpMax > Text.Length OrElse c.cpMax - c.cpMin <= 0 Then
' Return String.Empty
'End If
' *********
' c.cpMax can be greater than Text.Length if using friendly links
' with RichEdit50. so that check is not valid.
' instead of the hack above, first check that the number of characters is positive
' and then use the result of sending EM_GETTEXTRANGE to handle the
' possibilty of Text.Length < c.cpMax
' *********
Dim numCharacters As Int32 = (c.cpMax - c.cpMin) + 1 ' +1 for null termination
If numCharacters > 0 Then
Dim charBuffer As CharBuffer
charBuffer = CharBuffer.CreateBuffer(numCharacters)
Dim unmanagedBuffer As IntPtr
Try
unmanagedBuffer = charBuffer.AllocCoTaskMem()
If unmanagedBuffer = IntPtr.Zero Then
Throw New OutOfMemoryException()
End If
txrg.lpstrText = unmanagedBuffer
Dim len As Int32 = CInt(SendMessage(New HandleRef(Me, Handle), EM_GETTEXTRANGE, 0, txrg))
If len > 0 Then
charBuffer.PutCoTaskMem(unmanagedBuffer)
ret = charBuffer.GetString()
End If
Finally
If txrg.lpstrText <> IntPtr.Zero Then
Marshal.FreeCoTaskMem(unmanagedBuffer)
End If
End Try
End If
Return ret
End Function
End Class
虽然上面的代码不是那么重要，但它需要一些 methods/structures 来自不可公开访问的基础实现。下面介绍了这些方法的 VB 版本。大多数是从原始 C# 源代码直接转换而来。
Imports System.Runtime.InteropServices
Imports System.Text
Public Class NativeMthods
Friend Const EN_Link As Int32 = &H70B
Friend Const WM_NOTIFY As Int32 = &H4E
Friend Const WM_User As Int32 = &H400
Friend Const WM_REFLECT As Int32 = WM_User + &H1C00
Friend Const WM_ReflectNotify As Int32 = WM_REFLECT Or WM_NOTIFY
Friend Const WM_LBUTTONDOWN As Int32 = &H201
Friend Const EM_GETTEXTRANGE As Int32 = WM_User + 75
Public Structure NMHDR
Public hwndFrom As IntPtr
Public idFrom As IntPtr 'This is declared as UINT_PTR in winuser.h
Public code As Int32
End Structure
<StructLayout(LayoutKind.Sequential)>
Public Class ENLINK
Public nmhdr As NMHDR
Public msg As Int32 = 0
Public wParam As IntPtr = IntPtr.Zero
Public lParam As IntPtr = IntPtr.Zero
Public charrange As CHARRANGE = Nothing
End Class
<StructLayout(LayoutKind.Sequential)>
Public Class ENLINK64
<MarshalAs(UnmanagedType.ByValArray, SizeConst:=56)>
Public contents(0 To 55) As Byte
End Class
<StructLayout(LayoutKind.Sequential)>
Public Class CHARRANGE
Public cpMin As Int32
Public cpMax As Int32
End Class
<StructLayout(LayoutKind.Sequential)>
Public Class TEXTRANGE
Public chrg As CHARRANGE
Public lpstrText As IntPtr ' allocated by caller, zero terminated by RichEdit
End Class
Public MustInherit Class CharBuffer
Public Shared Function CreateBuffer(ByVal size As Int32) As CharBuffer
If Marshal.SystemDefaultCharSize = 1 Then
Return New AnsiCharBuffer(size)
End If
Return New UnicodeCharBuffer(size)
End Function
Public MustOverride Function AllocCoTaskMem() As IntPtr
Public MustOverride Function GetString() As String
Public MustOverride Sub PutCoTaskMem(ByVal ptr As IntPtr)
Public MustOverride Sub PutString(ByVal s As String)
End Class
Public Class AnsiCharBuffer : Inherits CharBuffer
Friend buffer() As Byte
Friend offset As Int32
Public Sub New(ByVal size As Int32)
buffer = New Byte(0 To size - 1) {}
End Sub
Public Overrides Function AllocCoTaskMem() As IntPtr
Dim result As IntPtr = Marshal.AllocCoTaskMem(buffer.Length)
Marshal.Copy(buffer, 0, result, buffer.Length)
Return result
End Function
Public Overrides Function GetString() As String
Dim i As Int32 = offset
Do While i < buffer.Length AndAlso buffer(i) <> 0
i += 1
Loop
Dim result As String = Encoding.Default.GetString(buffer, offset, i - offset)
If i < buffer.Length Then
i += 1
End If
offset = i
Return result
End Function
Public Overrides Sub PutCoTaskMem(ByVal ptr As IntPtr)
Marshal.Copy(ptr, buffer, 0, buffer.Length)
offset = 0
End Sub
Public Overrides Sub PutString(ByVal s As String)
Dim bytes() As Byte = Encoding.Default.GetBytes(s)
Dim count As Int32 = Math.Min(bytes.Length, buffer.Length - offset)
Array.Copy(bytes, 0, buffer, offset, count)
offset += count
If offset < buffer.Length Then
buffer(offset) = 0
offset += 1
End If
End Sub
End Class
Public Class UnicodeCharBuffer : Inherits CharBuffer
Friend buffer() As Char
Friend offset As Int32
Public Sub New(ByVal size As Int32)
buffer = New Char(size - 1) {}
End Sub
Public Overrides Function AllocCoTaskMem() As IntPtr
Dim result As IntPtr = Marshal.AllocCoTaskMem(buffer.Length * 2)
Marshal.Copy(buffer, 0, result, buffer.Length)
Return result
End Function
Public Overrides Function GetString() As String
Dim i As Int32 = offset
Do While i < buffer.Length AndAlso AscW(buffer(i)) <> 0
i += 1
Loop
Dim result As New String(buffer, offset, i - offset)
If i < buffer.Length Then
i += 1
End If
offset = i
Return result
End Function
Public Overrides Sub PutCoTaskMem(ByVal ptr As IntPtr)
Marshal.Copy(ptr, buffer, 0, buffer.Length)
offset = 0
End Sub
Public Overrides Sub PutString(ByVal s As String)
Dim count As Int32 = Math.Min(s.Length, buffer.Length - offset)
s.CopyTo(0, buffer, offset, count)
offset += count
If offset < buffer.Length Then
buffer(offset) = ChrW(0)
offset += 1
End If
End Sub
End Class
<DllImport("user32.dll", CharSet:=CharSet.Auto)>
Public Shared Function SendMessage(ByVal hWnd As HandleRef, ByVal msg As Int32, ByVal wParam As Int32, ByVal lParam As TEXTRANGE) As IntPtr
End Function
End Class
将这些 class 添加到我们的项目中并执行构建。 RichTextBoxFixedForFriendlyLinks 应该在工具箱中可用。您可以在通常使用 RichTextBox 控件的地方使用它。
编辑 2：
此问题已在 MS 开发人员社区上发布为：WinForm RichTextBox LinkClicked event fails to fire when control loaded with RTF containing a friendly name hyperlink
这是 @TnTinMn 的 VB 实现的 C# 转换，它对我有用。感谢 https://github.com/icsharpcode/CodeConverter 完成大部分转换。
显然，根据需要更改下面的命名空间。再次感谢@TnTinMn。
RichTextBoxFixedForFriendlyLinks.cs
using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using static TestRtf.NativeMthods;
namespace TestRtf
{
public partial class RichTextBoxFixedForFriendlyLinks : RichTextBox
{
internal ENLINK ConvertFromENLINK64(ENLINK64 es64)
{
// Note: the RichTextBox.ConvertFromENLINK64 method is written using C# unsafe code
// this is version uses a GCHandle to pin the byte array so that
// the same Marshal.Read_Xyz methods can be used
var es = new ENLINK();
GCHandle? hndl = null;
try
{
hndl = GCHandle.Alloc(es64.contents, GCHandleType.Pinned);
var es64p = hndl.Value.AddrOfPinnedObject();
es.nmhdr = new NMHDR();
es.charrange = new CHARRANGE();
es.nmhdr.hwndFrom = Marshal.ReadIntPtr(es64p);
es.nmhdr.idFrom = Marshal.ReadIntPtr(es64p + 8);
es.nmhdr.code = Marshal.ReadInt32(es64p + 16);
es.msg = Marshal.ReadInt32(es64p + 24);
es.wParam = Marshal.ReadIntPtr(es64p + 28);
es.lParam = Marshal.ReadIntPtr(es64p + 36);
es.charrange.cpMin = Marshal.ReadInt32(es64p + 44);
es.charrange.cpMax = Marshal.ReadInt32(es64p + 48);
}
finally
{
if (hndl.HasValue)
hndl.Value.Free();
}
return es;
}
protected override void WndProc(ref Message m)
{
if (m.Msg == WM_ReflectNotify)
{
NMHDR hdr = (NMHDR)m.GetLParam(typeof(NMHDR));
if (hdr.code == EN_Link)
{
ENLINK lnk;
if (IntPtr.Size == 4)
{
lnk = (ENLINK)m.GetLParam(typeof(ENLINK));
}
else
{
lnk = ConvertFromENLINK64((ENLINK64)m.GetLParam(typeof(ENLINK64)));
}
if (lnk.msg == WM_LBUTTONDOWN)
{
string linkUrl = CharRangeToString(lnk.charrange);
// Still check if linkUrl is not empty
if (!string.IsNullOrEmpty(linkUrl))
{
OnLinkClicked(new LinkClickedEventArgs(linkUrl));
}
m.Result = new IntPtr(1);
return;
}
}
}
base.WndProc(ref m);
}
private string CharRangeToString(CHARRANGE c)
{
string ret = string.Empty;
var txrg = new TEXTRANGE() { chrg = c };
// 'Windows bug: 64-bit windows returns a bad range for us. VSWhidbey 504502.
// 'Putting in a hack to avoid an unhandled exception.
// If c.cpMax > Text.Length OrElse c.cpMax - c.cpMin <= 0 Then
// Return String.Empty
// End If
// *********
// c.cpMax can be greater than Text.Length if using friendly links
// with RichEdit50. so that check is not valid.
// instead of the hack above, first check that the number of characters is positive
// and then use the result of sending EM_GETTEXTRANGE to handle the
// possibilty of Text.Length < c.cpMax
// *********
int numCharacters = c.cpMax - c.cpMin + 1; // +1 for null termination
if (numCharacters > 0)
{
var charBuffer = default(CharBuffer);
charBuffer = CharBuffer.CreateBuffer(numCharacters);
IntPtr unmanagedBuffer = IntPtr.Zero;
try
{
unmanagedBuffer = charBuffer.AllocCoTaskMem();
if (unmanagedBuffer == IntPtr.Zero)
{
throw new OutOfMemoryException();
}
txrg.lpstrText = unmanagedBuffer;
IntPtr len = SendMessage(new HandleRef(this, Handle), EM_GETTEXTRANGE, 0, txrg);
if (len != IntPtr.Zero)
{
charBuffer.PutCoTaskMem(unmanagedBuffer);
ret = charBuffer.GetString();
}
}
finally
{
if (txrg.lpstrText != IntPtr.Zero)
{
Marshal.FreeCoTaskMem(unmanagedBuffer);
}
}
}
return ret;
}
}
}
NativeMthods.cs:
using System;
using System.Runtime.InteropServices;
using System.Text;
namespace TestRtf
{
public partial class NativeMthods
{
internal const int EN_Link = 0x70B;
internal const int WM_NOTIFY = 0x4E;
internal const int WM_User = 0x400;
internal const int WM_REFLECT = WM_User + 0x1C00;
internal const int WM_ReflectNotify = WM_REFLECT | WM_NOTIFY;
internal const int WM_LBUTTONDOWN = 0x201;
internal const int EM_GETTEXTRANGE = WM_User + 75;
public partial struct NMHDR
{
public IntPtr hwndFrom;
public IntPtr idFrom; // This is declared as UINT_PTR in winuser.h
public int code;
}
[StructLayout(LayoutKind.Sequential)]
public partial class ENLINK
{
public NMHDR nmhdr;
public int msg = 0;
public IntPtr wParam = IntPtr.Zero;
public IntPtr lParam = IntPtr.Zero;
public CHARRANGE charrange = null;
}
[StructLayout(LayoutKind.Sequential)]
public partial class ENLINK64
{
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 56)]
public byte[] contents = new byte[56];
}
[StructLayout(LayoutKind.Sequential)]
public partial class CHARRANGE
{
public int cpMin;
public int cpMax;
}
[StructLayout(LayoutKind.Sequential)]
public partial class TEXTRANGE
{
public CHARRANGE chrg;
public IntPtr lpstrText; // allocated by caller, zero terminated by RichEdit
}
public abstract partial class CharBuffer
{
public static CharBuffer CreateBuffer(int size)
{
if (Marshal.SystemDefaultCharSize == 1)
{
return new AnsiCharBuffer(size);
}
return new UnicodeCharBuffer(size);
}
public abstract IntPtr AllocCoTaskMem();
public abstract string GetString();
public abstract void PutCoTaskMem(IntPtr ptr);
public abstract void PutString(string s);
}
public partial class AnsiCharBuffer : CharBuffer
{
internal byte[] buffer;
internal int offset;
public AnsiCharBuffer(int size)
{
buffer = new byte[size];
}
public override IntPtr AllocCoTaskMem()
{
var result = Marshal.AllocCoTaskMem(buffer.Length);
Marshal.Copy(buffer, 0, result, buffer.Length);
return result;
}
public override string GetString()
{
int i = offset;
while (i < buffer.Length && buffer[i] != 0)
i += 1;
string result = Encoding.Default.GetString(buffer, offset, i - offset);
if (i < buffer.Length)
{
i += 1;
}
offset = i;
return result;
}
public override void PutCoTaskMem(IntPtr ptr)
{
Marshal.Copy(ptr, buffer, 0, buffer.Length);
offset = 0;
}
public override void PutString(string s)
{
var bytes = Encoding.Default.GetBytes(s);
int count = Math.Min(bytes.Length, buffer.Length - offset);
Array.Copy(bytes, 0, buffer, offset, count);
offset += count;
if (offset < buffer.Length)
{
buffer[offset] = 0;
offset += 1;
}
}
}
public partial class UnicodeCharBuffer : CharBuffer
{
internal char[] buffer;
internal int offset;
public UnicodeCharBuffer(int size)
{
buffer = new char[size];
}
public override IntPtr AllocCoTaskMem()
{
var result = Marshal.AllocCoTaskMem(buffer.Length * 2);
Marshal.Copy(buffer, 0, result, buffer.Length);
return result;
}
public override string GetString()
{
int i = offset;
while (i < buffer.Length && buffer[i] != 0)
i += 1;
string result = new string(buffer, offset, i - offset);
if (i < buffer.Length)
{
i += 1;
}
offset = i;
return result;
}
public override void PutCoTaskMem(IntPtr ptr)
{
Marshal.Copy(ptr, buffer, 0, buffer.Length);
offset = 0;
}
public override void PutString(string s)
{
int count = Math.Min(s.Length, buffer.Length - offset);
s.CopyTo(0, buffer, offset, count);
offset += count;
if (offset < buffer.Length)
{
buffer[offset] = '[=11=]';
offset += 1;
}
}
}
[DllImport("user32.dll", CharSet = CharSet.Auto)]
public static extern IntPtr SendMessage(HandleRef hWnd, int msg, int wParam, TEXTRANGE lParam);
}
}