how to use the Char2Format Structure in VB .NET for Highlighting Text
Example
Private Sub SetCharFormatColour(ByVal RichTextBox As RichTextBox)
'Set-up Char2Format2 Structure
Dim CF2 As WinAPI.RichEditControl.CharFormat2
With CF2
.cbSize = System.Runtime.InteropServices.Marshal.SizeOf(CF2)
.dwMask = WinAPI.RichEditControl.CFM_COLOR
.crTextColor = RGB(255, 0, 0)
End With
Dim Win32Error As Integer
Win32Error = WinAPI.RichEditControl.SendMessageA(RichTextBox.Handle.ToInt32, WinAPI.RichEditControl.EM_SETCHARFORMAT, WinAPI.RichEditControl.SCF_SELECTION, CF2)
'If the operation fails, the return value is zero. So lets get the error description and display it.
If Win32Error = 0 Then
MsgBox(WinAPI.General.GetLastErrorMessageDescription)
End If
End Sub
The latter routine requires the following unit in order to provide the interface to the Windows API:
Option Strict On
Imports System.Runtime.InteropServices
Namespace WinAPI
Public Class General
Public Const WM_USER As Int32 = &H400
Public Const WM_SETREDRAW As Int32 = &HB
'Declare Function SendMessageByString Lib "user32" Alias "SendMessageA" _
' (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As String) As Long
' Declare Function SendMessageByLong Lib "user32" Alias "SendMessageA" _
' (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Public Declare Auto Function SendMessage Lib "user32" _
(ByVal hWnd As IntPtr, ByVal msg As Integer, ByVal wParam As Integer, ByVal lParam As Integer) As IntPtr
Private Declare Auto Function FormatMessage Lib "kernel32" Alias "FormatMessageA" (ByVal dwFlags As Integer, ByRef lpSource As Object, ByVal dwMessageId As Integer, ByVal dwLanguageId As Integer, ByVal lpBuffer As String, ByVal nSize As Integer, ByRef Arguments As Integer) As Integer
Public Shared Function GetLastErrorMessageDescription() As String
Const FORMAT_MESSAGE_FROM_SYSTEM As Short = &H1000S
Const LANG_NEUTRAL As Short = &H0S
Dim Win32Error As Integer
Win32Error = System.Runtime.InteropServices.Marshal.GetLastWin32Error()
Dim Buffer As String = Space(999)
FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, 0, Win32Error, LANG_NEUTRAL, Buffer, 999, 0)
Return Trim(Buffer)
End Function
End Class
Public Class RichEditControl
Public Declare Function SendMessageA Lib "user32.dll" _
(ByVal hWnd As Integer, ByVal Msg As Integer, ByVal wParam As Integer, ByRef lParam As CharFormat2) As Integer
Public cbSize As Int32
Public dwMask As Int32
Public dwEffects As Int32
Public yHeight As Int32
Public yOffset As Int32
Public crTextColor As Int32
Public bCharSet As Byte
Public bPitchAndFamily As Byte
Public wWeight As Int16
Public sSpacing As Int16
Public crBackColor As Int32
Public lcid As Int32
Public dwReserved As Int32
Public sStyle As Int16
Public wKerning As Int16
Public bUnderlineType As Byte
Public bAnimation As Byte
Public bRevAuthor As Byte
Public bReserved1 As Byte
End Structure
Public Declare Function SendMessageAv Lib "user32.dll" Alias "SendMessageA" _
(ByVal hWnd As Integer, ByVal Msg As Integer, ByVal wParam As Integer, ByRef lParam As CharRange) As Integer
Public cpMin As Int32
Public cpMax As Int32
End Structure
'RichEdit messages
Public Const EM_GETLIMITTEXT As Int32 = General.WM_USER + 37
Public Const EM_POSFROMCHAR As Int32 = General.WM_USER + 38
Public Const EM_CHARFROMPOS As Int32 = General.WM_USER + 39
Public Const EM_SCROLLCARET As Int32 = General.WM_USER + 49
Public Const EM_CANPASTE As Int32 = General.WM_USER + 50
Public Const EM_DISPLAYBAND As Int32 = General.WM_USER + 51
Public Const EM_EXGETSEL As Int32 = General.WM_USER + 52
Public Const EM_EXLIMITTEXT As Int32 = General.WM_USER + 53
Public Const EM_EXLINEFROMCHAR As Int32 = General.WM_USER + 54
Public Const EM_EXSETSEL As Int32 = General.WM_USER + 55
Public Const EM_FINDTEXT As Int32 = General.WM_USER + 56
Public Const EM_FORMATRANGE As Int32 = General.WM_USER + 57
Public Const EM_GETCHARFORMAT As Int32 = General.WM_USER + 58
Public Const EM_GETEVENTMASK As Int32 = General.WM_USER + 59
Public Const EM_GETOLEINTERFACE As Int32 = General.WM_USER + 60
Public Const EM_GETPARAFORMAT As Int32 = General.WM_USER + 61
Public Const EM_GETSELTEXT As Int32 = General.WM_USER + 62
Public Const EM_HIDESELECTION As Int32 = General.WM_USER + 63
Public Const EM_PASTESPECIAL As Int32 = General.WM_USER + 64
Public Const EM_REQUESTRESIZE As Int32 = General.WM_USER + 65
Public Const EM_SELECTIONTYPE As Int32 = General.WM_USER + 66
Public Const EM_SETBKGNDCOLOR As Int32 = General.WM_USER + 67
Public Const EM_SETCHARFORMAT As Int32 = General.WM_USER + 68
Public Const EM_SETEVENTMASK As Int32 = General.WM_USER + 69
Public Const EM_SETOLECALLBACK As Int32 = General.WM_USER + 70
Public Const EM_SETPARAFORMAT As Int32 = General.WM_USER + 71
Public Const EM_SETTARGETDEVICE As Int32 = General.WM_USER + 72
Public Const EM_STREAMIN As Int32 = General.WM_USER + 73
Public Const EM_STREAMOUT As Int32 = General.WM_USER + 74
Public Const EM_GETTEXTRANGE As Int32 = General.WM_USER + 75
Public Const EM_FINDWORDBREAK As Int32 = General.WM_USER + 76
Public Const EM_SETOPTIONS As Int32 = General.WM_USER + 77
Public Const EM_GETOPTIONS As Int32 = General.WM_USER + 78
Public Const EM_FINDTEXTEX As Int32 = General.WM_USER + 79
Public Const EM_GETWORDBREAKPROCEX As Int32 = General.WM_USER + 80
Public Const EM_SETWORDBREAKPROCEX As Int32 = General.WM_USER + 81
'Richedit v2.0 messages
Public Const EM_SETUNDOLIMIT As Int32 = General.WM_USER + 82
Public Const EM_REDO As Int32 = General.WM_USER + 84
Public Const EM_CANREDO As Int32 = General.WM_USER + 85
Public Const EM_GETUNDONAME As Int32 = General.WM_USER + 86
Public Const EM_GETREDONAME As Int32 = General.WM_USER + 87
Public Const EM_STOPGROUPTYPING As Int32 = General.WM_USER + 88
Public Const EM_SETTEXTMODE As Int32 = General.WM_USER + 89
Public Const EM_GETTEXTMODE As Int32 = General.WM_USER + 90
Public Const CFM_BOLD As Int32 = &H1
Public Const CFM_ITALIC As Int32 = &H2
Public Const CFM_UNDERLINE As Int32 = &H4
Public Const CFM_STRIKEOUT As Int32 = &H8
Public Const CFM_PROTECTED As Int32 = &H10
Public Const CFM_LINK As Int32 = &H20
Public Const CFM_SIZE As Int32 = &H80000000
Public Const CFM_COLOR As Int32 = &H40000000
Public Const CFM_FACE As Int32 = &H20000000
Public Const CFM_OFFSET As Int32 = &H10000000
Public Const CFM_CHARSET As Int32 = &H8000000
Public Const SCF_SELECTION As Int32 = &H1
Public Const SCF_WORD As Int32 = &H2
Public Const SCF_DEFAULT As Int32 = &H0
Public Const SCF_ALL As Int32 = &H4
Public Const SCF_USEUIRULES As Int32 = &H8
'Event notification masks
Public Const ENM_NONE As Int32 = &H0
Public Const ENM_CHANGE As Int32 = &H1
Public Const ENM_UPDATE As Int32 = &H2
Public Const ENM_SCROLL As Int32 = &H4
Public Const ENM_KEYEVENTS As Int32 = &H10000
Public Const ENM_MOUSEEVENTS As Int32 = &H20000
Public Const ENM_REQUESTRESIZE As Int32 = &H40000
Public Const ENM_SELCHANGE As Int32 = &H80000
Public Const ENM_DROPFILES As Int32 = &H100000
Public Const ENM_PROTECTED As Int32 = &H200000
Public Const ENM_CORRECTTEXT As Int32 = &H400000 ' PenWin specific
Public Const ENM_SCROLLEVENTS As Int32 = &H8
Public Const ENM_DRAGDROPDONE As Int32 = &H10
Public Const ENM_PARAGRAPHEXPANDED As Int32 = &H20
End Class
End Namespace
