RichTextBox，“查找上一个”功能

Question

我使用这个通用函数在 RichTextBox 中添加了“FindNext”功能。

#Region " FindNext In RichTextBox "

' [ FindNext In RichTextBox Function ]
'
' //By Elektro H@cker
'
' Examples :
'
' RichTextBox1.Text = "Hello World!, Hello World!, Hello World!"
' FindNext(RichTextBox1, "Hello")

' FindNext
Private Sub FindNext(ByVal [Control] As RichTextBox, _
                     ByVal SearchText As String, _
                     Optional ByVal Highlight_BackColor As Color = Nothing, _
                     Optional ByVal Highlight_ForeColor As Color = Nothing)

    ' Start searching at 'SelectionStart'.
    Dim Search_StartIndex As Integer = [Control].SelectionStart
    Static Next_Count As Integer = 0

    ' Restore Highlight colors of previous selection
    [Control].SelectionBackColor = [Control].BackColor
    [Control].SelectionColor = [Control].ForeColor

    ' Set next selection Highlight colors
    If Highlight_BackColor = Nothing Then Highlight_BackColor = [Control].BackColor
    If Highlight_ForeColor = Nothing Then Highlight_ForeColor = [Control].ForeColor

    ' If is not first FindNext call then...
    If Next_Count <> 0 Then
        Search_StartIndex += SearchText.Length
    Else ' If is first FindNext call then...
        Next_Count += 1
    End If

    ' Set Search_StartIndex
    Search_StartIndex = _
    [Control].Find(SearchText, Search_StartIndex, RichTextBoxFinds.NoHighlight Or RichTextBoxFinds.None)
    ' ...And prevent search at End Of File
    If Search_StartIndex = -1 Then
        Search_StartIndex = _
        [Control].Find(SearchText, 0, RichTextBoxFinds.NoHighlight Or RichTextBoxFinds.None)
    End If

    ' Set the match selection
    [Control].Select(Search_StartIndex, SearchText.Length)
    ' Set the BackColor
    [Control].SelectionBackColor = Highlight_BackColor
    ' Set the ForeColor
    [Control].SelectionColor = Highlight_ForeColor
    ' Scroll to Caret/Cursor position
    [Control].ScrollToCaret()

End Sub

#End Region

如何编写“查找上一个”功能？

我想我可以使用 RegEx MatchCollection 通过移动集合的当前 RegEx 匹配索引来轻松添加“查找下一个”或“查找上一个”，但是 regex 很慢，我还有其他使用简单字符串搜索的替代方法吗？

Answer 1

我终于可以自己完成了，是的，它使用了正则表达式：

http://www.youtube.com/watch?v=mWRMdlC5DH8

#Region " [RichTextBox] FindNext "

    ' [ FindNext ]
    '
    ' //By Elektro H@cker
    '
    ' Examples :
    '
    ' RichTextBox1.Text = "Hello World!, Hello World!, Hello World!"
    '
    ' FindNext(RichTextBox1, "hello", FindDirection.Down, RegexOptions.IgnoreCase, Color.LightBlue, Color.Black)
    ' FindNext(RichTextBox1, "hello", FindDirection.Up, RegexOptions.IgnoreCase, Color.Red, Color.Black)
    '
    ' Private Sub RichTextBox_Enter(sender As Object, e As EventArgs) ' Handles RichTextBox1.Enter
    '    ' Restore Selection Colors before search next match.
    '    sender.SelectionBackColor = DefaultBackColor
    '    sender.SelectionColor = DefaultForeColor
    ' End Sub

    Public Enum FindDirection As Short
        Up = 0
        Down = 1
    End Enum

    ' FindNext
    Private Sub FindNext(ByVal [Control] As RichTextBox, _
                               ByVal SearchText As String, _
                               ByVal Direction As FindDirection, _
                               Optional ByVal IgnoreCase As System.Text.RegularExpressions.RegexOptions = RegexOptions.None, _
                               Optional ByVal Highlight_BackColor As Color = Nothing, _
                               Optional ByVal Highlight_ForeColor As Color = Nothing)

        If [Control].TextLength = 0 Then Exit Sub

        ' Start searching at 'SelectionStart'.
        Dim Search_StartIndex As Integer = [Control].SelectionStart

        ' Stores the MatchIndex count
        Dim matchIndex As Integer = 0

        ' Flag to check if it's first find call
        Static First_Find As Boolean = True

        ' Checks to don't ommit the selection of first match if match index is exactly at 0 start point.
        If First_Find _
            AndAlso Search_StartIndex = 0 _
            AndAlso Direction = FindDirection.Down Then
            Search_StartIndex = -1
            First_Find = False
        ElseIf Not First_Find _
            AndAlso Search_StartIndex = 0 _
            AndAlso Direction = FindDirection.Down Then
            First_Find = False
            Search_StartIndex = 0
        End If

        ' Store the matches
        Dim matches As System.Text.RegularExpressions.MatchCollection = _
            System.Text.RegularExpressions.Regex.Matches([Control].Text, _
                                                         SearchText, _
                                                         IgnoreCase Or If(Direction = FindDirection.Up, _
                                                                          RegexOptions.RightToLeft, _
                                                                          RegexOptions.None))

        If matches.Count = 0 Then First_Find = True : Exit Sub

        ' Restore Highlight colors of previous selection
        [Control].SelectionBackColor = [Control].BackColor
        [Control].SelectionColor = [Control].ForeColor

        ' Set next selection Highlight colors
        If Highlight_BackColor = Nothing Then Highlight_BackColor = [Control].BackColor
        If Highlight_ForeColor = Nothing Then Highlight_ForeColor = [Control].ForeColor

        ' Set the match selection
        For Each match As System.Text.RegularExpressions.Match In matches

            matchIndex += 1

            Select Case Direction

                Case FindDirection.Down
                    If match.Index > Search_StartIndex Then ' Select next match
                        [Control].Select(match.Index, match.Length)
                        Exit For
                    ElseIf match.Index <= Search_StartIndex _
                    AndAlso matchIndex = matches.Count Then ' Select first match
                        [Control].Select(matches.Item(0).Index, matches.Item(0).Length)
                        Exit For
                    End If

                Case FindDirection.Up
                    If match.Index < Search_StartIndex Then ' Select previous match
                        [Control].Select(match.Index, match.Length)
                        Exit For
                    ElseIf match.Index >= Search_StartIndex _
                    AndAlso matchIndex = matches.Count Then ' Select last match
                        [Control].Select(matches.Item(0).Index, matches.Item(0).Length)
                        Exit For
                    End If

            End Select

        Next match

        ' Set the current selection BackColor
        [Control].SelectionBackColor = Highlight_BackColor
        ' Set the current selection ForeColor
        [Control].SelectionColor = Highlight_ForeColor
        ' Scroll to Caret/Cursor selection position
        [Control].ScrollToCaret()

    End Sub

#End Region