如何根据字符串的前缀为 RichTextBox 的文本着色？

Question

我想为richtextbox 中的所有字符串着色。例如，如果特定字符串的前缀是

1. Received: 那么它应该是蓝色的
2. Send: 那么它应该是红色的
3. Info: 那么它应该是绿色的

*The way I output the text in the RichTextBox is by ascending order, it means that all the newest messages will be outputted at the top of the RichTextBox, the old ones will go down.

截图：

代码：

Public Class Form1
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

        Dim msg_info As String = Nothing

        If RB_Info.Checked = True Then
            msg_info = "Info: "
        End If
        If RB_Send.Checked = True Then
            msg_info = "Send: "
        End If
        If RB_Received.Checked = True Then
            msg_info = "Received: "
        End If

        RichTextBox1.Text = RichTextBox1.Text.Insert(0, msg_info & TextBox1.Text & ControlChars.NewLine)
    End Sub
End Class

编辑：我试过应用这个子，但它改变了 ListBox 中所有项目的颜色

Sub HighlightPhrase(box As RichTextBox, phrase As String, color As Color)
        Dim pos As Integer = box.SelectionStart
        Dim s As String = box.Text
        Dim ix As Integer = 0
        While True
            Dim jx As Integer = s.IndexOf(phrase, ix, StringComparison.CurrentCultureIgnoreCase)
            If jx < 0 Then
                Exit While
            End If
            box.SelectionStart = jx
            box.SelectionLength = phrase.Length
            box.SelectionColor = color
            ix = jx + 1
        End While
        box.SelectionStart = pos
        box.SelectionLength = 0
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim msg_info As String = Nothing

        If RB_Info.Checked = True Then
            msg_info = "Info: "
            HighlightPhrase(RichTextBox1, "Info", Color.Blue)
        End If
        If RB_Send.Checked = True Then
            msg_info = "Send: "
            HighlightPhrase(RichTextBox1, "Send", Color.Green)
        End If
        If RB_Received.Checked = True Then
            msg_info = "Received: "
            HighlightPhrase(RichTextBox1, "Received", Color.Red)
        End If
        RichTextBox1.Text = RichTextBox1.Text.Insert(0, msg_info & TextBox1.Text & ControlChars.NewLine)
    End Sub

Answer 1

我已经编辑了我的解决方案，所以新行出现在 RichTextBox 的顶部。

我认为我的解决方案很难看，因为基本上它会在添加新行后重新绘制每行的颜色。想象一下，如果 RichTextBox 有数千行。我认为您可以通过限制 RTB 中的行数（例如 100 行）来最小化这种情况。

Public Class Form1

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

        Dim msg_info As String = Nothing

        If RB_Info.Checked = True Then
            msg_info = "Info: "
        End If
        If RB_Send.Checked = True Then
            msg_info = "Send: "
        End If
        If RB_Received.Checked = True Then
            msg_info = "Received: "
        End If

        RichTextBox1.Text = RichTextBox1.Text.Insert(0, msg_info & TextBox1.Text & ControlChars.NewLine)
        ChangeColor()

    End Sub

    Private Sub ChangeColor()

        Dim lines = RichTextBox1.Text.Split(vbLf)
        Dim startPos As Integer, endPos As Integer = -1
        Dim myColor As Color

        For i = 0 To lines.Length - 2 ' minus 2 because the last one is empty string
            startPos = endPos + 1
            endPos = startPos + lines(i).Length
            RichTextBox1.Select(startPos, endPos)

            If lines(i).StartsWith("Info: ") Then myColor = Color.Red
            If lines(i).StartsWith("Send: ") Then myColor = Color.Blue
            If lines(i).StartsWith("Received: ") Then myColor = Color.Green

            RichTextBox1.SelectionColor = myColor
        Next

    End Sub

End Class

使用 ListView 的替代解决方案

您可能想查看 ListView 控件。如果您不想在列表中写任何内容，我建议您将 RichTextBox 替换为 ListView。添加 ListView 后，将 View 属性更改为 List。

Public Class Form1

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click

        Dim msg_info As String = Nothing
        Dim myColor As Color

        If RB_Info.Checked = True Then
            msg_info = "Info: "
            myColor = Color.Green
        End If
        If RB_Send.Checked = True Then
            msg_info = "Send: "
            myColor = Color.Red
        End If
        If RB_Received.Checked = True Then
            msg_info = "Received: "
            myColor = Color.Blue
        End If

        Dim li = New ListViewItem()
        li.ForeColor = myColor
        li.Text = msg_info & TextBox1.Text
        ListView1.Items.Insert(0, li)

    End Sub

End Class