by Austin Leo Chambers (1 Submission)
Category: Custom Controls/Forms/Menus
Compatability: VB 6.0
Difficulty: Unknown Difficulty
Originally Published: Wed 23rd July 2003
Date Added: Mon 8th February 2021
Rating: 
(1 Votes)
Super fast append to a RichTextBox control. As the RichTextBox gets larger, the traditional append operation gets slower. This code
VBcoders
' to use the RichTextBox because of the darn 64K character limit in the
' TextBox. My task was to find a fast and practical way to append
' strings to a RichTextBox.
'
'Author: Austin Leo Chambers (2003)
'This function represents the "brute force" way of writing to a text box.
' Accordingly, it is quite slow. On the Microsoft performance chart,
' %Processor Time quickly rose as the RichTextBox got large. Setting
' a timer to execute this code every 50ms quickly demanded massive
' CPU time.
Public Sub AddStringSlowest(YourString As String)
RichTextBox1.Text = RichTextBox1.Text & YourString & vbCrLf
End Sub
'On the Microsoft performance chart, this subroutine did not raise
' %Processor Time as quickly as the previous. However, the
' RichTextBox again began to gradually demand more CPU time
' as the RichTextBox got larger. Setting a timer to execute
' this code every 50ms made this program gradually require
' more and more CPU time. Eventually, this subroutine began
' to take unreasonably long.
'
'I believe this is due to the Len function. As the RichTextBox
' gets larger, the Len function has to do more work.
Public Sub AddStringSlow(YourString As String)
RichTextBox1.SelStart = Len(RichTextBox.Text)
RichTextBox1.SelText = YourString & vbCrLf
End Sub
'Taking advantage of the fact that "Setting SelStart greater than the
' text length sets the property to the existing text length," I decided
' to replace the Len statement with a constant.
'
'The following code does not demand more CPU time as the RichTextBox
' increases in size. In fact, A timer to execute this code every
' 50ms had %Processor Time remain at 0-1%, and it stayed at 0-1%
'This is the fastest way to append text to a RichTextBox, making it
' essentially as practical as a textbox, but without the annoying 64K
' limitation.
Public Sub AddStringFastest(YourString As String)
RichTextBox1.SelStart = 2000000000
RichTextBox1.SelText = YourString & vbCrLf
End Sub
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