[RESOLVED] Rich Text Box : .txt file display upon loading / updating

[camoore]

A RTB is being used to load and display a text file. Then extra lines are written to the RTB (at the end) by the program. Finally the updated content of the RTB is written back into the source file. So far so good, it works perfectly.

The simple query is how to make the content of the RTB constantly scroll up as each new line is added - thus the bottom of the RTB would always show the last line which has been added (ie. the end of the text) At present each time the RTB content is updated the first line of content is at the top of the RTB, but the last (latest) line is way below the bottom. It can be found using the vertical scrollbar, but as soon as the program updates the RTB it reverts to the "standard" display of first line at the top.

I would appreciate any suggestion, or pointer to where to read up on this. I tried MSDN but without success.

camoore

Wales, UK

[Hack]

You will need to play around with the actual scrolling part.

Option Explicit

Private Declare Function SendMessage Lib "user32" Alias _
"SendMessageA" _
(ByVal hwnd As Long, _
ByVal wMsg As Long, _
ByVal wParam As Long, _
lParam As Any) As Long 

Private Const EM_LINESCROLL = &HB6

Private lScroll As Long
Private lLines As Long

'put this in an appropriate spot in your code that loads the richtextbox line by line
lScroll = SendMessage(RichTextBox1.hWnd, EM_LINESCROLL, 0, ByVal lLines)

You will also need to play around with lLines. For a first run set it to 1 (so it scrolls one line), but you may want to increase that.

[camoore]

Thank you Hack. I have tried this routine, but it does not work for me. However it does not produce any errors either. The program continues to work as before - I update the RTB and it goes back to displaying the first line, not the last (most recent).

The code works like this :

ASTRINGVAR = Richtextbox1.text 'sets ASTRINGVAR to content of RTB1

ASTRINGVAR = ASTRINGVAR & "*************************" & Chr(13)'add new line

'the program determines what "*************************" should be

Richtextbox1.text = ASTRINGVAR

At each iteration, it follows that RTB1 gets more and more full until the latter part of ASTRINGVAR is no longer visible in the RTB, because it is bigger than the RTB size limit.

So the problem is how somehow to make the RTB load ASTRINGVAR "back to front" such that the last line of it is visible (and preceeding lines) but only to the extent of the capacity of the RTB. At runtime I only want to see the last few lines of the data, including the latest entered.

Can you please advise where/how in this code I should enter the final line of your suggestion.

camoore

Wales, UK

[dee-u]

Why don't you parse your ASTRINGVAR and retrieve only the last lines and show it in the RichTextBox? You can use MID$ or RIGHT$, or perhaps SPLIT if you want.

[westconn1]

in the richtext box change event you can set the selstart to the end

rtb.selstart = len(rtb.text)

[dee-u]

Instead of appending the values to a variable can you try appending it directly to the RichTextBox if it makes any difference?

RichTextBox1.SelStart = Len(RichTextBox1.Text)
RichTextBox1.SelText vbNewLine & "*************************"

[camoore]

Thank you as always for such rapid replies.

The approach I followed was that suggested by dee-u, which also occurred to me a few hours after my last post. This works very well (ie. just parse out the last **** characters and display only these in RTB1).

A problem was that I needed to save the entire data file, each time it was re-written, to a source .txt file. For that I needed the whole file to be in a RTB. so as to be able to use the savefile.path,rtf text routine.

The simple solution was to create a second (physically tiny) hidden Rich Text Box (RTB2). I write the Mid$ parsed end of string data (last 1000 characters in this case) into the main RT box (1) for display to user and the whole of the data into a hidden RT box (2). Then it is from the hidden RT (2) box that the source file.txt is updated each time.

For information, the application is a tidegauge. RS232 data is received via a MSCOMM and parsed into its constituent elements. Every 30 seconds, or so, these elements are to be logged into a .txt file serving as a database. Those parsed elements are contained in Texts 15,14,53,2 and 51.

Code follows :


Dim PATH as String

Path = C:\SPEEDPLOTTIDEDATA.txt

Dim SPEEDPLOTTIDEDATA as STRING 'current value of .txt file (data file)

Dim DATASTRINGLEN as Single 'will be length of SPEEDPLOTTIDEDATA


'(Note below that Text 15, 14, 53, 2, 51 are updated data values in the program).

SPEEDPLOTTIDEDATA = SPEEDPLOTTIDEDATA & "#DATA, DATE:" & Text15 & ", TIME:" & Text14

SPEEDPLOTTIDEDATA = SPEEDPLOTTIDEDATA & ", SPEED:" & Text53 & ", DEPTH:" & Text2

SPEEDPLOTTIDEDATA = SPEEDPLOTTIDEDATA & ", TEMP(C):" & Text51 & "$" & Chr(13) & Chr(13)

DATASTRINGLEN = Len(SPEEDPLOTTIDEDATA)

Dim CHARNUM As Single

Dim CHARNUM1 As Single

CHARNUM1 = DATASTRINGLEN

CHARNUM = (CHARNUM1 - 1000) '1000 characters may be displayed in the current size of RTB 1

If CHARNUM < 1 Then CHARNUM = 1 'this to avoid errors if Charnum <1

RichTextBox1 = Mid$(SPEEDPLOTTIDEDATA, CHARNUM, CHARNUM1)

RichTextBox2.Text = SPEEDPLOTTIDEDATA

PATH = "C:\SPEEDPLOTTIDEDATA.txt"

RichTextBox2.SaveFile PATH, rtfText 'save the RT Box (2) content back to the source file

'end of illustrative program



Thanks to all, I will mark thread resolved.


camoore

Wales. UK

[dee-u]

Glad to be of help. =)