String editing on-screen for VT compatible Terminals

Modified on 2020/07/13 17:31 by CaptainBoing — Categorized as: Console, Dates, Time and Clocks, Program Flow, Strings

StrEdit$() allows the user to edit (or enter - start with "") a string at a given position in a terminal window and constrained to a specified length. It is a more intelligent version of Input in that it performs the same function but is non-blocking (with Input, your program loses control while it waits for the user), limits the amount of data, provides nice editing and nice displays reminiscent of the 80s & 90s terminal based input.

Your terminal emulator must be VT compliant to understand the ANSI codes (I use PuTTY)

Dependancies

Option Base 0

LTrim and RTRIM Functions (VB work-a-like) or the equivalent LTrim RTrim CFunctions (note this latter does not treat TABs as white-space and so are not trimmed).

VT Console Pack. Screen Positioning, Sane Key Scanning And a String Editing Routine

Example Usage
MyDT$=StrEdit$(MyDT$,10,10,8)

	'Edit the string at the position given limited to q characters long
	Function StrEdit$(l$,h As Integer,v As Integer,q As Integer)
		Local x$,a$
		a$=RTrim$(Left$(l$,q))
		SStr a$,h,v

		Do
			Do:x$=VTKey$():Loop Until x$<>""
			If Len(x$)=1 Then
				Select Case Asc(x$)
					Case 32 To 126
						If Len(a$)<q Then a$=a$+x$:SStr a$,h,v
					Case 127,8
						If Len(a$) Then
							a$=Left$(a$,Len(a$)-1):SStr a$,h,v
						EndIf
					Case 13
						StrEdit$=a$:Exit Function
					Case Else
						'ignore
				End Select
			Else
				If x$="_DL" Then
					If Len(a$) Then
						a$=Left$(a$,Len(a$)-1):SStr a$,h,v
					EndIf
				EndIf
			EndIf
		Loop
	End Function

	Sub SStr(a$,h As Integer, v As Integer)' support Sub for StrEdit$()
		Print At(h,v);a$;" ";:Print At(h,v);a$;
	End Sub