The LineEdit function defined in the attached LINEEDIT.BAS is an MMBasic 4.5 function to edit lines of text or even pages of text, as these five examples demonstrate:
'
' Edit a string until ENTER with LineEdit:
'
Sub Example1
a$ = "text to edit"
Do: k = LineEdit(a$): Loop Until k = 13 ' until ENTER
End Sub
'
' Edit a string until ENTER or ESC with ESC to restore the old string value:
'
Sub Example2
a$ = "text to edit"
b$ = a$ ' save old string value
Do: k = LineEdit(a$): Loop Until k = 13 Or k = 27 ' until ENTER or ESC
If k = 27 Then ' ESC pressed
Print b$;
If Len(a$) > Len(b$) Then Print Space$(Len(a$) - Len(b$));
a$ = b$ ' restore old value on ESC
EndIf
End Sub'
' Interactive editing of 10 lines with up/down screen navigation:
'
Sub Example3
Local a$(10) length 40
Cls
Print "Tiny edit | ESC to quit"
For row = 1 To 10
Print @(0,12*row) a$(row);Tab(11);"|"
Next row
row = 1 ' first row to edit
cur = 0 ' cursor at begin of the line
max = 40 ' max size of a$()
win = 10 ' edit in window of 10 chars
Do
Print @(0,12*row); ' place cursor where we want to edit the line
k = LineEdit(a$(row), cur, -1, max, win) ' -1: get next key press
If k = 128 Then
If row > 1 Then row = row - 1 ' UP key: move up
ElseIf k = 13 Or k = 129 Then
If row < 10 Then row = row + 1 ' DOWN key: move down
EndIf
Print @(0,132) "row:";row;" col:";cur;" key:";k;" ";
Loop Until k = 27 ' until ESC
End Sub'
' Interactive editing with screen navigation while continuously updating the screen with the current time:
'
Sub Example4
Local a$(10) length 120
Cls
Print " | Editor | ESC to quit"
For row = 1 To 10
Print @(0,12*row) a$(row);
Next row
row = 1 ' first row to edit
cur = 0 ' cursor at begin of the line
max = 120 ' max size of a$()
win = MM.HRes/6 ' edit in window up to window width
' show cursor
Font 1,,1: Print @(0,12*row) Mid$(a$(row)+" ", 1, 1);Chr$(8);: Font 1,,0
Do
Print @(0,0) Time$; ' continuously show the current time
k = Asc(Inkey$)
If k Then
Print @(0,12*row);
k = LineEdit(a$(row), cur, k, max, win) ' pass in key to edit line
If k = 128 Then ' UP key: move up
If row > 1 Then row = row - 1
Font 1,,1: Print @(0,12*row) Mid$(a$(row)+" ", 1, 1);Chr$(8);: Font 1,,0
cur = 0
ElseIf k = 13 Or k = 129 Then ' DOWN key: move down
If row < 10 Then row = row + 1
Font 1,,1: Print @(0,12*row) Mid$(a$(row)+" ", 1, 1);Chr$(8);: Font 1,,0
cur = 0
EndIf
EndIf
Loop Until k = 27 ' until ESC
End Sub'
' Edit a string of digits, masking key presses to digits
'
Sub Example5
a$ = "1234"
Font 1,,1: Print Mid$(a$, 1, 1);: Font 1,,0: Print Mid$(a$, 2);Chr$(13);
Do
k = Asc(Inkey$)
If k Then
If k < 32 Or k > 126 Or Instr("0123456789", Chr$(k)) Then
k = LineEdit(a$, cur, k)
EndIf
EndIf
Loop Until k = 13 Or k = 27 ' until ENTER or ESC
End Sub
Source code of LineEdit:
' LineEdit(a$, [cur [, key [, max [, win ]]]]) edit string a$ at position cur,
' use key parameter (when provided) to make the next edit of a$ and update cur, and
' return new key press, or if key press not provided (zero) keep editing until
' ESC, ENTER or special key such as F1, UP/DOWN etc. where max is the maximum
' string length and win is the "window" size. Use LEFT/RIGHT/HOME/END to
' navigate the line, BACKSPACE/DEL to delete a character.
'
' Supports three editing modes: key=0 (default) edit until ENTER or other
' special key, key=-1 wait for key and make one edit, returning the key value,
' key=X to pass a key press to LineEdit to make one edit, returning the key
' value.
'
' Curser position cur parameter is passed in and updated by LineEdit
'
' Use the max parameter when the string has a maximum length smaller than 255
'
' To edit within a smaller window, use the win parameter
'
Function LineEdit(a$, cur, key, max, win)
Local x, y, size, from, done
x = MM.HPos: y = MM.VPos
If max <= 0 Then max = 255
If win <= 0 Then win = 255
size = Len(a$)
If cur < 0 Then
cur = 0
ElseIf cur > size Then
cur = size
EndIf
done = key
Do
If key >= 32 And key < 127 Then
If size < max Then
a$ = Left$(a$, cur) + Chr$(key) + Mid$(a$, cur + 1)
cur = cur + 1
size = size + 1
EndIf
ElseIf key = 8 Then
If cur > 0 Then
cur = cur - 1
a$ = Left$(a$, cur) + Mid$(a$, cur + 2)
size = size - 1
EndIf
ElseIf key = 127 Then
If cur < size Then
a$ = Left$(a$, cur) + Mid$(a$, cur + 2)
size = size - 1
EndIf
ElseIf key = 130 Then
If cur > 0 Then cur = cur - 1
ElseIf key = 131 Then
If cur < size Then cur = cur + 1
ElseIf key = 134 Then
cur = 0
ElseIf key = 135 Then
cur = size
ElseIf key > 0 Then
' done editing, so print a clean line
Print @(x,y) Left$(a$, win);
' remove the cursor from the end of the line
If cur = size And size < win Then Print " ";
Exit
EndIf
' cursor cannot move beyond string max length
If cur >= max Then cur = max - 1
' cursor is offset from window start
If cur >= win Then from = cur - win + 2 Else from = 1
If cur = size Then
' print the line constrained to the window size
Print @(x,y) Mid$(a$, from);
' put the cursor at the end
Font 1,,1: Print " ";: Font 1,,0
' BACKSPACE may require removing the cursor from the end of the line
If key = 8 Then
If cur + 1 < win And size < win Then Print " ";
EndIf
Else
' print the line constrained to window size
Print @(x,y) Mid$(a$, from, cur - from + 1);
' invert character at the cursor
Font 1,,1: Print Mid$(a$, cur + 1, 1);: Font 1,,0
' print the rest of the line
Print Mid$(a$, cur + 2, win - cur + from - 2);
If cur < win And size < win Then Print " ";
EndIf
' if this is a non-blocking call then exit
If done > 0 Then Exit
' wait on key press
Do: key = Asc(Inkey$): Loop Until key
done = -done
Loop
' move cursor back to the start of the line before returning
Print @(x,y);
LineEdit = key
End Function