FotS

lineedit.bas.v2.zip lineedit.bas.v3.zip lineedit.bas.zip

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