Limiting nbr. of characters in a 'field'

[jfdutcher]

In wanting to guarantee the maximum number of characters enterable into a 'field' style....I think there is no 'facet' that does so. I note that I might use the 'size-text' function whose 'x' value seems to grow in proportion
to the number of characters entered....
length? seems to be for series...when I convert the 'field' content using 'form' I seem to get the same value rerturned no matter how many characters are in the 'field'.

i.e. : print [length? form num1]     ** num1 is a 'field'

I'm sure there is a better and easier way ??

[CarlRead]

size-text measures the length and height of the pixels used by a string and so isn't any use to measure the number of characters in one.  Example from the console...

>> layout [t: text "abc"] size-text t
== 22x15
>> layout [t: text "123"] size-text t
== 23x15

length? is the right word to use as a string, like blocks and many other REBOL datatypes is a series...

>> series? "a"
== true

See?  :-)

One way to restrict what you can fit in a field is to have a focus face in its block.  A quick example...

Code:

view layout [
   field [
       if 4 <> length? face/text [
           focus face
           system/view/caret
           system/view/highlight-start:
           system/view/highlight-end:
           tail system/view/caret
           show face
       ]
   ]
   field
]

The extra code there controls the block-marking of the text .  (Play with it to get the effect you'd like.)  There, you're restricted to 4 characters in the first field.

(Sorry - a rushed post - supposed to be somewhere;)

[Gabriele]

i.e. : print [length? form num1]     ** num1 is a 'field'
 

What about print length? num1/text ?

[jfdutcher]

Thanks all....progress is being made.

Gabriele,     print [length? num1/text]
works well.

I'm surprised that print [length? face/text]  does  not,
as it seems as though the face being passed to the
function IS  num1 (or num2, or num3  etc.)

Carl,
   The sample view adds new understanding...I tried running it...didn't seem to limit the entry of characters.

I could test all (6) fields (num1, num2, num3..etc.) after
each keystroke...but that's hardly efficient. I assume
that even though at the moment the
  print [length? face/text]  fails i.e. requires a field name
     as noted above.....
there is a way to recognize which
of the (6) faces  is being processed at the moment when
the keystroke enters the function.
Again, I assumed that would be 'the face' in the argument block of 'key-event'......yet only the global
field name seems to satisfy the 'length?' function now.  

[Gabriele]

face in the event func you mean? That's the window, not the field. Event functions are processed at the point where the event has not reached the field face yet.