Scrolling a field

[MaxV]

Hello,
I need to scroll a field to a specified line number, since all lines have different heights, I can't use vscroll property, and hilitedline doesn't work.
What property should I use?

[jmburnod]

Hi Max,
Just an idea.
If it possible to use a "find in fld" command, LC sets automaticaly the vScroll
Best regards
Jean-Marc

[dunbarx]

Hi.

Very interesting.

Jean-Marc's idea works to a point, but in a test I made, the foundLine always appears as the third line in the scrolled field (LC 6.5). If the foundText is within the visible portion of the top "screen" of the field, it simple boxes that text of course.

I made a small scrolling test field, about 150 pixels tall, with a few dozen lines in it and ran this:

Code: Select all

on mouseUp
   repeat with y = 1 to the number of lines of fld 1
      set the textSize of line y of fld 1 to random(20) + 6
   end repeat
end mouseUp

So when finding a line of text low down in the field, the boxed foundLine is always the third line showing. I am sure this can be used to advantage, since the textHeight of the two lines above the foundLine are known, and the scroll of the field is known after the find (pseudo):

Code: Select all

find the text
put the scroll of the field into tScroll
put the sum of the textHeights of the two lines above the foundLine into tOffset
set the scroll of the field to tScroll - tOffset

But this seems clunky, even as kluges go, and I am not sure how reliable that third line thingie is. Anyone can make this work, but is there a more grown-up way to set the scroll to so the foundline is always at the top?

Craig Newman

[jacque]

Try "select line x of fld y"

[dunbarx]

This works, sort of:

Code: Select all

on mouseUp
   repeat with y = 1 to the number of lines of fld 1
      put y && the textsize of line y of fld 1 into line y of tData
   end repeat
   ask "what line # ?"
   put it into tLine
   repeat with y = 1 to tLine
      add word 2 of line y of tData to tScroll
   end repeat
   set the scroll of fld 1 to  tScroll
end mouseUp

Jacque, selecting a line does not bring it to the top. And the above does not quite work, since the scroll is not well set. An array would be more compact. We need another way, or a new property, "the scrollLine"

Craig

[MaxV]

Ok, I get this idea, it works, but it can be very improved. Image to reach the X line:

########CODE#######
#14 is the standard line height
put 0 into totv
repeat with i=1 to x
put the textSize of line i of field 1 into temp
if temp is empty or temp is "mixed" then
put 14 into temp
end if
put totv + temp into totv
end repeat
put totv - (the height of field 1) into totv
if totv > 0 then
set the vscroll of field 1 to totv
end if
#####END OF CODE#####

[dunbarx]

Hi.

I guess that "x" is the line number sought?

This still places the line at the bottom. And still has my issue, the scroll is not well set.

Craig

[jacque]

I'll test it when I get back to my Mac, but I'm pretty sure select used to work. If not, get the formattedheight of line 1 to x and use that.

[dunbarx]

Jacque.

It seems that if the scroll starts out less than the desired scroll, the selectedLine is set at the bottom of the field. If greater, the scroll is set at the top. If in the middle, no movement.

Craig

[jacque]

If the field has listbehavior, this seems to work:

Code: Select all

on doScroll pNum
  put the formattedheight of line 1 to pNum of fld 1 into tScroll
  set the scroll of fld 1 to tScroll -- can overshoot a bit
  set the hilitedline of fld 1 to pNum -- corrects it
end doScroll

[dunbarx]

Yes, list behavior seems to possess its own discipline, greater than in ordinary fields.

I do not know if there is enough interest, assuming a reliable method is not forthcoming, to propose a new property, like "scrollLine", or whatever. Oddly, in the use-list, a very similar question came up just today.
I only threw together a solution because I was more interested in the fact that setting the selectedLine (and the scroll) works differently depending on the current scroll setting, whether greater or less than the desired value. So there are a couple of ancillary issues that are open right now...

Craig

[jameshale]

To scroll a field so that a desired line (line linenum) sits at the top of the field I use the following:

Code: Select all

 
   set the lockscreen to true
   --scroll section to line linenum where "linenum is the number of the line 
   --to sit at the top of the field
   select line  -1 of  field "TextToScroll"
   select line linenum of  field "TextToScroll" 
   set the lockscreen to false

[MaxV]

Good idea Jacque & jameshale!
I use this now:

########CODE#######
put the formattedheight of line 1 to X of field "testo" into totv
put totv - (the formattedHeight of line X of field "testo") into totv
set the vscroll of field "testo" to totv
#####END OF CODE#####

[dunbarx]

Hi.

The OP wanted to set the top of the visible field by finding text in that field, and to boot, the textSize of each line was different. The trick is to finely tune that. Try this. Make a new field, fairly small. In a button:

Code: Select all

on mouseUp
   lock screen
   repeat with y = 1 to 100
      put y into line y of last fld
      set the textSize of line y of last fld to random(20) + 6
   end repeat
   
   find "55" in last fld
   put word 2 of the foundLine into tLine
      --scroll section to line linenum where "linenum is the number of the line 
      --to sit at the top of the field
      select line  -1 of  last field 
      select line tLine of  last field 
      set the lockscreen to false
end mouseUp

Some of your stuff, some other stuff. Thoughts?

Craig

[mdoub]

A few of the solutions in the thread don't take into account a bug in livecode where the spaceabove and space below properties are not taken into account. Specifically (put the formattedHeight of line 1 to tLOS of fld 1 into tScroll) is a problem and it has been reported.

Here is my generalized solution to position a line at the top, center or bottom of a field.

Code: Select all

on __positionLineinFld  pline, obj, pWhere
   /* __positionLineinFld Fields
   Syntax:
   __positionLineinFld linenbr,long_ID_of_Field,["Top"\"Center"\"Bottom"]
   Examples:
   __positionLineinFld 20,the long ID of fld "foo"
   __positionLineinFld 20,the long ID of fld "foo", "Center"
   Description:
   Sets the scroll of a field so the line specified is in the specifed 
   location within the visiable field.  Both fixed and non-fixed line 
   heights are supported.
   Source:
   Michael Doub with a special thanks to James Hale for his help.
   __positionLineinFld */
   set the lockscreen to true
   put the height of obj  into tFieldHeight
   
   put 0 into tScroll
   if pline > 1 then
      repeat with x = 1 to pLine
         --         put x,\
         --         the spacebelow of line x-1 of obj,\
         --         the spaceabove of line x of obj ,\
         --         the formattedheight of line x of obj,\
         --         tScroll & return after msg
         Add the spacebelow of line x-1 of obj to tScroll
         Add the spaceabove of line x of obj to tScroll
         Add the formattedheight of line x of obj to tScroll
      end repeat
   else
      set the vscroll of obj to 0
   end if
   
   switch pWhere
      case "Top"
         subtract the formattedheight of line pline of obj from tScroll
         break
      case "Center"
         subtract  (tFieldHeight / 2) from tScroll
         subtract (the formattedheight of line pline of obj /2) from tScroll
         subtract the spaceabove  of line pline of obj  from tScroll
         add the topmargin of obj to tScroll
         break
      case "Bottom"
         subtract the formattedheight of line pline of obj from tScroll
         -- tScroll  is now the top of the line
         select line  -1 of  obj
         select line pLine of  obj
         select empty
         put the scroll of obj into bScroll -- this is the top of the last  wrapped line
         put the formattedheight of line pline of obj -(bScroll - tScroll) into lastLineHeight
         Add lastLineHeight to bScroll
         subtract tFieldHeight from bScroll
         add the bottommargin of obj to bScroll
         set the vscroll of obj  to trunc(bScroll)
         put bScroll into tScroll
         break
      default
         put tScroll - the formattedheight of line pline of obj  into tScroll
   end switch
   set the vscroll of obj  to trunc(tScroll)
   -- put the  vscroll of obj after msg
   set the lockscreen to false
end __positionLineinFld