Getting width of Tk text widget via tcltk

8 messages · John Fox, Brian Ripley, Peter Dalgaard

Original

1

8

John Fox

Mon, Feb 28, 2005 7:05 AM #

Dear list members,

Is it possible via a suitable tcltk command to get the *current* width, in
characters, of a Tk text widget that has been resized with the mouse? In the
following code, the reported width of the text widget doesn't change, even
though it has been resized. I can, however, get the current width in pixels:

<Tcl>

<Tcl>

<Tcl>

<Tcl> 80

<Tcl> 486

<Tcl> 80

<Tcl> 743 

I could convert pixels to characters, but wonder whether I can get the
latter directly.

Any help would be appreciated.

John

--------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario
Canada L8S 4M4
905-525-9140x23604
http://socserv.mcmaster.ca/jfox

Brian Ripley

Mon, Feb 28, 2005 7:25 AM #

On Mon, 28 Feb 2005, John Fox wrote:

I suspect you may have some difficulty with the latter, even in a 
monospace font.  Notice that 486 is not a multiple of 80, and if that is 
actually 81, 743 is not a multiple of 6.

I was trying to do this with heights for a listbox a few days ago, and it 
seems that the line spacing is actually 1 pixel greater than is reported. 
Since you can resize to a non-integer number of lines I don't believe (and 
I tried to read the source code) that Tcl/Tk works internally with 
characters.

Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

John Fox

Mon, Feb 28, 2005 7:41 AM #

Dear Brian,

As you guessed, I am using a monospaced font. I'll try the equivalent of
floor(743/(486/(80 + 1))) and see whether it's reliable. In particular,
thanks for the tip about the additional character (perhaps due to Tcl
0-based indexing?) -- a bit of experimentation shows that it's consistently
true.

Regards,
 John

--------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario
Canada L8S 4M4
905-525-9140x23604
http://socserv.mcmaster.ca/jfox 
--------------------------------

-----Original Message-----
From: Prof Brian Ripley [mailto:ripley@stats.ox.ac.uk] 
Sent: Monday, February 28, 2005 9:25 AM
To: John Fox
Cc: r-devel@stat.math.ethz.ch
Subject: Re: [Rd] Getting width of Tk text widget via tcltk

On Mon, 28 Feb 2005, John Fox wrote:

Dear list members,

Is it possible via a suitable tcltk command to get the *current* 
width, in characters, of a Tk text widget that has been

resized with

the mouse? In the following code, the reported width of the text 
widget doesn't change, even though it has been resized. I

can, however, get the current width in pixels:

library(tcltk)
top <- tktoplevel()
textWindow <- tktext(top, bg="white", height=20, width=80, 
wrap="none") tkgrid(textWindow, sticky="news")

<Tcl>

tkgrid.rowconfigure(top, 0, weight=1)

<Tcl>

tkgrid.columnconfigure(top, 0, weight=1)

<Tcl>

tkcget(textWindow, width=NULL)

<Tcl> 80

tkwinfo("width", textWindow$ID)

<Tcl> 486

# resize window with mouse
tkcget(textWindow, width=NULL)

<Tcl> 80

tkwinfo("width", textWindow$ID)

<Tcl> 743

I could convert pixels to characters, but wonder whether I

can get the

latter directly.

I suspect you may have some difficulty with the latter, even 
in a monospace font.  Notice that 486 is not a multiple of 
80, and if that is actually 81, 743 is not a multiple of 6.

I was trying to do this with heights for a listbox a few days 
ago, and it seems that the line spacing is actually 1 pixel 
greater than is reported. 
Since you can resize to a non-integer number of lines I don't 
believe (and I tried to read the source code) that Tcl/Tk 
works internally with characters.

-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

Mon, Feb 28, 2005 8:45 AM #

Prof Brian Ripley <ripley@stats.ox.ac.uk> writes:

I think that's actually an issue that involves the window manager too.
I don't think all WMs know how to deal in integer number of
characters. 

Anyways, the following piece of Tcl seems to do the trick:

% expr ([winfo width .a] - 2 * [.a cget -borderwidth] - 4)/[font measure [.a cget -font] 0]
27

Converting to R is left as an exercise...

If I got it right then the point is that at either side of the window
you have by 1 pixel, n border pixels, and 1 spacer pixel before the
first character.

O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907

John Fox

Mon, Feb 28, 2005 9:25 AM #

Dear Peter,

(as.numeric(tkwinfo("width", .output$ID))
    - 2*as.numeric(tkcget(.output, borderwidth=NULL)) - 2)/
    as.numeric(tkfont.measure(tkcget(.output, font=NULL), "0"))

(for the text widget .output) appears to do the trick (note, subtracting 2
rather than 4).

Thank you,
 John

--------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario
Canada L8S 4M4
905-525-9140x23604
http://socserv.mcmaster.ca/jfox 
--------------------------------

-----Original Message-----
From: r-devel-bounces@stat.math.ethz.ch 
[mailto:r-devel-bounces@stat.math.ethz.ch] On Behalf Of Peter Dalgaard
Sent: Monday, February 28, 2005 10:39 AM
To: Prof Brian Ripley
Cc: John Fox; r-devel@stat.math.ethz.ch
Subject: Re: [Rd] Getting width of Tk text widget via tcltk

Prof Brian Ripley <ripley@stats.ox.ac.uk> writes:

<Tcl> 743

I could convert pixels to characters, but wonder whether

I can get

the latter directly.

I suspect you may have some difficulty with the latter, even in a 
monospace font.  Notice that 486 is not a multiple of 80,

and if that

is actually 81, 743 is not a multiple of 6.

I was trying to do this with heights for a listbox a few

days ago, and

it seems that the line spacing is actually 1 pixel greater than is 
reported. Since you can resize to a non-integer number of lines I 
don't believe (and I tried to read the source code) that

Tcl/Tk works

internally with characters.

I think that's actually an issue that involves the window manager too.
I don't think all WMs know how to deal in integer number of 
characters. 

Anyways, the following piece of Tcl seems to do the trick:

% expr ([winfo width .a] - 2 * [.a cget -borderwidth] - 
4)/[font measure [.a cget -font] 0]
27

Converting to R is left as an exercise...

If I got it right then the point is that at either side of 
the window you have by 1 pixel, n border pixels, and 1 spacer 
pixel before the first character.

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: 
(+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: 
(+45) 35327907

______________________________________________
R-devel@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel

Mon, Feb 28, 2005 9:32 AM #

"John Fox" <jfox@mcmaster.ca> writes:

Hmm, that's odd. I needed the 4. Beware that Tcl does integer division
(%/%). Did you round() or floor() the result?

O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907

John Fox

Mon, Feb 28, 2005 10:01 AM #

Dear Peter,

As you can see from the expression, I didn't use integer division, nor did I
round() or floor(). Here's my original example, using a monospaced font:

+     font=tkfont.create(family="courier", size=10))

<Tcl>

<Tcl>

<Tcl>

<Tcl> 80

<Tcl> 646

+      - 2*as.numeric(tkcget(textWindow, borderwidth=NULL)) - 4) /
+      as.numeric(tkfont.measure(tkcget(textWindow, font=NULL), "0"))
[1] 79.75

+      - 2*as.numeric(tkcget(textWindow, borderwidth=NULL)) - 2) /
+      as.numeric(tkfont.measure(tkcget(textWindow, font=NULL), "0"))
[1] 80

I believe that the right answer is 80, and this appears correct visually,
confirmed by typing in the window.

My object was to be able to adjust R output to the width of the widget, and
I can now do this (actually, Brian's approach also worked well enough for
me).

Thank you again for your help.

John

--------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario
Canada L8S 4M4
905-525-9140x23604
http://socserv.mcmaster.ca/jfox 
--------------------------------

Mon, Feb 28, 2005 1:03 PM #

"John Fox" <jfox@mcmaster.ca> writes:

Interesting...

<Tcl> 488

+      - 2*as.numeric(tkcget(textWindow, borderwidth=NULL)) - 4) /
+   as.numeric(tkfont.measure(tkcget(textWindow, font=NULL), "0"))
[1] 80

+       - 2*as.numeric(tkcget(textWindow, borderwidth=NULL)) - 2) /
+       as.numeric(tkfont.measure(tkcget(textWindow, font=NULL), "0"))
[1] 80.33333

Notice, btw, that textWindow$ID  shouldnn't be necessary.

O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907