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comp.lang.ruby

Trouble with scrolling on a TK frame

Andreas Pinkert

6/23/2007 7:59:00 PM

Hi together,

Fist: Against all common sense I post a question without having read for
a few days in this group.
However, I used groups.google and the apropriate faqs in the www but all
I could come up with were examples that do not exactly cover my problem,
or python code which also doesn't help so much.

Here is my problem:
I want to have a GUI in a "Excel" - like way: displaying a long list of
data made up from different widgets. Since this list will grow quite
long, I need to scroll that list.

Here is what I gathered so far:
I understand that I cannot scroll a Frame (which I use to arrange my
widgets in a grid) so I wanted to use a canvas (which can be scrolled)
and paint my widgets to that.
However, now I can scroll the canvas but not the frame on top of that.

Here is the code I am unhappy with:

require 'tk'
root = TkRoot.new() { title "Canvas, Grid, and Scrollbars" }
vbar = TkScrollbar.new(root) { orient 'vert' }
canvas = TkCanvas.new(root) {
width 320
height 200
scrollregion '0 0 400 400'
}
canvas.yscrollbar(vbar)

TkGrid.grid(canvas, vbar, 'sticky'=>'ns')

TkGrid.columnconfigure(root, 0, 'weight'=>1)
TkGrid.rowconfigure( root, 0, 'weight'=>1)

TkcLine.new(canvas, 0, 0, 400, 400)
TkcLine.new(canvas, 0, 400, 400, 0)

################
# commenting these lines will result in a scrollable cross on the canvas

frame = TkFrame.new(canvas).grid

for i in 1..10
button = TkButton.new(frame, 'text'=>i)
button.grid
end
################

Tk.mainloop


As a relative newbie to both TK and Ruby (I wrote a minor project with
REXML about 5 years ago but never really returned to Ruby after that),
any help would be very much appreciated.

Thanks and regards,
Andreas.
3 Answers

Morton Goldberg

6/24/2007 2:07:00 AM

0

On Jun 23, 2007, at 4:00 PM, Andreas Pinkert wrote:

> Here is my problem:
> I want to have a GUI in a "Excel" - like way: displaying a long
> list of data made up from different widgets. Since this list will
> grow quite long, I need to scroll that list.
>
> Here is what I gathered so far:
> I understand that I cannot scroll a Frame (which I use to arrange
> my widgets in a grid) so I wanted to use a canvas (which can be
> scrolled) and paint my widgets to that.
> However, now I can scroll the canvas but not the frame on top of that.
>
> Here is the code I am unhappy with:
>
> require 'tk'
> root = TkRoot.new() { title "Canvas, Grid, and Scrollbars" }
> vbar = TkScrollbar.new(root) { orient 'vert' }
> canvas = TkCanvas.new(root) {
> width 320
> height 200
> scrollregion '0 0 400 400'
> }
> canvas.yscrollbar(vbar)
>
> TkGrid.grid(canvas, vbar, 'sticky'=>'ns')
>
> TkGrid.columnconfigure(root, 0, 'weight'=>1)
> TkGrid.rowconfigure( root, 0, 'weight'=>1)
>
> TkcLine.new(canvas, 0, 0, 400, 400)
> TkcLine.new(canvas, 0, 400, 400, 0)
>
> ################
> # commenting these lines will result in a scrollable cross on the
> canvas
>
> frame = TkFrame.new(canvas).grid
>
> for i in 1..10
> button = TkButton.new(frame, 'text'=>i)
> button.grid
> end
> ################
>
> Tk.mainloop

Perhaps this example will help. It's pretty rough, but I think it
might point you in the right direction. It also illustrates some
alternative ways of setting up widgets with Ruby/Tk. I'm not saying
these alternatives are necessarily better what you did -- just
thought you might like to know they exist. They do save on typing.

<code>
# Demonstrates adding a vetical row of buttons to a scrolling canvas.

require 'tk'

Tk.root.title("Test")

canvas = TkCanvas.new(Tk.root) {
width 320
height 200
scrollregion '0 0 400 400'
pack(:side => :left, :fill => :both, :expand => :true )
}

vbar = TkScrollbar.new(Tk.root) {
orient 'vert'
pack(:side => :right, :fill => :y)
}

canvas.yscrollbar(vbar)

frame = TkFrame.new(canvas) do |frm|
(1..10).each do |i|
TkButton.new(frm) {
text i
command { Tk.bell }
grid
}
end
end

TkcLine.new(canvas, 0, 0, 400, 400)
TkcLine.new(canvas, 0, 400, 400, 0)
TkcWindow.new(canvas, 200,
200, :width=>100, :height=>280, :window=>frame)

Tk.mainloop
</code>

I think the above does what you were asking for -- at least the
button array scrolls with the canvas and the buttons beep when
clicked (which proves that they function).

Regards, Morton

Andreas Pinkert

6/24/2007 12:06:00 PM

0

Thanks a lot!

I added only this line to my code and now it does what I want:
TkcWindow.new(canvas, 200, 200, :width=>100, :height=>280,
:window=>frame)

I have not found documentation on TkcWindow.
Where can I find such? I mean, I do not know what the API actually does.

regards,
Andreas.


Morton Goldberg wrote:


> On Jun 23, 2007, at 4:00 PM, Andreas Pinkert wrote:
>
>> Here is my problem:
>> I want to have a GUI in a "Excel" - like way: displaying a long list
>> of data made up from different widgets. Since this list will grow
>> quite long, I need to scroll that list.
>>
>> Here is what I gathered so far:
>> I understand that I cannot scroll a Frame (which I use to arrange my
>> widgets in a grid) so I wanted to use a canvas (which can be
>> scrolled) and paint my widgets to that.
>> However, now I can scroll the canvas but not the frame on top of that.
>>
>> Here is the code I am unhappy with:
>>
>> require 'tk'
>> root = TkRoot.new() { title "Canvas, Grid, and Scrollbars" }
>> vbar = TkScrollbar.new(root) { orient 'vert' }
>> canvas = TkCanvas.new(root) {
>> width 320
>> height 200
>> scrollregion '0 0 400 400'
>> }
>> canvas.yscrollbar(vbar)
>>
>> TkGrid.grid(canvas, vbar, 'sticky'=>'ns')
>>
>> TkGrid.columnconfigure(root, 0, 'weight'=>1)
>> TkGrid.rowconfigure( root, 0, 'weight'=>1)
>>
>> TkcLine.new(canvas, 0, 0, 400, 400)
>> TkcLine.new(canvas, 0, 400, 400, 0)
>>
>> ################
>> # commenting these lines will result in a scrollable cross on the canvas
>>
>> frame = TkFrame.new(canvas).grid
>>
>> for i in 1..10
>> button = TkButton.new(frame, 'text'=>i)
>> button.grid
>> end
>> ################
>>
>> Tk.mainloop
>
>
> Perhaps this example will help. It's pretty rough, but I think it might
> point you in the right direction. It also illustrates some alternative
> ways of setting up widgets with Ruby/Tk. I'm not saying these
> alternatives are necessarily better what you did -- just thought you
> might like to know they exist. They do save on typing.
>
> <code>
> # Demonstrates adding a vetical row of buttons to a scrolling canvas.
>
> require 'tk'
>
> Tk.root.title("Test")
>
> canvas = TkCanvas.new(Tk.root) {
> width 320
> height 200
> scrollregion '0 0 400 400'
> pack(:side => :left, :fill => :both, :expand => :true )
> }
>
> vbar = TkScrollbar.new(Tk.root) {
> orient 'vert'
> pack(:side => :right, :fill => :y)
> }
>
> canvas.yscrollbar(vbar)
>
> frame = TkFrame.new(canvas) do |frm|
> (1..10).each do |i|
> TkButton.new(frm) {
> text i
> command { Tk.bell }
> grid
> }
> end
> end
>
> TkcLine.new(canvas, 0, 0, 400, 400)
> TkcLine.new(canvas, 0, 400, 400, 0)
> TkcWindow.new(canvas, 200, 200, :width=>100, :height=>280, :window=>frame)
>
> Tk.mainloop
> </code>
>
> I think the above does what you were asking for -- at least the button
> array scrolls with the canvas and the buttons beep when clicked (which
> proves that they function).
>
> Regards, Morton
>

Morton Goldberg

6/24/2007 2:42:00 PM

0

On Jun 24, 2007, at 8:10 AM, Andreas Pinkert wrote:

> Thanks a lot!
>
> I added only this line to my code and now it does what I want:
> TkcWindow.new(canvas, 200,
> 200, :width=>100, :height=>280, :window=>frame)

I suggest you also change

frame = TkFrame.new(canvas).grid

to

frame = TkFrame.new(canvas)

since you're putting the frame into a TkcWindow.

> I have not found documentation on TkcWindow. Where can I find such?
> I mean, I do not know what the API actually does.

I know of no English documentation for Ruby/Tk, except

http://raa.ruby-lang.org/project/...

which is rather sparse and somewhat out of date. One has to fall back
on Perl/Tk documentation. Two sites I visit are:

http://aspn.activestate.com/ASPN/docs/ActivePerl/5.8/l...

http://www-users.cs.umn.edu/~amundson/perl/perlt...

Of course, reading the Ruby/Tk library source code can be helpful.

There are many Ruby/Tk examples that you can learn from posted at:

http://svn.ruby-lang.org/cgi-bin/viewvc.cgi/branches...
ext/tk/sample/

In particular, you will want to look at scrollframe.rb. It is highly
relevant to your problem.

Regards, Morton