Trouble with scrolling on a TK frame

Ruby
1

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.

2

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

canvas.yscrollbar(vbar)

commenting these lines will result in a scrollable cross on the

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.

# 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

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

3

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/rubytk_en/

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/lib/Tk.html

 http://www-users.cs.umn.edu/~amundson/perl/perltk/toc.html

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/ruby_1_8/

ext/tk/sample/

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

Regards, Morton

4

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.