From: Morton Goldberg <m_goldberg@...>
Date: 2007-08-18T09:54:25+09:00
Subject: Re: basic RubyTk questions

On Aug 17, 2007, at 11:45 AM, Pete Siemsen wrote:

> I have a Mac OS X system.  I wrote a Ruby program that uses RubyTk to
> display a TkLabel.  It works, but I'd like a bit more control over how
> it looks.  Here's the code minus the non-Tk stuff that isn't relevant
> to my questions:
>
> require 'tk'
>
> answer = 'test'
> TkLabel.new do
>   text answer
>   foreground 'yellow'
>   background 'black'
>   #     place('x' => 400, 'y' = 400)
>   pack('padx' => 15, 'pady' => 15)
> end
>
> def timer_loop3
>   exit
> end
> TkAfter.new(3000,              # milliseconds
>             -1,                # ?

The -1 requests an indefinite number of timeout events. Since you are  
going to exit on the first timeout, I suggest using 1 here, but it  
doesn't really matter.

>             proc{timer_loop3}  # what to call when the timer expires
> ).start
>
> Tk.mainloop
>
> The program displays a label for 3 seconds and exits, as intended,
> but...
>
> 1. How do I control the placement of the label on the screen?  It  
> now apppears
>    near the upper left-hand corner.  I tried "place" (commented  
> out) with no
>    luck.

The 'place' method affects the geometry of a widget within its  
container. It does not affect the placement of the window containing  
the widget on the screen.

> 2. How can I make the label appear on top of other windows?  It now  
> appears
>    "under" other windows, so I only see the label if I keep the  
> upper-left part
>    of my screen free of other windows.

The following ought to fix it, but it doesn't.

    root.focusmodel(:active)
    root.focus(true)

This appears to be a problem with Tk. I don't know a work-around.

> 3. Is there a way to remove the borders?  I don't need the title bar.

The borders, yes. The title bar I don't know how to remove.

> 4. I use this as a Mac OS X service, defined with ThisService, a  
> great little
>    program.  When I run it as a service, two windows appear.  One  
> is titled "tk"
>    and the other is the same as what I see when I run the program  
> from the
>    command line.  Can I get rid of the "tk" window?

If you watch carefully, sometimes you will see this window appear  
momentarily even when you run from the command line. I don't know why  
it persists when you run your script as a service.

> 5. Of course, is there a better way to do this?

There's always a better way to do something with Ruby :) The  
following is the best I can do with Ruby/Tk. I don't know if you will  
think it's good enough, but it solves some of your problems.

<code>
#! /usr/bin/ruby -w
require 'tk'

SEC = 3 # display duration in seconds

TkLabel.new do
    text 'Hello, World!'
    font "HelveticaBold 36"
    foreground 'yellow'
    background 'black'
    pack(:fill => :both, :expand => true)
end

root = Tk.root
root.title('') # suppress title (title bar remains)
# Set initial window geometry; i.e., size and placement
win_y, win_w, win_h = 50, 300, 80
win_x = (root.winfo_screenwidth - win_w) / 2 # center on screen
root.geometry("#{win_w}x#{win_h}+#{win_x}+#{win_y}")
# Suppress resizing window
root.resizable(false, false)

# One-shot timer
TkTimer.new(SEC * 1000, 1) { root.destroy }.start

Tk.mainloop
</code>

This may be a situation where Ruby/Tk just won't cut it. The better  
way you are looking for may require using a GUI library other than  
Ruby/Tk.

Regards, Morton