From: Hidetoshi NAGAI <nagai@...>
Date: 2004-04-25T16:17:12+09:00
Subject: Re: tk: how to dynamically remove / add widgets?

Hi, 

From: "Its Me" <itsme213@hotmail.com>
Subject: tk: how to dynamically remove / add widgets?
Date: Sun, 25 Apr 2004 06:04:06 +0900
Message-ID: <eCAic.21996$hR1.16476@fe2.texas.rr.com>
> On a certain event I want to modify the frame
> e.g. remove the widget @a, add another widget @b.

Use 'bind' method. 
The follwing is a sample of binding. 

# It will be included in the sample directry of the renewal 
# version of Ruby/Tk. 

--------------------------------------------------------
#!/usr/bin/env ruby

require 'tk'

class Button_clone < TkLabel
  def initialize(*args)
    @command = nil
    if args[-1].kind_of?(Hash)
      keys = _symbolkey2str(args.pop)
      @command = keys.delete('command')
      args.push(keys)
    end

    super(*args)

    self.configure(:highlightthickness=>1, 
		   :padx=>'3m', :pady=>'1m', 
		   :relief=>'raised')

    self.bind('Enter', proc{self.background(self.activebackground)})
    self.bind('Leave', proc{
		self.background(self.highlightbackground)
		self.relief('raised')
	      })

    self.bind('ButtonPress-1', proc{self.relief('sunken')})
    self.bind('ButtonRelease-1', proc{
		self.relief('raised')
		@command.call if @command
	      })
  end

  def command(cmd = Proc.new)
    @command = cmd
  end
end

TkLabel.new(:text=><<EOT).pack
This is a sample of 'event binding'.
The first button is a normal button widget.
And the second one is a normal label widget 
but with some bindings like a button widget.
EOT

lbl = TkLabel.new(:foreground=>'red').pack(:pady=>3)

v = TkVariable.new(0)

TkFrame.new{|f|
  TkLabel.new(f, :text=>'click count : ').pack(:side=>:left)
  TkLabel.new(f, :textvariable=>v).pack(:side=>:left)
}.pack

TkButton.new(:text=>'normal Button widget', 
	     :command=>proc{
	       puts 'button is clicked!!'
	       lbl.text 'button is clicked!!'
	       v.numeric += 1
	     }){
  pack(:fill=>:x, :expand=>true)
}

Button_clone.new(:text=>'Label with Button binding', 
		 :command=>proc{
		   puts 'label is clicked!!'
		   lbl.text 'label is clicked!!'
		   v.numeric += 1
		 }){
  pack(:fill=>:x, :expand=>true)
}

Tk.mainloop
--------------------------------------------------------
-- 
                                  Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp)