Ruby/Tk
Ruby/Tk provides Ruby with a graphical user interface (GUI). The Tk extension works on Windows, Mac OS X and Unix systems.
Previous versions of the Ruby One-Click Installer contained an (old) version of Tcl/Tk. Now this Ruby installer only contains the Ruby bindings to whatever version of Tcl/Tk you wish to install. It's recommended to use ActiveTcl. Download
the file ActiveTcl8.4.13.0.261555-win32-ix86-threaded.exe and
install it. Reboot your PC.
Tk works along a composition model - that is, you start by creating a container (such as a TkFrame or TkRoot)
and then create widgets (GUI components) that populate it, such as
buttons or labels. When you are ready to start the GUI, you invoke Tk.mainloop. The Tk engine then takes control of the program, displaying widgets and calling your code in response to GUI events.
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Simple Tk applications
Let's understand the following program hellotk.rb
require 'tk'
hello = TkRoot.new {title "Hello World"}
Tk.mainloop
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The Tk documentation shows
the class hierarchy. Briefly, the hierarchy is as follows:
Object->TclTkIp->TkKernel->TkObject->TkWindow->TkRoot
Object->TclTkIp->TkKernel->TkObject->TkWindow->TkLabel->TkButton
There are
many modules like:
Tk, Tk::Wm and many others.
TkKernel is the superclass of TkObject. The subclass redefines the class method new to
take a block.
TkObject is the superclass of all widgets and has
an included Tk module.
TkRoot class represents the root widget. The root
widget is at the top of the Ruby/Tk widget hierarchy and has the included
module Tk::Wm for communicating with a window manager.
The methods introduced here are normally used as instance methods of TkRoot.
In the
program, after loading the tk extension module, we create a root-level frame
using TkRoot.new. With Tk you create widgets and then bind
code blocks to them. When something happens (like the user clicking a widget),
Tk runs the appropriate code block. In our program, we use the title and
minsize instance methods (of module Tk::Wm) in
the code block to TkRoot.new. We are now ready with our GUI and we invoke Tk.mainloop
Let us now add some widgets to the above program,
namely a TkLabel.
The modified program is hellotk1.rb
require 'tk'
hello = TkRoot.new do
title "Hello World"
# the min size of window
minsize(400,400)
end
TkLabel.new(hello) do
text 'Hello World'
foreground 'red'
pack { padx 15; pady 15; side 'left'}
end
Tk.mainloop
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Here, we make a TkLabel widget (representing a label) as a child of the root frame, setting several options for the label. Finally, we pack the root frame and enter the main GUI event loop.
We also need to be able to get information back from our widgets while our program is running by setting up callbacks (routines invoked when certain events happen) and sharing data. The next example, hellotk2.rb does that.
require 'tk'
TkButton.new do
text "EXIT"
command { exit }
pack('side'=>'left', 'padx'=>10, 'pady'=>10)
end
Tk.mainloop
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Callbacks are very easy to setup. The command option takes a Proc object, which will be called when the callback fires. This means that the code block passed into the command method is run when the user clicks the button, allowing you to programmatically execute the same functionality that would be invoked on an actual button press. Note that the Kernel#exit method terminates your program here.
We shall now build a rudimentary GUI interface to our SOAP server hosted at www.puneruby.com. The program is the soapguiclient.rb
| require 'soap/rpc/driver' require 'tk' class SOAPGuiClient def
connect @buttonconnect.configure('text'
=> 'Reset') @buttonconnect.command
{ reset }
begin
driver = SOAP::RPC::Driver.new('http://217.160.200.122:12321/', 'urn:mySoapServer')
driver.add_method('sayhelloto', 'username')
s = driver.sayhelloto('Satish Talim') rescue
Exception => e
s = "Exception occured: " + e ensure
@label.configure('text' => s)
end end
#connect def
reset
@label.configure('text' => "") @buttonconnect.configure('text'
=> 'Connect')
@buttonconnect.command { connect } end
# reset #--- def
initialize
root = TkRoot.new do
title 'SOAP Client'
# the min size of window
minsize(535, 100) end #---
@label = TkLabel.new(root) do
pack end #---
@buttonconnect = TkButton.new(root)
@buttonconnect.configure('text' => 'Connect')
@buttonconnect.command { connect }
@buttonconnect.pack('side'=>'bottom') #---
Tk.mainloop end
#initialize end # class SOAPGuiClient.new #--- |
In the above program, we reconfigure a widget while it's running. Every widget supports the configure method, which takes a code block in the same manner as new. We have also modified the soapserver.rb program shown earlier to soapserver2.rb. We have included the Logger class.
| require 'logger' require 'soap/rpc/standaloneServer' class MyServer <
SOAP::RPC::StandaloneServer def
initialize(* args) super add_method(self,
'sayhelloto', 'username') @log
= Logger.new("soapserver.log", 5, 10*1024) end def
sayhelloto(username) t
= Time.now @log.info("#{username}
logged on #{t}") "Hello,
#{username} on #{t}." end end server =
MyServer.new('PuneRubyServer','urn:mySoapServer','www.puneruby.com',12321) trap('INT') {server.shutdown} server.start |
The Logger class helps write log messages to a file or stream. It supports time- or size-based rolling of log files. Messages can be assigned severities, and only those messages at or above the logger's current reporting level will be logged. Here, we log to a file called soapserver.log, which is rotated when it gets about 10K bytes and keeps up to five old files.
