From: Lyle Johnson <lyle@...>
Date: 2002-06-11T23:40:01+09:00
Subject: Re: FXRuby simple FXTextField question

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>   I've been learning to use FXRuby and it seems to be a to generate GUI apps.
>   I'm having a small problem with an example I'm working on. What I want is a
>   FXTextField that when I hit <return> its contents are then displayed in
>   another textfield. The first part is easy using the TEXTFIELD_ENTER_ONLY
>   flag on the first text field. The trouble that I'm having is when <return>
>   is pressed the text is only displayed in the second textfield for a short
>   time and the field then blanks itself.

One problem I see is that for the @ssnInput text field, you start out by 
assigning it one target (a data target) and then immediately replace 
that with a different target (when you call FXTextField#connect). Unlike 
perhaps some other toolkits, FOX objects only have one message target at 
a time. So as your code is currently written, the @ssnValue data target 
is effectively unused.

A workaround for this problem is to "chain" the messages by giving the 
data target its own message target. So replace this line in your code:

     @ssnInput.connect(SEL_COMMAND, method(:onSsnInput))

with this:

     @ssnValue.connect(SEL_COMMAND, method(:onSsnInput))

In other words, the text field continues to talk to the data target as 
its message target; but now, the data target sends messages to a 
different object when its contents change.

The next problem (the disappearing text in the second text field) has to 
do with the question of how that text field (@echoField) gets its 
contents. Since it's hooked up to a data target (@echoValue) you want to 
work with the contents of that data target instead of setting the text 
field's contents directly. What's currently happening in your program is 
that:

  1. onSsnInput() sets @echoField's contents to the current
     value of @ssnInput.

  2. Almost immediately after this, a GUI update occurs and
     @echoField asks its data target (@echoValue) for an update.

  3. @echoValue is still an empty string at this point and so
     that's what gets set into @echoField.

So a better fix is to change @echoValue in onSsnInput(), e.g.

     def onSsnInput(sender, sel, ptr)
       @echoValue.value = @ssnValue.value
       return 1
     end

I think this will probably give you the result you were looking for. If 
not, let me know and we'll see what to do next ;)

>   Below is the relevent snippit of code that I'm using. I have Ruby 1.6.7,
>   FXRuby 1.0.10, and fox 1.0.11 installed. Also, the inputs.rb example
>   supplied with FXRuby doesn't work correctly; you only see the output text of
>   the command when you left-click and drag the mouse over the output window.

Well, now, that's kinda weird. I'm seeing it too (obviously I haven't 
run this example lately!) Attached is an updated version that should 
work properly.

Hope this helps,

Lyle

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#!/usr/bin/env ruby

require 'fox'

include Fox

class InputHandlerWindow < FXMainWindow

  def initialize(app)
    # Initialize base class first
    super(app, "Input Handlers Test", nil, nil, DECOR_ALL, 0, 0, 400, 300)

    # Text area plus a button
    commands = FXHorizontalFrame.new(self, LAYOUT_SIDE_BOTTOM|LAYOUT_FILL_X)
    FXLabel.new(commands, "Command:")
    @cmdInput = FXTextField.new(commands, 30,
      nil, 0, FRAME_SUNKEN|FRAME_THICK|LAYOUT_FILL_X) 
    @cmdInput.connect(SEL_COMMAND, method(:onCmdText))
    FXHorizontalSeparator.new(self, LAYOUT_SIDE_BOTTOM|LAYOUT_FILL_X)
    textFrame = FXVerticalFrame.new(self,
        FRAME_SUNKEN|FRAME_THICK|LAYOUT_FILL_X|LAYOUT_FILL_Y)

    # Output will be displayed in a multiline text area
    @cmdOutput = FXText.new(textFrame, nil, 0, LAYOUT_FILL_X|LAYOUT_FILL_Y)

    # Initialize the pipe
    @pipe = nil
  end

  # Create and show the main window
  def create
    super
    show(PLACEMENT_SCREEN)
  end

  # Remove previous input (if any)
  def closePipe
    if @pipe
      getApp().removeInput(@pipe, INPUT_READ|INPUT_EXCEPT)
      @pipe = nil
    end
  end
  
  def onCmdText(sender, sel, ptr)
    # Stop previous command
    closePipe

    # Clean up the output window
    @cmdOutput.text = ""

    # Open a new pipe
    @pipe = IO.popen(@cmdInput.text)

    # Register input callbacks and return
    getApp().addInput(@pipe, INPUT_READ|INPUT_EXCEPT) { |sender, sel, ptr|
      case SELTYPE(sel)
        when SEL_IO_READ
	  text = @pipe.read
	  if text
            @cmdOutput.appendText(text)
	  else
	    closePipe
	  end
        when SEL_IO_EXCEPT
          puts 'onPipeExcept'
      end
    }
    return 1
  end
end

if $0 == __FILE__
  # Construct an application
  application = FXApp.new('InputHandler', 'FoxTest')

  # Open the display
  application.init(ARGV)

  # Construct the main window
  InputHandlerWindow.new(application)

  # Create and show the application windows
  application.create

  # Run the application
  application.run
end

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