From: Ronald Fischer <ronaldf@...>
Date: 2006-08-07T19:45:21+09:00
Subject: Re: Ruby/Tk : How to show tooltips (please correct my ugly implementation)

Hidetoshi NAGAI wrote as nagai@ai.kyutech.ac.jp on 07. Aug 2006:

> From: Ronald Fischer <ronaldf@eml.cc>
> Subject: Ruby/Tk : How to show tooltips (please correct my ugly implementation) 
> 
> Date: Mon, 7 Aug 2006 18:35:19 +0900
> Message-ID: <1154943284.46@user.newsoffice.de>
>> I would like to add kind of a "show tooltips" function to my 
>> application,
>> which means that some piece of text should be shown when the mourse 
>> moves
>> over a certain area. In my case, the "hot spot" area is a set of 
>> TkLabel.

> Please see "tkballoonhelp.rb" in "ext/tk/sample" directory 
> of Ruby source archive.

Arigatou Hidetoshi-san.

I studied the tkballoonhelp.rb and in particular I read about
the functions overrideredirect and transient, but I must admit
that I did not fully understand how it works. Nevertheless I
tried to adapt it to my case (the example uses a timer to
show and hide the tooltip, while I am using Enter and Leave
events - but these seem only minor differences, aren't they?).
I used part of the logic in tkballoonhelp, well knowing that
it is a bit dangerous to just copy some code without knowing
what it actually does. (In particular, I did not understand
the reason for the variables @path and @epath).

Here is my solution:

class TestForm
  @hw=nil
  @root = TkRoot.new() { title("rtktest:TestForm") }
  @field1 = TkLabel.new(@root, :text => "field1").pack();
  @field1.bind("Enter",
    proc {|e| puts("Entering field1")
      parent=@self
      @hw=TkToplevel.new()
      @hw.withdraw
      @hw.overrideredirect(true)
      @hw.transient(TkWinfo.toplevel(parent))
      @epath = @frame.path
      helptext=TkLabel.new(@hw,:text=>"This is an example 
helptext").pack();
      @path = @label
      @hw.deiconify
      @hw.raise
    }
  )
  ...
}

def epath
  @epath
end

When the label receives the focus, I get the error message
"bad window path name", so this might be due to my misunderstanding
(and misuse) of @path/@epath.

Could you please show me what I did wrong?

Ronald


-- 
Ronald Fischer <ronaldf@eml.cc>
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