From: Takaaki Tateishi <ttate@...>
Date: 2002-08-29T18:48:39+09:00
Subject: Re: Ruby/DL with GTK gtk_signal_connect

At Thu, 29 Aug 2002 17:55:18 +0900,
> english there. i've asked him to translate the Ruby/DL docs into
> english. hopfully he'll have the time to do it soon. i'll pass them
> along to you when he's done.

Thank you very much,

> jp docs :( i'm inserting text into a Text widget. and i need to define
> the GdkColor. how do i create s Struct to use with Ruby/DL? ex-
> Gtk.gtk_text_insert(@native, Gtk.gdk_font_load('courier'), GdkColor?,
> GdkColor?, @meta.value, -1)

Use `struct' in the module which extends DL::Importable as follows:

require 'dl/struct'    # load dl/struct.rb
module Gdk
  extend DL::Importable

  GdkColor = struct [  # see gdk/gdktypes.h
   "long pixel",
   "short red",
   "short green",
   "short blue",
  ]
end

Gdk::GdkColor.malloc allocates enough memory for GdkColor defined in
`gdk/gdktypes.h', and you can access each member in the dot-notation:

c1 = Gdk::GdkColor.malloc
c1.pixel = ...
...
c2 = Gdk::GdkColor.malloc
...

Gtk.gtk_text_insert(@native, Gtk.gdk_font_load('courier'),
                    c1, c2, @meta.value, -1)

However, `struct' method have not been fully tested yet.
If you don't want to use the module such as Gdk, use DL::PtrData.malloc
and DL::PtrData#struct! as follows:

c1 = DL::PtrData.malloc(DL.sizeof('LHHH'))
c1.struct!('LHHH', :pixel, :red, :green, :blue)
c2 = DL::PtrData.malloc(DL.sizeof('LHHH'))
c2.struct!('LHHH', :pixel, :red, :green, :blue)
c1[:pixel] = 0
...

Regards,
-- 
Takaaki Tateishi <ttate@kt.jaist.ac.jp>