From: brabuhr@...
Date: 2009-12-05T01:55:07+09:00
Subject: Re: Graphics mode again

On Fri, Dec 4, 2009 at 11:12 AM, Teodor Carstea <teodorcarstea@yahoo.com> wrote:
> It works! As you said, a single ball on the screen.
>
> Question 1: what kind of parameters a these:
>
>>:x1 => 10, :y1 => 10,
>>:x2 => 20, :y2 => 20,
>
> is it a kind of width/height? which variables point to the center of da
> ball,? I need it in order to manage its position using the coordinates.

Assuming you had the center of the ball in instance variables @x and @y:

    :x1 => @x - 5, :y1 => @y - 5,
    :x2 => @x + 5, :y2 => @y + 5,

> Question 2:
>
> what method like "repaint()" or "clrscr()" or "cleardevice()" could I
> use in Ruby to make the ball dissappear?

I don't know, that's the first ruby-gnome code I've written.  Looking
at the clock example, I made a change:

#!/usr/bin/env ruby

require 'gnomecanvas2'

class Foozle < Gtk::Window
  def initialize
    super

    @canvas = Gnome::Canvas.new(true)

    @foozle = Gnome::CanvasEllipse.new(
      @canvas.root,
      {
        :x1 => 10, :y1 => 20,
        :x2 => 30, :y2 => 40,
        :fill_color => "white",
        :outline_color => "steelblue",
        :width_pixels => 1
      }
    )

    @canvas.show
    add(@canvas)

    Gtk::timeout_add(1000) { @foozle.x1-=5; true }
    Gtk::timeout_add(1100) { @foozle.y1-=5; true }
    Gtk::timeout_add(1200) { @foozle.x2+=5; true }
    Gtk::timeout_add(1300) { @foozle.y2+=5; true }
    Gtk::timeout_add(9000) { @foozle.hide }
  end
end

Gtk.init(); Foozle.new.show; Gtk.main()