Task

Create a window and draw a pixel in it, subject to the following:

  the window is 320 x 240
  the color of the pixel must be red (255,0,0)
  the position of the pixel is x = 100, y = 100
require 'gtk3'
 
Width, Height = 320, 240
PosX, PosY = 100, 100
 
window = Gtk::Window.new
window.set_default_size(Width, Height)
window.title = 'Draw a pixel'
 
window.signal_connect(:draw) do |widget, context|
  context.set_antialias(Cairo::Antialias::NONE)
  # paint out bg with white
  # context.set_source_rgb(1.0, 1.0, 1.0)
  # context.paint(1.0)
  # draw a rectangle
  context.set_source_rgb(1.0, 0.0, 0.0)
  context.fill do
    context.rectangle(PosX, PosY, 1, 1)
  end
end
 
window.signal_connect(:destroy) { Gtk.main_quit }
 
window.show
Gtk.main
 