Gosu Basics - Developing Games With Ruby - page 10

8 @draws = 0
9 @buttons_down = 0
10 end
11
12 def update
13 @x -= 1 if button_down?( Gosu :: KbLeft )
14 @x += 1 if button_down?( Gosu :: KbRight )
15 @y -= 1 if button_down?( Gosu :: KbUp )
16 @y += 1 if button_down?( Gosu :: KbDown )
17 end
18
19 def button_down ( id )
20 close if id == Gosu :: KbEscape
21 @buttons_down += 1
22 end
23
24 def button_up ( id )
25 @buttons_down -= 1
26 end
27
28 def needs_redraw?
29 @draws == 0 || @buttons_down > 0
30 end
31
32 def draw
33 @draws += 1
34 @message = Gosu :: Image . from_text(
35 self , info, Gosu . default_font_name, 30 )
36 @message . draw( @x , @y , 0 )
37 end
38
39

private

40
41 def info
42 "[x: #{ @x } ;y: #{ @y } ;draws: #{ @draws } ]"
43 end
44 end
45
46 window = GameWindow . new
47 window . show

Run the program and try pressing arrow keys:

$ ruby 01-hello/hello_movement.rb