1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
|
# Copyright (c) 2005 Ruby-GNOME2 Project Team
# This program is licenced under the same licence as Ruby-GNOME2.
#
# $Id: cairo-arc-negative.rb,v 1.1 2005/10/12 05:38:30 ktou Exp $
=begin
= cairo/Arc Negative
This demo shows how to use GDK and cairo to draw arc in negative.
From http://cairographics.org/samples/arc_negative.html.
=end
require 'common'
module Demo
class CairoArcNegative < CairoWindow
CENTER_X = 0.5
CENTER_Y = 0.5
RADIUS = 0.4
ANGLE1 = 45.0 * (Math::PI / 180.0) # angles are specified
ANGLE2 = 180.0 * (Math::PI / 180.0) # in radians
def initialize
super('cairo arc_negative')
end
def draw(cr)
cr.arc_negative(CENTER_X, CENTER_Y, RADIUS, ANGLE1, ANGLE2)
cr.stroke
# draw helping lines
cr.set_source_rgba(1, 0.2, 0.2, 0.6)
cr.arc(CENTER_X, CENTER_Y, 0.05, 0, 2 * Math::PI)
cr.fill
cr.set_line_width(0.03)
cr.arc(CENTER_X, CENTER_Y, RADIUS, ANGLE1, ANGLE1)
cr.line_to(CENTER_X, CENTER_Y)
cr.arc(CENTER_X, CENTER_Y, RADIUS, ANGLE2, ANGLE2)
cr.line_to(CENTER_X, CENTER_Y)
cr.stroke
end
end
end
|
