42 lines
1.1 KiB
Ruby
42 lines
1.1 KiB
Ruby
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# Copyright (c) 2005 Ruby-GNOME2 Project Team
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# This program is licenced under the same licence as Ruby-GNOME2.
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#
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# $Id: cairo-arc-negative.rb,v 1.1 2005/10/12 05:38:30 ktou Exp $
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=begin
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= cairo/Arc Negative
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This demo shows how to use GDK and cairo to draw arc in negative.
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From http://cairographics.org/samples/arc_negative.html.
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=end
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require 'common'
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module Demo
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class CairoArcNegative < CairoWindow
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CENTER_X = 0.5
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CENTER_Y = 0.5
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RADIUS = 0.4
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ANGLE1 = 45.0 * (Math::PI / 180.0) # angles are specified
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ANGLE2 = 180.0 * (Math::PI / 180.0) # in radians
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def initialize
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super('cairo arc_negative')
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end
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def draw(cr)
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cr.arc_negative(CENTER_X, CENTER_Y, RADIUS, ANGLE1, ANGLE2)
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cr.stroke
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# draw helping lines
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cr.set_source_rgba(1, 0.2, 0.2, 0.6)
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cr.arc(CENTER_X, CENTER_Y, 0.05, 0, 2 * Math::PI)
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cr.fill
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cr.set_line_width(0.03)
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cr.arc(CENTER_X, CENTER_Y, RADIUS, ANGLE1, ANGLE1)
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cr.line_to(CENTER_X, CENTER_Y)
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cr.arc(CENTER_X, CENTER_Y, RADIUS, ANGLE2, ANGLE2)
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cr.line_to(CENTER_X, CENTER_Y)
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cr.stroke
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end
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end
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end
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