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=begin
cairo.rb - Ruby/Pango with cairo sample script.
Copyright (c) 2005 Ruby-GNOME2 Project
This program is licenced under the same licence as Ruby-GNOME2.
$Id: pango_cairo.rb,v 1.1 2005/10/15 07:57:52 mutoh Exp $
=end
require 'pango'
unless Pango.cairo_available?
STDERR.puts "This sample requires Pango 1.0.0 or later and cairo support"
exit 1
end
filename = ARGV.shift
filename ||= "cairo.png"
RADIUS = 150
N_WORDS = 10
FONT = "Sans Bold 27"
def draw_text(cr)
# Center coordinates on the middle of the region we are drawing
cr.translate(RADIUS, RADIUS);
# Create a PangoLayout, set the font and text
layout = cr.create_pango_layout
layout.set_text("Text")
desc = Pango::FontDescription.new(FONT)
layout.set_font_description(desc)
# Draw the layout N_WORDS times in a circle
N_WORDS.times do |i|
angle = (360.0 * i) / N_WORDS;
cr.save do
# Gradient from red at angle == 60 to blue at angle == 300
red = (1 + Math.cos((angle - 60) * Math::PI / 180.0)) / 2
cr.set_source_rgb(red, 0, 1.0 - red)
cr.rotate(angle * Math::PI / 180.0)
# Inform Pango to re-layout the text with the new transformation
cr.update_pango_layout(layout)
width, height = layout.size
cr.move_to(-(width.to_f / Pango::SCALE) / 2, -RADIUS)
cr.show_pango_layout(layout)
end
end
end
diameter = 2 * RADIUS
surface = Cairo::ImageSurface.new(Cairo::FORMAT_ARGB32, diameter, diameter)
cr = Cairo::Context.new(surface)
cr.set_source_rgb(1.0, 1.0, 1.0)
cr.rectangle(0, 0, diameter, diameter);
cr.fill
draw_text(cr)
File.open(filename, "wb") do |f|
cr.target.write_to_png(f)
end
# or
# cr.target.write_to_png(filename)
|
