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#!/usr/bin/env ruby
=begin
alpha-demo.rb - alpha blended window sample script. (need xcompmgr)
Original: alphademo.py by Mike Hearn (*1) and David Trowbridge (*2)
* (1) http://plan99.net/~mike/blog/2006/06/05/alpha-blended-windows-in-python/
* (2) http://david.navi.cx/blog/?p=91
Translated to Ruby by Juergen Mangler <juergen.mangler@univie.ac.at>
Copyright (c) 2006-2015 Ruby-GNOME2 Project Team
This program is licenced under the same licence as Ruby-GNOME2.
=end
require "gtk3"
require "cairo"
class AlphaDemo < Gtk::Window
def initialize
super()
set_app_paintable(true)
set_title("AlphaDemo")
set_decorated(false)
set_default_size(200, 220)
signal_connect("delete_event") do
Gtk.main_quit
end
set_double_buffered(false)
signal_connect("draw") do |widget, _event|
cr = widget.window.create_cairo_context
rgba = [1.0, 1.0, 1.0]
rgba << 0.0 if @supports_alpha
cr.set_source_rgba(rgba)
cr.set_operator(Cairo::OPERATOR_SOURCE)
cr.paint
twidth, theight = widget.size
cr.set_source_rgba(1.0, 0.2, 0.2, 0.6)
radius = [twidth, theight].min.to_f / 2 - 0.8
cr.arc(twidth.to_f / 2, theight.to_f / 2, radius, 0, 2.0 * Math::PI)
cr.fill_preserve
cr.stroke
end
signal_connect("screen-changed") do |widget, _old_screen|
screen_changed(widget)
end
screen_changed(self)
end
def screen_changed(widget)
visual = widget.screen.rgba_visual
if visual && widget.screen.composited?
set_visual(visual)
@supports_alpha = true
else
set_visual(widget.screen.system_visual)
@supports_alpha = false
end
end
end
alpha = AlphaDemo.new
alpha.show
Gtk.main
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