#!/usr/bin/ruby
# vim: set ts=8 sw=4 noet

require 'gtk2'
require 'libglade2'

class MainProgram
    @gxml	# GladeXML for the user interface.
    @sliders	# Sliders in user interface.
    @labels	# Labels in user interface.
    @drawing	# Gtk::DrawingArea to fill with pretty colors.
    @colors	# Array of colors (r, g, b)

    # Creates GUI from glade XML file, and initializes class members.
    # Also it initiates Gtk (and goes into the Gtk main loop when done),
    # seeds the random number generator, and sets the color to black.
    def initialize()
	Gtk.init
	srand()
	@colors = [0, 0, 0]

	# Parse glade file.
	@gxml = GladeXML.new("color-test.glade") { |handler_name|
	    method(handler_name)
	}

	# Get widgets from the XML object.
	@sliders = [
	    @gxml.get_widget("slider_red"),
	    @gxml.get_widget("slider_green"),
	    @gxml.get_widget("slider_blue")
	]

	@labels = [
	    @gxml.get_widget("label_red"),
	    @gxml.get_widget("label_green"),
	    @gxml.get_widget("label_blue")
	]

	@drawing = @gxml.get_widget("drawingarea")
	
	# Enter main loop.
	Gtk.main
    end

    # Updates foreground color for Gtk::DrawingArea based on the values in
    # @colors, where @colors[0] is the amount of red, @colors[1] is the
    # amount of green, and @colors[2] is the amount of blue.
    def update_drawing_color()
	color = Gdk::Color.new(@colors[0] * 255, @colors[1] * 255, @colors[2] * 255)
	@drawing.modify_fg(@drawing.state, color)
    end

    # Handles termination of the window (quits the Gtk main loop).
    def on_window_delete_event()
	Gtk.main_quit
    end

    # Generates random values for red, green and blue, and set the values in
    # the corresponding sliders.
    def on_button_random_clicked()
	# Genrate new values.
	@colors = [rand(255), rand(255), rand(255)]

	# Set valus for sliders.
	@sliders[0].value = @colors[0]
	@sliders[1].value = @colors[1]
	@sliders[2].value = @colors[2]
    end

    # Sets the red color to the value of the slider, and updates the
    # corresponding label and the drawing area.
    def on_slider_red_value_changed()
	@colors[0] = @sliders[0].value.to_i
	@labels[0].text = "R: " + @sliders[0].value.to_i.to_s
	update_drawing_color()
    end

    # Sets the green color to the value of the slider, and updates the
    # corresponding label and the drawing area.
    def on_slider_green_value_changed()
	@colors[1] = @sliders[1].value.to_i
	@labels[1].text = "G: " + @sliders[1].value.to_i.to_s
	update_drawing_color()
    end

    # Sets the blue color to the value of the slider, and updates the
    # corresponding label and the drawing area.
    def on_slider_blue_value_changed()
	@colors[2] = @sliders[2].value.to_i
	@labels[2].text = "B: " + @sliders[2].value.to_i.to_s
	update_drawing_color()
    end

    # Draws a circle on the Gtk::DrawingArea.
    def on_drawingarea_expose_event()
	# Get width and height.
	alloc = @drawing.allocation

	# Draw a circle.
	@drawing.window.draw_arc(@drawing.style.fg_gc(@drawing.state), true,
				 0, 0, alloc.width, alloc.height, 0, 64 * 360)

	# Draw a rectangle.
	#@drawing.window.draw_rectangle(@drawing.style.fg_gc(@drawing.state), 
	#    				true, 0, 0, alloc.width, alloc.height)
    end
end

# Create an instance of the class if this file is run by itself.
if $0 == __FILE__
    prog = MainProgram.new
end