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|
=begin
drawing.rb - Ruby/GTK version of gtk+/examples/drawing.c.
https://git.gnome.org/browse/gtk+/tree/examples/drawing.c?h=gtk-3-16
Copyright (c) 2015 Ruby-GNOME2 Project Team
This program is licenced under the same licence as Ruby-GNOME2.
=end
require "gtk3"
surface = nil
def clear_surface(surface)
cr = Cairo::Context.new(surface)
cr.set_source_rgb(1, 1, 1)
cr.paint
cr.destroy
end
def draw_brush(widget, surface, x, y)
cr = Cairo::Context.new(surface)
cr.rectangle(x - 3, y - 3, 6, 6)
cr.fill
cr.destroy
widget.queue_draw_area(x - 3, y - 3, 6, 6)
end
myapp = Gtk::Application.new "org.gtk.example", :flags_none
myapp.signal_connect "activate" do |app|
win = Gtk::ApplicationWindow.new app
win.set_title "Drawing Area"
win.signal_connect "delete-event" do
win.destroy
end
win.set_border_width 8
frame = Gtk::Frame.new
frame.shadow_type = Gtk::ShadowType::IN
win.add frame
drawing_area = Gtk::DrawingArea.new
# Set a minimum size
drawing_area.set_size_request 100, 100
frame.add drawing_area
# Signals used to handle the backing surface
drawing_area.signal_connect "draw" do |_da, cr|
cr.set_source(surface, 0, 0)
cr.paint
false
end
drawing_area.signal_connect "configure-event" do |da, _ev|
surface.destroy if surface
surface = win.window.create_similar_surface(Cairo::CONTENT_COLOR,
da.allocated_width,
da.allocated_height)
# Initialize the surface to white
clear_surface(surface)
# the configure event have been handled, no need for further
# processing
true
end
# Event signals
drawing_area.signal_connect "motion-notify-event" do |da, ev|
return false unless surface
if ((ev.state & Gdk::EventMask::BUTTON_PRESS_MASK.to_i) != 0)
draw_brush(da, surface, ev.x, ev.y)
end
end
drawing_area.signal_connect "button-press-event" do |da, ev|
return false unless surface
if (ev.button == Gdk::BUTTON_PRIMARY)
draw_brush(da, surface, ev.x, ev.y)
elsif (ev.button == Gdk::BUTTON_SECONDARY)
clear_surface(surface)
da.queue_draw
end
true
end
# Ask to receive events the drawing area doesn't normally
# subscribe to. In particular, we need to ask for the
# button press and motion notify events that we want to handle.
drawing_area.add_events([:button_press_mask, :pointer_motion_mask])
win.show_all
end
myapp.run ARGV
|
