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#!/usr/bin/env ruby
#
# Copyright (C) 2018 Ruby-GNOME2 Project Team
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
# example from https://github.com/GNOME/gtk/blob/master/examples/drawing.c
require_relative "utils"
require_gtk4
def clear_surface(surface)
cr = Cairo::Context.new(surface)
cr.set_source_rgb(1, 1, 1)
cr.paint
cr.destroy
end
# Draw a rectangle on the surface at the given position
def draw_brush(widget, surface, x, y)
cr = Cairo::Context.new(surface)
cr.rectangle(x - 3, y - 3, 6, 6)
cr.fill
widget.queue_draw
end
def generate_surface_from_widget(widget)
widget.native.surface.create_similar_surface(Cairo::CONTENT_COLOR,
widget.allocated_width,
widget.allocated_height)
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")
surface = nil
win.signal_connect "destroy" do
surface.destroy if surface
win.destroy
end
drawing_area = Gtk::DrawingArea.new
# Set a minimum size
drawing_area.set_size_request(100, 100)
win.set_child(drawing_area)
drawing_area.set_draw_func do |da, cr|
if surface.nil?
surface = generate_surface_from_widget(da)
## Initialize the surface to white
clear_surface(surface)
end
# Redraw the screen from the surface. Note that the draw
# callback receives a ready-to-be-used cairo_t that is already
# clipped to only draw the exposed areas of the widget
cr.set_source(surface, 0, 0)
cr.paint
end
drawing_area.signal_connect_after "resize" do |da, alloc|
surface.destroy if surface
surface = generate_surface_from_widget(da)
# Initialize the surface to white
clear_surface(surface) if surface
end
drag = Gtk::GestureDrag.new
drag.button = Gdk::BUTTON_PRIMARY
drawing_area.add_controller(drag)
start_x = 0.0
start_y = 0.0
drag.signal_connect "drag-begin" do |gesture, x, y|
start_x = x
start_y = y
draw_brush(drawing_area, surface, x, y)
end
drag.signal_connect "drag-update" do |gesture, x, y|
draw_brush(drawing_area, surface, start_x + x, start_y + y)
end
drag.signal_connect "drag-end" do |gesture, x, y|
draw_brush(drawing_area, surface, start_x + x, start_y + y)
end
press = Gtk::GestureClick.new
press.button = Gdk::BUTTON_SECONDARY
drawing_area.add_controller(press)
press.signal_connect "pressed" do |gesture, n_press, x, y|
clear_surface(surface)
drawing_area.queue_draw
end
win.show
end
myapp.run ARGV
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