cairo-gtk-interactivity.py

   1 #!/usr/bin/env python
   2
   3 # An example of mouse interaction with cairo and Gtk+
   4 #
   5 # Copyright (C) 2013  Antonio Ospite <ospite@studenti.unina.it>
   6 #
   7 # This program is free software: you can redistribute it and/or modify
   8 # it under the terms of the GNU General Public License as published by
   9 # the Free Software Foundation, either version 3 of the License, or
  10 # (at your option) any later version.
  11 #
  12 # This program is distributed in the hope that it will be useful,
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 # GNU General Public License for more details.
  16 #
  17 # You should have received a copy of the GNU General Public License
  18 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19
  20 # References:
  21 # https://developer.gnome.org/gtk3/3.6/gtk-getting-started.html#idm140520417717488
  22
  23 import gi
  24
  25 gi.require_version('Gtk', '3.0')
  26 from gi.repository import Gdk, Gtk, GObject, Gio
  27
  28 import math
  29 import colorsys
  30
  31
  32 # from http://stackoverflow.com/questions/481144/
  33 def in_circle(c_x, c_y, r, x, y):
  34     return math.hypot(c_x - x, c_y - y) <= r
  35
  36
  37 def clamp(x, interval):
  38     if x < interval[0]:
  39         return interval[0]
  40     elif x > interval[1]:
  41         return interval[1]
  42     else:
  43         return x
  44
  45
  46 class InteractiveCanvas(Gtk.DrawingArea):
  47     def __init__(self, width, height, *args, **kwargs):
  48         super(InteractiveCanvas, self).__init__(*args, **kwargs)
  49
  50         self.width = width
  51         self.height = height
  52
  53         self.x_offset = self.width / 2.0
  54         self.y_offset = self.height / 2.0
  55         self.radius = 20
  56         self.border = 4
  57
  58         self.selectable = False
  59         self.selected = False
  60         self.drag_offset_x = 0
  61         self.drag_offset_y = 0
  62
  63         self.x = self.width / 2.0
  64         self.y = self.height / 2.0
  65
  66         self.set_size_request(width, height)
  67         self.connect('draw', self.on_draw)
  68         self.connect('configure-event', self.on_configure_event)
  69
  70         self.add_events(Gdk.EventMask.BUTTON_PRESS_MASK |
  71                         Gdk.EventMask.BUTTON_RELEASE_MASK |
  72                         Gdk.EventMask.POINTER_MOTION_MASK)
  73         self.connect('button-press-event', self.on_button_press_event)
  74         self.connect('button-release-event', self.on_button_release_event)
  75         self.connect('motion-notify-event', self.on_motion_notify_event)
  76
  77     def on_configure_event(self, widget, event):
  78         self.width = event.width
  79         self.height = event.height
  80
  81     def on_draw(self, widget, cr):
  82         cr.rectangle(0, 0, self.width, self.height)
  83         cr.set_source_rgb(1.0, 0.5, 0.5)
  84         cr.fill()
  85
  86         cr.arc(self.x, self.y, self.radius, 0, 2 * math.pi)
  87
  88         _h = self.x / float(self.width)
  89         if self.selected:
  90             _l = 0.6
  91         else:
  92             if self.selectable:
  93                 _l = 0.5
  94             else:
  95                 _l = 0.2
  96         _s = self.y / float(self.height)
  97         _r, _g, _b = colorsys.hls_to_rgb(_h, _l, _s)
  98         cr.set_source_rgb(_r, _g, _b)
  99         cr.fill_preserve()
 100
 101         cr.set_source_rgb(0, 0, 0)
 102         cr.set_line_width(self.border)
 103         cr.stroke()
 104
 105     def on_button_press_event(self, widget, event):
 106         if self.selectable:
 107             self.selected = True
 108             self.drag_offset_x = self.x - event.x
 109             self.drag_offset_y = self.y - event.y
 110             self.queue_draw()
 111
 112     def on_button_release_event(self, widget, event):
 113         self.selected = False
 114         self.queue_draw()
 115
 116     def on_motion_notify_event(self, widget, event):
 117         if self.selected:
 118             self.x = clamp(event.x + self.drag_offset_x, [0, self.width])
 119             self.y = clamp(event.y + self.drag_offset_y, [0, self.height])
 120             self.queue_draw()
 121         else:
 122             old_selectable = self.selectable
 123             if in_circle(self.x, self.y, self.radius + self.border,
 124                          event.x, event.y):
 125                 self.selectable = True
 126             else:
 127                 self.selectable = False
 128
 129             if self.selectable != old_selectable:
 130                 self.queue_draw()
 131
 132
 133 class InteractiveApp(Gtk.Application):
 134     def __init__(self, title, width, height, *args, **kwargs):
 135         super(InteractiveApp, self).__init__(*args, **kwargs)
 136         self.connect("activate", self.on_activate)
 137         self.title = title
 138         self.width = width
 139         self.height = height
 140
 141     def on_activate(self, data=None):
 142         window = Gtk.Window(type=Gtk.WindowType.TOPLEVEL)
 143         window.set_title(self.title)
 144
 145         canvas = InteractiveCanvas(self.width, self.height)
 146         window.add(canvas)
 147         window.show_all()
 148         self.add_window(window)
 149
 150
 151 if __name__ == "__main__":
 152     app = InteractiveApp(
 153         "InteractiveApp", 640, 480,
 154         application_id="apps.test.interactiveapp",
 155         flags=Gio.ApplicationFlags.FLAGS_NONE)
 156     app.run(None)