Added first X11 example (clock)

examples/clock.py

@@ -0,0 +1,74 @@
+"""
+This file is part of "blighty" which is released under GPL.
+
+See file LICENCE or go to http://www.gnu.org/licenses/ for full license
+details.
+
+blighty is a desktop widget creation and management library for Python 3.
+
+Copyright (c) 2018 Gabriele N. Tornetta <[email protected]>.
+All rights reserved.
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program 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 General Public License for more details.
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+
+from blighty import CanvasGravity
+from blighty.x11 import Canvas, start_event_loop
+
+import datetime
+
+from math import pi as PI
+
+
+class Clock(Canvas):
+    def on_button_pressed(self, button, state, x, y):
+        self.dispose()
+
+    @staticmethod
+    def hand(ctx, angle, length, thickness):
+        ctx.save()
+        ctx.set_source_rgba(1, 1, 1, 1)
+        ctx.set_line_width(thickness)
+        ctx.rotate(angle)
+        ctx.move_to(0, length * .2)
+        ctx.line_to(0, -length)
+        ctx.stroke()
+        ctx.restore()
+
+    def on_draw(self, ctx):
+        now = datetime.datetime.now()
+
+        ctx.translate(self.width >> 1, self.height >> 1)
+
+        Clock.hand(ctx,
+                   angle = now.second / 30 * PI,
+                   length = (self.height >> 1) * .9,
+                   thickness = 1)
+
+        mins = now.minute + now.second / 60
+        Clock.hand(ctx,
+                   angle = mins / 30 * PI,
+                   length = (self.height >> 1) * .8,
+                   thickness = 3)
+
+        hours = (now.hour % 12) + mins / 60
+        Clock.hand(ctx,
+                   angle = hours / 6 * PI,
+                   length = (self.height >> 1) * .5,
+                   thickness = 6)
+
+
+if __name__ == "__main__":
+    clock = Clock(0, 0, 400, 400, gravity = CanvasGravity.CENTER)
+    clock.show()
+    start_event_loop()