[pyclutter] examples: Add 2D clock demo for Clutter.Canvas

[Emmanuele Bassi <ebassi src gnome org>]

commit ac10839e8717ad91f30f44f675d7bbb81b6a6fbd
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Wed Apr 15 15:12:20 2015 +0100

    examples: Add 2D clock demo for Clutter.Canvas

 examples/Makefile.am |    1 +
 examples/canvas.py   |  104 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+), 0 deletions(-)
---
diff --git a/examples/Makefile.am b/examples/Makefile.am
index 241cb83..eb0280d 100644
--- a/examples/Makefile.am
+++ b/examples/Makefile.am
@@ -1,5 +1,6 @@
 EXTRA_DIST = \
        basic-actor.py \
+       canvas.py \
        constraints.py \
        layout-manager.py \
        rounded-rectangle.py
diff --git a/examples/canvas.py b/examples/canvas.py
new file mode 100644
index 0000000..d2e11b8
--- /dev/null
+++ b/examples/canvas.py
@@ -0,0 +1,104 @@
+import math
+import cairo
+
+from gi.repository import GLib
+from gi.repository import Clutter
+
+resize_id = 0
+
+def draw_clock(canvas, cr, width, height):
+    # Clear the canvas
+    cr.save()
+    cr.set_operator(cairo.OPERATOR_CLEAR)
+    cr.paint()
+    cr.restore()
+
+    # Get the current time, and compute the angles
+    now = GLib.DateTime.new_now_local()
+    seconds = now.get_second() * math.pi / 30
+    minutes = now.get_minute() * math.pi / 30
+    hours = now.get_hour() * math.pi / 6
+
+    # Normalize the coordinate space 
+    cr.scale(width, height)
+
+    cr.set_line_cap(cairo.LINE_CAP_ROUND)
+    cr.set_line_width(0.1)
+
+    # The black rail that holds the seconds indicator
+    color = Clutter.Color.get_static(Clutter.StaticColor.BLACK)
+    Clutter.cairo_set_source_color(cr, color)
+    cr.translate(0.5, 0.5)
+    cr.arc(0, 0, 0.4, 0, math.pi * 2)
+    cr.stroke()
+
+    # The seconds indicator
+    color = Clutter.Color.get_static(Clutter.StaticColor.WHITE)
+    color.alpha = 196
+    Clutter.cairo_set_source_color(cr, color)
+    cr.move_to(0, 0)
+    cr.arc(math.sin(seconds) * 0.4, - math.cos(seconds) * 0.4, 0.05, 0, math.pi * 2)
+    cr.fill()
+
+    # The minutes hand
+    color = Clutter.Color.get_static(Clutter.StaticColor.CHAMELEON_DARK)
+    color.alpha = 196
+    Clutter.cairo_set_source_color(cr, color)
+    cr.move_to(0, 0)
+    cr.line_to(math.sin(minutes) * 0.4, - math.cos(minutes) * 0.4)
+    cr.stroke()
+
+    # The hours hand
+    cr.move_to(0, 0)
+    cr.line_to(math.sin(hours) * 0.2, - math.cos(hours) * 0.2)
+    cr.stroke()
+
+    return True
+
+def invalidate_clock(canvas):
+    canvas.invalidate()
+    return True
+
+def idle_resize(actor):
+    global resize_id
+
+    # Match the size of the canvas with the size of the actor
+    width, height = actor.get_size()
+    actor.get_content().set_size(math.ceil(width), math.ceil(height))
+
+    resize_id = 0
+
+    return False
+
+def on_actor_resize(actor, allocation, flags):
+    global resize_id
+
+    # Throttle multiple allocations to a single canvas resize
+    if resize_id == 0:
+        resize_id = GLib.timeout_add(500, idle_resize, actor)
+
+if __name__ == '__main__':
+    # Our stage
+    stage = Clutter.Stage(title='2D Clock', user_resizable=True)
+    stage.props.background_color = Clutter.Color.get_static(Clutter.StaticColor.SKY_BLUE_LIGHT)
+    stage.set_size(300, 300)
+    stage.connect('destroy', Clutter.main_quit)
+    stage.show()
+
+    # The canvas, courtesy of Cairo
+    canvas = Clutter.Canvas(width=300, height=300)
+    canvas.connect('draw', draw_clock)
+    canvas.invalidate()
+
+    # The actor that displays the canvas
+    actor = Clutter.Actor(content=canvas)
+    actor.set_content_scaling_filters(Clutter.ScalingFilter.TRILINEAR,
+                                      Clutter.ScalingFilter.LINEAR)
+    actor.add_constraint(Clutter.BindConstraint(source=stage, coordinate=Clutter.BindCoordinate.SIZE))
+    actor.connect('allocation-changed', on_actor_resize)
+    stage.add_child(actor)
+
+    # Set up a timeout that invalidates the contents of the canvas every second
+    GLib.timeout_add(1000, invalidate_clock, canvas)
+
+    Clutter.main()