gistfile1.py

#!/usr/bin/env python
from gi.repository import Clutter
import cairo
import math

color = lambda string: Clutter.color_from_string(string)[1]  # shortcut


class CairoActor(Clutter.Actor):
    '''a horizontal item inside a row'''

    def __init__(self):
        super(CairoActor, self).__init__()
        self.set_background_color(color('orange'))
        self.canvas = Clutter.Canvas()
        self.set_content(self.canvas)
        self.canvas.connect('draw', self.draw)
        self.line_width = 5

    def do_allocate(self, box, flags):
        self.canvas.set_size(*box.get_size())
        self.canvas.invalidate()
        self.set_allocation(box, flags)

    def draw(self, canvas, ctx, width, height):
        # clear the previous frame
        ctx.set_operator(cairo.OPERATOR_CLEAR)
        ctx.paint()

        ctx.set_operator(cairo.OPERATOR_OVER)
        ctx.arc(width / 2, height / 2, height / 3, 0, 2 * math.pi)
        Clutter.cairo_set_source_color(ctx, color('#33f9'))
        ctx.fill_preserve()
        ctx.set_line_width(self.line_width)
        Clutter.cairo_set_source_color(ctx, color('red'))
        ctx.stroke()


if __name__ == '__main__':
    def stage_key(element, event):
        if event.keyval == Clutter.Escape:
            clutter_quit()

    def clutter_quit(*args):
        Clutter.main_quit()

    Clutter.init([])
    stage = Clutter.Stage()
    stage.set_size(800, 800)
    stage.set_title('Clutter - Cairo content')
    stage.set_background_color(color('orange'))
    stage.set_user_resizable(True)

    # quit when the window gets closed
    stage.connect('destroy', clutter_quit)

    # close window on escape
    stage.connect('key-press-event', stage_key)

    cairo_actor = CairoActor()
    stage.add_child(cairo_actor)

    # bind the size of cairo_actor to the size of the stage
    cairo_actor.add_constraint(Clutter.BindConstraint.new(stage, Clutter.BindCoordinate.SIZE, 0.0))

    stage.show()
    Clutter.main()