sugar-toolkit-gtk3/shell/view/home/snowflakelayout.py

# Copyright (C) 2006-2007 Red Hat, Inc.
#
# 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 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., 59 Temple Place - Suite 330,
# Boston, MA 02111-1307, USA.

import math

import gobject
import hippo

from sugar.graphics import units

_BASE_RADIUS = units.points_to_pixels(20)
_CHILDREN_FACTOR = 1

class SnowflakeLayout(gobject.GObject,hippo.CanvasLayout):
    __gtype_name__ = 'SugarSnowflakeLayout'
    def __init__(self):
        gobject.GObject.__init__(self)
        self._nflakes = 0

    def add(self, child):
        self._box.append(child)

        box_child = self._box.find_box_child(child)
        box_child.is_center = False

        self._nflakes += 1

    def add_center(self, child):
        self._box.append(child)
        box_child = self._box.find_box_child(child)
        box_child.is_center = True

    def do_set_box(self, box):
        self._box = box

    def do_get_height_request(self, for_width):
        size = self._calculate_size()
        return (size, size)

    def do_get_width_request(self):
        size = self._calculate_size()        
        return (size, size)

    def do_allocate(self, x, y, width, height,
                    req_width, req_height, origin_changed):
        r = self._get_radius()
        index = 0

        for child in self._box.get_layout_children():
            cx = x + width / 2
            cy = x + height / 2

            min_width, child_width = child.get_width_request()
            min_height, child_height = child.get_height_request(child_width)

            if child.is_center:
                child.allocate(x + (width - child_width) / 2,
                               y + (height - child_height) / 2,
                               child_width, child_height, origin_changed)
            else:
                angle = 2 * math.pi * index / self._nflakes

                dx = math.cos(angle) * r
                dy = math.sin(angle) * r

                child_x = int(x + (width - child_width) / 2 + dx)
                child_y = int(y + (height - child_height) / 2 + dy)

                child.allocate(child_x, child_y, child_width,
                               child_height, origin_changed)

                index += 1

    def _get_radius(self):
        return int(_BASE_RADIUS + _CHILDREN_FACTOR * self._nflakes)

    def _calculate_size(self):
        size = 0
        for child in self._box.get_layout_children():
            [min_width, child_width] = child.get_width_request()
            [min_height, child_height] = child.get_height_request(child_width)

            new_size = max(child_width, child_height)
            if not child.is_center:
                new_size += self._get_radius() * 2

            if new_size > size:
                size = new_size

        return size