sugar-toolkit-gtk3/sugar/graphics/spreadbox.py

# Copyright (C) 2006, 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 random
import math

import cairo
import hippo

_DISTANCE_THRESHOLD = 10.0
_FORCE_CONSTANT = 0.1

class SpreadBox(hippo.CanvasBox, hippo.CanvasItem):
    __gtype_name__ = 'SugarSpreadBox'

    def __init__(self, **kwargs):
        hippo.CanvasBox.__init__(self, **kwargs)

        self._items_to_position = []
        self._stable = False

    def add_item(self, item):
        self._items_to_position.append(item)
        self.append(item, hippo.PACK_FIXED)

    def remove_item(self, item):
        if self._items_to_position.count(item) > 0:
            self._items_to_position.remove(item)
        self.remove(item)

    def _get_item_radius(self, item):
        [width, height] = item.get_request()
        return math.sqrt(width ** 2  + height ** 2) / 2

    def _get_item_center(self, item):
        [width, height] = item.get_request()
        [x, y] = self.get_position(item)

        c_x = int(x + float(width) / 2.0)
        c_y = int(y + float(height) / 2.0)

        return [c_x, c_y]

    def _get_repulsion(self, icon1, icon2):
        [c1_x, c1_y] = self._get_item_center(icon1)
        [c2_x, c2_y] = self._get_item_center(icon2)

        a = c2_x - c1_x
        b = c2_y - c1_y

        r1 = self._get_item_radius(icon1)
        r2 = self._get_item_radius(icon2)
        distance = math.sqrt(a ** 2  + b ** 2) - r1 - r2

        if distance < _DISTANCE_THRESHOLD:
            f_x = int(math.ceil(-_FORCE_CONSTANT * float(a)))
            f_y = int(math.ceil(-_FORCE_CONSTANT * float(b)))
        else:
            f_x = 0
            f_y = 0

        return [f_x, f_y]

    def _clamp_position(self, icon, x, y):
        x = max(0, x)
        y = max(0, y)

        [item_w, item_h] = icon.get_request()
        [box_w, box_h] = self.get_allocation()

        x = min(box_w - item_w, x)
        y = min(box_h - item_h, y)

        return [x, y]

    def _spread_icons(self):
        self._stable = True

        for icon1 in self.get_children():
            vx = 0
            vy = 0

            for icon2 in self.get_children():
                if icon1 != icon2:
                    [f_x, f_y] = self._get_repulsion(icon1, icon2)
                    if f_x != 0 or f_y != 0:
                        self._stable = False
                        vx += f_x
                        vy += f_y

            if vx != 0 or vy != 0:
                [x, y] = self.get_position(icon1)
                new_x = x + vx
                new_y = y + vy

                [new_x, new_y] = self._clamp_position(icon1, new_x, new_y)

                self.move(icon1, new_x, new_y)

    def do_allocate(self, width, height):
        hippo.CanvasBox.do_allocate(self, width, height)

        for item in self._items_to_position:
            [item_w, item_h] = item.get_request()

            x = int(random.random() * width - item_w)
            y = int(random.random() * height - item_h)

            [x, y] = self._clamp_position(item, x, y)
            self.move(item, x, y)

        self._items_to_position = []

        tries = 20
        self._spread_icons()
        while not self._stable and tries > 0:
            self._spread_icons()
            tries -= 1