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

import random
import math

import cairo

class IconLayout:
	DISTANCE_THRESHOLD = 120.0

	def __init__(self, grid):
		self._icons = []
		self._constraints = {}
		self._grid = grid

		[self._x1, self._y1] = self._grid.convert_to_canvas(1, 1)
		[self._x2, self._y2] = self._grid.convert_to_canvas(78, 59)

	def add_icon(self, icon):
		self._icons.append(icon)
		self._layout_icon(icon)

	def remove_icon(self, icon):
		self._icons.remove(icon)
		del self._constraints[icon]

	def _get_distance(self, icon1, icon2):
		[icon1_x, icon1_y] = self._constraints[icon1]
		[icon2_x, icon2_y] = self._constraints[icon2]

		a = icon1_x - icon2_x
		b = icon1_y - icon2_y

		return math.sqrt(a * a  + b * b)

	def _get_repulsion(self, icon1, icon2):
		[icon1_x, icon1_y] = self._constraints[icon1]
		[icon2_x, icon2_y] = self._constraints[icon2]

		f_x = icon1_x - icon2_x
		f_y = icon1_y - icon2_y

		return [f_x, f_y]

	def _spread_icons(self):
		self._stable = True

		for icon1 in self._icons:
			vx = 0
			vy = 0

			[x, y] = self._constraints[icon1]

			for icon2 in self._icons:
				if icon1 != icon2:
					distance = self._get_distance(icon1, icon2)
					if distance <= IconLayout.DISTANCE_THRESHOLD:
						self._stable = False
						[f_x, f_y] = self._get_repulsion(icon1, icon2)
						vx += f_x
						vy += f_y

			new_x = x + vx
			new_y = y + vy

			new_x = max(self._x1, new_x)
			new_y = max(self._y1, new_y)

			[width, height] = icon1.get_size_request()
			new_x = min(self._x2 - width, new_x)
			new_y = min(self._y2 - height, new_y)

			self._constraints[icon1] = [new_x, new_y]

			matrix = cairo.Matrix(1, 0, 0, 1, 0, 0)
			matrix.translate(new_x, new_y)
			icon1.set_transform(matrix)

	def _layout_icon(self, icon):
		[width, height] = icon.get_size_request()
		x = random.random() * (self._x2 - self._x1 - width) 
		y = random.random() * (self._y2 - self._y1 - height)

		self._constraints[icon] = [x, y]

		tries = 10
		self._spread_icons()
		while not self._stable and tries > 0:
			self._spread_icons()
			tries -= 1