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import math
import cairo
class SnowflakeLayout:
_BASE_RADIUS = 65
_CHILDREN_FACTOR = 1
_FLAKE_DISTANCE = 6
def __init__(self):
self._root = None
self._children = []
self._r = 0
def set_root(self, icon):
self._root = icon
def add_child(self, icon):
self._children.append(icon)
self._layout()
def remove_child(self, icon):
self._children.remove(icon)
self._layout()
def _layout_root(self):
[width, height] = self._root.get_size_request()
matrix = cairo.Matrix(1, 0, 0, 1, 0, 0)
matrix.translate(self._cx - (width / 2), self._cy - (height / 2))
self._root.set_transform(matrix)
def _layout_child(self, child, index):
r = self._r
if (len(self._children) > 10):
r += SnowflakeLayout._FLAKE_DISTANCE * (index % 3)
angle = 2 * math.pi / len(self._children) * index
[width, height] = child.get_size_request()
x = self._cx + math.cos(angle) * r - (width / 2)
y = self._cy + math.sin(angle) * r - (height / 2)
matrix = cairo.Matrix(1, 0, 0, 1, 0, 0)
matrix.translate(x, y)
child.set_transform(matrix)
def get_size(self):
max_child_size = 0
for child in self._children:
[width, height] = child.get_size_request()
max_child_size = max (max_child_size, width)
max_child_size = max (max_child_size, height)
return self._r * 2 + max_child_size + \
SnowflakeLayout._FLAKE_DISTANCE * 2
def _layout(self):
self._r = SnowflakeLayout._BASE_RADIUS + \
SnowflakeLayout._CHILDREN_FACTOR * len(self._children)
size = self.get_size()
self._cx = size / 2
self._cy = size / 2
self._layout_root()
index = 0
for child in self._children:
self._layout_child(child, index)
index += 1
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