Initial snow flake layout implementation

sugar/canvas/Makefile.am

@@ -10,4 +10,5 @@ sugar_PYTHON =			\
 	Menu.py			\
 	MenuIcon.py		\
 	MenuShell.py		\
+	SnowflakeLayout.py	\
 	Timeline.py

sugar/canvas/SnowflakeLayout.py

@@ -0,0 +1,62 @@
+import math
+
+import cairo
+
+class SnowflakeLayout:
+	_BASE_RADIUS = 65
+	_CHILDREN_FACTOR = 1
+	_FLAKE_DISTANCE = 6
+	_BORDER = 20
+
+	def __init__(self):
+		self._root = None
+		self._children = []
+
+	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, self._cy)
+		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
+
+		x = self._cx + math.cos(angle) * r
+		y = self._cy + math.sin(angle) * r
+
+		matrix = cairo.Matrix(1, 0, 0, 1, 0, 0)
+		matrix.translate(x, y)
+		child.set_transform(matrix)
+
+	def _layout(self):
+		self._r = SnowflakeLayout._BASE_RADIUS + \
+				  SnowflakeLayout._CHILDREN_FACTOR * len(self._children)
+
+		c = self._r + SnowflakeLayout._BORDER + \
+			SnowflakeLayout._FLAKE_DISTANCE * 2 
+
+		self._cx = c
+		self._cy = c
+
+		self._layout_root()
+
+		index = 0
+		for child in self._children:
+			self._layout_child(child, index)
+			index += 1

tests/test-snowflake.py

@@ -0,0 +1,66 @@
+#!/usr/bin/python
+import pygtk
+pygtk.require('2.0')
+import gobject
+
+from sugar.session.UITestSession import UITestSession
+
+session = UITestSession()
+session.start()
+
+import sys
+import random
+
+import gtk
+import goocanvas
+
+from sugar.canvas.SnowflakeLayout import SnowflakeLayout
+from sugar.canvas import IconColor
+from sugar.canvas.IconItem import IconItem
+from sugar.canvas.CanvasView import CanvasView
+from sugar.canvas.Grid import Grid
+
+def _create_snowflake(group, children):
+	color = IconColor.IconColor()
+	icon = IconItem(size=60, color=color,
+					icon_name='activity-groupchat')
+	group.add_child(icon)
+	layout.set_root(icon)
+
+	for i in range(0, children):
+		color = IconColor.IconColor()
+		icon = IconItem(size=60, color=color,
+						icon_name='stock-buddy')
+		group.add_child(icon)
+		layout.add_child(icon)
+
+window = gtk.Window()
+window.connect("destroy", lambda w: gtk.main_quit())
+window.show()
+
+canvas = CanvasView()
+canvas.show()
+window.add(canvas)
+
+canvas_model = goocanvas.CanvasModelSimple()
+root = canvas_model.get_root_item()
+
+item = goocanvas.Rect(x=0, y=0, width=1200, height=900,
+                      line_width=0.0, fill_color='#e2e2e2')
+root.add_child(item)
+
+layout = SnowflakeLayout()
+group = goocanvas.Group()
+snow_flake = _create_snowflake(group, 30)
+root.add_child(group)
+
+layout = SnowflakeLayout()
+group = goocanvas.Group()
+group.translate(500, 500)
+_create_snowflake(group, 8)
+root.add_child(group)
+
+
+canvas.set_model(canvas_model)
+
+gtk.main()