Improved layout strategy

sugar/canvas/GridBox.py

@@ -0,0 +1,33 @@
+import goocanvas
+
+from sugar.canvas.GridLayout import GridGroup
+from sugar.canvas.GridLayout import GridConstraints
+
+class GridBox(GridGroup, goocanvas.Item):
+	VERTICAL = 0
+	HORIZONTAL = 1
+
+	def __init__(self, direction, size, padding):
+		if direction == GridBox.VERTICAL:
+			GridGroup.__init__(self, 1, size)
+		else:
+			GridGroup.__init__(self, size, 1)
+
+		self._direction = direction
+		self._padding = padding
+
+	def add_child(self, item, position=-1):
+		if position == -1:
+			position = self.get_n_children()
+		
+		if self._direction == GridBox.HORIZONTAL:
+			col = position
+			row = 0
+		else:
+			col = 0
+			row = position
+
+		constraints = GridConstraints(col, row, 1, 1, self._padding)
+		self._layout.set_constraints(item, constraints)
+
+		GridGroup.add_child(self, item, position)

sugar/canvas/GridLayout.py

@@ -43,23 +43,18 @@ class GridLayout:
 
 		return [x, y, width, height]
 
-	def layout_canvas_group(self, group):
-		i = 0
-		while i < group.get_n_children():
-			item = group.get_child(i)
+	def layout_canvas_item(self, item):
+		group = item.get_parent()
+		[x, y, width, height] = self._get_geometry(group, item)
 
-			[x, y, width, height] = self._get_geometry(group, item)
+		item.props.x = x
+		item.props.y = y
 
-			item.props.x = x
-			item.props.y = y
-
-			try:
-				item.props.width = width
-				item.props.height = height
-			except:
-				item.props.size = width
-
-			i += 1
+		try:
+			item.props.width = width
+			item.props.height = height
+		except:
+			item.props.size = width
 
 	def layout_screen(self, screen):
 		for window in screen.get_windows():
@@ -85,13 +80,19 @@ class GridGroup(goocanvas.Group):
 			matrix.translate(self._x, self._y)
 			self.set_transform(matrix)
 
+	def _update_layout(self):
+		i = 0
+		while i < self.get_n_children():
+			self._layout.layout_canvas_item(self.get_child(i))
+			i += 1
+
 	def do_set_property(self, pspec, value):
 		if pspec.name == 'width':
 			self._width = value
-			self._layout.layout_canvas_group(self)
+			self._update_layout()
 		elif pspec.name == 'height':
 			self._height = value
-			self._layout.layout_canvas_group(self)
+			self._update_layout()
 		elif pspec.name == 'x':
 			self._x = value
 			self._update_position()
@@ -127,5 +128,6 @@ class GridGroup(goocanvas.Group):
 	def get_layout(self):
 		return self._layout
 
-	def __child_added_cb(self, child, position):
-		self._layout.layout_canvas_group(self)
+	def __child_added_cb(self, group, position):
+		item = group.get_child(position)
+		self._layout.layout_canvas_item(item)