Added API to remove and insert children

tests/test_node.py

@@ -143,3 +143,51 @@ def __init__(self, style, children=None):
         self.assertEqual(child1.applicator.tasks, [])
         self.assertEqual(child2.applicator.tasks, [])
         self.assertEqual(child3.applicator.tasks, [])
+
+    def test_add(self):
+        "Nodes can be added as children to another node"
+
+        style = Style()
+        node = Node(style=style, children=[])
+
+        child = Node(style=style)
+        node.add(child)
+
+        self.assertTrue(child in node.children)
+        self.assertEqual(child.parent, node)
+        self.assertEqual(child.root, node.root)
+
+    def test_insert(self):
+        "Node can be inserted at a specific position as a child"
+
+        style = Style()
+        child1 = Node(style=style)
+        child2 = Node(style=style)
+        child3 = Node(style=style)
+        node = Node(style=style, children=[child1, child2, child3])
+
+        child4 = Node(style=style)
+
+        index = 2
+        node.insert(index, child4)
+
+        self.assertTrue(child4 in node.children)
+        self.assertEqual(child4.parent, node)
+        self.assertEqual(child4.root, node.root)
+
+        self.assertEqual(node.children.index(child4), index)
+
+    def test_remove(self):
+        "Children can be removed from node"
+
+        style = Style()
+        child1 = Node(style=style)
+        child2 = Node(style=style)
+        child3 = Node(style=style)
+        node = Node(style=style, children=[child1, child2, child3])
+
+        node.remove(child1)
+
+        self.assertFalse(child1 in node.children)
+        self.assertEqual(child1.parent, None)
+        self.assertEqual(child1.root, child1)

travertino/layout.py

@@ -119,23 +119,21 @@ def content_top(self):
 
     @content_top.setter
     def content_top(self, value):
-        if value != self._content_top:
-            self._content_top = value
-            for child in self.node.children:
-                if child.layout:
-                    child.layout._origin_top = self.absolute_content_top
+        self._content_top = value
+        for child in self.node.children:
+            if child.layout:
+                child.layout._origin_top = self.absolute_content_top
 
     @property
     def content_left(self):
         return self._content_left
 
     @content_left.setter
     def content_left(self, value):
-        if value != self._content_left:
-            self._content_left = value
-            for child in self.node.children:
-                if child.layout:
-                    child.layout._origin_left = self.absolute_content_left
+        self._content_left = value
+        for child in self.node.children:
+            if child.layout:
+                child.layout._origin_left = self.absolute_content_left
 
     ######################################################################
     # Absolute content box position

travertino/node.py

@@ -79,6 +79,37 @@ def add(self, child):
         child._parent = self
         set_root(child, self.root)
 
+    def insert(self, index, child):
+        """Insert a node as a child of this one.
+        Args:
+            index: Index of child position.
+            child: A node to insert as a child to this node.
+
+        Raises:
+            ValueError: If this node is a leaf, and cannot have children.
+        """
+        if self._children is None:
+            raise ValueError('Cannot insert child')
+
+        self._children.insert(index, child)
+        child._parent = self
+        set_root(child, self.root)
+
+    def remove(self, child):
+        """Remove child from this node.
+        Args:
+            child: The child to remove from this node.
+
+        Raises:
+            ValueError: If this node is a leaf, and cannot have children.
+        """
+        if self._children is None:
+            raise ValueError('Cannot remove children')
+
+        self._children.remove(child)
+        child._parent = None
+        set_root(child, None)
+
     def refresh(self, viewport):
         """Refresh the layout and appearance of the tree this node is contained in."""
         if self._root: