Fix debug rendering for constraints and tweak the constraints demo

enable/layout/debug_constraints.py

@@ -14,14 +14,14 @@ class Coords(HasTraits):
     bottom = Float()
     left = Float()
     right = Float()
-    width = Float()
-    height = Float()
+    layout_width = Float()
+    layout_height = Float()
 
     v_center = Property()
     _v_center = Any()
     def _get_v_center(self):
         if self._v_center is None:
-            return self.bottom + 0.5 * self.height
+            return self.bottom + 0.5 * self.layout_height
         else:
             return self._v_center
     def _set_v_center(self, value):
@@ -31,7 +31,7 @@ def _set_v_center(self, value):
     _h_center = Any()
     def _get_h_center(self):
         if self._h_center is None:
-            return self.left + 0.5 * self.width
+            return self.left + 0.5 * self.layout_width
         else:
             return self._h_center
     def _set_h_center(self, value):
@@ -90,17 +90,17 @@ def overlay(self, other_component, gc, view_bounds=None, mode="normal"):
             for name, attr in sorted(term_attrs):
                 box = self.boxes[name]
                 if attr == 'top':
-                    self.hline(gc, box.left, box.top, box.width)
+                    self.hline(gc, box.left, box.top, box.layout_width)
                 elif attr == 'bottom':
-                    self.hline(gc, box.left, box.bottom, box.width)
+                    self.hline(gc, box.left, box.bottom, box.layout_width)
                 elif attr == 'left':
-                    self.vline(gc, box.left, box.bottom, box.height)
+                    self.vline(gc, box.left, box.bottom, box.layout_height)
                 elif attr == 'right':
-                    self.vline(gc, box.right, box.bottom, box.height)
-                elif attr == 'width':
-                    self.hline(gc, box.left, box.v_center, box.width)
-                elif attr == 'height':
-                    self.vline(gc, box.h_center, box.bottom, box.height)
+                    self.vline(gc, box.right, box.bottom, box.layout_height)
+                elif attr == 'layout_width':
+                    self.hline(gc, box.left, box.v_center, box.layout_width)
+                elif attr == 'layout_height':
+                    self.vline(gc, box.h_center, box.bottom, box.layout_height)
                 gc.stroke_path()
 
     def vline(self, gc, x, y0, length):

examples/enable/constraints_demo.py

@@ -1,8 +1,8 @@
 
 from enable.api import Component, ComponentEditor, ConstraintsContainer
-from enable.layout.layout_helpers import (expand_constraints, hbox, vbox,
-    align, grid, horizontal, vertical, spacer)
-from traits.api import HasTraits, Any, Instance, List, Property, Str
+from enable.layout.layout_helpers import (align, grid, horizontal, hbox, vbox,
+    spacer, vertical)
+from traits.api import HasTraits, Any, Event, Instance, List, Property, Str
 from traitsui.api import Item, View, HGroup, VGroup, TabularEditor, CodeEditor
 from traitsui.tabular_adapter import TabularAdapter
 
@@ -19,7 +19,8 @@ def _get_id_text(self):
 class Demo(HasTraits):
     canvas = Instance(Component)
 
-    constraints = Property(List)
+    constraints = Property(List, depends_on='constraints_changed')
+    constraints_changed = Event
 
     constraints_def = Str
 
@@ -94,12 +95,13 @@ def _constraints_def_changed(self):
         except Exception, ex:
             return
 
-        self.selected_constraints = []
         self.canvas.layout_constraints = new_cns
+        self.selected_constraints = []
+        self.constraints_changed = True
         self.canvas.request_redraw()
 
     def _selected_constraints_changed(self, new):
-        if new is None or new == []:
+        if new is None:
             return
 
         if self.canvas.debug: