Add a constraint list with selection to the constraints demo.

This should help with the layout helper debugging...

enable/constraints_container.py

@@ -124,8 +124,6 @@ def __layout_constraints_changed(self, name, old, new):
         """ Invalidate the layout when the private constraints list changes.
         """
         self._layout_manager.replace_constraints(old, new)
-        if self.debug:
-            self._debug_overlay.selected_constraints = new
         self.relayout()
 
     def __components_items_changed(self, event):

enable/layout/debug_constraints.py

@@ -49,7 +49,7 @@ class DebugConstraintsOverlay(AbstractOverlay):
     boxes = Any()
 
     # Style options for the lines.
-    term_color = ColorTrait('lightblue')
+    term_color = ColorTrait('orange')
     term_line_style = LineStyle('solid')
 
     def update_from_constraints(self, layout_mgr):
@@ -76,7 +76,9 @@ def overlay(self, other_component, gc, view_bounds=None, mode="normal"):
         """
         if len(self.selected_constraints) == 0:
             return
+        origin = other_component.position
         with gc:
+            gc.translate_ctm(*origin)
             gc.set_stroke_color(self.term_color_)
             gc.set_line_dash(self.term_line_style_)
             gc.set_line_width(3)

examples/enable/constraints_demo.py

@@ -1,26 +1,51 @@
 
 from enable.api import Component, ComponentEditor, ConstraintsContainer
 from enable.layout.layout_helpers import hbox, align, grid
-from traits.api import HasTraits, Instance
-from traitsui.api import Item, View
+from traits.api import HasTraits, Any, Instance, List, Property
+from traitsui.api import Item, View, HGroup, TabularEditor
+from traitsui.tabular_adapter import TabularAdapter
+
+
+class ConstraintAdapter(TabularAdapter):
+    """ Display Constraints in a TabularEditor.
+    """
+    columns = [('Constraint', 'id')]
+    id_text = Property
+    def _get_id_text(self):
+        return self.item.__repr__()
 
 
 class Demo(HasTraits):
     canvas = Instance(Component)
 
+    constraints = Property(List)
+
+    selected_constraints = Any
+
     traits_view = View(
-                        Item('canvas',
-                             editor=ComponentEditor(),
-                             show_label=False,
+                        HGroup(
+                            Item('constraints',
+                                 editor=TabularEditor(
+                                    adapter=ConstraintAdapter(),
+                                    editable=False,
+                                    multi_select=True,
+                                    selected='selected_constraints',
+                                 ),
+                                 show_label=False,
+                            ),
+                            Item('canvas',
+                                 editor=ComponentEditor(),
+                                 show_label=False,
+                            ),
                         ),
                         resizable=True,
                         title="Constraints Demo",
-                        width=500,
+                        width=1000,
                         height=500,
                  )
 
     def _canvas_default(self):
-        parent = ConstraintsContainer(bounds=(500,500), debug=True)
+        parent = ConstraintsContainer(bounds=(500,500), padding=20, debug=True)
 
         hugs = {'hug_width':'weak', 'hug_height':'weak'}
         one = Component(id="one", bgcolor=0xFF0000, **hugs)
@@ -39,6 +64,18 @@ def _canvas_default(self):
 
         return parent
 
+    def _get_constraints(self):
+        return list(self.canvas._layout_manager._constraints)
+
+    def _selected_constraints_changed(self, new):
+        if new is None or new == []:
+            return
+
+        if self.canvas.debug:
+            canvas = self.canvas
+            canvas._debug_overlay.selected_constraints = new
+            canvas.request_redraw()
+
 
 if __name__ == "__main__":
     Demo().configure_traits()