moved Canvas._normalize() meat to Item.normalize()

git-svn-id: http://svn.devjavu.com/gaphor/gaphas/trunk@2563 a8418922-720d-0410-834f-a69b97ada669

2 files changed, 42 insertions, 14 deletions

diff --git a/gaphas/canvas.py b/gaphas/canvas.py
index b656748..8ba2be5 100644
--- a/gaphas/canvas.py
+++ b/gaphas/canvas.py
@@ -544,6 +544,11 @@ class Canvas(object):
             for h in item.handles():
                 request_resolve(h.x, projections_only=True)
                 request_resolve(h.y, projections_only=True)
+            # TODO: force updates for ports. Keep in mind the types:
+            #       PointPort and LinePort
+            #for p in item.ports():
+            #    request_resolve(p.x, projections_only=True)
+            #    request_resolve(p.y, projections_only=True)
 
         # solve all constraints
         self._solver.solve()
@@ -583,21 +588,9 @@ class Canvas(object):
         """
         dirty_matrix_items = set()
         for item in items:
-            handles = item.handles()
-            if not handles:
-                continue
-            x, y = map(float, handles[0].pos)
-            if x:
-                item.matrix._matrix.translate(x, 0)
-                dirty_matrix_items.add(item)
-                for h in handles:
-                    h.x._value -= x
-            if y:
-                item.matrix._matrix.translate(0, y)
+            if item.normalize():
                 dirty_matrix_items.add(item)
-                for h in handles:
-                    h.y._value -= y
-
+                
         return dirty_matrix_items
 
 
diff --git a/gaphas/item.py b/gaphas/item.py
index 85a5070..9cb84e9 100644
--- a/gaphas/item.py
+++ b/gaphas/item.py
@@ -143,6 +143,41 @@ class Item(object):
         """
         pass
 
+
+    def normalize(self):
+        """
+        Update handle positions of the item, so the first handle is always
+        located at (0, 0).
+        
+        Note that, since this method basically does some housekeeping during
+        the update phase, there's no need to keep track of the changes.
+
+        Alternative implementation can also be created, e.g. set (0, 0) in
+        the center of a circle or change it depending on the location of a
+        rotation poiny.
+
+        Returns ``True`` if some updates have been done, ``False`` otherwise.
+
+        TODO: Add a decorator that prevents the matrix and handle position to
+              be observed.
+        """
+        updated = False
+        handles = self._handles
+        if handles:
+            x, y = map(float, handles[0].pos)
+            if x:
+                self.matrix._matrix.translate(x, 0)
+                updated = True
+                for h in handles:
+                    h.x._value -= x
+            if y:
+                self.matrix._matrix.translate(0, y)
+                updated = True
+                for h in handles:
+                    h.y._value -= y
+        return updated
+
+
     def draw(self, context):
         """
         Render the item to a canvas view.