From 1d4b89a909a0e6234862942fa754452116254475 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Andr=C3=A9=20Wobst?= <wobsta@users.sourceforge.net>
Date: Mon, 10 Oct 2011 21:17:23 +0000
Subject: [PATCH] default bbox method of canvasitem is weird; for the moment
 just document the issue

git-svn-id: https://pyx.svn.sourceforge.net/svnroot/pyx/trunk/pyx@3224 069f4177-920e-0410-937b-c2a4a81bcd90
---
 pyx/canvasitem.py  |  5 +++++
 pyx/dvi/dvifile.py | 16 ++++++++++++----
 pyx/style.py       |  2 ++
 3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/pyx/canvasitem.py b/pyx/canvasitem.py
index fce9d69f..726bb9dc 100644
--- a/pyx/canvasitem.py
+++ b/pyx/canvasitem.py
@@ -26,6 +26,11 @@ class canvasitem:
 
     def bbox(self):
         """return bounding box of canvasitem"""
+        # TODO: we either should raise a NotImplementedError here or return
+        # an empty bounding box instance, as adding empty to a bouding box is
+        # allowed. (We could also alter the merging behavior of bboxes to allow
+        # None. Currently, canvasitem instances not overwriting this bbox method
+        # lead to an error.)
         pass
 
     def processPS(self, file, writer, context, registry, bbox):
diff --git a/pyx/dvi/dvifile.py b/pyx/dvi/dvifile.py
index b1e81237..010b0e4a 100644
--- a/pyx/dvi/dvifile.py
+++ b/pyx/dvi/dvifile.py
@@ -79,7 +79,14 @@ class DVIError(Exception): pass
 
 # save and restore colors
 
-class _savecolor(canvasitem.canvasitem):
+class _canvasitem(canvasitem.canvasitem):
+
+    def bbox(self):
+        # TODO: see TODO in bbox method of canvasitem
+        return bbox.empty()
+
+
+class _savecolor(_canvasitem):
     def processPS(self, file, writer, context, registry, bbox):
         file.write("currentcolor currentcolorspace\n")
 
@@ -87,14 +94,15 @@ class _savecolor(canvasitem.canvasitem):
         file.write("q\n")
 
 
-class _restorecolor(canvasitem.canvasitem):
+class _restorecolor(_canvasitem):
     def processPS(self, file, writer, context, registry, bbox):
         file.write("setcolorspace setcolor\n")
 
     def processPDF(self, file, writer, context, registry, bbox):
         file.write("Q\n")
 
-class _savetrafo(canvasitem.canvasitem):
+
+class _savetrafo(_canvasitem):
     def processPS(self, file, writer, context, registry, bbox):
         file.write("matrix currentmatrix\n")
 
@@ -102,7 +110,7 @@ class _savetrafo(canvasitem.canvasitem):
         file.write("q\n")
 
 
-class _restoretrafo(canvasitem.canvasitem):
+class _restoretrafo(_canvasitem):
     def processPS(self, file, writer, context, registry, bbox):
         file.write("setmatrix\n")
 
diff --git a/pyx/style.py b/pyx/style.py
index b862c464..39883c82 100644
--- a/pyx/style.py
+++ b/pyx/style.py
@@ -31,10 +31,12 @@ import bbox as bboxmodule
 
 class strokestyle(canvasitem.canvasitem):
     def bbox(self):
+        # TODO: see TODO in bbox method of canvasitem
         return bboxmodule.empty()
 
 class fillstyle(canvasitem.canvasitem):
     def bbox(self):
+        # TODO: see TODO in bbox method of canvasitem
         return bboxmodule.empty()
 
 #
-- 
2.11.4.GIT