relative path support

svgpathtools/path.py

@@ -2261,71 +2261,107 @@ def end(self, pt):
         self._end = pt
         self._segments[-1].end = pt
 
-    def d(self, useSandT=False, use_closed_attrib=False):
+    def d(self, useSandT=False, use_closed_attrib=False, rel=False):
         """Returns a path d-string for the path object.
         For an explanation of useSandT and use_closed_attrib, see the
         compatibility notes in the README."""
-
+    
         if use_closed_attrib:
-            self_closed = self.closed(warning_on=False)
+            self_closed = self.iscontinuous() and self.isclosed()
             if self_closed:
                 segments = self[:-1]
             else:
                 segments = self[:]
         else:
             self_closed = False
             segments = self[:]
-
+    
         current_pos = None
         parts = []
         previous_segment = None
         end = self[-1].end
-
+    
         for segment in segments:
             seg_start = segment.start
             # If the start of this segment does not coincide with the end of
             # the last segment or if this segment is actually the close point
             # of a closed path, then we should start a new subpath here.
             if current_pos != seg_start or \
                     (self_closed and seg_start == end and use_closed_attrib):
-                parts.append('M {},{}'.format(seg_start.real, seg_start.imag))
-
+                if rel:
+                    _seg_start = seg_start - current_pos if current_pos is not None else seg_start
+                else:
+                    _seg_start = seg_start
+                parts.append('M {},{}'.format(_seg_start.real, _seg_start.imag))
+
             if isinstance(segment, Line):
-                args = segment.end.real, segment.end.imag
-                parts.append('L {},{}'.format(*args))
+                if rel:
+                    _seg_end = segment.end - seg_start
+                else:
+                    _seg_end = segment.end
+                parts.append('L {},{}'.format(_seg_end.real, _seg_end.imag))
             elif isinstance(segment, CubicBezier):
                 if useSandT and segment.is_smooth_from(previous_segment,
                                                        warning_on=False):
-                    args = (segment.control2.real, segment.control2.imag,
-                            segment.end.real, segment.end.imag)
+                    if rel:
+                        _seg_control2 = segment.control2 - seg_start
+                        _seg_end = segment.end - seg_start
+                    else:
+                        _seg_control2 = segment.control2
+                        _seg_end = segment.end
+                    args = (_seg_control2.real, _seg_control2.imag,
+                            _seg_end.real, _seg_end.imag)
                     parts.append('S {},{} {},{}'.format(*args))
                 else:
-                    args = (segment.control1.real, segment.control1.imag,
-                            segment.control2.real, segment.control2.imag,
-                            segment.end.real, segment.end.imag)
+                    if rel:
+                        _seg_control1 = segment.control1 - seg_start
+                        _seg_control2 = segment.control2 - seg_start
+                        _seg_end = segment.end - seg_start
+                    else:
+                        _seg_control1 = segment.control1
+                        _seg_control2 = segment.control2
+                        _seg_end = segment.end
+                    args = (_seg_control1.real, _seg_control1.imag,
+                            _seg_control2.real, _seg_control2.imag,
+                            _seg_end.real, _seg_end.imag)
                     parts.append('C {},{} {},{} {},{}'.format(*args))
             elif isinstance(segment, QuadraticBezier):
                 if useSandT and segment.is_smooth_from(previous_segment,
                                                        warning_on=False):
-                    args = segment.end.real, segment.end.imag
+                    if rel:
+                        _seg_end = segment.end - seg_start
+                    else:
+                        _seg_end = segment.end
+                    args = _seg_end.real, _seg_end.imag
                     parts.append('T {},{}'.format(*args))
                 else:
-                    args = (segment.control.real, segment.control.imag,
-                            segment.end.real, segment.end.imag)
+                    if rel:
+                        _seg_control = segment.control - seg_start
+                        _seg_end = segment.end - seg_start
+                    else:
+                        _seg_control = segment.control
+                        _seg_end = segment.end
+                    args = (_seg_control.real, _seg_control.imag,
+                            _seg_end.real, _seg_end.imag)
                     parts.append('Q {},{} {},{}'.format(*args))
-
+    
             elif isinstance(segment, Arc):
+                if rel:
+                    _seg_end = segment.end - seg_start
+                else:
+                    _seg_end = segment.end
                 args = (segment.radius.real, segment.radius.imag,
                         segment.rotation,int(segment.large_arc),
-                        int(segment.sweep),segment.end.real, segment.end.imag)
+                        int(segment.sweep),_seg_end.real, _seg_end.imag)
                 parts.append('A {},{} {} {:d},{:d} {},{}'.format(*args))
             current_pos = segment.end
             previous_segment = segment
-
+    
         if self_closed:
             parts.append('Z')
-
-        return ' '.join(parts)
+
+        s = ' '.join(parts)
+        return s if not rel else s.lower()
 
     def joins_smoothly_with(self, previous, wrt_parameterization=False):
         """Checks if this Path object joins smoothly with previous