Get unit conversion working for Gerber/Excellon files

Started operations module for file operations/transforms

16 files changed, 859 insertions, 94 deletions

diff --git a/gerber/am_statements.py b/gerber/am_statements.py
index dc97dfa..bdb12dd 100644
--- a/gerber/am_statements.py
+++ b/gerber/am_statements.py
@@ -16,7 +16,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from .utils import validate_coordinates
+from .utils import validate_coordinates, inch, metric
 
 
 # TODO: Add support for aperture macro variables
@@ -26,12 +26,6 @@ __all__ = ['AMPrimitive', 'AMCommentPrimitive', 'AMCirclePrimitive',
            'AMMoirePrimitive', 'AMThermalPrimitive', 'AMCenterLinePrimitive',
            'AMLowerLeftLinePrimitive', 'AMUnsupportPrimitive']
 
-def metric(value):
-    return value * 25.4
-
-def inch(value):
-    return value / 25.4
-
 
 class AMPrimitive(object):
     """ Aperture Macro Primitive Base Class
@@ -58,7 +52,7 @@ class AMPrimitive(object):
     TypeError, ValueError
     """
     def __init__(self, code, exposure=None):
-        VALID_CODES = (0, 1, 2, 4, 5, 6, 7, 20, 21, 22)
+        VALID_CODES = (0, 1, 2, 4, 5, 6, 7, 20, 21, 22, 9999)
         if not isinstance(code, int):
             raise TypeError('Aperture Macro Primitive code must be an integer')
         elif code not in VALID_CODES:
@@ -74,6 +68,8 @@ class AMPrimitive(object):
     def to_metric(self):
         raise NotImplementedError('Subclass must implement `to-metric`')
 
+    def __eq__(self, other):
+        return self.__dict__ == other.__dict__
 
 class AMCommentPrimitive(AMPrimitive):
     """ Aperture Macro Comment primitive. Code 0
@@ -818,11 +814,12 @@ class AMUnsupportPrimitive(AMPrimitive):
         return cls(primitive)
 
     def __init__(self, primitive):
+        super(AMUnsupportPrimitive, self).__init__(9999)
         self.primitive = primitive
 
     def to_inch(self):
         pass
-    
+
     def to_metric(self):
         pass
 
diff --git a/gerber/cam.py b/gerber/cam.py
index caca517..243070d 100644
--- a/gerber/cam.py
+++ b/gerber/cam.py
@@ -225,9 +225,9 @@ class CamFile(object):
 
     @property
     def bounds(self):
-        """ File baundaries
+        """ File boundaries
         """
-        raise NotImplementedError('bounds must be implemented in a subclass')
+        pass
 
     def render(self, ctx, filename=None):
         """ Generate image of layer.
diff --git a/gerber/excellon.py b/gerber/excellon.py
index a7f3a27..a339827 100755
--- a/gerber/excellon.py
+++ b/gerber/excellon.py
@@ -23,12 +23,12 @@ Excellon File module
 This module provides Excellon file classes and parsing utilities

 """

 

+import math

 

 from .excellon_statements import *

 from .cam import CamFile, FileSettings

 from .primitives import Drill

-import math

-import re

+

 

 def read(filename):

     """ Read data from filename and return an ExcellonFile

@@ -122,6 +122,31 @@ class ExcellonFile(CamFile):
             for statement in self.statements:

                 f.write(statement.to_excellon(self.settings) + '\n')

 

+    def to_inch(self):

+        """

+        Convert units to inches

+        """

+        if self.units != 'inch':

+            self.units = 'inch'

+            for statement in self.statements:

+                statement.to_inch()

+            for tool in self.tools.itervalues():

+                tool.to_inch()

+            for primitive in self.primitives:

+                primitive.to_inch()

+

+    def to_metric(self):

+        """  Convert units to metric

+        """

+        if self.units != 'metric':

+            self.units = 'metric'

+            for statement in self.statements:

+                statement.to_metric()

+            for tool in self.tools.itervalues():

+                tool.to_metric()

+            for primitive in self.primitives:

+                primitive.to_metric()

+

 

 class ExcellonParser(object):

     """ Excellon File Parser

diff --git a/gerber/excellon_statements.py b/gerber/excellon_statements.py
index 7e2772c..99f7d46 100644
--- a/gerber/excellon_statements.py
+++ b/gerber/excellon_statements.py
@@ -21,16 +21,19 @@ Excellon Statements
 
 """
 
-from .utils import parse_gerber_value, write_gerber_value, decimal_string
 import re
 
+from .utils import (parse_gerber_value, write_gerber_value, decimal_string,
+                    inch, metric)
+
+
 __all__ = ['ExcellonTool', 'ToolSelectionStmt', 'CoordinateStmt',
            'CommentStmt', 'HeaderBeginStmt', 'HeaderEndStmt',
            'RewindStopStmt', 'EndOfProgramStmt', 'UnitStmt',
            'IncrementalModeStmt', 'VersionStmt', 'FormatStmt', 'LinkToolStmt',
-           'MeasuringModeStmt', 'RouteModeStmt', 'DrillModeStmt', 'AbsoluteModeStmt',
-           'RepeatHoleStmt', 'UnknownStmt', 'ExcellonStatement'
-           ]
+           'MeasuringModeStmt', 'RouteModeStmt', 'DrillModeStmt',
+           'AbsoluteModeStmt', 'RepeatHoleStmt', 'UnknownStmt',
+           'ExcellonStatement',]
 
 
 class ExcellonStatement(object):
@@ -38,11 +41,21 @@ class ExcellonStatement(object):
     """
     @classmethod
     def from_excellon(cls, line):
-        raise NotImplementedError('`from_excellon` must be implemented in a subclass')
+        raise NotImplementedError('from_excellon must be implemented in a '
+                                  'subclass')
 
     def to_excellon(self, settings=None):
-        raise NotImplementedError('`to_excellon` must be implemented in a subclass')
+        raise NotImplementedError('to_excellon must be implemented in a '
+                                  'subclass')
+
+    def to_inch(self):
+        pass
+
+    def to_metric(self):
+        pass
 
+    def __eq__(self, other):
+        return self.__dict__ == other.__dict__
 
 class ExcellonTool(ExcellonStatement):
     """ Excellon Tool class
@@ -179,12 +192,17 @@ class ExcellonTool(ExcellonStatement):
         return stmt
 
     def to_inch(self):
-        if self.diameter is not None:
-            self.diameter = self.diameter / 25.4
+        if self.settings.units != 'inch':
+            self.settings.units = 'inch'
+            if self.diameter is not None:
+                self.diameter = inch(self.diameter)
+
 
     def to_metric(self):
-        if self.diameter is not None:
-            self.diameter = self.diameter * 25.4
+        if self.settings.units != 'metric':
+            self.settings.units = 'metric'
+            if self.diameter is not None:
+                self.diameter = metric(self.diameter)
 
     def _hit(self):
         self.hit_count += 1
@@ -240,11 +258,14 @@ class CoordinateStmt(ExcellonStatement):
         y_coord = None
         if line[0] == 'X':
             splitline = line.strip('X').split('Y')
-            x_coord = parse_gerber_value(splitline[0], settings.format, settings.zero_suppression)
+            x_coord = parse_gerber_value(splitline[0], settings.format,
+                                         settings.zero_suppression)
             if len(splitline) == 2:
-                y_coord = parse_gerber_value(splitline[1], settings.format, settings.zero_suppression)
+                y_coord = parse_gerber_value(splitline[1], settings.format,
+                                             settings.zero_suppression)
         else:
-            y_coord = parse_gerber_value(line.strip(' Y'), settings.format, settings.zero_suppression)
+            y_coord = parse_gerber_value(line.strip(' Y'), settings.format,
+                                         settings.zero_suppression)
         return cls(x_coord, y_coord)
 
     def __init__(self, x=None, y=None):
@@ -254,22 +275,24 @@ class CoordinateStmt(ExcellonStatement):
     def to_excellon(self, settings):
         stmt = ''
         if self.x is not None:
-            stmt += 'X%s' % write_gerber_value(self.x, settings.format, settings.zero_suppression)
+            stmt += 'X%s' % write_gerber_value(self.x, settings.format,
+                                               settings.zero_suppression)
         if self.y is not None:
-            stmt += 'Y%s' % write_gerber_value(self.y, settings.format, settings.zero_suppression)
+            stmt += 'Y%s' % write_gerber_value(self.y, settings.format,
+                                               settings.zero_suppression)
         return stmt
 
     def to_inch(self):
         if self.x is not None:
-            self.x = self.x / 25.4
+            self.x = inch(self.x)
         if self.y is not None:
-            self.y = self.y / 25.4
+            self.y = inch(self.y)
 
     def to_metric(self):
         if self.x is not None:
-            self.x = self.x * 25.4
+            self.x = metric(self.x)
         if self.y is not None:
-            self.y = self.y * 25.4
+            self.y = metric(self.y)
 
     def __str__(self):
         coord_str = ''
@@ -285,7 +308,8 @@ class RepeatHoleStmt(ExcellonStatement):
 
     @classmethod
     def from_excellon(cls, line, settings):
-        match = re.compile(r'R(?P<rcount>[0-9]*)X?(?P<xdelta>\d*\.?\d*)?Y?(?P<ydelta>\d*\.?\d*)?').match(line)
+        match = re.compile(r'R(?P<rcount>[0-9]*)X?(?P<xdelta>\d*\.?\d*)?Y?'
+                           '(?P<ydelta>\d*\.?\d*)?').match(line)
         stmt = match.groupdict()
         count = int(stmt['rcount'])
         xdelta = (parse_gerber_value(stmt['xdelta'], settings.format,
@@ -304,11 +328,21 @@ class RepeatHoleStmt(ExcellonStatement):
     def to_excellon(self, settings):
         stmt = 'R%d' % self.count
         if self.xdelta != 0.0:
-            stmt += 'X%s' % write_gerber_value(self.xdelta, settings.format, settings.zero_suppression)
+            stmt += 'X%s' % write_gerber_value(self.xdelta, settings.format,
+                                               settings.zero_suppression)
         if self.ydelta != 0.0:
-            stmt += 'Y%s' % write_gerber_value(self.ydelta, settings.format, settings.zero_suppression)
+            stmt += 'Y%s' % write_gerber_value(self.ydelta, settings.format,
+                                               settings.zero_suppression)
         return stmt
 
+    def to_inch(self):
+        self.xdelta = inch(self.xdelta)
+        self.ydelta = inch(self.ydelta)
+
+    def to_metric(self):
+        self.xdelta = metric(self.xdelta)
+        self.ydelta = metric(self.ydelta)
+
     def __str__(self):
         return '<Repeat Hole: %d times>' % self.count
 
@@ -357,7 +391,8 @@ class EndOfProgramStmt(ExcellonStatement):
 
     @classmethod
     def from_excellon(cls, line, settings):
-        match = re.compile(r'M30X?(?P<x>\d*\.?\d*)?Y?(?P<y>\d*\.?\d*)?').match(line)
+        match = re.compile(r'M30X?(?P<x>\d*\.?\d*)?Y?'
+                           '(?P<y>\d*\.?\d*)?').match(line)
         stmt = match.groupdict()
         x = (parse_gerber_value(stmt['x'], settings.format,
                                 settings.zero_suppression)
@@ -379,6 +414,17 @@ class EndOfProgramStmt(ExcellonStatement):
             stmt += 'Y%s' % write_gerber_value(self.y)
         return stmt
 
+    def to_inch(self):
+        if self.x is not None:
+            self.x = inch(self.x)
+        if self.y is not None:
+            self.y = inch(self.y)
+
+    def to_metric(self):
+        if self.x is not None:
+            self.x = metric(self.x)
+        if self.y is not None:
+            self.y = metric(self.y)
 
 class UnitStmt(ExcellonStatement):
 
@@ -398,6 +444,11 @@ class UnitStmt(ExcellonStatement):
                           else 'TZ')
         return stmt
 
+    def to_inch(self):
+        self.units = 'inch'
+
+    def to_metric(self):
+        self.units = 'metric'
 
 class IncrementalModeStmt(ExcellonStatement):
 
@@ -479,6 +530,11 @@ class MeasuringModeStmt(ExcellonStatement):
     def to_excellon(self, settings=None):
         return 'M72' if self.units == 'inch' else 'M71'
 
+    def to_inch(self):
+        self.units = 'inch'
+
+    def to_metric(self):
+        self.units = 'metric'
 
 class RouteModeStmt(ExcellonStatement):
 
diff --git a/gerber/gerber_statements.py b/gerber/gerber_statements.py
index a6feef6..b231cdb 100644
--- a/gerber/gerber_statements.py
+++ b/gerber/gerber_statements.py
@@ -20,7 +20,8 @@ Gerber (RS-274X) Statements
 **Gerber RS-274X file statement classes**
 
 """
-from .utils import parse_gerber_value, write_gerber_value, decimal_string
+from .utils import (parse_gerber_value, write_gerber_value, decimal_string,
+                    inch, metric)
 from .am_statements import *
 
 
@@ -51,6 +52,15 @@ class Statement(object):
         s = s.rstrip() + ">"
         return s
 
+    def to_inch(self):
+        pass
+
+    def to_metric(self):
+        pass
+
+    def __eq__(self, other):
+        return self.__dict__ == other.__dict__
+
 
 class ParamStmt(Statement):
     """ Gerber parameter statement Base class
@@ -180,6 +190,12 @@ class MOParamStmt(ParamStmt):
         mode = 'MM' if self.mode == 'metric' else 'IN'
         return '%MO{0}*%'.format(mode)
 
+    def to_inch(self):
+        self.mode = 'inch'
+
+    def to_metric(self):
+        self.mode = 'metric'
+
     def __str__(self):
         mode_str = 'millimeters' if self.mode == 'metric' else 'inches'
         return ('<Mode: %s>' % mode_str)
@@ -267,10 +283,10 @@ class ADParamStmt(ParamStmt):
             self.modifiers = []
 
     def to_inch(self):
-        self.modifiers = [tuple([x / 25.4 for x in modifier]) for modifier in self.modifiers]
+        self.modifiers = [tuple([inch(x) for x in modifier]) for modifier in self.modifiers]
 
     def to_metric(self):
-        self.modifiers = [tuple([x * 25.4 for x in modifier]) for modifier in self.modifiers]
+        self.modifiers = [tuple([metric(x) for x in modifier]) for modifier in self.modifiers]
 
     def to_gerber(self, settings=None):
         if len(self.modifiers):
@@ -599,6 +615,18 @@ class OFParamStmt(ParamStmt):
             ret += 'B' + decimal_string(self.b, precision=5)
         return ret + '*%'
 
+    def to_inch(self):
+        if self.a is not None:
+            self.a = inch(self.a)
+        if self.b is not None:
+            self.b = inch(self.b)
+
+    def to_metric(self):
+        if self.a is not None:
+            self.a = metric(self.a)
+        if self.b is not None:
+            self.b = metric(self.b)
+
     def __str__(self):
         offset_str = ''
         if self.a is not None:
@@ -651,6 +679,18 @@ class SFParamStmt(ParamStmt):
             ret += 'B' + decimal_string(self.b, precision=5)
         return ret + '*%'
 
+    def to_inch(self):
+        if self.a is not None:
+            self.a = inch(self.a)
+        if self.b is not None:
+            self.b = inch(self.b)
+
+    def to_metric(self):
+        if self.a is not None:
+            self.a = metric(self.a)
+        if self.b is not None:
+            self.b = metric(self.b)
+
     def __str__(self):
         scale_factor = ''
         if self.a is not None:
@@ -775,25 +815,25 @@ class CoordStmt(Statement):
 
     def to_inch(self):
         if self.x is not None:
-            self.x = self.x / 25.4
+            self.x = inch(self.x)
         if self.y is not None:
-            self.y = self.y / 25.4
+            self.y = inch(self.y)
         if self.i is not None:
-            self.i = self.i / 25.4
+            self.i = inch(self.i)
         if self.j is not None:
-            self.j = self.j / 25.4
+            self.j = inch(self.j)
         if self.function == "G71":
             self.function = "G70"
 
     def to_metric(self):
         if self.x is not None:
-            self.x = self.x * 25.4
+            self.x = metric(self.x)
         if self.y is not None:
-            self.y = self.y * 25.4
+            self.y = metric(self.y)
         if self.i is not None:
-            self.i = self.i * 25.4
+            self.i = metric(self.i)
         if self.j is not None:
-            self.j = self.j * 25.4
+            self.j = metric(self.j)
         if self.function == "G70":
             self.function = "G71"
 
diff --git a/gerber/operations.py b/gerber/operations.py
new file mode 100644
index 0000000..9624a16
--- /dev/null
+++ b/gerber/operations.py
@@ -0,0 +1,120 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# copyright 2015 Hamilton Kibbe <ham@hamiltonkib.be>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+CAM File Operations
+===================
+**Transformations and other operations performed on Gerber and Excellon files**
+
+"""
+import copy
+
+def to_inch(cam_file):
+    """ Convert Gerber or Excellon file units to imperial
+
+    Parameters
+    ----------
+    cam_file : `gerber.cam.CamFile` subclass
+        Gerber or Excellon file to convert
+
+    Returns
+    -------
+    gerber_file : `gerber.cam.CamFile` subclass
+        A deep copy of the source file with units converted to imperial.
+    """
+    cam_file = copy.deepcopy(cam_file)
+    cam_file.to_inch()
+    return cam_file
+
+def to_metric(cam_file):
+    """ Convert Gerber or Excellon file units to metric
+
+    Parameters
+    ----------
+    cam_file : `gerber.cam.CamFile` subclass
+        Gerber or Excellon file to convert
+
+    Returns
+    -------
+    gerber_file : `gerber.cam.CamFile` subclass
+        A deep copy of the source file with units converted to metric.
+    """
+    cam_file = copy.deepcopy(cam_file)
+    cam_file.to_metric()
+    return cam_file
+
+def offset(cam_file, x_offset, y_offset):
+    """ Offset a Cam file by a specified amount in the X and Y directions.
+
+    Parameters
+    ----------
+    cam_file : `gerber.cam.CamFile` subclass
+        Gerber or Excellon file to offset
+
+    x_offset : float
+        Amount to offset the file in the X direction
+
+    y_offset : float
+        Amount to offset the file in the Y direction
+
+    Returns
+    -------
+    gerber_file : `gerber.cam.CamFile` subclass
+        An offset deep copy of the source file.
+    """
+    # TODO
+    pass
+
+def scale(cam_file, x_scale, y_scale):
+    """ Scale a Cam file by a specified amount in the X and Y directions.
+
+    Parameters
+    ----------
+    cam_file : `gerber.cam.CamFile` subclass
+        Gerber or Excellon file to scale
+
+    x_scale : float
+        X-axis scale factor
+
+    y_scale : float
+        Y-axis scale factor
+
+    Returns
+    -------
+    gerber_file : `gerber.cam.CamFile` subclass
+        An scaled deep copy of the source file.
+    """
+    # TODO
+    pass
+
+def rotate(cam_file, angle):
+    """ Rotate a Cam file a specified amount about the origin.
+
+    Parameters
+    ----------
+    cam_file : `gerber.cam.CamFile` subclass
+        Gerber or Excellon file to rotate
+
+    angle : float
+        Angle to rotate the file in degrees.
+
+    Returns
+    -------
+    gerber_file : `gerber.cam.CamFile` subclass
+        An rotated deep copy of the source file.
+    """
+    # TODO
+    pass
diff --git a/gerber/primitives.py b/gerber/primitives.py
index ffdbea7..cb6e4ea 100644
--- a/gerber/primitives.py
+++ b/gerber/primitives.py
@@ -16,7 +16,8 @@
 # limitations under the License.

 import math

 from operator import sub

-from .utils import validate_coordinates

+

+from .utils import validate_coordinates, inch, metric

 

 

 class Primitive(object):

@@ -46,7 +47,11 @@ class Primitive(object):
 

         Return ((min x, max x), (min y, max y))

         """

-        raise NotImplementedError('Bounding box calculation must be implemented in subclass')

+        raise NotImplementedError('Bounding box calculation must be '

+                                  'implemented in subclass')

+

+    def __eq__(self, other):

+        return self.__dict__ == other.__dict__

 

 

 class Line(Primitive):

@@ -91,18 +96,18 @@ class Line(Primitive):
             # Find all the corners of the start and end position

             start_ll = (start[0] - (width / 2.),

                         start[1] - (height / 2.))

-            start_lr = (start[0] - (width / 2.),

-                        start[1] + (height / 2.))

-            start_ul = (start[0] + (width / 2.),

+            start_lr = (start[0] + (width / 2.),

                         start[1] - (height / 2.))

+            start_ul = (start[0] - (width / 2.),

+                        start[1] + (height / 2.))

             start_ur = (start[0] + (width / 2.),

                         start[1] + (height / 2.))

             end_ll = (end[0] - (width / 2.),

                       end[1] - (height / 2.))

-            end_lr = (end[0] - (width / 2.),

-                      end[1] + (height / 2.))

-            end_ul = (end[0] + (width / 2.),

+            end_lr = (end[0] + (width / 2.),

                       end[1] - (height / 2.))

+            end_ul = (end[0] - (width / 2.),

+                      end[1] + (height / 2.))

             end_ur = (end[0] + (width / 2.),

                       end[1] + (height / 2.))

 

@@ -124,10 +129,17 @@ class Line(Primitive):
                 return (end_ll, start_lr, start_ur, end_ul)

             elif end[0] < start[0] and end[1] > start[1]:

                 return (start_ll, start_lr, start_ur, end_ur, end_ul, end_ll)

-            else:

-                return None

 

 

+    def to_inch(self):

+        self.aperture.to_inch()

+        self.start = tuple(map(inch, self.start))

+        self.end = tuple(map(inch, self.end))

+

+    def to_metric(self):

+        self.aperture.to_metric()

+        self.start = tuple(map(metric, self.start))

+        self.end = tuple(map(metric, self.end))

 

 

 class Arc(Primitive):

@@ -206,6 +218,18 @@ class Arc(Primitive):
         max_y = max(y) + self.aperture.radius

         return ((min_x, max_x), (min_y, max_y))

 

+    def to_inch(self):

+        self.aperture.to_inch()

+        self.start = tuple(map(inch, self.start))

+        self.end = tuple(map(inch, self.end))

+        self.center = tuple(map(inch, self.center))

+

+    def to_metric(self):

+        self.aperture.to_metric()

+        self.start = tuple(map(metric, self.start))

+        self.end = tuple(map(metric, self.end))

+        self.center = tuple(map(metric, self.center))

+

 

 class Circle(Primitive):

     """

@@ -228,9 +252,15 @@ class Circle(Primitive):
         max_y = self.position[1] + self.radius

         return ((min_x, max_x), (min_y, max_y))

 

-    @property

-    def stroke_width(self):

-        return self.diameter

+    def to_inch(self):

+        if self.position is not None:

+            self.position = tuple(map(inch, self.position))

+        self.diameter = inch(self.diameter)

+

+    def to_metric(self):

+        if self.position is not None:

+            self.position = tuple(map(metric, self.position))

+        self.diameter = metric(self.diameter)

 

 

 class Ellipse(Primitive):

@@ -276,12 +306,12 @@ class Rectangle(Primitive):
 

     @property

     def lower_left(self):

-        return (self.position[0] - (self._abs_width / 2.), 

+        return (self.position[0] - (self._abs_width / 2.),

                 self.position[1] - (self._abs_height / 2.))

 

     @property

     def upper_right(self):

-        return (self.position[0] + (self._abs_width / 2.), 

+        return (self.position[0] + (self._abs_width / 2.),

                 self.position[1] + (self._abs_height / 2.))

 

     @property

@@ -292,6 +322,15 @@ class Rectangle(Primitive):
         max_y = self.upper_right[1]

         return ((min_x, max_x), (min_y, max_y))

 

+    def to_inch(self):

+        self.position = tuple(map(inch, self.position))

+        self.width = inch(self.width)

+        self.height = inch(self.height)

+

+    def to_metric(self):

+        self.position = tuple(map(metric, self.position))

+        self.width = metric(self.width)

+        self.height = metric(self.height)

 

 

 class Diamond(Primitive):

@@ -311,12 +350,12 @@ class Diamond(Primitive):
 

     @property

     def lower_left(self):

-        return (self.position[0] - (self._abs_width / 2.), 

+        return (self.position[0] - (self._abs_width / 2.),

                 self.position[1] - (self._abs_height / 2.))

 

     @property

     def upper_right(self):

-        return (self.position[0] + (self._abs_width / 2.), 

+        return (self.position[0] + (self._abs_width / 2.),

                 self.position[1] + (self._abs_height / 2.))

 

     @property

@@ -327,6 +366,16 @@ class Diamond(Primitive):
         max_y = self.upper_right[1]

         return ((min_x, max_x), (min_y, max_y))

 

+    def to_inch(self):

+        self.position = tuple(map(inch, self.position))

+        self.width = inch(self.width)

+        self.height = inch(self.height)

+

+    def to_metric(self):

+        self.position = tuple(map(metric, self.position))

+        self.width = metric(self.width)

+        self.height = metric(self.height)

+

 

 class ChamferRectangle(Primitive):

     """

@@ -347,12 +396,12 @@ class ChamferRectangle(Primitive):
 

     @property

     def lower_left(self):

-        return (self.position[0] - (self._abs_width / 2.), 

+        return (self.position[0] - (self._abs_width / 2.),

                 self.position[1] - (self._abs_height / 2.))

 

     @property

     def upper_right(self):

-        return (self.position[0] + (self._abs_width / 2.), 

+        return (self.position[0] + (self._abs_width / 2.),

                 self.position[1] + (self._abs_height / 2.))

 

     @property

@@ -363,6 +412,18 @@ class ChamferRectangle(Primitive):
         max_y = self.upper_right[1]

         return ((min_x, max_x), (min_y, max_y))

 

+    def to_inch(self):

+        self.position = tuple(map(inch, self.position))

+        self.width = inch(self.width)

+        self.height = inch(self.height)

+        self.chamfer = inch(self.chamfer)

+

+    def to_metric(self):

+        self.position = tuple(map(metric, self.position))

+        self.width = metric(self.width)

+        self.height = metric(self.height)

+        self.chamfer = metric(self.chamfer)

+

 

 class RoundRectangle(Primitive):

     """

@@ -383,12 +444,12 @@ class RoundRectangle(Primitive):
 

     @property

     def lower_left(self):

-        return (self.position[0] - (self._abs_width / 2.), 

+        return (self.position[0] - (self._abs_width / 2.),

                 self.position[1] - (self._abs_height / 2.))

 

     @property

     def upper_right(self):

-        return (self.position[0] + (self._abs_width / 2.), 

+        return (self.position[0] + (self._abs_width / 2.),

                 self.position[1] + (self._abs_height / 2.))

 

     @property

@@ -399,6 +460,18 @@ class RoundRectangle(Primitive):
         max_y = self.upper_right[1]

         return ((min_x, max_x), (min_y, max_y))

 

+    def to_inch(self):

+        self.position = tuple(map(inch, self.position))

+        self.width = inch(self.width)

+        self.height = inch(self.height)

+        self.radius = inch(self.radius)

+

+    def to_metric(self):

+        self.position = tuple(map(metric, self.position))

+        self.width = metric(self.width)

+        self.height = metric(self.height)

+        self.radius = metric(self.radius)

+

 

 class Obround(Primitive):

     """

@@ -417,12 +490,12 @@ class Obround(Primitive):
 

     @property

     def lower_left(self):

-        return (self.position[0] - (self._abs_width / 2.), 

+        return (self.position[0] - (self._abs_width / 2.),

                 self.position[1] - (self._abs_height / 2.))

 

     @property

     def upper_right(self):

-        return (self.position[0] + (self._abs_width / 2.), 

+        return (self.position[0] + (self._abs_width / 2.),

                 self.position[1] + (self._abs_height / 2.))

 

     @property

@@ -455,6 +528,16 @@ class Obround(Primitive):
                             self.height)

         return {'circle1': circle1, 'circle2': circle2, 'rectangle': rect}

 

+    def to_inch(self):

+        self.position = tuple(map(inch, self.position))

+        self.width = inch(self.width)

+        self.height = inch(self.height)

+

+    def to_metric(self):

+        self.position = tuple(map(metric, self.position))

+        self.width = metric(self.width)

+        self.height = metric(self.height)

+

 

 class Polygon(Primitive):

     """

@@ -474,6 +557,14 @@ class Polygon(Primitive):
         max_y = self.position[1] + self.radius

         return ((min_x, max_x), (min_y, max_y))

 

+    def to_inch(self):

+        self.position = tuple(map(inch, self.position))

+        self.radius = inch(self.radius)

+

+    def to_metric(self):

+        self.position = tuple(map(metric, self.position))

+        self.radius = metric(self.radius)

+

 

 class Region(Primitive):

     """

@@ -491,6 +582,12 @@ class Region(Primitive):
         max_y = max(y_list)

         return ((min_x, max_x), (min_y, max_y))

 

+    def to_inch(self):

+        self.points = [tuple(map(inch, point)) for point in self.points]

+

+    def to_metric(self):

+        self.points = [tuple(map(metric, point)) for point in self.points]

+

 

 class RoundButterfly(Primitive):

     """ A circle with two diagonally-opposite quadrants removed

@@ -513,6 +610,15 @@ class RoundButterfly(Primitive):
         max_y = self.position[1] + self.radius

         return ((min_x, max_x), (min_y, max_y))

 

+    def to_inch(self):

+        self.position = tuple(map(inch, self.position))

+        self.diameter = inch(self.diameter)

+

+    def to_metric(self):

+        self.position = tuple(map(metric, self.position))

+        self.diameter = metric(self.diameter)

+

+

 class SquareButterfly(Primitive):

     """ A square with two diagonally-opposite quadrants removed

     """

@@ -531,6 +637,14 @@ class SquareButterfly(Primitive):
         max_y = self.position[1] + (self.side / 2.)

         return ((min_x, max_x), (min_y, max_y))

 

+    def to_inch(self):

+        self.position = tuple(map(inch, self.position))

+        self.side = inch(self.side)

+

+    def to_metric(self):

+        self.position = tuple(map(metric, self.position))

+        self.side = metric(self.side)

+

 

 class Donut(Primitive):

     """ A Shape with an identical concentric shape removed from its center

@@ -558,12 +672,12 @@ class Donut(Primitive):
 

     @property

     def lower_left(self):

-        return (self.position[0] - (self.width / 2.), 

+        return (self.position[0] - (self.width / 2.),

                 self.position[1] - (self.height / 2.))

 

     @property

     def upper_right(self):

-        return (self.position[0] + (self.width / 2.), 

+        return (self.position[0] + (self.width / 2.),

                 self.position[1] + (self.height / 2.))

 

     @property

@@ -574,6 +688,20 @@ class Donut(Primitive):
         max_y = self.upper_right[1]

         return ((min_x, max_x), (min_y, max_y))

 

+    def to_inch(self):

+        self.position = tuple(map(inch, self.position))

+        self.width = inch(self.width)

+        self.height = inch(self.height)

+        self.inner_diameter = inch(self.inner_diameter)

+        self.outer_diaemter = inch(self.outer_diameter)

+

+    def to_metric(self):

+        self.position = tuple(map(metric, self.position))

+        self.width = metric(self.width)

+        self.height = metric(self.height)

+        self.inner_diameter = metric(self.inner_diameter)

+        self.outer_diaemter = metric(self.outer_diameter)

+

 

 class Drill(Primitive):

     """ A drill hole

@@ -597,3 +725,11 @@ class Drill(Primitive):
         max_y = self.position[1] + self.radius

         return ((min_x, max_x), (min_y, max_y))

 

+    def to_inch(self):

+        self.position = tuple(map(inch, self.position))

+        self.diameter = inch(self.diameter)

+

+    def to_metric(self):

+        self.position = tuple(map(metric, self.position))

+        self.diameter = metric(self.diameter)

+

diff --git a/gerber/rs274x.py b/gerber/rs274x.py
index 71ca111..21947e1 100644
--- a/gerber/rs274x.py
+++ b/gerber/rs274x.py
@@ -18,14 +18,15 @@
 """ This module provides an RS-274-X class and parser.
 """
 
-
 import copy
 import json
 import re
+
 from .gerber_statements import *
 from .primitives import *
 from .cam import CamFile, FileSettings
 
+
 def read(filename):
     """ Read data from filename and return a GerberFile
 
@@ -112,6 +113,21 @@ class GerberFile(CamFile):
                 f.write(statement.to_gerber(settings or self.settings))
                 f.write("\n")
 
+    def to_inch(self):
+        if self.units != 'inch':
+            self.units = 'inch'
+            for statement in self.statements:
+                statement.to_inch()
+            for primitive in self.primitives:
+                primitive.to_inch()
+
+    def to_metric(self):
+        if self.units != 'metric':
+            self.units = 'metric'
+            for statement in self.statements:
+                statement.to_metric()
+            for primitive in self.primitives:
+                primitive.to_metric()
 
 
 class GerberParser(object):
diff --git a/gerber/tests/test_am_statements.py b/gerber/tests/test_am_statements.py
index 696d951..0cee13d 100644
--- a/gerber/tests/test_am_statements.py
+++ b/gerber/tests/test_am_statements.py
@@ -324,6 +324,11 @@ def test_AMUnsupportPrimitive():
     u = AMUnsupportPrimitive('Test')
     assert_equal(u.to_gerber(), 'Test')
 
+def test_AMUnsupportPrimitive_smoketest():
+    u = AMUnsupportPrimitive.from_gerber('Test')
+    u.to_inch()
+    u.to_metric()
+
 
 
 def test_inch():
diff --git a/gerber/tests/test_cam.py b/gerber/tests/test_cam.py
index 185e716..6296cc9 100644
--- a/gerber/tests/test_cam.py
+++ b/gerber/tests/test_cam.py
@@ -65,9 +65,9 @@ def test_camfile_settings():
     cf = CamFile()
     assert_equal(cf.settings, FileSettings())
 
-#def test_bounds_override():
-#    cf = CamFile()
-#    assert_raises(NotImplementedError, cf.bounds)
+def test_bounds_override_smoketest():
+    cf = CamFile()
+    cf.bounds
 
 
 def test_zeros():
diff --git a/gerber/tests/test_excellon.py b/gerber/tests/test_excellon.py
index ea067b5..24cf793 100644
--- a/gerber/tests/test_excellon.py
+++ b/gerber/tests/test_excellon.py
@@ -2,12 +2,13 @@
 # -*- coding: utf-8 -*-
 
 # Author: Hamilton Kibbe <ham@hamiltonkib.be>
+import os
+
 from ..cam import FileSettings
 from ..excellon import read, detect_excellon_format, ExcellonFile, ExcellonParser
 from ..excellon_statements import ExcellonTool
 from tests import *
 
-import os
 
 NCDRILL_FILE = os.path.join(os.path.dirname(__file__),
                                 'resources/ncdrill.DRD')
@@ -37,6 +38,29 @@ def test_bounds():
 def test_report():
     ncdrill = read(NCDRILL_FILE)
 
+
+def test_conversion():
+    import copy
+    ncdrill = read(NCDRILL_FILE)
+    assert_equal(ncdrill.settings.units, 'inch')
+    ncdrill_inch = copy.deepcopy(ncdrill)
+    ncdrill.to_metric()
+    assert_equal(ncdrill.settings.units, 'metric')
+
+    for tool in ncdrill_inch.tools.itervalues():
+        tool.to_metric()
+    for primitive in ncdrill_inch.primitives:
+        primitive.to_metric()
+    for statement in ncdrill_inch.statements:
+        statement.to_metric()
+
+    for m_tool, i_tool in zip(ncdrill.tools.itervalues(), ncdrill_inch.tools.itervalues()):
+        assert_equal(i_tool, m_tool)
+
+    for m, i in zip(ncdrill.primitives,ncdrill_inch.primitives):
+        assert_equal(m, i)
+
+
 def test_parser_hole_count():
     settings = FileSettings(**detect_excellon_format(NCDRILL_FILE))
     p = ExcellonParser(settings)
diff --git a/gerber/tests/test_excellon_statements.py b/gerber/tests/test_excellon_statements.py
index 35bd045..4daeb4b 100644
--- a/gerber/tests/test_excellon_statements.py
+++ b/gerber/tests/test_excellon_statements.py
@@ -3,7 +3,7 @@
 
 # Author: Hamilton Kibbe <ham@hamiltonkib.be>
 
-from .tests import assert_equal, assert_raises
+from .tests import assert_equal, assert_not_equal, assert_raises
 from ..excellon_statements import *
 from ..cam import FileSettings
 
@@ -65,19 +65,34 @@ def test_excellontool_order():
     assert_equal(tool1.rpm, tool2.rpm)
 
 def test_excellontool_conversion():
-    tool = ExcellonTool.from_dict(FileSettings(), {'number': 8, 'diameter': 25.4})
+    tool = ExcellonTool.from_dict(FileSettings(units='metric'), {'number': 8, 'diameter': 25.4})
     tool.to_inch()
     assert_equal(tool.diameter, 1.)
-    tool = ExcellonTool.from_dict(FileSettings(), {'number': 8, 'diameter': 1})
+    tool = ExcellonTool.from_dict(FileSettings(units='inch'), {'number': 8, 'diameter': 1.})
     tool.to_metric()
     assert_equal(tool.diameter, 25.4)
 
+    # Shouldn't change units if we're already using target units
+    tool = ExcellonTool.from_dict(FileSettings(units='inch'), {'number': 8, 'diameter': 25.4})
+    tool.to_inch()
+    assert_equal(tool.diameter, 25.4)
+    tool = ExcellonTool.from_dict(FileSettings(units='metric'), {'number': 8, 'diameter': 1.})
+    tool.to_metric()
+    assert_equal(tool.diameter, 1.)
+
+
 def test_excellontool_repr():
     tool = ExcellonTool.from_dict(FileSettings(), {'number': 8, 'diameter': 0.125})
     assert_equal(str(tool), '<ExcellonTool 08: 0.125in. dia.>')
     tool = ExcellonTool.from_dict(FileSettings(units='metric'), {'number': 8, 'diameter': 0.125})
     assert_equal(str(tool), '<ExcellonTool 08: 0.125mm dia.>')
 
+def test_excellontool_equality():
+    t = ExcellonTool.from_dict(FileSettings(), {'number': 8, 'diameter': 0.125})
+    t1 = ExcellonTool.from_dict(FileSettings(), {'number': 8, 'diameter': 0.125})
+    assert_equal(t, t1)
+    t1 = ExcellonTool.from_dict(FileSettings(units='metric'), {'number': 8, 'diameter': 0.125})
+    assert_not_equal(t, t1)
 def test_toolselection_factory():
     """ Test ToolSelectionStmt factory method
     """
@@ -166,6 +181,19 @@ def test_repeatholestmt_dump():
     stmt = RepeatHoleStmt.from_excellon(line, FileSettings())
     assert_equal(stmt.to_excellon(FileSettings()), line)
 
+def test_repeatholestmt_conversion():
+    line = 'R4X0254Y254'
+    stmt = RepeatHoleStmt.from_excellon(line, FileSettings())
+    stmt.to_inch()
+    assert_equal(stmt.xdelta, 0.1)
+    assert_equal(stmt.ydelta, 1.)
+
+    line = 'R4X01Y1'
+    stmt = RepeatHoleStmt.from_excellon(line, FileSettings())
+    stmt.to_metric()
+    assert_equal(stmt.xdelta, 25.4)
+    assert_equal(stmt.ydelta, 254.)
+
 def test_repeathole_str():
     stmt = RepeatHoleStmt.from_excellon('R4X015Y32', FileSettings())
     assert_equal(str(stmt), '<Repeat Hole: 4 times>')
@@ -223,6 +251,16 @@ def test_endofprogramStmt_dump():
         stmt = EndOfProgramStmt.from_excellon(line, FileSettings())
         assert_equal(stmt.to_excellon(FileSettings()), line)
 
+def test_endofprogramstmt_conversion():
+    stmt = EndOfProgramStmt.from_excellon('M30X0254Y254', FileSettings())
+    stmt.to_inch()
+    assert_equal(stmt.x, 0.1)
+    assert_equal(stmt.y, 1.0)
+
+    stmt = EndOfProgramStmt.from_excellon('M30X01Y1', FileSettings())
+    stmt.to_metric()
+    assert_equal(stmt.x, 25.4)
+    assert_equal(stmt.y, 254.)
 
 def test_unitstmt_factory():
     """ Test UnitStmt factory method
@@ -256,6 +294,14 @@ def test_unitstmt_dump():
         stmt = UnitStmt.from_excellon(line)
         assert_equal(stmt.to_excellon(), line)
 
+def test_unitstmt_conversion():
+    stmt = UnitStmt.from_excellon('METRIC,TZ')
+    stmt.to_inch()
+    assert_equal(stmt.units, 'inch')
+
+    stmt = UnitStmt.from_excellon('INCH,TZ')
+    stmt.to_metric()
+    assert_equal(stmt.units, 'metric')
 
 def test_incrementalmode_factory():
     """ Test IncrementalModeStmt factory method
@@ -385,6 +431,18 @@ def test_measmodestmt_validation():
     assert_raises(ValueError, MeasuringModeStmt.from_excellon, 'M70')
     assert_raises(ValueError, MeasuringModeStmt, 'millimeters')
 
+def test_measmodestmt_conversion():
+    line = 'M72'
+    stmt = MeasuringModeStmt.from_excellon(line)
+    assert_equal(stmt.units, 'inch')
+    stmt.to_metric()
+    assert_equal(stmt.units, 'metric')
+
+    line = 'M71'
+    stmt = MeasuringModeStmt.from_excellon(line)
+    assert_equal(stmt.units, 'metric')
+    stmt.to_inch()
+    assert_equal(stmt.units, 'inch')
 
 def test_routemode_stmt():
     stmt = RouteModeStmt()
@@ -406,3 +464,11 @@ def test_unknownstmt():
 def test_unknownstmt_dump():
     stmt = UnknownStmt('TEST')
     assert_equal(stmt.to_excellon(FileSettings()), 'TEST')
+
+
+def test_excellontstmt():
+    """ Smoke test ExcellonStatement
+    """
+    stmt = ExcellonStatement()
+    stmt.to_inch()
+    stmt.to_metric()
\ No newline at end of file
diff --git a/gerber/tests/test_gerber_statements.py b/gerber/tests/test_gerber_statements.py
index c6040c0..bf7035f 100644
--- a/gerber/tests/test_gerber_statements.py
+++ b/gerber/tests/test_gerber_statements.py
@@ -7,6 +7,12 @@ from .tests import *
 from ..gerber_statements import *
 from ..cam import FileSettings
 
+def test_Statement_smoketest():
+    stmt = Statement('Test')
+    assert_equal(stmt.type, 'Test')
+    stmt.to_inch()
+    stmt.to_metric()
+    assert_equal(str(stmt), '<Statement type=Test>')
 
 def test_FSParamStmt_factory():
     """ Test FSParamStruct factory
@@ -114,6 +120,17 @@ def test_MOParamStmt_dump():
     assert_equal(mo.to_gerber(), '%MOMM*%')
 
 
+def test_MOParamStmt_conversion():
+    stmt = {'param': 'MO', 'mo': 'MM'}
+    mo = MOParamStmt.from_dict(stmt)
+    mo.to_inch()
+    assert_equal(mo.mode, 'inch')
+
+    stmt = {'param': 'MO', 'mo': 'IN'}
+    mo = MOParamStmt.from_dict(stmt)
+    mo.to_metric()
+    assert_equal(mo.mode, 'metric')
+
 def test_MOParamStmt_string():
     """ Test MOParamStmt.__str__()
     """
@@ -213,6 +230,20 @@ def test_OFParamStmt_dump():
     assert_equal(of.to_gerber(), '%OFA0.12345B0.12345*%')
 
 
+def test_OFParamStmt_conversion():
+    stmt = {'param': 'OF', 'a': '2.54', 'b': '25.4'}
+    of = OFParamStmt.from_dict(stmt)
+    of.to_inch()
+    assert_equal(of.a, 0.1)
+    assert_equal(of.b, 1.0)
+
+    stmt = {'param': 'OF', 'a': '0.1', 'b': '1.0'}
+    of = OFParamStmt.from_dict(stmt)
+    of.to_metric()
+    assert_equal(of.a, 2.54)
+    assert_equal(of.b, 25.4)
+
+
 def test_OFParamStmt_string():
     """ Test OFParamStmt __str__
     """
@@ -232,6 +263,19 @@ def test_SFParamStmt_dump():
     sf = SFParamStmt.from_dict(stmt)
     assert_equal(sf.to_gerber(), '%SFA1.4B0.9*%')
 
+def test_SFParamStmt_conversion():
+    stmt = {'param': 'OF', 'a': '2.54', 'b': '25.4'}
+    of = SFParamStmt.from_dict(stmt)
+    of.to_inch()
+    assert_equal(of.a, 0.1)
+    assert_equal(of.b, 1.0)
+
+    stmt = {'param': 'OF', 'a': '0.1', 'b': '1.0'}
+    of = SFParamStmt.from_dict(stmt)
+    of.to_metric()
+    assert_equal(of.a, 2.54)
+    assert_equal(of.b, 25.4)
+
 def test_SFParamStmt_string():
     stmt = {'param': 'SF', 'a': '1.4', 'b': '0.9'}
     sf = SFParamStmt.from_dict(stmt)
@@ -651,4 +695,3 @@ def test_aperturestmt_dump():
     assert_equal(str(ast), '<Aperture: 3>')
 
 
-    
\ No newline at end of file
diff --git a/gerber/tests/test_primitives.py b/gerber/tests/test_primitives.py
index f8b8620..cada6d4 100644
--- a/gerber/tests/test_primitives.py
+++ b/gerber/tests/test_primitives.py
@@ -51,6 +51,57 @@ def test_line_bounds():
         l = Line(start, end, r)
         assert_equal(l.bounding_box, expected)
 
+def test_line_vertices():
+    c = Circle((0, 0), 2)
+    l = Line((0, 0), (1, 1), c)
+    assert_equal(l.vertices, None)
+
+    # All 4 compass points, all 4 quadrants and the case where start == end
+    test_cases = [((0, 0), (1, 0), ((-1, -1), (-1, 1), (2, 1), (2, -1))),
+        ((0, 0), (1, 1), ((-1, -1), (-1, 1), (0, 2), (2, 2), (2, 0), (1,-1))),
+        ((0, 0), (0, 1), ((-1, -1), (-1, 2), (1, 2), (1, -1))),
+        ((0, 0), (-1, 1), ((-1, -1), (-2, 0), (-2, 2), (0, 2), (1, 1), (1, -1))),
+        ((0, 0), (-1, 0), ((-2, -1), (-2, 1), (1, 1), (1, -1))),
+        ((0, 0), (-1, -1), ((-2, -2), (1, -1), (1, 1), (-1, 1), (-2, 0), (0,-2))),
+        ((0, 0), (0, -1), ((-1, -2), (-1, 1), (1, 1), (1, -2))),
+        ((0, 0), (1, -1), ((-1, -1), (0, -2), (2, -2), (2, 0), (1, 1), (-1, 1))),
+        ((0, 0), (0, 0), ((-1, -1), (-1, 1), (1, 1), (1, -1))),]
+    r = Rectangle((0, 0), 2, 2)
+
+    for start, end, vertices in test_cases:
+        l = Line(start, end, r)
+        assert_equal(set(vertices), set(l.vertices))
+
+def test_line_conversion():
+    c = Circle((0, 0), 25.4)
+    l = Line((2.54, 25.4), (254.0, 2540.0), c)
+    l.to_inch()
+    assert_equal(l.start, (0.1, 1.0))
+    assert_equal(l.end, (10.0, 100.0))
+    assert_equal(l.aperture.diameter, 1.0)
+
+    c = Circle((0, 0), 1.0)
+    l = Line((0.1, 1.0), (10.0, 100.0), c)
+    l.to_metric()
+    assert_equal(l.start, (2.54, 25.4))
+    assert_equal(l.end, (254.0, 2540.0))
+    assert_equal(l.aperture.diameter, 25.4)
+
+    r = Rectangle((0, 0), 25.4, 254.0)
+    l = Line((2.54, 25.4), (254.0, 2540.0), r)
+    l.to_inch()
+    assert_equal(l.start, (0.1, 1.0))
+    assert_equal(l.end, (10.0, 100.0))
+    assert_equal(l.aperture.width, 1.0)
+    assert_equal(l.aperture.height, 10.0)
+
+    r = Rectangle((0, 0), 1.0, 10.0)
+    l = Line((0.1, 1.0), (10.0, 100.0), r)
+    l.to_metric()
+    assert_equal(l.start, (2.54, 25.4))
+    assert_equal(l.end, (254.0, 2540.0))
+    assert_equal(l.aperture.width, 25.4)
+    assert_equal(l.aperture.height, 254.0)
 
 
 def test_arc_radius():
@@ -89,6 +140,24 @@ def test_arc_bounds():
         a = Arc(start, end, center, direction, c)
         assert_equal(a.bounding_box, bounds)
 
+def test_arc_conversion():
+    c = Circle((0, 0), 25.4)
+    a = Arc((2.54, 25.4), (254.0, 2540.0), (25400.0, 254000.0),'clockwise', c)
+    a.to_inch()
+    assert_equal(a.start, (0.1, 1.0))
+    assert_equal(a.end, (10.0, 100.0))
+    assert_equal(a.center, (1000.0, 10000.0))
+    assert_equal(a.aperture.diameter, 1.0)
+
+    c = Circle((0, 0), 1.0)
+    a = Arc((0.1, 1.0), (10.0, 100.0), (1000.0, 10000.0),'clockwise', c)
+    a.to_metric()
+    assert_equal(a.start, (2.54, 25.4))
+    assert_equal(a.end, (254.0, 2540.0))
+    assert_equal(a.center, (25400.0, 254000.0))
+    assert_equal(a.aperture.diameter, 25.4)
+
+
 
 def test_circle_radius():
     """ Test Circle primitive radius calculation
@@ -146,7 +215,7 @@ def test_rectangle_bounds():
     xbounds, ybounds = r.bounding_box
     assert_array_almost_equal(xbounds, (-math.sqrt(2), math.sqrt(2)))
     assert_array_almost_equal(ybounds, (-math.sqrt(2), math.sqrt(2)))
-    
+
 def test_diamond_ctor():
     """ Test diamond creation
     """
@@ -169,6 +238,19 @@ def test_diamond_bounds():
     assert_array_almost_equal(xbounds, (-1, 1))
     assert_array_almost_equal(ybounds, (-1, 1))
 
+def test_diamond_conversion():
+    d = Diamond((2.54, 25.4), 254.0, 2540.0)
+    d.to_inch()
+    assert_equal(d.position, (0.1, 1.0))
+    assert_equal(d.width, 10.0)
+    assert_equal(d.height, 100.0)
+
+    d = Diamond((0.1, 1.0), 10.0, 100.0)
+    d.to_metric()
+    assert_equal(d.position, (2.54, 25.4))
+    assert_equal(d.width, 254.0)
+    assert_equal(d.height, 2540.0)
+
 
 def test_chamfer_rectangle_ctor():
     """ Test chamfer rectangle creation
@@ -198,6 +280,21 @@ def test_chamfer_rectangle_bounds():
     assert_array_almost_equal(ybounds, (-math.sqrt(2), math.sqrt(2)))
 
 
+def test_chamfer_rectangle_conversion():
+    r = ChamferRectangle((2.54, 25.4), 254.0, 2540.0, 0.254, (True, True, False, False))
+    r.to_inch()
+    assert_equal(r.position, (0.1, 1.0))
+    assert_equal(r.width, 10.0)
+    assert_equal(r.height, 100.0)
+    assert_equal(r.chamfer, 0.01)
+
+    r = ChamferRectangle((0.1, 1.0), 10.0, 100.0, 0.01, (True, True, False, False))
+    r.to_metric()
+    assert_equal(r.position, (2.54,25.4))
+    assert_equal(r.width, 254.0)
+    assert_equal(r.height, 2540.0)
+    assert_equal(r.chamfer, 0.254)
+
 def test_round_rectangle_ctor():
     """ Test round rectangle creation
     """
@@ -226,6 +323,21 @@ def test_round_rectangle_bounds():
     assert_array_almost_equal(ybounds, (-math.sqrt(2), math.sqrt(2)))
 
 
+def test_round_rectangle_conversion():
+    r = RoundRectangle((2.54, 25.4), 254.0, 2540.0, 0.254, (True, True, False, False))
+    r.to_inch()
+    assert_equal(r.position, (0.1, 1.0))
+    assert_equal(r.width, 10.0)
+    assert_equal(r.height, 100.0)
+    assert_equal(r.radius, 0.01)
+
+    r = RoundRectangle((0.1, 1.0), 10.0, 100.0, 0.01, (True, True, False, False))
+    r.to_metric()
+    assert_equal(r.position, (2.54,25.4))
+    assert_equal(r.width, 254.0)
+    assert_equal(r.height, 2540.0)
+    assert_equal(r.radius, 0.254)
+
 def test_obround_ctor():
     """ Test obround creation
     """
@@ -270,7 +382,22 @@ def test_obround_subshapes():
     assert_array_almost_equal(ss['rectangle'].position, (0, 0))
     assert_array_almost_equal(ss['circle1'].position, (1.5, 0))
     assert_array_almost_equal(ss['circle2'].position, (-1.5, 0))
-    
+
+
+def test_obround_conversion():
+    o = Obround((2.54,25.4), 254.0, 2540.0)
+    o.to_inch()
+    assert_equal(o.position, (0.1, 1.0))
+    assert_equal(o.width, 10.0)
+    assert_equal(o.height, 100.0)
+
+    o= Obround((0.1, 1.0), 10.0, 100.0)
+    o.to_metric()
+    assert_equal(o.position, (2.54, 25.4))
+    assert_equal(o.width, 254.0)
+    assert_equal(o.height, 2540.0)
+
+
 def test_polygon_ctor():
     """ Test polygon creation
     """
@@ -282,7 +409,7 @@ def test_polygon_ctor():
         assert_equal(p.position, pos)
         assert_equal(p.sides, sides)
         assert_equal(p.radius, radius)
-        
+
 def test_polygon_bounds():
     """ Test polygon bounding box calculation
     """
@@ -296,6 +423,18 @@ def test_polygon_bounds():
     assert_array_almost_equal(ybounds, (-2, 6))
 
 
+def test_polygon_conversion():
+    p = Polygon((2.54, 25.4), 3, 254.0)
+    p.to_inch()
+    assert_equal(p.position, (0.1, 1.0))
+    assert_equal(p.radius, 10.0)
+
+    p = Polygon((0.1, 1.0), 3, 10.0)
+    p.to_metric()
+    assert_equal(p.position, (2.54, 25.4))
+    assert_equal(p.radius, 254.0)
+
+
 def test_region_ctor():
     """ Test Region creation
     """
@@ -313,8 +452,20 @@ def test_region_bounds():
     xbounds, ybounds = r.bounding_box
     assert_array_almost_equal(xbounds, (0, 1))
     assert_array_almost_equal(ybounds, (0, 1))
-    
-    
+
+def test_region_conversion():
+    points = ((2.54, 25.4), (254.0,2540.0), (25400.0,254000.0), (2.54,25.4))
+    r = Region(points)
+    r.to_inch()
+    assert_equal(set(r.points), {(0.1, 1.0), (10.0, 100.0), (1000.0, 10000.0)})
+
+    points = ((0.1, 1.0), (10.0, 100.0), (1000.0, 10000.0), (0.1, 1.0))
+    r = Region(points)
+    r.to_metric()
+    assert_equal(set(r.points), {(2.54, 25.4), (254.0, 2540.0), (25400.0, 254000.0)})
+
+
+
 def test_round_butterfly_ctor():
     """ Test round butterfly creation
     """
@@ -331,6 +482,18 @@ def test_round_butterfly_ctor_validation():
     assert_raises(TypeError, RoundButterfly, 3, 5)
     assert_raises(TypeError, RoundButterfly, (3,4,5), 5)
 
+
+def test_round_butterfly_conversion():
+     b = RoundButterfly((2.54, 25.4), 254.0)
+     b.to_inch()
+     assert_equal(b.position, (0.1, 1.0))
+     assert_equal(b.diameter, 10.0)
+
+     b = RoundButterfly((0.1, 1.0), 10.0)
+     b.to_metric()
+     assert_equal(b.position, (2.54, 25.4))
+     assert_equal(b.diameter, (254.0))
+
 def test_round_butterfly_bounds():
     """ Test RoundButterfly bounding box calculation
     """
@@ -338,7 +501,7 @@ def test_round_butterfly_bounds():
     xbounds, ybounds = b.bounding_box
     assert_array_almost_equal(xbounds, (-1, 1))
     assert_array_almost_equal(ybounds, (-1, 1))
-    
+
 def test_square_butterfly_ctor():
     """ Test SquareButterfly creation
     """
@@ -363,6 +526,17 @@ def test_square_butterfly_bounds():
     assert_array_almost_equal(xbounds, (-1, 1))
     assert_array_almost_equal(ybounds, (-1, 1))
 
+def test_squarebutterfly_conversion():
+     b = SquareButterfly((2.54, 25.4), 254.0)
+     b.to_inch()
+     assert_equal(b.position, (0.1, 1.0))
+     assert_equal(b.side, 10.0)
+
+     b = SquareButterfly((0.1, 1.0), 10.0)
+     b.to_metric()
+     assert_equal(b.position, (2.54, 25.4))
+     assert_equal(b.side, (254.0))
+
 def test_donut_ctor():
     """ Test Donut primitive creation
     """
@@ -380,9 +554,28 @@ def test_donut_ctor_validation():
     assert_raises(TypeError, Donut, (3, 4, 5), 'round', 5, 7)
     assert_raises(ValueError, Donut, (0, 0), 'triangle', 3, 5)
     assert_raises(ValueError, Donut, (0, 0), 'round', 5, 3)
-    
+
 def test_donut_bounds():
-    pass
+    d = Donut((0, 0), 'round', 0.0, 2.0)
+    assert_equal(d.lower_left, (-1.0, -1.0))
+    assert_equal(d.upper_right, (1.0, 1.0))
+    xbounds, ybounds = d.bounding_box
+    assert_equal(xbounds, (-1., 1.))
+    assert_equal(ybounds, (-1., 1.))
+
+def test_donut_conversion():
+    d = Donut((2.54, 25.4), 'round', 254.0, 2540.0)
+    d.to_inch()
+    assert_equal(d.position, (0.1, 1.0))
+    assert_equal(d.inner_diameter, 10.0)
+    assert_equal(d.outer_diaemter, 100.0)
+
+    d = Donut((0.1, 1.0), 'round', 10.0, 100.0)
+    d.to_metric()
+    assert_equal(d.position, (2.54, 25.4))
+    assert_equal(d.inner_diameter, 254.0)
+    assert_equal(d.outer_diaemter, 2540.0)
+
 
 def test_drill_ctor():
     """ Test drill primitive creation
@@ -393,13 +586,15 @@ def test_drill_ctor():
         assert_equal(d.position, position)
         assert_equal(d.diameter, diameter)
         assert_equal(d.radius, diameter/2.)
-    
+
+
 def test_drill_ctor_validation():
     """ Test drill argument validation
     """
     assert_raises(TypeError, Drill, 3, 5)
     assert_raises(TypeError, Drill, (3,4,5), 5)
-    
+
+
 def test_drill_bounds():
     d = Drill((0, 0), 2)
     xbounds, ybounds = d.bounding_box
@@ -409,5 +604,21 @@ def test_drill_bounds():
     xbounds, ybounds = d.bounding_box
     assert_array_almost_equal(xbounds, (0, 2))
     assert_array_almost_equal(ybounds, (1, 3))
-    
-    
\ No newline at end of file
+
+def test_drill_conversion():
+    d = Drill((2.54, 25.4), 254.)
+    d.to_inch()
+    assert_equal(d.position, (0.1, 1.0))
+    assert_equal(d.diameter, 10.0)
+
+    d = Drill((0.1, 1.0), 10.)
+    d.to_metric()
+    assert_equal(d.position, (2.54, 25.4))
+    assert_equal(d.diameter, 254.0)
+
+def test_drill_equality():
+    d = Drill((2.54, 25.4), 254.)
+    d1 = Drill((2.54, 25.4), 254.)
+    assert_equal(d, d1)
+    d1 = Drill((2.54, 25.4), 254.2)
+    assert_not_equal(d, d1)
diff --git a/gerber/tests/test_rs274x.py b/gerber/tests/test_rs274x.py
index 5d528dc..27f6f49 100644
--- a/gerber/tests/test_rs274x.py
+++ b/gerber/tests/test_rs274x.py
@@ -2,10 +2,11 @@
 # -*- coding: utf-8 -*-
 
 # Author: Hamilton Kibbe <ham@hamiltonkib.be>
+import os
+
 from ..rs274x import read, GerberFile
 from tests import *
 
-import os
 
 TOP_COPPER_FILE = os.path.join(os.path.dirname(__file__),
                                 'resources/top_copper.GTL')
@@ -25,3 +26,20 @@ def test_size_parameter():
     assert_equal(size[0], 2.2869)
     assert_equal(size[1], 1.8064)
 
+def test_conversion():
+    import copy
+    top_copper = read(TOP_COPPER_FILE)
+    assert_equal(top_copper.units, 'inch')
+    top_copper_inch = copy.deepcopy(top_copper)
+    top_copper.to_metric()
+    for statement in top_copper_inch.statements:
+        statement.to_metric()
+    for primitive in top_copper_inch.primitives:
+        primitive.to_metric()
+    assert_equal(top_copper.units, 'metric')
+    for i, m in zip(top_copper.statements, top_copper_inch.statements):
+        assert_equal(i, m)
+
+    for i, m in zip(top_copper.primitives, top_copper_inch.primitives):
+        assert_equal(i, m)
+
diff --git a/gerber/utils.py b/gerber/utils.py
index 23575b3..542611d 100644
--- a/gerber/utils.py
+++ b/gerber/utils.py
@@ -26,6 +26,7 @@ files.
 # Author: Hamilton Kibbe <ham@hamiltonkib.be>
 # License:
 
+MILLIMETERS_PER_INCH = 25.4
 
 def parse_gerber_value(value, format=(2, 5), zero_suppression='trailing'):
     """ Convert gerber/excellon formatted string to floating-point number
@@ -235,3 +236,10 @@ def validate_coordinates(position):
             for coord in position:
                 if not (isinstance(coord, int) or isinstance(coord, float)):
                     raise TypeError('Coordinates must be integers or floats')
+
+
+def metric(value):
+    return value * MILLIMETERS_PER_INCH
+
+def inch(value):
+    return value / MILLIMETERS_PER_INCH