Fix hard requirement of cairo per #83, and add stubs for required subclass methods to GerberContext per #84

8 files changed, 90 insertions, 69 deletions

diff --git a/examples/cairo_example.py b/examples/cairo_example.py
index fcd7a44..ecfed4d 100644
--- a/examples/cairo_example.py
+++ b/examples/cairo_example.py
@@ -25,7 +25,8 @@ a .png file.
 
 import os
 from gerber import load_layer
-from gerber.render import GerberCairoContext, RenderSettings, theme
+from gerber.render import RenderSettings, theme
+from gerber.render.cairo_backend import GerberCairoContext
 
 GERBER_FOLDER = os.path.abspath(os.path.join(os.path.dirname(__file__), 'gerbers'))
 
diff --git a/examples/pcb_example.py b/examples/pcb_example.py
index 9e066a8..34afee6 100644
--- a/examples/pcb_example.py
+++ b/examples/pcb_example.py
@@ -22,7 +22,8 @@ images using the PCB interface
 
 import os
 from gerber import PCB
-from gerber.render import GerberCairoContext, theme
+from gerber.render import theme
+from gerber.render.cairo_backend import GerberCairoContext
 
 
 GERBER_FOLDER = os.path.abspath(os.path.join(os.path.dirname(__file__), 'gerbers'))
diff --git a/gerber/cam.py b/gerber/cam.py
index 15b801a..4f20283 100644
--- a/gerber/cam.py
+++ b/gerber/cam.py
@@ -250,6 +250,10 @@ class CamFile(object):
         """
         pass
 
+    @property
+    def bounding_box(self):
+        pass
+
     def to_inch(self):
         pass
 
@@ -271,12 +275,12 @@ class CamFile(object):
             from .render import GerberCairoContext
             ctx = GerberCairoContext()
         ctx.set_bounds(self.bounding_box)
-        ctx._paint_background()
+        ctx.paint_background()
         ctx.invert = invert
-        ctx._new_render_layer()
+        ctx.new_render_layer()
         for p in self.primitives:
             ctx.render(p)
-        ctx._flatten()
+        ctx.flatten()
 
         if filename is not None:
             ctx.dump(filename)
diff --git a/gerber/render/__init__.py b/gerber/render/__init__.py
index 3598c4d..fe08d50 100644
--- a/gerber/render/__init__.py
+++ b/gerber/render/__init__.py
@@ -23,6 +23,4 @@ This module provides contexts for rendering images of gerber layers. Currently
 SVG is the only supported format.
 """
 
-
-from .cairo_backend import GerberCairoContext
 from .render import RenderSettings
diff --git a/gerber/render/cairo_backend.py b/gerber/render/cairo_backend.py
index 0e3a721..e1d1408 100644
--- a/gerber/render/cairo_backend.py
+++ b/gerber/render/cairo_backend.py
@@ -91,7 +91,7 @@ class GerberCairoContext(GerberContext):
                 self.set_bounds(bounds)
             else:
                 self.set_bounds(layer.bounds)
-            self._paint_background(bgsettings)
+            self.paint_background(bgsettings)
         if verbose:
             print('[Render]: Rendering {} Layer.'.format(layer.layer_class))
         self._render_count += 1
@@ -193,11 +193,11 @@ class GerberCairoContext(GerberContext):
     def _render_layer(self, layer, settings):
         self.invert = settings.invert
         # Get a new clean layer to render on
-        self._new_render_layer(mirror=settings.mirror)
+        self.new_render_layer(mirror=settings.mirror)
         for prim in layer.primitives:
             self.render(prim)
         # Add layer to image
-        self._flatten(settings.color, settings.alpha)
+        self.flatten(settings.color, settings.alpha)
 
     def _render_line(self, line, color):
         start = self.scale_point(line.start)
@@ -530,7 +530,7 @@ class GerberCairoContext(GerberContext):
         self.ctx.show_text(primitive.net_name)
         self.ctx.scale(1, -1)
 
-    def _new_render_layer(self, color=None, mirror=False):
+    def new_render_layer(self, color=None, mirror=False):
         size_in_pixels = self.scale_point(self.size_in_inch)
         matrix = copy.copy(self._xform_matrix)
         layer = cairo.SVGSurface(None, size_in_pixels[0], size_in_pixels[1])
@@ -548,8 +548,7 @@ class GerberCairoContext(GerberContext):
         self.active_layer = layer
         self.active_matrix = matrix
 
-
-    def _flatten(self, color=None, alpha=None):
+    def flatten(self, color=None, alpha=None):
         color = color if color is not None else self.color
         alpha = alpha if alpha is not None else self.alpha
         self.output_ctx.set_source_rgba(color[0], color[1], color[2], alpha)
@@ -558,7 +557,7 @@ class GerberCairoContext(GerberContext):
         self.active_layer = None
         self.active_matrix = None
 
-    def _paint_background(self, settings=None):
+    def paint_background(self, settings=None):
         color = settings.color if settings is not None else self.background_color
         alpha = settings.alpha if settings is not None else 1.0
         if not self.has_bg:
diff --git a/gerber/render/excellon_backend.py b/gerber/render/excellon_backend.py
index da5b22b..765d68c 100644
--- a/gerber/render/excellon_backend.py
+++ b/gerber/render/excellon_backend.py
@@ -4,13 +4,13 @@ from ..excellon import DrillSlot
 from ..excellon_statements import *
 
 class ExcellonContext(GerberContext):
-    
+
     MODE_DRILL = 1
-    MODE_SLOT =2 
-    
+    MODE_SLOT =2
+
     def __init__(self, settings):
         GerberContext.__init__(self)
-        
+
         # Statements that we write
         self.comments = []
         self.header = []
@@ -18,57 +18,57 @@ class ExcellonContext(GerberContext):
         self.body_start = [RewindStopStmt()]
         self.body = []
         self.start = [HeaderBeginStmt()]
-        
+
         # Current tool and position
         self.handled_tools = set()
         self.cur_tool = None
         self.drill_mode = ExcellonContext.MODE_DRILL
         self.drill_down = False
         self._pos = (None, None)
-        
+
         self.settings = settings
 
         self._start_header()
         self._start_comments()
-        
+
     def _start_header(self):
         """Create the header from the settings"""
-        
+
         self.header.append(UnitStmt.from_settings(self.settings))
-        
+
         if self.settings.notation == 'incremental':
             raise NotImplementedError('Incremental mode is not implemented')
         else:
             self.body.append(AbsoluteModeStmt())
-        
+
     def _start_comments(self):
-        
+
         # Write the digits used - this isn't valid Excellon statement, so we write as a comment
         self.comments.append(CommentStmt('FILE_FORMAT=%d:%d' % (self.settings.format[0], self.settings.format[1])))
-        
+
     def _get_end(self):
         """How we end depends on our mode"""
-        
+
         end = []
-        
+
         if self.drill_down:
             end.append(RetractWithClampingStmt())
             end.append(RetractWithoutClampingStmt())
-            
+
         end.append(EndOfProgramStmt())
-        
+
         return end
-        
+
     @property
     def statements(self):
         return self.start + self.comments + self.header + self.body_start + self.body + self._get_end()
-        
-    def set_bounds(self, bounds):
+
+    def set_bounds(self, bounds, *args, **kwargs):
         pass
-    
-    def _paint_background(self):
+
+    def paint_background(self):
         pass
-        
+
     def _render_line(self, line, color):
         raise ValueError('Invalid Excellon object')
     def _render_arc(self, arc, color):
@@ -76,7 +76,7 @@ class ExcellonContext(GerberContext):
 
     def _render_region(self, region, color):
         raise ValueError('Invalid Excellon object')
-        
+
     def _render_level_polarity(self, region):
         raise ValueError('Invalid Excellon object')
 
@@ -85,105 +85,104 @@ class ExcellonContext(GerberContext):
 
     def _render_rectangle(self, rectangle, color):
         raise ValueError('Invalid Excellon object')
-        
+
     def _render_obround(self, obround, color):
         raise ValueError('Invalid Excellon object')
-        
+
     def _render_polygon(self, polygon, color):
         raise ValueError('Invalid Excellon object')
-    
+
     def _simplify_point(self, point):
         return (point[0] if point[0] != self._pos[0] else None, point[1] if point[1] != self._pos[1] else None)
 
     def _render_drill(self, drill, color):
-        
+
         if self.drill_mode != ExcellonContext.MODE_DRILL:
             self._start_drill_mode()
-        
+
         tool = drill.hit.tool
         if not tool in self.handled_tools:
             self.handled_tools.add(tool)
             self.header.append(ExcellonTool.from_tool(tool))
-    
+
         if tool != self.cur_tool:
             self.body.append(ToolSelectionStmt(tool.number))
             self.cur_tool = tool
-            
+
         point = self._simplify_point(drill.position)
         self._pos = drill.position
         self.body.append(CoordinateStmt.from_point(point))
-        
+
     def _start_drill_mode(self):
         """
         If we are not in drill mode, then end the ROUT so we can do basic drilling
         """
-        
+
         if self.drill_mode == ExcellonContext.MODE_SLOT:
-            
+
             # Make sure we are retracted before changing modes
             last_cmd = self.body[-1]
             if self.drill_down:
                 self.body.append(RetractWithClampingStmt())
                 self.body.append(RetractWithoutClampingStmt())
                 self.drill_down = False
-            
+
             # Switch to drill mode
             self.body.append(DrillModeStmt())
             self.drill_mode = ExcellonContext.MODE_DRILL
-            
+
         else:
             raise ValueError('Should be in slot mode')
-        
+
     def _render_slot(self, slot, color):
-        
+
         # Set the tool first, before we might go into drill mode
         tool = slot.hit.tool
         if not tool in self.handled_tools:
             self.handled_tools.add(tool)
             self.header.append(ExcellonTool.from_tool(tool))
-            
+
         if tool != self.cur_tool:
             self.body.append(ToolSelectionStmt(tool.number))
             self.cur_tool = tool
-        
+
         # Two types of drilling - normal drill and slots
         if slot.hit.slot_type == DrillSlot.TYPE_ROUT:
 
             # For ROUT, setting the mode is part of the actual command.
-            
+
             # Are we in the right position?
             if slot.start != self._pos:
                 if self.drill_down:
                     # We need to move into the right position, so retract
                     self.body.append(RetractWithClampingStmt())
                     self.drill_down = False
-                    
+
                 # Move to the right spot
                 point = self._simplify_point(slot.start)
                 self._pos = slot.start
                 self.body.append(CoordinateStmt.from_point(point, mode="ROUT"))
-                
+
             # Now we are in the right spot, so drill down
             if not self.drill_down:
                 self.body.append(ZAxisRoutPositionStmt())
                 self.drill_down = True
-                
+
             # Do a linear move from our current position to the end position
             point = self._simplify_point(slot.end)
             self._pos = slot.end
             self.body.append(CoordinateStmt.from_point(point, mode="LINEAR"))
 
             self.drill_mode = ExcellonContext.MODE_SLOT
-                
+
         else:
             # This is a G85 slot, so do this in normally drilling mode
             if self.drill_mode != ExcellonContext.MODE_DRILL:
                 self._start_drill_mode()
-        
+
             # Slots don't use simplified points
             self._pos = slot.end
             self.body.append(SlotStmt.from_points(slot.start, slot.end))
 
     def _render_inverted_layer(self):
         pass
-        
\ No newline at end of file
diff --git a/gerber/render/render.py b/gerber/render/render.py
index 79f43d6..580a7ea 100644
--- a/gerber/render/render.py
+++ b/gerber/render/render.py
@@ -139,7 +139,7 @@ class GerberContext(object):
         if not primitive:
             return
 
-        self._pre_render_primitive(primitive)
+        self.pre_render_primitive(primitive)
 
         color = self.color
         if isinstance(primitive, Line):
@@ -167,16 +167,35 @@ class GerberContext(object):
         elif isinstance(primitive, TestRecord):
             self._render_test_record(primitive, color)
 
-        self._post_render_primitive(primitive)
+        self.post_render_primitive(primitive)
 
-    def _pre_render_primitive(self, primitive):
+    def set_bounds(self, bounds, *args, **kwargs):
+        """Called by the renderer to set the extents of the file to render.
+
+        Parameters
+        ----------
+        bounds: Tuple[Tuple[float, float], Tuple[float, float]]
+            ( (x_min, x_max), (y_min, y_max)
+        """
+        pass
+
+    def paint_background(self):
+        pass
+
+    def new_render_layer(self):
+        pass
+
+    def flatten(self):
+        pass
+
+    def pre_render_primitive(self, primitive):
         """
         Called before rendering a primitive. Use the callback to perform some action before rendering
         a primitive, for example adding a comment.
         """
         return
 
-    def _post_render_primitive(self, primitive):
+    def post_render_primitive(self, primitive):
         """
         Called after rendering a primitive. Use the callback to perform some action after rendering
         a primitive
diff --git a/gerber/render/rs274x_backend.py b/gerber/render/rs274x_backend.py
index d32602a..30048c4 100644
--- a/gerber/render/rs274x_backend.py
+++ b/gerber/render/rs274x_backend.py
@@ -148,10 +148,10 @@ class Rs274xContext(GerberContext):
     def statements(self):
         return self.comments + self.header + self.body + self.end
 
-    def set_bounds(self, bounds):
+    def set_bounds(self, bounds, *args, **kwargs):
         pass
 
-    def _paint_background(self):
+    def paint_background(self):
         pass
 
     def _select_aperture(self, aperture):
@@ -173,7 +173,7 @@ class Rs274xContext(GerberContext):
                 self.body.append(ApertureStmt(aper.d))
                 self._dcode = aper.d
 
-    def _pre_render_primitive(self, primitive):
+    def pre_render_primitive(self, primitive):
 
         if hasattr(primitive, 'comment'):
             self.body.append(CommentStmt(primitive.comment))
@@ -489,11 +489,11 @@ class Rs274xContext(GerberContext):
     def _render_inverted_layer(self):
         pass
 
-    def _new_render_layer(self):
+    def new_render_layer(self):
         # TODO Might need to implement this
         pass
 
-    def _flatten(self):
+    def flatten(self):
         # TODO Might need to implement this
         pass