Add alternative autoplating method based on a packing algorithm

Packing algorithm is unlicensed for now, will import it when/if it gets a
GPL-compatible license

printrun/objectplater.py

@@ -150,6 +150,23 @@ class Plater(wx.Frame):
     def autoplate(self, event = None):
         print _("Autoplating")
         separation = 2
+        try:
+            from printrun import packer
+            p = packer.Packer()
+            for i in self.models:
+                width = abs(self.models[i].dims[0] - self.models[i].dims[1])
+                height = abs(self.models[i].dims[2] - self.models[i].dims[3])
+                p.add_rect(width, height, data = i)
+            # FIXME: probably wrong, not taking offsets into account
+            centerx = self.build_dimensions[0] / 2
+            centery = self.build_dimensions[1] / 2
+            rects = p.pack(padding = separation,
+                           center = packer.Vector2(centerx, centery))
+            for rect in rects:
+                i = rect.data
+                self.models[i].offsets[0] = rect.position.x
+                self.models[i].offsets[1] = rect.position.y
+        except ImportError:
             bedsize = self.build_dimensions[0:3]
             cursor = [0, 0, 0]
             newrow = 0
@@ -159,14 +176,16 @@ class Plater(wx.Frame):
                 x = abs(self.models[i].dims[0] - self.models[i].dims[1])
                 y = abs(self.models[i].dims[2] - self.models[i].dims[3])
                 centre = [x / 2, y / 2]
-            centreoffset = [self.models[i].dims[0] + centre[0], self.models[i].dims[2] + centre[1]]
+                centreoffset = [self.models[i].dims[0] + centre[0],
+                                self.models[i].dims[2] + centre[1]]
                 if (cursor[0] + x + separation) >= bedsize[0]:
                     cursor[0] = 0
                     cursor[1] += newrow + separation
                     newrow = 0
                 if (newrow == 0) or (newrow < y):
                     newrow = y
-            #To the person who works out why the offsets are applied differently here:
+                # To the person who works out why the offsets are applied
+                # differently here:
                 #    Good job, it confused the hell out of me.
                 self.models[i].offsets[0] = cursor[0] + centre[0] - centreoffset[0]
                 self.models[i].offsets[1] = cursor[1] + centre[1] - centreoffset[1]