Add overlay python object to act as inverse roi

Signed-off-by: Andrew Butt <butta@seas.upenn.edu>

prjxray/overlay.py

@@ -0,0 +1,60 @@
+class Overlay(object):
+    """ Object that represents an overlay.
+
+    Can be used to iterate over tiles and sites not inside a partition region.
+
+    """
+
+    def __init__(self, db, region_dict):
+        self.grid = db.grid()
+        self.region_dict = region_dict
+
+    def tile_in_roi(self, grid_loc):
+        """ Returns true if grid_loc (GridLoc tuple) is within the overlay. """
+        x = grid_loc.grid_x
+        y = grid_loc.grid_y
+        for _, bounds in self.region_dict.items():
+            x1, x2, y1, y2 = bounds
+            if x1 <= x and x <= x2 and y1 <= y and y <= y2:
+                return False
+        return True
+
+    def gen_tiles(self, tile_types=None):
+        ''' Yield tile names within overlay.
+
+        tile_types: list of tile types to keep, or None for all
+        '''
+
+        for tile_name in self.grid.tiles():
+            loc = self.grid.loc_of_tilename(tile_name)
+
+            if not self.tile_in_roi(loc):
+                continue
+
+            gridinfo = self.grid.gridinfo_at_loc(loc)
+
+            if tile_types is not None and gridinfo.tile_type not in tile_types:
+                continue
+
+            yield tile_name
+
+    def gen_sites(self, site_types=None):
+        ''' Yield (tile_name, site_name, site_type) within overlay.
+
+        site_types: list of site types to keep, or None for all
+
+        '''
+
+        for tile_name in self.grid.tiles():
+            loc = self.grid.loc_of_tilename(tile_name)
+
+            if not self.tile_in_roi(loc):
+                continue
+
+            gridinfo = self.grid.gridinfo_at_loc(loc)
+
+            for site_name, site_type in gridinfo.sites.items():
+                if site_types is not None and site_type not in site_types:
+                    continue
+
+                yield (tile_name, site_name, site_type)