ugly bounding polygon hack for openiti

expands bounding polygons to offset from baseline at maximum seam
distance. Should solve dots getting cut off in Arabic print.

kraken/lib/segmentation.py

@@ -599,16 +599,14 @@ def _extract_patch(env_up, env_bottom, baseline, offset_baseline, end_points, di
     upper_seam = geom.LineString(upper_seam).simplify(5)
     bottom_seam = geom.LineString(bottom_seam).simplify(5)
 
-    # ugly workaround against GEOM parallel_offset bug creating a
-    # MultiLineString out of offset LineString
-    if upper_seam.parallel_offset(offset//2, side='right').geom_type == 'MultiLineString' or offset == 0:
-        upper_seam = np.array(upper_seam.coords, dtype=int)
-    else:
-        upper_seam = np.array(upper_seam.parallel_offset(offset//2, side='right').coords, dtype=int)[::-1]
-    if bottom_seam.parallel_offset(offset//2, side='left').geom_type == 'MultiLineString' or offset == 0:
-        bottom_seam = np.array(bottom_seam.coords, dtype=int)
-    else:
-        bottom_seam = np.array(bottom_seam.parallel_offset(offset//2, side='left').coords, dtype=int)
+    # XXX: hacky trick to make sure dotting is included in bounding polygon by
+    #      expanding it to its maximum distance from baseline.
+    baseline = geom.LineString(baseline)
+    us_dist = upper_seam.hausdorff_distance(baseline)
+    bs_dist = bottom_seam.hausdorff_distance(baseline)
+
+    upper_seam = np.array(baseline.parallel_offset(us_dist, side='right'), dtype=int)[::-1]
+    bottom_seam = np.array(baseline.parallel_offset(bs_dist, side='left'), dtype=int)
 
     # offsetting might produce bounds outside the image. Clip it to the image bounds.
     polygon = np.concatenate(([end_points[0]], upper_seam, [end_points[-1]], bottom_seam[::-1]))