Merge pull request #1 from v7labs/simplify-polygon

Simplify polygons

setup.py

@@ -10,6 +10,7 @@
 extensions = [
     setuptools.Extension("draw_polygon", ["upolygon/draw_polygon" + ext], extra_compile_args=["-O3", "-Wall"]),
     setuptools.Extension("find_contours", ["upolygon/find_contours" + ext], extra_compile_args=["-O3", "-Wall"]),
+    setuptools.Extension("simplify_polygon", ["upolygon/simplify_polygon" + ext], extra_compile_args=["-O3", "-Wall"]),
 ]
 
 if USE_CYTHON:

tests/test_find_contours.py

@@ -1,6 +1,6 @@
 import numpy as np
 
-from upolygon import draw_polygon, find_contours
+from upolygon import draw_polygon, find_contours, simplify_polygon
 
 
 def test_single_pixel():

tests/test_simplify_polygon.py

@@ -0,0 +1,32 @@
+import numpy as np
+
+from upolygon import simplify_polygon
+
+
+def test_empty_path():
+    assert len(simplify_polygon([], 1)) == 0
+
+
+def test_empty_sub_path():
+    assert len(simplify_polygon([[]], 1)) == 1
+
+
+def test_removes_linear_points():
+    path = [0, 0, 0, 5, 0, 10, 0, 15]
+    assert simplify_polygon([path], 0) == [[0, 0, 0, 15]]
+
+
+def test_keeps_non_linear_points():
+    path = [0, 0, 0, 5, 0, 7, 10, 10, 0, 15]
+    assert simplify_polygon([path], 1) == [[0, 0, 0, 7, 10, 10, 0, 15]]
+
+
+def test_respects_epsilon():
+    path = [0, 0, 1, 1, 0, 10]
+    assert simplify_polygon([path], 1) == [[0, 0, 0, 10]]
+    assert simplify_polygon([path], 0.1) == [[0, 0, 1, 1, 0, 10]]
+
+
+def test_handles_repeats():
+    path = [0, 0, 0, 0, 0, 0, 1, 1]
+    assert simplify_polygon([path], 1) == [[0, 0, 1, 1]]

upolygon/__init__.py

@@ -1,2 +1,3 @@
 from draw_polygon import draw_polygon  # noqa
 from find_contours import find_contours  # noqa
+from simplify_polygon import simplify_polygon  # noqa

upolygon/find_contours.pyx

@@ -2,6 +2,7 @@
 
 cimport cython
 import numpy as np
+from simplify_polygon import simplify_polygon
 
 # This implementation is based on https://www.iis.sinica.edu.tw/papers/fchang/1362-F.pdf
 
@@ -108,4 +109,6 @@ def find_contours(unsigned char[:,:] image):
         if px > width-1:
             px = 1
             py = py + 1
-    return labels, outer_paths, inner_paths
+
+    # return labels, outer_paths, inner_paths
+    return labels, simplify_polygon(outer_paths, 0), simplify_polygon(inner_paths, 0)