implementation of bresenham

skais/tests/utils/test_geometry.py

+import unittest
+
+from skais.utils.geometry import bresenham
+
+
+class TestGeometry(unittest.TestCase):
+    def test_bresenham(self):
+        result = bresenham(3, 4, 16, 9)
+        expected = [(3, 4), (4, 4), (5, 5), (6, 5), (7, 6), (8, 6), (9, 6), (10, 7), (11, 7), (12, 7), (13, 8), (14, 8),
+                    (15, 9), (16, 9)]
+
+        self.assertListEqual(result, expected)
+
+    def test_bresenham_inverted(self):
+        result = bresenham(16, 9, 3, 4)
+        expected = [(3, 4), (4, 4), (5, 5), (6, 5), (7, 6), (8, 6), (9, 6), (10, 7), (11, 7), (12, 7), (13, 8),
+                    (14, 8), (15, 9), (16, 9)]
+
+        self.assertListEqual(result, expected)
+
+    def test_bresenham_same_line(self):
+        result = bresenham(3, 4, 10, 4)
+        expected = [(3, 4), (4, 4), (5, 4), (6, 4), (7, 4), (8, 4), (9, 4), (10, 4)]
+
+        self.assertListEqual(result, expected)
+
+    def test_bresenham_same_column(self):
+        result = bresenham(3, 4, 3, 10)
+        expected = [(3, 4), (3, 5), (3, 6), (3, 7), (3, 8), (3, 9), (3, 10)]
+
+        self.assertListEqual(result, expected)
+
+
+if __name__ == '__main__':
+    unittest.main()

skais/utils/geometry.py

+def bresenham(x1, y1, x2, y2):
+    if x1 > x2:
+        tmp = x2
+        x2 = x1
+        x1 = tmp
+    if y1 > y2:
+        tmp = y2
+        y2 = y1
+        y1 = tmp
+
+    pixels = [(x1, y1)]
+    if x1 == x2:
+        x = x1
+        for y in range(y1 + 1, y2 + 1):
+            pixels.append((x, y))
+    else:
+        a = 2*(y2 - y1)
+        b = a - 2*(x2 - x1)
+        p = a - (x2 - x1)
+
+        y = y1
+        for x in range(x1+1, x2+1):
+            if p < 0:
+                p += a
+            else:
+                y += 1
+                p += b
+            pixels.append((x, y))
+    return pixels
+