Fixed issue #1

Scaling of the circle was not corect when the target enclosure was not centered on (0, 0).

circlify.py

@@ -315,12 +315,13 @@ def scale(circles, enclosure, target):
 
     """
     r = target.r / enclosure.r
-    dx = target.x - enclosure.x
-    dy = target.y - enclosure.y
+    t_x, t_y = target.x, target.y
+    e_x, e_y = enclosure.x, enclosure.y
     scaled = []
     for circle in circles:
-        x_c, y_c, r_c = circle
-        scaled.append(Circle((x_c + dx) * r, (y_c + dy) * r, r_c * r))
+        c_x, c_y, c_r = circle
+        scaled.append(Circle((c_x - e_x) * r + t_x,
+                             (c_y - e_y) * r + t_y, c_r * r))
     return scaled
 
 
@@ -347,6 +348,7 @@ def enclose(circles):
     return e
 
 
+# FIXME: remove with_enclosure because it complicates the interface.
 def circlify(data, target_enclosure=None, with_enclosure=False):
     """Pack and enclose circles whose radius is linked to the input data.
 

tests.py

@@ -6,7 +6,7 @@
 
 import unittest
 
-from circlify import Circle, circlify
+from circlify import Circle, circlify, scale
 
 
 # Set this variable to True to get a display of the layout (req matlplotlib)
@@ -137,6 +137,40 @@ def test_circlify(self):
         self.assertEqual(actual, expected)
 
 
+class EnclosureScalingTestCase(unittest.TestCase):
+    """Test scale function"""
+
+    def test_simple_zoom(self):
+        """Trivial zoom test when the enclosure is the same as the circle."""
+        input = Circle(0, 0, 0.5)
+        target = Circle(0, 0, 1.0)
+        actual = scale([input], input, target)
+        self.assertEqual([target], actual)
+
+    def test_simple_zoom_off_center(self):
+        """Zoom test with off center circle equal to enclosure."""
+        input = Circle(0.5, 0.5, 0.5)
+        target = Circle(0.5, 0.5, 1.0)
+        actual = scale([input], input, target)
+        self.assertEqual([target], actual)
+
+    def test_simple_zoom_and_translation(self):
+        """Pan and zoom test with off center circle equal to enclosure."""
+        input = Circle(0.5, 0.5, 0.5)
+        target = Circle(-0.5, 0, 1.0)
+        actual = scale([input], input, target)
+        self.assertEqual([target], actual)
+
+    def test_zoom_with_enclosure(self):
+        """Zoom test with off center circle and difference enclosure"""
+        input = Circle(1.0, 0.0, 1.0)
+        enclosure = Circle(0.0, 0.0, 2.0)
+        target = Circle(0.0, 0.0, 1.0)
+        actual = scale([input], enclosure, target)
+        expected = Circle(0.5, 0.0, 0.5)
+        self.assertEqual([expected], actual)
+
+
 if __name__ == '__main__':
     import logging
     logging.basicConfig(level='INFO')