Add access functions for ImagingEffectMandelbrot with a test

PIL/Image.py

@@ -2424,9 +2424,21 @@ def _showxv(image, title=None, **options):
 # --------------------------------------------------------------------
 # Effects
 
+def effect_mandelbrot(size, extent, quality):
+    """
+    Generate a Mandelbrot set covering the given extent.
+
+    :param size: The requested size in pixels, as a 2-tuple:
+       (width, height).
+    :param extent: The extent to cover, as a 4-tuple:
+       (x0, y0, x1, y2).
+    :param quality: Quality.
+    """
+    return Image()._new(core.effect_mandelbrot(size, extent, quality))
+
 def effect_noise(size, sigma):
     """
-    Generate Gaussian noise centered around 128
+    Generate Gaussian noise centered around 128.
 
     :param size: The requested size in pixels, as a 2-tuple:
        (width, height).

Tests/test_image.py

@@ -141,6 +141,20 @@ class TestImage(PillowTestCase):
         img_colors = sorted(img.getcolors())
         self.assertEqual(img_colors, expected_colors)
 
+    def test_effect_mandelbrot(self):
+        # Arrange
+        size = (512, 512)
+        extent = (-3, -2.5, 2, 2.5)
+        quality = 100
+
+        # Act
+        im = Image.effect_mandelbrot(size, extent, quality)
+
+        # Assert
+        self.assertEqual(im.size, (512, 512))
+        im2 = Image.open('Tests/images/mandelbrot.png')
+        self.assert_image_equal(im, im2)
+
     @unittest.skipUnless(sys.platform.startswith('win32'),
                          "Stalls on Travis CI, passes on Windows")
     def test_effect_noise(self):
@@ -156,7 +170,6 @@ class TestImage(PillowTestCase):
         self.assertEqual(im.getpixel((0, 0)), 60)
         self.assertEqual(im.getpixel((0, 1)), 28)
 
-
 if __name__ == '__main__':
     unittest.main()
 

libImaging/Effects.c

@@ -48,25 +48,25 @@ ImagingEffectMandelbrot(int xsize, int ysize, double extent[4], int quality)
 
     for (y = 0; y < ysize; y++) {
         UINT8* buf = im->image8[y];
-	for (x = 0; x < xsize; x++) {
-	    x1 = y1 = xi2 = yi2 = 0.0;
-	    cr = x*dr + extent[0];
-	    ci = y*di + extent[1];
-	    for (k = 1;; k++) {
-		y1 = 2*x1*y1 + ci;
-		x1 = xi2 - yi2 + cr;
-		xi2 = x1*x1;
-		yi2 = y1*y1;
-		if ((xi2 + yi2) > radius) {
-		    buf[x] = k*255/quality;
-		    break;
-		}
-		if (k > quality) {
-		    buf[x] = 0;
-		    break;
-		}
-	    }
-	}
+        for (x = 0; x < xsize; x++) {
+            x1 = y1 = xi2 = yi2 = 0.0;
+            cr = x*dr + extent[0];
+            ci = y*di + extent[1];
+            for (k = 1;; k++) {
+                y1 = 2*x1*y1 + ci;
+                x1 = xi2 - yi2 + cr;
+                xi2 = x1*x1;
+                yi2 = y1*y1;
+                if ((xi2 + yi2) > radius) {
+                    buf[x] = k*255/quality;
+                    break;
+                }
+                if (k > quality) {
+                    buf[x] = 0;
+                    break;
+                }
+            }
+        }
     }
     return im;
 }