Merge pull request #2382 from hugovk/test-effects

Test linear and radial gradient effects

PIL/Image.py

@@ -144,6 +144,7 @@ def isImageType(t):
     """
     return hasattr(t, "im")
 
+
 #
 # Constants (also defined in _imagingmodule.c!)
 
@@ -339,6 +340,7 @@ def getmodebands(mode):
     """
     return len(ImageMode.getmode(mode).bands)
 
+
 # --------------------------------------------------------------------
 # Helpers
 
@@ -691,7 +693,7 @@ class Image(object):
         return b"".join(data)
 
     def tostring(self, *args, **kw):
-        raise NotImplementedError("tostring() has been removed. " +
+        raise NotImplementedError("tostring() has been removed. "
                                   "Please call tobytes() instead.")
 
     def tobitmap(self, name="image"):
@@ -742,7 +744,7 @@ class Image(object):
             raise ValueError("cannot decode image data")
 
     def fromstring(self, *args, **kw):
-        raise NotImplementedError("fromstring() has been removed. " +
+        raise NotImplementedError("fromstring() has been removed. "
                                   "Please call frombytes() instead.")
 
     def load(self):
@@ -879,7 +881,7 @@ class Image(object):
                             try:
                                 t = trns_im.palette.getcolor(t)
                             except:
-                                raise ValueError("Couldn't allocate a palette " +
+                                raise ValueError("Couldn't allocate a palette "
                                                  "color for transparency")
                     trns_im.putpixel((0, 0), t)
 
@@ -1036,7 +1038,6 @@ class Image(object):
 
         return self._new(self.im.crop((x0, y0, x1, y1)))
 
-
     def draft(self, mode, size):
         """
         Configures the image file loader so it returns a version of the
@@ -1254,7 +1255,7 @@ class Image(object):
         return self.im.histogram()
 
     def offset(self, xoffset, yoffset=None):
-        raise NotImplementedError("offset() has been removed. " +
+        raise NotImplementedError("offset() has been removed. "
                                   "Please call ImageChops.offset() instead.")
 
     def paste(self, im, box=None, mask=None):
@@ -1553,7 +1554,8 @@ class Image(object):
 
         return self._new(self.im.resize(size, resample))
 
-    def rotate(self, angle, resample=NEAREST, expand=0, center=None, translate=None):
+    def rotate(self, angle, resample=NEAREST, expand=0, center=None,
+               translate=None):
         """
         Returns a rotated copy of this image.  This method returns a
         copy of this image, rotated the given number of degrees counter
@@ -1622,10 +1624,13 @@ class Image(object):
             round(math.cos(angle), 15), round(math.sin(angle), 15), 0.0,
             round(-math.sin(angle), 15), round(math.cos(angle), 15), 0.0
         ]
+
         def transform(x, y, matrix):
             (a, b, c, d, e, f) = matrix
             return a*x + b*y + c, d*x + e*y + f
-        matrix[2], matrix[5] = transform(-center[0] - translate[0], -center[1] - translate[1], matrix)
+
+        matrix[2], matrix[5] = transform(-center[0] - translate[0],
+                                         -center[1] - translate[1], matrix)
         matrix[2] += center[0]
         matrix[5] += center[1]
 
@@ -1641,9 +1646,11 @@ class Image(object):
             nh = int(math.ceil(max(yy)) - math.floor(min(yy)))
 
             # We multiply a translation matrix from the right.  Because of its
-            # special form, this is the same as taking the image of the translation vector
-            # as new translation vector.
-            matrix[2], matrix[5] = transform(-(nw - w) / 2.0, -(nh - h) / 2.0, matrix)
+            # special form, this is the same as taking the image of the
+            # translation vector as new translation vector.
+            matrix[2], matrix[5] = transform(-(nw - w) / 2.0,
+                                             -(nh - h) / 2.0,
+                                             matrix)
             w, h = nw, nh
 
         return self.transform((w, h), AFFINE, matrix, resample)
@@ -1759,8 +1766,8 @@ class Image(object):
         PPM file, and calls either the **xv** utility or the **display**
         utility, depending on which one can be found.
 
-        On macOS, this method saves the image to a temporary BMP file, and opens
-        it with the native Preview application.
+        On macOS, this method saves the image to a temporary BMP file, and
+        opens it with the native Preview application.
 
         On Windows, it saves the image to a temporary BMP file, and uses
         the standard BMP display utility to show it (usually Paint).
@@ -1988,7 +1995,6 @@ class Image(object):
         return ImageQt.toqpixmap(self)
 
 
-
 # --------------------------------------------------------------------
 # Abstract handlers.
 
@@ -2013,6 +2019,7 @@ def _wedge():
 
     return Image()._new(core.wedge("L"))
 
+
 def _check_size(size):
     """
     Common check to enforce type and sanity check on size tuples
@@ -2030,6 +2037,7 @@ def _check_size(size):
 
     return True
 
+
 def new(mode, size, color=0):
     """
     Creates a new image with the given mode and size.
@@ -2230,6 +2238,7 @@ def fromqpixmap(im):
         raise ImportError("Qt bindings are not installed")
     return ImageQt.fromqpixmap(im)
 
+
 _fromarray_typemap = {
     # (shape, typestr) => mode, rawmode
     # first two members of shape are set to one
@@ -2558,3 +2567,21 @@ def effect_noise(size, sigma):
     :param sigma: Standard deviation of noise.
     """
     return Image()._new(core.effect_noise(size, sigma))
+
+
+def linear_gradient(mode):
+    """
+    Generate 256x256 linear gradient from black to white, top to bottom.
+
+    :param mode: Input mode.
+    """
+    return Image()._new(core.linear_gradient(mode))
+
+
+def radial_gradient(mode):
+    """
+    Generate 256x256 radial gradient from black to white, centre to edge.
+
+    :param mode: Input mode.
+    """
+    return Image()._new(core.radial_gradient(mode))

Tests/test_image.py

@@ -280,7 +280,8 @@ class TestImage(PillowTestCase):
         self.assert_image_similar(im2, im3, 110)
 
     def test_check_size(self):
-        # Checking that the _check_size function throws value errors when we want it to.
+        # Checking that the _check_size function throws value errors
+        # when we want it to.
         with self.assertRaises(ValueError):
             Image.new('RGB', 0)  # not a tuple
         with self.assertRaises(ValueError):
@@ -316,6 +317,58 @@ class TestImage(PillowTestCase):
     def test_fromstring(self):
         self.assertRaises(NotImplementedError, Image.fromstring)
 
+    def test_linear_gradient_wrong_mode(self):
+        # Arrange
+        wrong_mode = "RGB"
+
+        # Act / Assert
+        self.assertRaises(ValueError,
+                          lambda: Image.linear_gradient(wrong_mode))
+        return
+
+    def test_linear_gradient(self):
+
+        # Arrange
+        target_file = "Tests/images/linear_gradient.png"
+        for mode in ["L", "P"]:
+
+            # Act
+            im = Image.linear_gradient(mode)
+
+            # Assert
+            self.assertEqual(im.size, (256, 256))
+            self.assertEqual(im.mode, mode)
+            self.assertEqual(im.getpixel((0, 0)), 0)
+            self.assertEqual(im.getpixel((255, 255)), 255)
+            target = Image.open(target_file).convert(mode)
+            self.assert_image_equal(im, target)
+
+    def test_radial_gradient_wrong_mode(self):
+        # Arrange
+        wrong_mode = "RGB"
+
+        # Act / Assert
+        self.assertRaises(ValueError,
+                          lambda: Image.radial_gradient(wrong_mode))
+        return
+
+    def test_radial_gradient(self):
+
+        # Arrange
+        target_file = "Tests/images/radial_gradient.png"
+        for mode in ["L", "P"]:
+
+            # Act
+            im = Image.radial_gradient(mode)
+
+            # Assert
+            self.assertEqual(im.size, (256, 256))
+            self.assertEqual(im.mode, mode)
+            self.assertEqual(im.getpixel((0, 0)), 255)
+            self.assertEqual(im.getpixel((128, 128)), 0)
+            target = Image.open(target_file).convert(mode)
+            self.assert_image_equal(im, target)
+
 
 if __name__ == '__main__':
     unittest.main()

libImaging/Fill.c

@@ -64,15 +64,18 @@ ImagingFillLinearGradient(const char *mode)
     Imaging im;
     int y;
 
-    if (strlen(mode) != 1)
+    if (strlen(mode) != 1) {
         return (Imaging) ImagingError_ModeError();
+    }
 
     im = ImagingNew(mode, 256, 256);
-    if (!im)
+    if (!im) {
         return NULL;
+    }
 
-    for (y = 0; y < 256; y++)
+    for (y = 0; y < 256; y++) {
         memset(im->image8[y], (unsigned char) y, 256);
+    }
 
     return im;
 }
@@ -84,21 +87,25 @@ ImagingFillRadialGradient(const char *mode)
     int x, y;
     int d;
 
-    if (strlen(mode) != 1)
+    if (strlen(mode) != 1) {
         return (Imaging) ImagingError_ModeError();
+    }
 
     im = ImagingNew(mode, 256, 256);
-    if (!im)
+    if (!im) {
         return NULL;
+    }
 
-    for (y = 0; y < 256; y++)
+    for (y = 0; y < 256; y++) {
         for (x = 0; x < 256; x++) {
             d = (int) sqrt((double) ((x-128)*(x-128) + (y-128)*(y-128)) * 2.0);
-	    if (d >= 255)
+            if (d >= 255) {
                 im->image8[y][x] = 255;
-	    else
+            } else {
                 im->image8[y][x] = d;
             }
+        }
+    }
 
     return im;
 }