use new pyvips8 array constant syntax

also add median filter convenience function

TODO

@@ -1,17 +1,4 @@
 
-- add imageize from 2D arrays, eg. we should be able to write
-
-        im = im.erode([[128, 255, 128], 
-		       [255, 255, 255], 
-		       [128, 255, 128]])
-
-  see test_morphology.py
-
-  seems to work ... add note to docs, update morph and conv tests
-
-- add median convenience function, see test_morphology.py
-
-
 
 - use vips_resize() in vipsthumbnail?
 

doc/reference/using-python.xml

@@ -218,9 +218,24 @@ profile = im.get_value("icc-profile-data")
     </para>
 
     <para>
-      If an operation takes several input images, you can use a constant
+      You can use array constants instead of images. A 2D array is simply 
-      for all but one of them and the wrapper will expand the constant
+      changed into a one-band double image. This is handy for things like 
-      to an image for you.  For example, <code>.ifthenelse()</code> uses
+      <code>.erode()</code>, for example:
+
+<programlisting language="Python">
+im = im.erode([[128, 255, 128],
+               [255, 255, 255],
+               [128, 255, 128]])
+</programlisting>
+
+      will erode an image with a 4-connected structuring element.
+    </para>
+
+    <para>
+      If an operation takes several input images, you can use a 1D array 
+      constant or a number constant
+      for all but one of them and the wrapper will expand it
+      to an image for you. For example, <code>.ifthenelse()</code> uses
       a condition image to pick pixels between a then and an else image:
 
 <programlisting language="Python">
@@ -241,7 +256,7 @@ result_image = condition_image.ifthenelse([0, 255, 0], [255, 0, 0])
     </para>
 
     <para>
-      This is useful for <code>.bandjoin()</code>, the thing to join 
+      This is also useful for <code>.bandjoin()</code>, the thing to join 
       two or more images up bandwise. You can write:
 
 <programlisting language="Python">
@@ -360,9 +375,12 @@ result_image = image.sin()
     <title>Convenience functions</title>
     <para>
       The wrapper defines a few extra useful utility functions: 
-      <code>.get_value()</code>, <code>.set_value()</code>
+      <code>.get_value()</code>, 
-      <code>.bandsplit()</code>, <code>.maxpos()</code>
+      <code>.set_value()</code>,
-      <code>.minpos()</code>.
+      <code>.bandsplit()</code>, 
+      <code>.maxpos()</code>,
+      <code>.minpos()</code>,
+      <code>.median()</code>.
       Again, see <code>help(Vips.Image)</code> for a list. 
     </para>
   </refsect1>

python/Vips.py

@@ -901,6 +901,10 @@ class Image(Vips.Image):
         """Dilate with a structuring element."""
         return self.morph(mask, Vips.OperationMorphology.DILATE)
 
+    def median(self, size):
+        """size x size median filter."""
+        return self.rank(size, size, (size * size) / 2)
+
     # we need different imageize rules for this operator ... we need to 
     # imageize th and el to match each other first
     @add_doc(generate_docstring("ifthenelse"))

test/test_conversion.py

@@ -566,12 +566,11 @@ class TestConversion(unittest.TestCase):
             self.assertAlmostEqualObjects(result, predict)
 
     def test_recomb(self):
-        array = [[0.2, 0.5, 0.3]] 
+        array = [[0.2, 0.5, 0.3]]
-        mask = Vips.Image.new_from_array(array)
 
         def recomb(x):
             if isinstance(x, Vips.Image):
-                return x.recomb(mask)
+                return x.recomb(array)
             else:
                 sum = 0
                 for i, c in zip(array[0], x):

test/test_morphology.py

@@ -33,11 +33,6 @@ class TestMorphology(unittest.TestCase):
         for x, y in zip_expand(a, b):
             self.assertAlmostEqual(x, y, places = places, msg = msg)
 
-    def setUp(self):
-        self.mask = Vips.Image.new_from_array([[128, 255, 128], 
-                                               [255, 255, 255], 
-                                               [128, 255, 128]])
-
     def test_countlines(self):
         im = Vips.Image.black(100, 100)
         im = im.draw_line(255, 0, 50, 100, 50)
@@ -55,7 +50,9 @@ class TestMorphology(unittest.TestCase):
     def test_erode(self):
         im = Vips.Image.black(100, 100)
         im = im.draw_circle(255, 50, 50, 25, fill = True)
-        im2 = im.erode(self.mask)
+        im2 = im.erode([[128, 255, 128], 
+                        [255, 255, 255], 
+                        [128, 255, 128]])
         self.assertEqual(im.width, im2.width)
         self.assertEqual(im.height, im2.height)
         self.assertEqual(im.bands, im2.bands)
@@ -64,7 +61,9 @@ class TestMorphology(unittest.TestCase):
     def test_dilate(self):
         im = Vips.Image.black(100, 100)
         im = im.draw_circle(255, 50, 50, 25, fill = True)
-        im2 = im.dilate(self.mask)
+        im2 = im.dilate([[128, 255, 128], 
+                         [255, 255, 255], 
+                         [128, 255, 128]])
         self.assertEqual(im.width, im2.width)
         self.assertEqual(im.height, im2.height)
         self.assertEqual(im.bands, im2.bands)