support 2D image array constants in py

TODO

@@ -7,6 +7,8 @@
 
   see test_morphology.py
 
+  seems to work ... add note to docs, update morph and conv tests
+
 - add median convenience function, see test_morphology.py
 
 

python/Vips.py

@@ -56,10 +56,32 @@ vips_type_blob = GObject.GType.from_name("VipsBlob")
 vips_type_image = GObject.GType.from_name("VipsImage")
 vips_type_operation = GObject.GType.from_name("VipsOperation")
 
-def imageize(match_image, value):
-    if match_image is None:
-        return value
+def is_2D(value):
+    if not isinstance(value, list):
+        return False
 
+    for x in value:
+        if not isinstance(x, list):
+            return False
+
+        if len(x) != len(value[0]):
+            return False
+
+    return True
+
+def imageize(match_image, value):
+    logging.debug('imageize match_image=%s, value=%s' % (match_image, value))
+
+    # 2D arrays become array images
+    if is_2D(value):
+        return Vips.Image.new_from_array(value)
+
+    # if there's nothing to match to, also make an array
+    if match_image is None:
+        return Vips.Image.new_from_array(value)
+
+    # assume this is a pixel constant ... expand into an image using
+    # match as a template
     pixel = (Vips.Image.black(1, 1) + value).cast(match_image.format)
     image = pixel.embed(0, 0, match_image.width, match_image.height,
                         extend = Vips.Extend.COPY)

python/example/try16.py

@@ -0,0 +1,20 @@
+#!/usr/bin/python3
+
+import sys
+
+import logging
+logging.basicConfig(level = logging.DEBUG)
+
+from gi.repository import Vips
+
+#Vips.cache_set_trace(True)
+
+a = Vips.Image.new_from_file(sys.argv[1])
+
+x = a.erode([[128, 255, 128], 
+             [255, 255, 255],
+             [128, 255, 128]])
+
+x.write_to_file(sys.argv[2])
+
+