Beef up class constructors. Ensure data value is populated.

enable/primitives/image.py

@@ -23,7 +23,7 @@ class Image(Component):
     """
 
     #: the image data as an array
-    data = Array(dtype='uint8')
+    data = Array(shape=(None, None, (3,4)), dtype='uint8')
 
     #: the format of the image data (eg. RGB vs. RGBA)
     format = Property(Enum('rgb24', 'rgba32'))
@@ -35,11 +35,16 @@ class Image(Component):
     _image = Property(Instance(GraphicsContext), depends_on='data')
 
     @classmethod
-    def from_file(cls, filename):
+    def from_file(cls, filename, **traits):
         from PIL import Image
         from numpy import asarray
         data = asarray(Image.open(filename))
-        return cls(data=data, bounds=data.shape[:2])
+        return cls(data=data, **traits)
+
+    def __init__(self, data, **traits):
+        # the default bounds are the size of the image
+        traits.setdefault('bounds', data.shape[:2])
+        super(Image, self).__init__(data=data, **traits)
 
     def _draw_mainlayer(self, gc, view_bounds=None, mode="normal"):
         """ Draws the image. """

examples/enable/image_draw.py

@@ -1,21 +1,22 @@
 """
-This demonstrates the most basic drawing capabilities using Enable.  A new
-component is created and added to a container.
+This demonstrates the use of the simple Image component.
 """
 import os
-from enable.example_support import DemoFrame, demo_main
+
 from enable.api import ConstraintsContainer, Window
+from enable.example_support import DemoFrame, demo_main
 from enable.primitives.image import Image
 
 THIS_DIR = os.path.split(__file__)[0]
 
+
 class MyFrame(DemoFrame):
 
     def _create_window(self):
         path = os.path.join(THIS_DIR, 'deepfield.jpg')
-        image = Image.from_file(path)
-        image.resist_width = 'weak'
-        image.resist_height = 'weak'
+        image = Image.from_file(path, resist_width='weak',
+                                resist_height='weak')
+
         container = ConstraintsContainer(bounds=[500, 500])
         container.add(image)
         ratio = float(image.data.shape[1])/image.data.shape[0]