A FunctionImageData class which is to ImageData as FunctionDataSource…

… is to ArrayDataSource.

enthought/chaco/function_image_data.py

@@ -0,0 +1,45 @@
+from enthought.chaco.api import DataRange2D, ImageData
+
+# Adapted (ie. copied and modified) from function_data_source.
+
+# Given the time frequently required for image manipulation,
+# it would be awesome if there was a mechanism for returning
+# partial results as they become available.
+
+class FunctionImageData(ImageData):
+    """ A class that provides data for a 2-D image based upon the range
+    supplied.
+    
+    Computation should be fairly swift for acceptable interactive performance.
+    """
+
+    # The function to call with the low and high values of the range
+    # in the x and y dimensions.  It should return a 2-D array of values.
+    func = Callable
+
+    # the 2D data_range required for the data shown
+    data_range = Instance(DataRange2D)
+
+    def __init__(self, **kw):
+        super(FunctionImageData, self).__init__(**kw)
+        # Explicitly construct the initial data set for ImageData
+        self.recalculate()
+
+    @on_trait_change('data_range.updated')
+    def recalculate(self):
+        if self.func is not None and self.data_range is not None:
+            newarray = self.func(self.data_range.x_range.low, self.data_range.x_range.high,
+                self.data_range.y_range.low, self.data_range.y_range.high)
+            ImageData.set_data(self, newarray)
+        else:
+            self._data = array([], dtype=float)
+
+    def set_data(self, *args, **kw):
+        raise RuntimeError("Cannot set numerical data on a FunctionDataSource")
+
+    def set_mask(self, mask):
+        # This would be REALLY FREAKING SLICK, but it's currently unimplemented
+        raise NotImplementedError
+
+    def remove_mask(self):
+        raise NotImplementedError