Merge branch 'rf/image_save' into 'master'

Rf/image save

See merge request fsl/fslpy!188

COPYRIGHT

-Copyright 2016-2019 University of Oxford, Oxford, UK
+Copyright 2016-2020 University of Oxford, Oxford, UK

LICENSE

 The fslpy library
 
-Copyright 2016-2019 University of Oxford, Oxford, UK.
+Copyright 2016-2020 University of Oxford, Oxford, UK.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.

fsl/data/image.py

@@ -1362,6 +1362,10 @@ class Image(Nifti):
     def save(self, filename=None):
         """Saves this ``Image`` to the specifed file, or the :attr:`dataSource`
         if ``filename`` is ``None``.
+
+        Note that calling ``save`` on an image with modified data will cause
+        the entire image data to be loaded into memory if it has not already
+        been loaded.
         """
 
         import fsl.utils.imcp as imcp

tests/test_image_advanced.py

@@ -187,6 +187,15 @@ def _test_image_indexed_save(threaded):
         # make sure the data range is correct
         assert img.dataRange == (0, 40)
 
+        # Save the image to a different
+        # location (no changes to data though)
+        filename = op.join(testdir, 'image2.nii.gz')
+        img.save(filename)
+
+        # known data range
+        # should not have changed
+        assert img.dataRange == (0, 40)
+
         # change some data
         data = np.zeros((100, 100, 100))
         data[:] = 45
@@ -195,35 +204,21 @@ def _test_image_indexed_save(threaded):
         if threaded:
             img.getImageWrapper().getTaskThread().waitUntilIdle()
 
-        # save the image
+        # save the image - this will
+        # cause the image data to be
+        # loaded into memory
         img.save()
 
-        assert img.dataRange == (0, 45)
-
-        # access the data  - index should
-        # get rebuilt to this point
-        img[..., 0]
-        img[..., 40]
-
         if threaded:
             img.getImageWrapper().getTaskThread().waitUntilIdle()
 
-        # make sure we got the modified data
-        assert img.dataRange == (0, 45)
-
-        img[..., 49]
-
-        if threaded:
-            img.getImageWrapper().getTaskThread().waitUntilIdle()
-
-        # make sure we got the modified data
         assert img.dataRange == (0, 49)
-
+        assert np.all(img[..., 40] == data)
 
         # Finally, reload, and verify the change
         img = fslimage.Image(filename)
 
-        assert np.all(img[..., 40] == 45)
+        assert np.all(img[..., 40] == data)
 
 
 @pytest.mark.longtest