Merge pull request #551 from wiredfool/with

Image.close, Context manager support

PIL/Image.py

@@ -92,7 +92,7 @@ except ImportError:
 
 from PIL import ImageMode
 from PIL._binary import i8, o8
-from PIL._util import isPath, isStringType
+from PIL._util import isPath, isStringType, deferred_error
 
 import os, sys
 
@@ -497,6 +497,35 @@ class Image:
 
     _makeself = _new # compatibility
 
+    # Context Manager Support
+    def __enter__(self):
+        return self
+    def __exit__(self, *args):
+        self.close()
+        
+    def close(self):
+        """
+        Closes the file pointer, if possible.
+
+        This operation will destroy the image core and release it's memory.
+        The image data will be unusable afterward.
+
+        This function is only required to close images that have not
+        had their file read and closed by the
+        :py:meth:`~PIL.Image.Image.load` method.
+        """
+        try:
+            self.fp.close()
+        except Exception as msg:
+            if Image.DEBUG:
+                print ("Error closing: %s" %msg)
+
+        # Instead of simply setting to None, we're setting up a
+        # deferred error that will better explain that the core image
+        # object is gone.
+        self.im = deferred_error(ValueError("Operation on closed image"))
+        
+
     def _copy(self):
         self.load()
         self.im = self.im.copy()
@@ -642,7 +671,8 @@ class Image:
         Allocates storage for the image and loads the pixel data.  In
         normal cases, you don't need to call this method, since the
         Image class automatically loads an opened image when it is
-        accessed for the first time.
+        accessed for the first time. This method will close the file
+        associated with the image. 
 
         :returns: An image access object.
         """
@@ -2074,10 +2104,11 @@ def open(fp, mode="r"):
     """
     Opens and identifies the given image file.
 
-    This is a lazy operation; this function identifies the file, but the
+    This is a lazy operation; this function identifies the file, but
-    actual image data is not read from the file until you try to process
+    the file remains open and the actual image data is not read from
-    the data (or call the :py:meth:`~PIL.Image.Image.load` method).
+    the file until you try to process the data (or call the
-    See :py:func:`~PIL.Image.new`.
+    :py:meth:`~PIL.Image.Image.load` method).  See
+    :py:func:`~PIL.Image.new`.
 
     :param file: A filename (string) or a file object.  The file object
        must implement :py:meth:`~file.read`, :py:meth:`~file.seek`, and

PIL/ImageCms.py

@@ -89,8 +89,8 @@ try:
 except ImportError as ex:
     # Allow error import for doc purposes, but error out when accessing
     # anything in core. 
-    from _util import import_err
+    from _util import deferred_error
-    _imagingcms = import_err(ex)
+    _imagingcms = deferred_error(ex)
 from PIL._util import isStringType
 
 core = _imagingcms

PIL/_util.py

@@ -15,7 +15,7 @@ else:
 def isDirectory(f):
     return isPath(f) and os.path.isdir(f)
 
-class import_err(object):
+class deferred_error(object):
     def __init__(self, ex):
         self.ex = ex
     def __getattr__(self, elt):

Tests/test_image_load.py

@@ -2,6 +2,8 @@ from tester import *
 
 from PIL import Image
 
+import os
+
 def test_sanity():
 
     im = lena()
@@ -9,3 +11,17 @@ def test_sanity():
     pix = im.load()
 
     assert_equal(pix[0, 0], (223, 162, 133))
+
+def test_close():    
+    im = Image.open("Images/lena.gif")
+    assert_no_exception(lambda: im.close())
+    assert_exception(ValueError, lambda: im.load())
+    assert_exception(ValueError, lambda: im.getpixel((0,0)))
+
+def test_contextmanager():
+    fn = None
+    with Image.open("Images/lena.gif") as im:
+        fn = im.fp.fileno()
+        assert_no_exception(lambda: os.fstat(fn))
+
+    assert_exception(OSError, lambda: os.fstat(fn))    

docs/handbook/tutorial.rst

@@ -126,7 +126,7 @@ Identify Image Files
 
     for infile in sys.argv[1:]:
         try:
-            im = Image.open(infile)
+            with Image.open(infile) as im:
                 print(infile, im.format, "%dx%d" % im.size, im.mode)
         except IOError:
             pass

docs/reference/Image.rst

@@ -136,9 +136,9 @@ ITU-R 709, using the D65 luminant) to the CIE XYZ color space:
 .. automethod:: PIL.Image.Image.verify
 
 .. automethod:: PIL.Image.Image.fromstring
-.. deprecated:: 2.0
 
 .. automethod:: PIL.Image.Image.load
+.. automethod:: PIL.Image.Image.close
 
 Attributes
 ----------