A few small patches to image handling

IPython/core/display.py

@@ -7,7 +7,7 @@
 """
 
 #-----------------------------------------------------------------------------
-#       Copyright (C) 2008-2011 The IPython Development Team
+#       Copyright (C) 2013 The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
@@ -19,6 +19,8 @@
 
 from __future__ import print_function
 
+import os
+
 from .displaypub import (
     publish_pretty, publish_html,
     publish_latex, publish_svg,
@@ -28,6 +30,17 @@
 
 from IPython.utils.py3compat import string_types
 
+#-----------------------------------------------------------------------------
+# utility functions
+#-----------------------------------------------------------------------------
+
+def _safe_exists(path):
+    """check path, but don't let exceptions raise"""
+    try:
+        return os.path.exists(path)
+    except Exception:
+        return False
+
 #-----------------------------------------------------------------------------
 # Main functions
 #-----------------------------------------------------------------------------
@@ -248,20 +261,26 @@ def __init__(self, data=None, url=None, filename=None):
         Parameters
         ----------
         data : unicode, str or bytes
-            The raw data or a URL to download the data from.
+            The raw data or a URL or file to load the data from
         url : unicode
             A URL to download the data from.
         filename : unicode
             Path to a local file to load the data from.
         """
-        if data is not None and isinstance(data, string_types) and data.startswith('http'):
-            self.url = data
-            self.filename = None
-            self.data = None
-        else:
-            self.data = data
-            self.url = url
-            self.filename = None if filename is None else unicode(filename)
+        if data is not None and isinstance(data, string_types):
+            if data.startswith('http') and url is None:
+                url = data
+                filename = None
+                data = None
+            elif _safe_exists(data) and filename is None:
+                url = None
+                filename = data
+                data = None
+
+        self.data = data
+        self.url = url
+        self.filename = None if filename is None else unicode(filename)
+
         self.reload()
 
     def reload(self):
@@ -420,6 +439,9 @@ def _repr_javascript_(self):
         r += lib_t2*len(self.lib)
         return r
 
+# constants for identifying png/jpeg data
+_PNG = b'\x89PNG\r\n\x1a\n'
+_JPEG = b'\xff\xd8'
 
 class Image(DisplayObject):
 
@@ -476,7 +498,9 @@ def __init__(self, data=None, url=None, filename=None, format=u'png', embed=None
             ext = self._find_ext(url)
         elif data is None:
             raise ValueError("No image data found. Expecting filename, url, or data.")
-        elif isinstance(data, string_types) and data.startswith('http'):
+        elif isinstance(data, string_types) and (
+            data.startswith('http') or _safe_exists(data)
+        ):
             ext = self._find_ext(data)
         else:
             ext = None
@@ -487,6 +511,11 @@ def __init__(self, data=None, url=None, filename=None, format=u'png', embed=None
                 format = self._FMT_JPEG
             if ext == u'png':
                 format = self._FMT_PNG
+        elif isinstance(data, bytes) and format == 'png':
+            # infer image type from image data header,
+            # only if format might not have been specified.
+            if data[:2] == _JPEG:
+                format = 'jpeg'
 
         self.format = unicode(format).lower()
         self.embed = embed if embed is not None else (url is None)

IPython/utils/jsonutil.py

@@ -97,7 +97,11 @@ def date_default(obj):
 
 # constants for identifying png/jpeg data
 PNG = b'\x89PNG\r\n\x1a\n'
+# front of PNG base64-encoded
+PNG64 = b'iVBORw0KG'
 JPEG = b'\xff\xd8'
+# front of JPEG base64-encoded
+JPEG64 = b'/9'
 
 def encode_images(format_dict):
     """b64-encodes images in a displaypub format dict
@@ -120,12 +124,21 @@ def encode_images(format_dict):
 
     """
     encoded = format_dict.copy()
+
     pngdata = format_dict.get('image/png')
-    if isinstance(pngdata, bytes) and pngdata[:8] == PNG:
-        encoded['image/png'] = encodebytes(pngdata).decode('ascii')
+    if isinstance(pngdata, bytes):
+        # make sure we don't double-encode
+        if not pngdata.startswith(PNG64):
+            pngdata = encodebytes(pngdata)
+        encoded['image/png'] = pngdata.decode('ascii')
+
     jpegdata = format_dict.get('image/jpeg')
-    if isinstance(jpegdata, bytes) and jpegdata[:2] == JPEG:
-        encoded['image/jpeg'] = encodebytes(jpegdata).decode('ascii')
+    if isinstance(jpegdata, bytes):
+        # make sure we don't double-encode
+        if not jpegdata.startswith(JPEG64):
+            jpegdata = encodebytes(jpegdata)
+        encoded['image/jpeg'] = jpegdata.decode('ascii')
+
     return encoded