Make PNG images in the Qt console work in Python 3.

IPython/frontend/qt/console/rich_ipython_widget.py

@@ -83,7 +83,7 b' class RichIPythonWidget(IPythonWidget):'
                 self._append_html(self._make_out_prompt(prompt_number), True)
                 # This helps the output to look nice.
                 self._append_plain_text('\n', True)
-                self._append_png(decodestring(data['image/png']), True)
+                self._append_png(decodestring(data['image/png'].encode('ascii')), True)
                 self._append_html(self.output_sep2, True)
             else:
                 # Default back to the plain text representation.
@@ -104,7 +104,7 b' class RichIPythonWidget(IPythonWidget):'
             elif data.has_key('image/png'):
                 # PNG data is base64 encoded as it passes over the network
                 # in a JSON structure so we decode it.
-                png = decodestring(data['image/png'])
+                png = decodestring(data['image/png'].encode('ascii'))
                 self._append_png(png, True)
             else:
                 # Default back to the plain text representation.

IPython/lib/pylabtools.py

@@ -19,7 +19,7 b' Authors'
 # Imports
 #-----------------------------------------------------------------------------
 
-from cStringIO import StringIO
+from io import BytesIO
 
 from IPython.utils.decorators import flag_calls
 
@@ -99,11 +99,11 b" def print_figure(fig, fmt='png'):"
     fig.set_facecolor('white')
     fig.set_edgecolor('white')
     try:
-        string_io = StringIO()
+        bytes_io = BytesIO()
         # use 72 dpi to match QTConsole's dpi
-        fig.canvas.print_figure(string_io, format=fmt, dpi=72,
+        fig.canvas.print_figure(bytes_io, format=fmt, dpi=72,
                                 bbox_inches='tight')
-        data = string_io.getvalue()
+        data = bytes_io.getvalue()
     finally:
         fig.set_facecolor(fc)
         fig.set_edgecolor(ec)

IPython/zmq/displayhook.py

@@ -30,10 +30,10 b' class ZMQDisplayHook(object):'
 def _encode_binary(format_dict):
     pngdata = format_dict.get('image/png')
     if pngdata is not None:
-        format_dict['image/png'] = encodestring(pngdata)
+        format_dict['image/png'] = encodestring(pngdata).decode('ascii')
     jpegdata = format_dict.get('image/jpeg')
     if jpegdata is not None:
-        format_dict['image/jpeg'] = encodestring(jpegdata)
+        format_dict['image/jpeg'] = encodestring(jpegdata).decode('ascii')
 
 
 class ZMQShellDisplayHook(DisplayHook):