Updated nbagg backend to default to a transparent figure patch.

Author: pelson

lib/matplotlib/backends/backend_nbagg.py

@@ -1,5 +1,6 @@
 """Interactive figures in the IPython notebook"""
 from base64 import b64encode
+from contextlib import contextmanager
 import json
 import io
 import os
@@ -10,11 +11,14 @@
 from IPython.display import display, Javascript, HTML
 from IPython.kernel.comm import Comm
 
+from matplotlib import rcParams
 from matplotlib.figure import Figure
+from matplotlib.backends import backend_agg
 from matplotlib.backends.backend_webagg_core import (FigureManagerWebAgg,
                                                      FigureCanvasWebAggCore,
                                                      NavigationToolbar2WebAgg)
-from matplotlib.backend_bases import ShowBase, NavigationToolbar2, TimerBase
+from matplotlib.backend_bases import (ShowBase, NavigationToolbar2,
+                                      TimerBase, FigureCanvasBase)
 
 
 class Show(ShowBase):
@@ -179,6 +183,25 @@ class FigureCanvasNbAgg(FigureCanvasWebAggCore):
     def new_timer(self, *args, **kwargs):
         return TimerTornado(*args, **kwargs)
 
+    def start_event_loop(self, timeout):
+        FigureCanvasBase.start_event_loop_default(self, timeout)
+
+    def stop_event_loop(self):
+        FigureCanvasBase.stop_event_loop_default(self)
+
+    def draw(self):
+        renderer = self.get_renderer()
+
+        self._png_is_old = True
+
+        backend_agg.RendererAgg.lock.acquire()
+        try:
+            self.figure.draw(renderer)
+        finally:
+            backend_agg.RendererAgg.lock.release()
+            # Swap the frames
+            self.manager.refresh_all()
+
 
 def new_figure_manager(num, *args, **kwargs):
     """
@@ -194,6 +217,8 @@ def new_figure_manager_given_figure(num, figure):
     Create a new figure manager instance for the given figure.
     """
     canvas = FigureCanvasNbAgg(figure)
+    if rcParams['nbagg.transparent']:
+        figure.patch.set_alpha(0)
     manager = FigureManagerNbAgg(canvas, num)
     return manager
 

lib/matplotlib/backends/web_backend/nbagg_uat.ipynb

@@ -1,7 +1,7 @@
 {
  "metadata": {
   "name": "",
-  "signature": "sha256:9a73a15660e6912c6bcfaf7c9e8247503738ce5d590a34e08789c2e16de93080"
+  "signature": "sha256:34c3a5a9d82d5a3c433f0c03f0717d43e1d14eaf78f88a64f094d104fa636ddc"
  },
  "nbformat": 3,
  "nbformat_minor": 0,
@@ -92,7 +92,7 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "print matplotlib.backends.backend_nbagg.connection_info()"
+      "print(matplotlib.backends.backend_nbagg.connection_info())"
      ],
      "language": "python",
      "metadata": {},
@@ -354,9 +354,42 @@
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "### UAT ?? - Keyboard shortcuts in IPython after close of figure (Current known bug)\n",
-      "### UAT ?? - Race condition to show means that \"run all\" ends up collapsing some figures into one (Current known bug)"
+      "### UAT 14 - Keyboard shortcuts in IPython after close of figure\n",
+      "\n",
+      "After closing the previous figure (with the close button above the figure) the IPython keyboard shortcuts should still function.\n",
+      "\n",
+      "### UAT 15 - Figure face colours\n",
+      "\n",
+      "The nbagg honours all colours appart from that of the figure.patch. The two plots below should produce a figure with a transparent background and a red background respectively (check the transparency by closing the figure, and dragging the resulting image over other content). There should be no yellow figure."
      ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "import matplotlib\n",
+      "matplotlib.rcParams.update({'figure.facecolor': 'red',\n",
+      "                            'savefig.facecolor': 'yellow'})\n",
+      "plt.figure()\n",
+      "plt.plot([3, 2, 1])\n",
+      "\n",
+      "with matplotlib.rc_context({'nbagg.transparent': False}):\n",
+      "    plt.figure()\n",
+      "\n",
+      "plt.plot([3, 2, 1])\n",
+      "plt.show()"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
     }
    ],
    "metadata": {}

lib/matplotlib/rcsetup.py

@@ -485,6 +485,7 @@ def __call__(self, s):
     'webagg.port':       [8988, validate_int],
     'webagg.open_in_browser': [True, validate_bool],
     'webagg.port_retries': [50, validate_int],
+    'nbagg.transparent':       [True, validate_bool],
     'toolbar':           ['toolbar2', validate_toolbar],
     'datapath':          [None, validate_path_exists],  # handled by
                                                         # _get_data_path_cached

matplotlibrc.template

@@ -57,6 +57,10 @@ backend      : %(backend)s
 # When True, open the webbrowser to the plot that is shown
 # webagg.open_in_browser : True
 
+# When True, the figures rendered in the nbagg backend are created with
+# a transparent background.
+# nbagg.transparent : True
+
 # if you are running pyplot inside a GUI and your backend choice
 # conflicts, we will automatically try to find a compatible one for
 # you if backend_fallback is True