matplotlib · bdice · Mar 16, 2020 · Mar 16, 2020 · Mar 16, 2020 · Mar 17, 2020
diff --git a/doc/api/next_api_changes/deprecations/17891-BDD.rst b/doc/api/next_api_changes/deprecations/17891-BDD.rst
@@ -0,0 +1,6 @@
+Removing ``ipython_inline_display`` from Webagg backend
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The function ``matplotlib.backends.backend_webagg.ipython_inline_display`` is
+deprecated. It relies on outdated functionality of the tornado server and
+asyncio event loop and appears to be broken.
diff --git a/doc/users/next_whats_new/figure_repr_png.rst b/doc/users/next_whats_new/figure_repr_png.rst
@@ -0,0 +1,7 @@
+Add ``_repr_png_`` for figures with no configured IPython backend
+-----------------------------------------------------------------
+
+Previously, IPython would not show figures as images unless using the
+``matplotlib.pyplot`` interface or with an IPython magic statement like
+``%matplotlib backend``. Now, no magic is required to view PNG figure
+representations.
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
@@ -1701,6 +1701,26 @@ def __init__(self, figure):
         self.toolbar = None  # NavigationToolbar2 will set me
         self._is_idle_drawing = False
 
+    def _repr_png_(self):
+        """Generate a PNG representation of the FigureCanvasBase."""
+        # Defer to IPython to handle output if possible.
+        if 'IPython' in sys.modules:
+            from IPython.core.pylabtools import configure_inline_support
+            # Check whether %matplotlib was run.
+            if hasattr(configure_inline_support, 'current_backend'):
+                return
+
+        png_bytes = io.BytesIO()
+        self.print_figure(
+            png_bytes,
+            format='png',
+            facecolor=self.figure.get_facecolor(),
+            edgecolor=self.figure.get_edgecolor(),
+            dpi=self.figure.dpi,
+            bbox_inches=self.figure.bbox_inches
+        )
+        return png_bytes.getvalue()
+
     @classmethod
     @functools.lru_cache()
     def _fix_ipython_backend2gui(cls):

diff --git a/lib/matplotlib/backends/backend_webagg.py b/lib/matplotlib/backends/backend_webagg.py
@@ -33,6 +33,7 @@
 import tornado.websocket
 
 import matplotlib as mpl
+from matplotlib import cbook
 from matplotlib.backend_bases import _Backend
 from matplotlib._pylab_helpers import Gcf
 from . import backend_webagg_core as core
@@ -282,6 +283,7 @@ def catch_sigint():
             ioloop.start()
 
 
+@cbook.deprecated("3.4")
 def ipython_inline_display(figure):
     import tornado.template
 

diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
@@ -365,16 +365,10 @@ def __init__(self,
         # list of child gridspecs for this figure
         self._gridspecs = []
 
-    # TODO: I'd like to dynamically add the _repr_html_ method
-    # to the figure in the right context, but then IPython doesn't
-    # use it, for some reason.
-
-    def _repr_html_(self):
-        # We can't use "isinstance" here, because then we'd end up importing
-        # webagg unconditionally.
-        if 'WebAgg' in type(self.canvas).__name__:
-            from matplotlib.backends import backend_webagg
-            return backend_webagg.ipython_inline_display(self)
+    def _repr_png_(self):
+        """Generate a PNG representation of the Figure."""
+        if hasattr(self.canvas, '_repr_png_'):
+            return self.canvas._repr_png_()
 
     def show(self, warn=True):
         """

diff --git a/lib/matplotlib/tests/test_figure.py b/lib/matplotlib/tests/test_figure.py
@@ -780,6 +780,14 @@ def test_hashable_keys(self, fig_test, fig_ref):
         fig_ref.subplot_mosaic([["A", "B"]])
 
 
+def test_figure_repr_png():
+    from matplotlib.figure import Figure
+    fig = Figure(figsize=(4, 2))
+    ax = fig.add_subplot()
+    png_bytes = fig._repr_png_()
+    assert len(png_bytes) > 0
+
+
 def test_reused_gridspec():
     """Test that these all use the same gridspec"""
     fig = plt.figure()