From e64af6d64d92e35575c3daaed07f0f2b97118e0f Mon Sep 17 00:00:00 2001
From: Shreeya Ramesh <shreeyar@umich.edu>
Date: Sat, 9 Apr 2022 21:26:06 -0400
Subject: [PATCH] FIX: savefig(...,transparent=True) now makes inset_axes
 transparent

---
 lib/matplotlib/figure.py                      |  16 +++++++++++++++-
 .../test_figure/transparent_background.png    | Bin 0 -> 4960 bytes
 lib/matplotlib/tests/test_figure.py           |  18 ++++++++++++++++++
 3 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 lib/matplotlib/tests/baseline_images/test_figure/transparent_background.png

diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
index bd6e99de0350..a1e28e63be55 100644
--- a/lib/matplotlib/figure.py
+++ b/lib/matplotlib/figure.py
@@ -3061,10 +3061,24 @@ def savefig(self, fname, *, transparent=None, **kwargs):
             if transparent:
                 kwargs.setdefault('facecolor', 'none')
                 kwargs.setdefault('edgecolor', 'none')
+                # set subfigure to appear transparent in printed image
+                for subfig in self.subfigs:
+                    stack.enter_context(
+                        subfig.patch._cm_set(
+                            facecolor='none', edgecolor='none'))
+                    for subfig_ax in subfig.axes:
+                        stack.enter_context(
+                            subfig_ax.patch._cm_set(
+                                facecolor='none', edgecolor='none'))
+                # set axes to be transparent
                 for ax in self.axes:
                     stack.enter_context(
                         ax.patch._cm_set(facecolor='none', edgecolor='none'))
-
+                    # set inset axes to be transparent as well
+                    for child_ax in ax.child_axes:
+                        stack.enter_context(
+                            child_ax.patch._cm_set(
+                                facecolor='none', edgecolor='none'))
             self.canvas.print_figure(fname, **kwargs)
 
     def ginput(self, n=1, timeout=30, show_clicks=True,
diff --git a/lib/matplotlib/tests/baseline_images/test_figure/transparent_background.png b/lib/matplotlib/tests/baseline_images/test_figure/transparent_background.png
new file mode 100644
index 0000000000000000000000000000000000000000..4fa6440e78c20dcae125beaa8c5b86e4afd078c0
GIT binary patch
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diff --git a/lib/matplotlib/tests/test_figure.py b/lib/matplotlib/tests/test_figure.py
index 9f68f63e5236..29cd33115601 100644
--- a/lib/matplotlib/tests/test_figure.py
+++ b/lib/matplotlib/tests/test_figure.py
@@ -557,6 +557,24 @@ def test_savefig_pixel_ratio(backend):
     assert ratio1 == ratio2
 
 
+@image_comparison(['transparent_background'],
+                    extensions=['png'], savefig_kwarg={'transparent': True},
+                    remove_text=True)
+def test_savefig_transparent():
+    # create two transparent subfigures with corresponding transparent inset
+    # axes. the entire background of the image should be transparent.
+    fig = plt.gcf()
+    gs = fig.add_gridspec(3, 3)
+    fig.add_subfigure(gs[0, 0])
+    fig.add_subplot(gs[0, 0])
+    ax = plt.gca()
+    ax.inset_axes([.1, .2, .3, .4])
+    fig.add_subfigure(gs[0:2, 1])
+    fig.add_subplot(gs[0:2, 1])
+    ax2 = plt.gca()
+    ax2.inset_axes([.1, .2, .3, .4])
+
+
 def test_figure_repr():
     fig = plt.figure(figsize=(10, 20), dpi=10)
     assert repr(fig) == "<Figure size 100x200 with 0 Axes>"