FIX: make inset axes transparent on figures

sramesh750 · chahak13 · chahak13 · commit c59a7fa8db84 · 2022-12-26T22:03:53.000+05:30
Co-authored-by: Shreeya Ramesh &lt;shreeyar@umich.edu&gt;
Co-authored-by: Chahak Mehta &lt;chahakmehta013@gmail.com&gt;
diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
@@ -3059,12 +3059,37 @@ def savefig(self, fname, *, transparent=None, **kwargs):
 
         with ExitStack() as stack:
             if transparent:
+                def _recursively_make_subfig_transparent(exit_stack, subfig):
+                    exit_stack.enter_context(
+                        subfig.patch._cm_set(
+                            facecolor="none", edgecolor="none"))
+                    for ax in subfig.axes:
+                        exit_stack.enter_context(
+                            ax.patch._cm_set(
+                                facecolor="none", edgecolor="none"))
+                    for sub_subfig in subfig.subfigs:
+                        _recursively_make_subfig_transparent(
+                            exit_stack, sub_subfig)
+
+                def _recursively_make_axes_transparent(exit_stack, ax):
+                    exit_stack.enter_context(
+                        ax.patch._cm_set(facecolor="none", edgecolor="none"))
+                    for child_ax in ax.child_axes:
+                        exit_stack.enter_context(
+                            child_ax.patch._cm_set(
+                                facecolor="none", edgecolor="none"))
+                    for child_childax in ax.child_axes:
+                        _recursively_make_axes_transparent(
+                            exit_stack, child_childax)
+
                 kwargs.setdefault('facecolor', 'none')
                 kwargs.setdefault('edgecolor', 'none')
+                # set subfigure to appear transparent in printed image
+                for subfig in self.subfigs:
+                    _recursively_make_subfig_transparent(stack, subfig)
+                # set axes to be transparent
                 for ax in self.axes:
-                    stack.enter_context(
-                        ax.patch._cm_set(facecolor='none', edgecolor='none'))
-
+                    _recursively_make_axes_transparent(stack, ax)
             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
diff --git a/lib/matplotlib/tests/test_figure.py b/lib/matplotlib/tests/test_figure.py
@@ -557,6 +557,33 @@ 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()
+
+    gs1 = fig.add_gridspec(3, 3, left=0.05, wspace=0.05)
+    f1 = fig.add_subfigure(gs1[:, :])
+    f2 = f1.add_subfigure(gs1[0, 0])
+    ax12 = f2.add_subplot(gs1[:, :])
+    ax12.set(xticks=[], yticks=[])
+
+    ax1 = f1.add_subplot(gs1[:-1, :])
+    ax1.set(xticks=[], yticks=[])
+    iax1 = ax1.inset_axes([.1, .2, .3, .4])
+    iax1.set(xticks=[], yticks=[])
+    iax2 = iax1.inset_axes([.1, .2, .3, .4])
+    iax2.set(xticks=[], yticks=[])
+
+    ax2 = fig.add_subplot(gs1[-1, :-1])
+    ax2.set(xticks=[], yticks=[])
+    ax3 = fig.add_subplot(gs1[-1, -1])
+    ax3.set(xticks=[], yticks=[])
+
+
 def test_figure_repr():
     fig = plt.figure(figsize=(10, 20), dpi=10)
     assert repr(fig) == "<Figure size 100x200 with 0 Axes>"
