Fix issue with empty line in ps backend

oscargus · oscargus · commit 4aef735564ec · 2022-09-20T15:49:49.000+02:00
diff --git a/lib/matplotlib/backends/backend_ps.py b/lib/matplotlib/backends/backend_ps.py
@@ -665,8 +665,9 @@ def draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None):
                 curr_stream[1].append(
                     (item.x, item.ft_object.get_glyph_name(item.glyph_idx))
                 )
-            # append the last entry
-            stream.append(curr_stream)
+            # append the last entry if exists
+            if curr_stream:
+                stream.append(curr_stream)
 
         self.set_color(*gc.get_rgb())
 
diff --git a/lib/matplotlib/tests/test_backend_ps.py b/lib/matplotlib/tests/test_backend_ps.py
@@ -256,6 +256,17 @@ def test_linedash():
     assert buf.tell() > 0
 
 
+def test_empty_line():
+    # Smoke-test for gh#23954
+    figure = Figure()
+    ax = figure.add_subplot(111)
+    ax.set_title('\nLower title')  # this would cause an error as well
+    ax.annotate(text='\nLower label', xy=(0, 0))
+    buf = io.BytesIO()
+    figure.savefig(buf, format='eps')
+    figure.savefig(buf, format='ps')
+
+
 def test_no_duplicate_definition():
 
     fig = Figure()
