Merge pull request matplotlib#22689 from has2k1/patheffects-empty-string

FIX: path_effects to work on text with spaces only

Author: tacaswell

lib/matplotlib/tests/baseline_images/test_patheffects/spaces_and_newlines.png

@@ -189,3 +189,16 @@ def test_tickedstroke():
 
     ax3.set_xlim(0, 4)
     ax3.set_ylim(0, 4)
+
+
+@image_comparison(['spaces_and_newlines.png'], remove_text=True)
+def test_patheffects_spaces_and_newlines():
+    ax = plt.subplot()
+    s1 = "         "
+    s2 = "\nNewline also causes problems"
+    text1 = ax.text(0.5, 0.75, s1, ha='center', va='center', size=20,
+                    bbox={'color': 'salmon'})
+    text2 = ax.text(0.5, 0.25, s2, ha='center', va='center', size=20,
+                    bbox={'color': 'thistle'})
+    text1.set_path_effects([path_effects.Normal()])
+    text2.set_path_effects([path_effects.Normal()])

lib/matplotlib/tests/test_patheffects.py

@@ -129,6 +129,11 @@ def get_text_path(self, prop, s, ismath=False):
             verts.extend(verts1)
             codes.extend(codes1)
 
+        # Make sure an empty string or one with nothing to print
+        # (e.g. only spaces & newlines) will be valid/empty path
+        if not verts:
+            verts = np.empty((0, 2))
+
         return verts, codes
 
     def get_glyphs_with_font(self, font, s, glyph_map=None,