Made it so that PatchCollection uses the hatch of the patch in the collection.

hhalwan · hhalwan · commit 43f16a010b55 · 2022-04-09T14:48:37.000-04:00
PatchCollection will currently ignore hatches of the provided patches, only allowing a hatch passed as a keyword into the constructor. If match_original is true, we now keep the hatch of the first patch provided in the collection. Additionally, the hatchcolor is determined by the edge color, so we will only pass the edgecolors of the patches to the Collection if the edgecolor is not blank - its default color of [0, 0, 0, 0]. This ensures that the hatch will use its default of black in the case where no edgecolor of the patches was ever set.
diff --git a/lib/matplotlib/collections.py b/lib/matplotlib/collections.py
@@ -1808,9 +1808,10 @@ def __init__(self, patches, match_original=False, **kwargs):
 
         *match_original*
             If True, use the colors and linewidths of the original
-            patches.  If False, new colors may be assigned by
-            providing the standard collection arguments, facecolor,
-            edgecolor, linewidths, norm or cmap.
+            patches. Also use the hatch of the first patch provided.
+            If False, new colors may be assigned by providing the
+            standard collection arguments, facecolor, edgecolor,
+            linewidths, norm or cmap.
 
         If any of *edgecolors*, *facecolors*, *linewidths*, *antialiaseds* are
         None, they default to their `.rcParams` patch setting, in sequence
@@ -1827,12 +1828,20 @@ def determine_facecolor(patch):
                 if patch.get_fill():
                     return patch.get_facecolor()
                 return [0, 0, 0, 0]
-
+            def is_default(c):
+                return mcolors.same_color([0, 0, 0, 0], c)
             kwargs['facecolors'] = [determine_facecolor(p) for p in patches]
-            kwargs['edgecolors'] = [p.get_edgecolor() for p in patches]
+            edgecolors = [p.get_edgecolor() for p in patches]
+            # Since the hatch color is updated when the edge color
+            # is updated, we will ignore the edge color if it is blank (the
+            # default of [0, 0, 0, 0]).
+            if not all(is_default(c) for c in edgecolors):
+                kwargs['edgecolors'] = edgecolors
             kwargs['linewidths'] = [p.get_linewidth() for p in patches]
             kwargs['linestyles'] = [p.get_linestyle() for p in patches]
             kwargs['antialiaseds'] = [p.get_antialiased() for p in patches]
+            if patches:
+                kwargs['hatch'] = patches[0].get_hatch()
 
         super().__init__(**kwargs)
 
