Fix alpha also for foreground color

joh · joh · commit 93cd39a74d3c · 2018-11-14T11:46:05.000+01:00
diff --git a/lib/matplotlib/backends/backend_cairo.py b/lib/matplotlib/backends/backend_cairo.py
@@ -303,17 +303,22 @@ def _draw_paths():
             gc_vars, rgb_fc = reuse_key
             gc = copy.copy(gc0)
             # We actually need to call the setters to reset the internal state.
+            vars(gc).update(gc_vars)
             for k, v in gc_vars.items():
                 if k == "_linestyle":  # Deprecated, no effect.
                     continue
                 elif k == "_dashes":
                     gc.set_dashes(*v)  # Needs to be unpacked.
+                elif k == "_alpha":    # Avoid touching forced_alpha
+                    if gc.get_forced_alpha():
+                        gc.set_alpha(v)
+                elif k == "_rgb":      # rgb -> set_foreground
+                    gc.set_foreground(v)
                 else:
                     try:
                         getattr(gc, "set" + k)(v)
                     except (AttributeError, TypeError) as e:
                         pass
-            vars(gc).update(gc_vars)
             gc.ctx.new_path()
             paths, transforms = zip(*grouped_draw)
             grouped_draw.clear()
