Support passing rgbaFace as an array to agg's draw_path.

This occurs (rarely) when combining patheffects and mplot3d.

Author: anntzer

lib/matplotlib/tests/test_agg.py

@@ -7,7 +7,8 @@
 
 
 from matplotlib import (
-    collections, path, pyplot as plt, transforms as mtransforms, rcParams)
+    collections, path, patheffects, pyplot as plt, transforms as mtransforms,
+    rcParams)
 from matplotlib.backends.backend_agg import RendererAgg
 from matplotlib.figure import Figure
 from matplotlib.image import imread
@@ -349,3 +350,11 @@ def test_chunksize_toobig_chunks(chunk_limit_setup):
     rcParams['agg.path.chunksize'] = 90_000
     with pytest.raises(OverflowError, match='Please reduce'):
         ra.draw_path(gc, p, idt)
+
+
+def test_non_tuple_rgbaface():
+    # This passes rgbaFace as a ndarray to draw_path.
+    fig = plt.figure()
+    fig.add_subplot(projection="3d").scatter(
+        [0, 1, 2], [0, 1, 2], path_effects=[patheffects.Stroke(linewidth=4)])
+    fig.canvas.draw()

src/py_converters.cpp

@@ -191,21 +191,28 @@ int convert_rect(PyObject *rectobj, void *rectp)
 int convert_rgba(PyObject *rgbaobj, void *rgbap)
 {
     agg::rgba *rgba = (agg::rgba *)rgbap;
-
+    PyObject *rgbatuple = NULL;
+    int success = 1;
     if (rgbaobj == NULL || rgbaobj == Py_None) {
         rgba->r = 0.0;
         rgba->g = 0.0;
         rgba->b = 0.0;
         rgba->a = 0.0;
     } else {
+        if (!(rgbatuple = PySequence_Tuple(rgbaobj))) {
+            success = 0;
+            goto exit;
+        }
         rgba->a = 1.0;
         if (!PyArg_ParseTuple(
-                 rgbaobj, "ddd|d:rgba", &(rgba->r), &(rgba->g), &(rgba->b), &(rgba->a))) {
-            return 0;
+                 rgbatuple, "ddd|d:rgba", &(rgba->r), &(rgba->g), &(rgba->b), &(rgba->a))) {
+            success = 0;
+            goto exit;
         }
     }
-
-    return 1;
+exit:
+    Py_XDECREF(rgbatuple);
+    return success;
 }
 
 int convert_dashes(PyObject *dashobj, void *dashesp)