Fix svg plotting of quadratic 2D meshes (#809)

README.md

@@ -225,6 +225,8 @@ with respect to documented and/or tested features.
 ### Unreleased
 
 - Fixed: `ElementDG` was not included in the wildcard import
+- Fixed: Automatic visualization of `MeshTri2` and `MeshQuad2` in Jupyter
+  notebooks raised exception
 
 ### [5.0.0] - 2021-11-21
 

skfem/mesh/mesh.py

@@ -649,6 +649,15 @@ def init_refdom(cls):
         """Initialize a mesh corresponding to the reference domain."""
         return cls(cls.elem.refdom.p, cls.elem.refdom.t, validate=False)
 
+    def morphed(self, *args):
+        """Morph the mesh using functions."""
+        p = self.p.copy()
+        for i, arg in enumerate(args):
+            if arg is None:
+                continue
+            p[i] = arg(self.p)
+        return replace(self, doflocs=p)
+
     def refined(self, times_or_ix: Union[int, ndarray] = 1):
         """Return a refined mesh.
 

skfem/mesh/mesh_2d_2.py

@@ -7,3 +7,7 @@ def _repr_svg_(self) -> str:
 
     def element_finder(self, *args, **kwargs):
         raise NotImplementedError
+
+    @classmethod
+    def init_refdom(cls):
+        return cls.__bases__[-1].init_refdom()

tests/test_visuals.py

@@ -1,7 +1,12 @@
 import unittest
+import pytest
 
-from skfem.mesh import MeshTri, MeshQuad, MeshTet, MeshLine1
+from skfem.assembly import CellBasis
+from skfem.mesh import (MeshTri, MeshQuad, MeshTet, MeshLine1, MeshTri2,
+                        MeshQuad2)
 from skfem.visuals.matplotlib import draw, plot, plot3
+from skfem.visuals.svg import draw as drawsvg
+from skfem.visuals.svg import plot as plotsvg
 
 
 class CallDraw(unittest.TestCase):
@@ -42,3 +47,19 @@ class CallPlot3(unittest.TestCase):
     def runTest(self):
         m = self.mesh_type()
         plot3(m, m.p[0])
+
+
+@pytest.mark.parametrize(
+    "mtype",
+    [
+        MeshTri,
+        MeshQuad,
+        MeshTri2,
+        MeshQuad2,
+    ]
+)
+def test_call_svg_plot(mtype):
+    m = mtype()
+    svg = drawsvg(m, nrefs=2)
+    basis = CellBasis(m, mtype.elem())
+    svg_plot = plotsvg(basis, m.p[0], nrefs=2)