Support transforming a single point

Author: mdboom

lib/matplotlib/tests/test_transforms.py

@@ -487,6 +487,11 @@ def test_bbox_as_strings():
         assert_equal(eval(format(getattr(b, k), fmt)), v)
 
 
+def test_transform_single_point():
+    t = mtrans.Affine2D()
+    t.transform_affine((1, 1))
+
+
 if __name__=='__main__':
     import nose
     nose.runmodule(argv=['-s','--with-doctest'], exit=False)

src/_path.h

@@ -687,9 +687,9 @@ clip_path_to_rect(PathIterator &path, agg::rect_d &rect, bool inside, std::vecto
 }
 
 template <class VerticesArray, class ResultArray>
-void affine_transform(VerticesArray &vertices, agg::trans_affine &trans, ResultArray &result)
+void affine_transform_2d(VerticesArray &vertices, agg::trans_affine &trans, ResultArray &result)
 {
-    if (vertices.dim(0) != 0 && vertices.dim(1) != 2) {
+    if (vertices.dim(0) != 1 && vertices.dim(1) != 2) {
         throw "Invalid vertices array.";
     }
 
@@ -716,6 +716,33 @@ void affine_transform(VerticesArray &vertices, agg::trans_affine &trans, ResultA
     }
 }
 
+template <class VerticesArray, class ResultArray>
+void affine_transform_1d(VerticesArray &vertices, agg::trans_affine &trans, ResultArray &result)
+{
+    if (vertices.dim(0) != 2) {
+        throw "Invalid vertices array.";
+    }
+
+    double x;
+    double y;
+    double t0;
+    double t1;
+    double t;
+
+    x = vertices(0);
+    y = vertices(1);
+
+    t0 = trans.sx * x;
+    t1 = trans.shx * y;
+    t = t0 + t1 + trans.tx;
+    result(0) = t;
+
+    t0 = trans.shy * x;
+    t1 = trans.sy * y;
+    t = t0 + t1 + trans.ty;
+    result(1) = t;
+}
+
 template <class BBoxArray>
 int count_bboxes_overlapping_bbox(agg::rect_d &a, BBoxArray &bboxes)
 {

src/_path_wrapper.cpp

@@ -419,24 +419,30 @@ const char *Py_affine_transform__doc__ = "affine_transform(points, trans)";
 
 static PyObject *Py_affine_transform(PyObject *self, PyObject *args, PyObject *kwds)
 {
-    numpy::array_view<const double, 2> vertices;
+    PyObject *vertices_obj;
     agg::trans_affine trans;
 
     if (!PyArg_ParseTuple(args,
-                          "O&O&:affine_transform",
-                          &vertices.converter,
-                          &vertices,
+                          "OO&:affine_transform",
+                          &vertices_obj,
                           &convert_trans_affine,
                           &trans)) {
         return NULL;
     }
 
-    npy_intp dims[] = { vertices.dim(0), 2 };
-    numpy::array_view<double, 2> result(dims);
-
-    CALL_CPP("affine_transform", (affine_transform(vertices, trans, result)));
-
-    return result.pyobj();
+    try {
+        numpy::array_view<double, 2> vertices(vertices_obj);
+        npy_intp dims[] = { vertices.dim(0), 2 };
+        numpy::array_view<double, 2> result(dims);
+        CALL_CPP("affine_transform", (affine_transform_2d(vertices, trans, result)));
+        return result.pyobj();
+    } catch (py::exception) {
+        numpy::array_view<double, 1> vertices(vertices_obj);
+        npy_intp dims[] = { vertices.dim(0) };
+        numpy::array_view<double, 1> result(dims);
+        CALL_CPP("affine_transform", (affine_transform_1d(vertices, trans, result)));
+        return result.pyobj();
+    }
 }
 
 const char *Py_count_bboxes_overlapping_bbox__doc__ = "count_bboxes_overlapping_bbox(bbox, bboxes)";