handling Ptr<> arguments and return values in Python wrappers

partially wrapped features2d framework
added feature_homography.py sample

modules/python/src2/cv2.cpp

@@ -64,9 +64,15 @@ typedef vector<Vec4i> vector_Vec4i;
 typedef vector<Rect> vector_Rect;
 typedef vector<KeyPoint> vector_KeyPoint;
 typedef vector<Mat> vector_Mat;
+typedef vector<DMatch> vector_DMatch;
 typedef vector<vector<Point> > vector_vector_Point;
 typedef vector<vector<Point2f> > vector_vector_Point2f;
 typedef vector<vector<Point3f> > vector_vector_Point3f;
+typedef vector<vector<DMatch> > vector_vector_DMatch;
+
+typedef Ptr<FeatureDetector> Ptr_FeatureDetector;
+typedef Ptr<DescriptorExtractor> Ptr_DescriptorExtractor;
+typedef Ptr<DescriptorMatcher> Ptr_DescriptorMatcher;
 
 static PyObject* failmsgp(const char *fmt, ...)
 {
@@ -312,6 +318,14 @@ static PyObject* pyopencv_from(size_t value)
     return PyLong_FromUnsignedLong((unsigned long)value);
 }
 
+static bool pyopencv_to(PyObject* obj, size_t& value, const char* name = "<unknown>")
+{
+    if(!obj || obj == Py_None)
+        return true;
+    value = (int)PyLong_AsUnsignedLong(obj);
+    return value != -1 || !PyErr_Occurred();
+}
+
 static PyObject* pyopencv_from(int value)
 {
     return PyInt_FromLong(value);
@@ -605,6 +619,7 @@ template<typename _Tp> static inline PyObject* pyopencv_from(const vector<_Tp>&
 }
 
 static PyObject* pyopencv_from(const KeyPoint&);
+static PyObject* pyopencv_from(const DMatch&);
 
 template<typename _Tp> static inline bool pyopencv_to_generic_vec(PyObject* obj, vector<_Tp>& value, const char* name="<unknown>")
 {
@@ -689,6 +704,19 @@ template<> struct pyopencvVecConverter<KeyPoint>
     }
 };
 
+template<> struct pyopencvVecConverter<DMatch>
+{
+    static bool to(PyObject* obj, vector<DMatch>& value, const char* name="<unknown>")
+    {
+        return pyopencv_to_generic_vec(obj, value, name);
+    }
+    
+    static PyObject* from(const vector<DMatch>& value)
+    {
+        return pyopencv_from_generic_vec(value);
+    }
+};
+
 
 static inline bool pyopencv_to(PyObject *obj, CvTermCriteria& dst, const char *name="<unknown>")
 {

modules/python/src2/gen2.py

@@ -7,7 +7,11 @@ gen_template_check_self = Template("""    if(!PyObject_TypeCheck(self, &pyopencv
 """)
 
 gen_template_call_constructor = Template("""self = PyObject_NEW(pyopencv_${name}_t, &pyopencv_${name}_Type);
-        if(self) ERRWRAP2(self->v = $op$cname""")
+        new (&(self->v)) Ptr<$cname>(); // init Ptr with placement new
+        if(self) ERRWRAP2(self->v = new $cname""")
+
+gen_template_simple_call_constructor = Template("""self = PyObject_NEW(pyopencv_${name}_t, &pyopencv_${name}_Type);
+        if(self) ERRWRAP2(self->v = $cname""")
 
 gen_template_parse_args = Template("""const char* keywords[] = { $kw_list, NULL };
     if( PyArg_ParseTupleAndKeywords(args, kw, "$fmtspec", (char**)keywords, $parse_arglist)$code_cvt )""")
@@ -66,7 +70,7 @@ gen_template_type_decl = Template("""
 struct pyopencv_${name}_t
 {
     PyObject_HEAD
-    ${cname}* v;
+    Ptr<${cname}> v;
 };
 
 static PyTypeObject pyopencv_${name}_Type =
@@ -79,9 +83,31 @@ static PyTypeObject pyopencv_${name}_Type =
 
 static void pyopencv_${name}_dealloc(PyObject* self)
 {
-    delete ((pyopencv_${name}_t*)self)->v;
+    ((pyopencv_${name}_t*)self)->v = NULL;
     PyObject_Del(self);
 }
+
+static PyObject* pyopencv_from(const Ptr<${cname}>& r)
+{
+    pyopencv_${name}_t *m = PyObject_NEW(pyopencv_${name}_t, &pyopencv_${name}_Type);
+    new (&(m->v)) Ptr<$cname>(); // init Ptr with placement new
+    m->v = r;
+    return (PyObject*)m;
+}
+
+static bool pyopencv_to(PyObject* src, Ptr<${cname}>& dst, const char* name="<unknown>")
+{
+    if( src == NULL || src == Py_None )
+        return true;
+    if(!PyObject_TypeCheck(src, &pyopencv_${name}_Type))
+    {
+        failmsg("Expected ${cname} for argument '%s'", name);
+        return false;
+    }
+    dst = ((pyopencv_${name}_t*)src)->v;
+    return true;
+}
+
 """)
 
 gen_template_map_type_cvt = Template("""
@@ -490,10 +516,10 @@ class FuncInfo(object):
 
             if self.isconstructor:
                 code_decl += "    pyopencv_%s_t* self = 0;\n" % selfinfo.name
-                op = "new "
+                templ = gen_template_call_constructor
                 if selfinfo.issimple:
-                    op = ""
-                code_fcall = gen_template_call_constructor.substitute(name=selfinfo.name, cname=selfinfo.cname, op=op)
+                    templ = gen_template_simple_call_constructor
+                code_fcall = templ.substitute(name=selfinfo.name, cname=selfinfo.cname)
             else:
                 code_fcall = "ERRWRAP2( "
                 if v.rettype: