Implementation of pygame.(F)Rect.relcenter

buildconfig/stubs/pygame/rect.pyi

@@ -93,6 +93,10 @@ class _GenericRect(Collection[_N]):
     @center.setter
     def center(self, value: Coordinate) -> None: ...
     @property
+    def rel_center(self) -> Tuple[_N, _N]: ...
+    @rel_center.setter
+    def rel_center(self, value: Point) -> None: ...
+    @property
     def centerx(self) -> _N: ...
     @centerx.setter
     def centerx(self, value: float) -> None: ...

docs/reST/ref/rect.rst

@@ -47,7 +47,7 @@
        top, left, bottom, right
        topleft, bottomleft, topright, bottomright
        midtop, midleft, midbottom, midright
-       center, centerx, centery
+       center, rel_center, centerx, centery
        size, width, height
        w,h
 
@@ -92,6 +92,25 @@
       However, the subclass's ``__init__()`` method is not called,
       and ``__new__()`` is assumed to take no arguments. So these methods should be
       overridden if any extra attributes need to be copied.
+
+   .. versionadded:: 2.5.2
+      ``rel_center`` added to Rect / FRect. This will return you a ``Point`` of
+      the center relative to the topleft of the Rect. Setting a ``Point`` to it will 
+      modify the size of the rect to 2 times the ``Point`` used. Below you can find a 
+      code example of how it should work :
+
+      .. code-block:: python
+
+         > my_rect = pygame.Rect(0, 0, 2, 2)
+         > my_rect.rel_center
+         > (1, 1)
+         > my_rect.rel_center = (128, 128)
+         > my_rect.rel_center, my_rect.size
+         > ((128, 128), (256, 256))
+
+      Beware of non integer relative centers ! Using a Rect instead of FRect will round down
+      the values of the returned ``Point``.
+
 
    .. method:: copy
 

src_c/rect.c

@@ -133,6 +133,8 @@ four_floats_from_obj(PyObject *obj, float *val1, float *val2, float *val3,
 #define RectExport_setmidright pg_rect_setmidright
 #define RectExport_getcenter pg_rect_getcenter
 #define RectExport_setcenter pg_rect_setcenter
+#define RectExport_getrelcenter pg_rect_getrelcenter
+#define RectExport_setrelcenter pg_rect_setrelcenter
 #define RectExport_getsize pg_rect_getsize
 #define RectExport_setsize pg_rect_setsize
 #define RectImport_primitiveType int
@@ -250,6 +252,8 @@ four_floats_from_obj(PyObject *obj, float *val1, float *val2, float *val3,
 #define RectExport_setmidright pg_frect_setmidright
 #define RectExport_getcenter pg_frect_getcenter
 #define RectExport_setcenter pg_frect_setcenter
+#define RectExport_getrelcenter pg_frect_getrelcenter
+#define RectExport_setrelcenter pg_frect_setrelcenter
 #define RectExport_getsize pg_frect_getsize
 #define RectExport_setsize pg_frect_setsize
 #define RectImport_primitiveType float
@@ -684,6 +688,8 @@ static PyGetSetDef pg_frect_getsets[] = {
     {"size", (getter)pg_frect_getsize, (setter)pg_frect_setsize, NULL, NULL},
     {"center", (getter)pg_frect_getcenter, (setter)pg_frect_setcenter, NULL,
      NULL},
+    {"rel_center", (getter)pg_frect_getrelcenter,
+     (setter)pg_frect_setrelcenter, NULL, NULL},
 
     {"__safe_for_unpickling__", (getter)pg_rect_getsafepickle, NULL, NULL,
      NULL},
@@ -726,6 +732,8 @@ static PyGetSetDef pg_rect_getsets[] = {
     {"size", (getter)pg_rect_getsize, (setter)pg_rect_setsize, NULL, NULL},
     {"center", (getter)pg_rect_getcenter, (setter)pg_rect_setcenter, NULL,
      NULL},
+    {"rel_center", (getter)pg_rect_getrelcenter, (setter)pg_rect_setrelcenter,
+     NULL, NULL},
 
     {"__safe_for_unpickling__", (getter)pg_rect_getsafepickle, NULL, NULL,
      NULL},

src_c/rect_impl.h

@@ -284,6 +284,12 @@
 #ifndef RectExport_setcenter
 #error RectExport_setcenter needs to be defined
 #endif
+#ifndef RectExport_getrelcenter
+#error RectExport_getrelcenter needs to be defined
+#endif
+#ifndef RectExport_setrelcenter
+#error RectExport_setrelcenter needs to be defined
+#endif
 #ifndef RectExport_getsize
 #error RectExport_getsize needs to be defined
 #endif
@@ -604,6 +610,10 @@ RectExport_getcenter(RectObject *self, void *closure);
 static int
 RectExport_setcenter(RectObject *self, PyObject *value, void *closure);
 static PyObject *
+RectExport_getrelcenter(RectObject *self, void *closure);
+static int
+RectExport_setrelcenter(RectObject *self, PyObject *value, void *closure);
+static PyObject *
 RectExport_getsize(RectObject *self, void *closure);
 static int
 RectExport_setsize(RectObject *self, PyObject *value, void *closure);
@@ -2804,6 +2814,33 @@ RectExport_getcenter(RectObject *self, void *closure)
                                   self->r.y + (self->r.h / 2));
 }
 
+/*center*/
+static PyObject *
+RectExport_getrelcenter(RectObject *self, void *closure)
+{
+    return TupleFromTwoPrimitives(self->r.w / 2, self->r.h / 2);
+}
+
+static int
+RectExport_setrelcenter(RectObject *self, PyObject *value, void *closure)
+{
+    PrimitiveType val1, val2;
+
+    if (NULL == value) {
+        /* Attribute deletion not supported. */
+        PyErr_SetString(PyExc_AttributeError, "can't delete attribute");
+        return -1;
+    }
+
+    if (!twoPrimitivesFromObj(value, &val1, &val2)) {
+        PyErr_SetString(PyExc_TypeError, "invalid rect assignment");
+        return -1;
+    }
+    self->r.w = val1 * 2;
+    self->r.h = val2 * 2;
+    return 0;
+}
+
 static int
 RectExport_setcenter(RectObject *self, PyObject *value, void *closure)
 {
@@ -2958,6 +2995,8 @@ RectExport_iterator(RectObject *self)
 #undef RectExport_setmidright
 #undef RectExport_getcenter
 #undef RectExport_setcenter
+#undef RectExport_getrelcenter
+#undef RectExport_setrelcenter
 #undef RectExport_getsize
 #undef RectExport_setsize
 #undef RectExport_iterator