Adds the following attributes:

- center
- centerx/y
- angle
- slope

Co-authored-by: Emc2356 <[email protected]>
Co-authored-by: NovialRiptide <[email protected]>
Co-authored-by: ScriptLineStudios <[email protected]>
Co-authored-by: Avaxar <[email protected]>
Co-authored-by: maqa41 <[email protected]>

buildconfig/stubs/pygame/geometry.pyi

@@ -165,6 +165,14 @@ class Line:
     def b(self, value: Point) -> None: ...
     @property
     def length(self) -> float: ...
+    @property
+    def center(self) -> tuple[float, float]: ...
+    @center.setter
+    def center(self, value: Point) -> None: ...
+    @property
+    def slope(self) -> float: ...
+    @property
+    def angle(self) -> float: ...
     @overload
     def __init__(self, ax: float, ay: float, bx: float, by: float) -> None: ...
     @overload

docs/reST/ref/geometry.rst

@@ -610,6 +610,76 @@
 
          .. ## Line.length ##
 
+   .. attribute:: center
+
+         | :sl:`the coordinate of the middle point of the line`
+         | :sg:`center -> (float, float)`
+
+         The center of the line. Calculated using the `((xa + xb) / 2, (ya + yb) / 2)` formula.
+         It can be reassigned to move the `Line`. If reassigned the `xa`, `ya`, `xb`, `yb`
+         attributes will be changed in order to produce a `Line` with matching center.
+
+         .. versionadded:: 2.5.3
+
+         .. ## Line.center ##
+
+   .. attribute:: centerx
+
+         | :sl:`the x coordinate of the middle point of the line`
+         | :sg:`centerx -> float`
+
+         The `x` coordinate of the center of the line, it's calculated using
+         the `((xa + xb) / 2)` formula. It can be reassigned to move the `Line`.
+         If reassigned the `xa` and `xb` attributes will be changed in order to
+         produce a `Line` with matching center. The `ya` and `yb` attributes will not
+         be affected.
+
+         .. versionadded:: 2.5.3
+
+         .. ## Line.centerx ##
+
+   .. attribute:: centery
+
+         | :sl:`the y coordinate of the middle point of the line`
+         | :sg:`centery -> float`
+
+         The `y` coordinate of the center of the `Line`, it's calculated using
+         the `((ya + yb) / 2)` formula. It can be reassigned to move the `Line`.
+         If reassigned the `ya` and `yb` attributes will be changed in order to
+         produce a `Line` with matching center. The `xa` and `xb` attributes will not
+         be affected.
+
+         .. versionadded:: 2.5.3
+
+         .. ## Line.centery ##
+
+   .. attribute:: angle
+
+         | :sl:`the angle of the line`
+         | :sg:`angle -> float`
+
+         The angle of the line representing its orientation. Calculated using
+         the `atan2(yb - ya, xb - xa)` formula. This attribute is read-only, it cannot
+         be reassigned. To change the line's angle use the `rotate` method or change
+         its `a` or `b` attributes.
+
+         .. versionadded:: 2.5.3
+
+         .. ## Line.angle ##
+
+   .. attribute:: slope
+
+         | :sl:`the slope of the line`
+         | :sg:`slope -> float`
+
+         The slope of the line. Calculated using the `(yb - ya) / (xb - xa)` formula.
+         This attribute is read-only, it cannot be reassigned. To change the line's slope
+         use the `rotate` method or change its `a` or `b` attributes.
+
+         .. versionadded:: 2.5.3
+
+         .. ## Line.slope ##
+
    **Line Methods**
 
    ----

src_c/doc/geometry_doc.h

@@ -37,6 +37,11 @@
 #define DOC_LINE_A "a -> (float, float)\nthe first point of the line"
 #define DOC_LINE_B "b -> (float, float)\nthe second point of the line"
 #define DOC_LINE_LENGTH "length -> float\nthe length of the line"
+#define DOC_LINE_CENTER "center -> (float, float)\nthe coordinate of the middle point of the line"
+#define DOC_LINE_CENTERX "centerx -> float\nthe x coordinate of the middle point of the line"
+#define DOC_LINE_CENTERY "centery -> float\nthe y coordinate of the middle point of the line"
+#define DOC_LINE_ANGLE "angle -> float\nthe angle of the line"
+#define DOC_LINE_SLOPE "slope -> float\nthe slope of the line"
 #define DOC_LINE_COPY "copy() -> Line\ncopies the line"
 #define DOC_LINE_MOVE "move((x, y)) -> Line\nmove(x, y) -> Line\nmoves the line by a given amount"
 #define DOC_LINE_MOVEIP "move_ip((x, y)) -> None\nmove_ip(x, y) -> None\nmoves the line by a given amount"

src_c/geometry.h

@@ -52,6 +52,13 @@ static PyTypeObject pgLine_Type;
 #define M_PI_QUO_180 0.01745329251994329577
 #endif
 
+/* Converts radians to degrees */
+static inline double
+RAD_TO_DEG(double rad)
+{
+    return rad / M_PI_QUO_180;
+}
+
 /* Converts degrees to radians */
 static inline double
 DEG_TO_RAD(double deg)

src_c/line.c

@@ -347,6 +347,115 @@ pg_line_getlength(pgLineObject *self, void *closure)
     return PyFloat_FromDouble(pgLine_Length(&self->line));
 }
 
+static PyObject *
+pg_line_get_center(pgLineObject *self, void *closure)
+{
+    return pg_tuple_couple_from_values_double(
+        (self->line.ax + self->line.bx) / 2,
+        (self->line.ay + self->line.by) / 2);
+}
+
+static int
+pg_line_set_center(pgLineObject *self, PyObject *value, void *closure)
+{
+    double m_x, m_y;
+    DEL_ATTR_NOT_SUPPORTED_CHECK_NO_NAME(value);
+    if (!pg_TwoDoublesFromObj(value, &m_x, &m_y)) {
+        PyErr_SetString(
+            PyExc_TypeError,
+            "Invalid center value, expected a sequence of 2 numbers");
+        return -1;
+    }
+
+    double dx = m_x - (self->line.ax + self->line.bx) / 2;
+    double dy = m_y - (self->line.ay + self->line.by) / 2;
+
+    self->line.ax += dx;
+    self->line.ay += dy;
+    self->line.bx += dx;
+    self->line.by += dy;
+
+    return 0;
+}
+
+static PyObject *
+pg_line_get_centerx(pgLineObject *self, void *closure)
+{
+    return PyFloat_FromDouble((self->line.ax + self->line.bx) / 2);
+}
+
+static int
+pg_line_set_centerx(pgLineObject *self, PyObject *value, void *closure)
+{
+    double m_x;
+    DEL_ATTR_NOT_SUPPORTED_CHECK_NO_NAME(value);
+    if (!pg_DoubleFromObj(value, &m_x)) {
+        PyErr_SetString(PyExc_TypeError,
+                        "Invalid centerx value, expected a numeric value");
+        return -1;
+    }
+
+    double dx = m_x - (self->line.ax + self->line.bx) / 2;
+
+    self->line.ax += dx;
+    self->line.bx += dx;
+
+    return 0;
+}
+
+static PyObject *
+pg_line_get_centery(pgLineObject *self, void *closure)
+{
+    return PyFloat_FromDouble((self->line.ay + self->line.by) / 2);
+}
+
+static int
+pg_line_set_centery(pgLineObject *self, PyObject *value, void *closure)
+{
+    double m_y;
+    DEL_ATTR_NOT_SUPPORTED_CHECK_NO_NAME(value);
+    if (!pg_DoubleFromObj(value, &m_y)) {
+        PyErr_SetString(PyExc_TypeError,
+                        "Invalid centery value, expected a numeric value");
+        return -1;
+    }
+
+    double dy = m_y - (self->line.ay + self->line.by) / 2;
+
+    self->line.ay += dy;
+    self->line.by += dy;
+
+    return 0;
+}
+
+static PyObject *
+pg_line_getangle(pgLineObject *self, void *closure)
+{
+    double dx = self->line.bx - self->line.ax;
+
+    if (dx == 0.0)
+        return (self->line.by > self->line.ay) ? PyFloat_FromDouble(-90.0)
+                                               : PyFloat_FromDouble(90.0);
+
+    double dy = self->line.by - self->line.ay;
+    double gradient = dy / dx;
+
+    return PyFloat_FromDouble(-RAD_TO_DEG(atan(gradient)));
+}
+
+static PyObject *
+pg_line_getslope(pgLineObject *self, void *closure)
+{
+    double dem = self->line.bx - self->line.ax;
+    if (dem == 0) {
+        return PyFloat_FromDouble(0);
+    }
+
+    double slope = (self->line.by - self->line.ay) / dem;
+
+    return PyFloat_FromDouble(slope);
+}
+
 static PyGetSetDef pg_line_getsets[] = {
     {"ax", (getter)pg_line_getax, (setter)pg_line_setax, DOC_LINE_AX, NULL},
     {"ay", (getter)pg_line_getay, (setter)pg_line_setay, DOC_LINE_AY, NULL},
@@ -355,6 +464,14 @@ static PyGetSetDef pg_line_getsets[] = {
     {"a", (getter)pg_line_geta, (setter)pg_line_seta, DOC_LINE_A, NULL},
     {"b", (getter)pg_line_getb, (setter)pg_line_setb, DOC_LINE_B, NULL},
     {"length", (getter)pg_line_getlength, NULL, DOC_LINE_LENGTH, NULL},
+    {"center", (getter)pg_line_get_center, (setter)pg_line_set_center,
+     DOC_LINE_CENTER, NULL},
+    {"centerx", (getter)pg_line_get_centerx, (setter)pg_line_set_centerx,
+     DOC_LINE_CENTERX, NULL},
+    {"centery", (getter)pg_line_get_centery, (setter)pg_line_set_centery,
+     DOC_LINE_CENTERY, NULL},
+    {"angle", (getter)pg_line_getangle, NULL, DOC_LINE_ANGLE, NULL},
+    {"slope", (getter)pg_line_getslope, NULL, DOC_LINE_SLOPE, NULL},
     {NULL, 0, NULL, NULL, NULL}};
 
 static PyTypeObject pgLine_Type = {

test/geometry_test.py

@@ -2017,6 +2017,125 @@ def test_attrib_length(self):
         expected_length = 5.414794548272353
         self.assertAlmostEqual(line.length, expected_length)
 
+    def test_attrib_center(self):
+        """a full test for the center attribute"""
+        expected_x1 = 10.0
+        expected_y1 = 2.0
+        expected_x2 = 5.0
+        expected_y2 = 6.0
+        expected_a = expected_x1, expected_y1
+        expected_b = expected_x2, expected_y2
+        expected_center = (expected_x1 + expected_x2) / 2, (
+                expected_y1 + expected_y2
+        ) / 2
+        line = Line(expected_a, expected_b)
+
+        self.assertEqual(line.center, expected_center)
+
+        line.center = expected_center[0] - 1, expected_center[1] + 1.321
+
+        self.assertEqual(
+            line.center, (expected_center[0] - 1, expected_center[1] + 1.321)
+        )
+
+        line = Line(0, 0, 1, 0)
+
+        for value in (None, [], "1", (1,), [1, 2, 3], 1, 1.2):
+            with self.assertRaises(TypeError):
+                line.center = value
+
+        with self.assertRaises(AttributeError):
+            del line.center
+
+    def test_attrib_centerx(self):
+        """a full test for the centerx attribute"""
+        expected_x1 = 10.0
+        expected_y1 = 2.0
+        expected_x2 = 5.0
+        expected_y2 = 6.0
+        expected_a = expected_x1, expected_y1
+        expected_b = expected_x2, expected_y2
+        expected_center = (expected_x1 + expected_x2) / 2, (
+                expected_y1 + expected_y2
+        ) / 2
+        line = Line(expected_a, expected_b)
+
+        self.assertEqual(line.centerx, expected_center[0])
+
+        line.centerx = expected_center[0] - 1
+
+        self.assertEqual(line.centerx, expected_center[0] - 1)
+
+        line = Line(0, 0, 1, 0)
+
+        for value in (None, [], "1", (1,), [1, 2, 3]):
+            with self.assertRaises(TypeError):
+                line.centerx = value
+
+        with self.assertRaises(AttributeError):
+            del line.centerx
+
+    def test_attrib_centery(self):
+        """a full test for the centery attribute"""
+        expected_x1 = 10.0
+        expected_y1 = 2.0
+        expected_x2 = 5.0
+        expected_y2 = 6.0
+        expected_a = expected_x1, expected_y1
+        expected_b = expected_x2, expected_y2
+        expected_center = (expected_x1 + expected_x2) / 2, (
+                expected_y1 + expected_y2
+        ) / 2
+        line = Line(expected_a, expected_b)
+
+        self.assertEqual(line.centery, expected_center[1])
+
+        line.centery = expected_center[1] - 1.321
+
+        self.assertEqual(line.centery, expected_center[1] - 1.321)
+
+        line = Line(0, 0, 1, 0)
+
+        for value in (None, [], "1", (1,), [1, 2, 3]):
+            with self.assertRaises(TypeError):
+                line.centery = value
+
+        with self.assertRaises(AttributeError):
+            del line.centery
+
+    def test_attrib_angle(self):
+        """a full test for the angle attribute"""
+        expected_angle = -83.93394864782331
+        line = Line(300.0, 400.0, 400.0, 1341.0)
+        self.assertEqual(line.angle, expected_angle)
+
+        expected_angle = 16.17215901578255
+        line = Line(300.0, 400.0, 400.0, 371.0)
+        self.assertEqual(line.angle, expected_angle)
+
+        expected_angle = -35.53767779197438
+        line = Line(45.0, 32.0, 94.0, 67.0)
+        self.assertEqual(line.angle, expected_angle)
+
+        expected_angle = -53.88065915052025
+        line = Line(544.0, 235.0, 382.0, 13.0)
+        self.assertEqual(line.angle, expected_angle)
+
+    def test_attrib_slope(self):
+        """a full test for the slope attribute"""
+        lines = [
+            [Line(2, 2, 4, 4), 1, False],
+            [Line(4.6, 2.3, 1.6, 7.3), -5 / 3, True],
+            [Line(2, 0, 2, 1), 0, False],
+            [Line(1.2, 3.2, 4.5, 3.2), 0, False],
+        ]
+
+        for l in lines:
+            if l[2]:
+                self.assertAlmostEqual(l[0].slope, l[1])
+            else:
+                self.assertEqual(l[0].slope, l[1])
+
     def test_meth_copy(self):
         line = Line(1, 2, 3, 4)
         # check 1 arg passed