Added Line methods and 'length: attribute

## Credits

**Geometry Project:**
For code, docs and tests:
@novialriptide @Emc2356 @itzpr3d4t0r @ScriptLineStudios @avaxar @Matiiss @newpaxonian @maqa41 @blankRiot96
Also thanks to @Starbuck5 for kickstarting the idea and the occasional help!

**Functionality added in this PR**
- `line.c`
https://github.com/pygame-community/pygame-geometry/blame/main/src_c/line.c
Credits to @Emc2356 @itzpr3d4t0r @novialriptide @ScriptLineStudios @avaxar
- `geometry.pyi`
https://github.com/pygame-community/pygame-geometry/blame/main/geometry.pyi
Credits to @Emc2356 @itzpr3d4t0r @novialriptide @ScriptLineStudios @avaxar
- `geometry_test.py`
https://github.com/pygame-community/pygame-geometry/blame/main/test/test_line.py
Credits to @Emc2356 @itzpr3d4t0r @novialriptide @ScriptLineStudios @avaxar
- `geometry.rst`
https://github.com/pygame-community/pygame-geometry/blame/main/docs/line.rst
Credits to @itzpr3d4t0r @avaxar @ScriptLineStudios
- `geometry.h`
https://github.com/pygame-community/pygame-geometry/blame/main/src_c/include/geometry.h
Credits to @Emc2356 @itzpr3d4t0r @maqa41

buildconfig/stubs/pygame/geometry.pyi

@@ -27,6 +27,16 @@ class _HasLineAttribute(Protocol):
     @property
     def line(self) -> Union[_LineLike, Callable[[], _LineLike]]: ...
 
+_CanBeLine = Union[
+    Rect,
+    Line,
+    Tuple[float, float, float, float],
+    Tuple[Point, Point],
+    Sequence[float],
+    Sequence[Point],
+]
+LineValue = Union[_CanBeLine, _HasLineAttribute]
+
 _LineLike = Union[Line, SequenceLike[float], SequenceLike[Point], _HasLineAttribute]
 
 _CanBeCollided = Union[Circle, Rect, FRect, Point]
@@ -168,6 +178,7 @@ class Line:
     def b(self) -> Tuple[float, float]: ...
     @b.setter
     def b(self, value: Point) -> None: ...
+    length: float
     @overload
     def __init__(self, ax: float, ay: float, bx: float, by: float) -> None: ...
     @overload
@@ -176,3 +187,28 @@ class Line:
     def __init__(self, line: _LineLike) -> None: ...
     def __copy__(self) -> Line: ...
     def copy(self) -> Line: ...
+
+    @overload
+    def update(self, xa: float, ya: float, xb: float, yb: float) -> None: ...
+    @overload
+    def update(self, a: Point, b: Point) -> None: ...
+    @overload
+    def update(self, single_arg: LineValue) -> None: ...
+    @overload
+    def move(self, x: float, y: float) -> Line: ...
+    @overload
+    def move(self, move_by: Point) -> Line: ...
+    @overload
+    def move_ip(self, x: float, y: float) -> None: ...
+    @overload
+    def move_ip(self, move_by: Point) -> None: ...
+    @overload
+    def scale(self, factor: float, origin: float) -> Line: ...
+    @overload
+    def scale_ip(self, factor: float, origin: float) -> None: ...
+    @overload
+    def scale(self, factor_and_origin: Sequence[float, float]) -> Line: ...
+    @overload
+    def scale_ip(self, factor_and_origin: Sequence[float, float]) -> None: ...
+    def flip_ab(self) -> Line: ...
+    def flip_ab_ip(self) -> None: ...

docs/reST/ref/geometry.rst

@@ -597,6 +597,18 @@
 
          .. ## Line.b ##
 
+   .. attribute:: length
+         | :sl:`the length of the line`
+         | :sg:`length -> float`
+
+         The length of the line. Calculated using the `sqrt((xb-xa)**2 + (yb-ya)**2)` formula.
+         This attribute is read-only, it cannot be reassigned. To change the line's length
+         use the `scale` method or change its `a` or `b` attributes.
+
+         .. versionadded:: 2.5.3
+
+         .. ## Line.length ##
+
    **Line Methods**
 
    ----
@@ -611,3 +623,122 @@
          .. versionadded:: 2.5.2
 
          .. ## Line.copy ##
+
+   .. method:: move
+
+         | :sl:`moves the line by a given amount`
+         | :sg:`move((x, y)) -> Line`
+         | :sg:`move(x, y) -> Line`
+
+         Returns a new `Line` that is moved by the given offset. The original `Line` is
+         not modified.
+
+         .. note::
+            This method is equivalent(behaviour wise) to the following code:
+
+         .. code-block:: python
+
+             Line(line.ax + x, line.ay + y, line.bx + x, line.by + y)
+
+         .. versionadded:: 2.5.3
+
+      .. ## Line.move ##
+
+   .. method:: move_ip
+
+         | :sl:`moves the line by a given amount`
+         | :sg:`move_ip((x, y)) -> None`
+         | :sg:`move_ip(x, y) -> None`
+
+         Moves the `Line` by the given offset. The original `Line` is modified. Always returns
+         `None`.
+
+         .. note::
+            This method is equivalent(behaviour wise) to the following code:
+
+         .. code-block:: python
+
+             line.ax += x
+             line.ay += y
+             line.bx += x
+             line.by += y
+
+         .. versionadded:: 2.5.3
+
+      .. ## Line.move_ip ##
+
+   .. method:: update
+
+         | :sl:`updates the line's attributes`
+         | :sg:`update((xa, ya), (xb, yb)) -> None`
+         | :sg:`update(xa, ya, xb, yb) -> None`
+         | :sg:`update(Line) -> None`
+
+         Updates the `Line`'s attributes. The original `Line` is modified. Always returns `None`.
+
+         .. note::
+            This method is equivalent(behaviour wise) to the following code:
+
+         .. code-block:: python
+
+             line.ax = ax
+             line.ay = ay
+             line.bx = bx
+             line.by = by
+
+         .. versionadded:: 2.5.3
+
+      .. ## Line.update ##
+
+   .. method:: scale
+
+         | :sl:`scales the line by the given factor from the given origin`
+         | :sg:`scale(factor, origin) -> Line`
+         | :sg:`scale(factor_and_origin) -> Line`
+
+         Returns a new `Line` which is scaled by the given factor from the specified origin with 0.0 being
+         the startpoint, 0.5 being the center and 1.0 being the end point.
+         The original `Line` is not modified.
+
+         .. versionadded:: 2.5.3
+
+      .. ## Line.scale ##
+
+   .. method:: scale_ip
+
+         | :sl:`scales the line by the given factor from the given origin in place`
+         | :sg:`scale_ip(factor, origin) -> None`
+         | :sg:`scale_ip(factor_and_origin) -> None`
+
+         Scales the `Line` by the given factor from the specified origin with 0.0 being
+         the startpoint, 0.5 being the center and 1.0 being the end point.
+         The original `Line` is modified.
+         Always returns `None`.
+
+         .. versionadded:: 2.5.3
+
+      .. ## Line.scale_ip ##
+
+   .. method:: flip_ab
+
+         | :sl:`flips the line a and b points`
+         | :sg:`flip_ab() -> Line`
+
+         Returns a new `Line` that has the `a` and `b` points flipped.
+         The original `Line` is not modified.
+
+         .. versionadded:: 2.5.3
+
+      .. ## Line.flip_ab ##
+
+   .. method:: flip_ab_ip
+
+         | :sl:`flips the line a and b points, in place`
+         | :sg:`flip_ab_ip() -> None`
+
+         Flips the `Line`'s `b` and `b` points. The original `Line` is modified.
+         Always returns `None`.
+
+         .. versionadded:: 2.5.3
+
+      .. ## Line.flip_ab_ip ##

src_c/doc/geometry_doc.h

@@ -36,4 +36,12 @@
 #define DOC_LINE_BY "by -> float\ny coordinate of the end point of the line"
 #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_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"
+#define DOC_LINE_UPDATE "update((xa, ya), (xb, yb)) -> None\nupdate(xa, ya, xb, yb) -> None\nupdate(Line) -> None\nupdates the line's attributes"
+#define DOC_LINE_SCALE "scale(factor, origin) -> Line\nscale(factor_and_origin) -> Line\nscales the line by the given factor from the given origin"
+#define DOC_LINE_SCALEIP "scale_ip(factor, origin) -> None\nscale_ip(factor_and_origin) -> None\nscales the line by the given factor from the given origin in place"
+#define DOC_LINE_FLIPAB "flip_ab() -> Line\nflips the line a and b points"
+#define DOC_LINE_FLIPABIP "flip_ab_ip() -> None\nflips the line a and b points, in place"