Add optional acceleration to the mouse macro. (sezanzeb#931)

* Add optional acceleration to the mouse macro.

* Make accelerated mouse motion more accurate by accumulating fractional component of the speed.

* Apply suggestions from code review

Co-authored-by: Tobi <28510156+sezanzeb@users.noreply.github.com>

---------

Co-authored-by: Tobi <28510156+sezanzeb@users.noreply.github.com>

inputremapper/injection/macros/macro.py

@@ -469,10 +469,16 @@ def add_event(self, type_: Union[str, int], code: Union[str, int], value: int):
         self.tasks.append(lambda handler: handler(type_, code, value))
         self.tasks.append(self._keycode_pause)
 
-    def add_mouse(self, direction: str, speed: int):
+    def add_mouse(
+        self,
+        direction: str,
+        speed: int,
+        acceleration: Optional[float] = None,
+    ):
         """Move the mouse cursor."""
         _type_check(direction, [str], "mouse", 1)
         speed = _type_check(speed, [int], "mouse", 2)
+        acceleration = _type_check(acceleration, [float, None], "mouse", 3)
 
         code, value = {
             "up": (REL_Y, -1),
@@ -482,9 +488,29 @@ def add_mouse(self, direction: str, speed: int):
         }[direction.lower()]
 
         async def task(handler: Callable):
-            resolved_speed = value * _resolve(speed, [int])
+            resolved_speed = _resolve(speed, [int])
+            resolved_accel = _resolve(acceleration, [float, None])
+
+            if resolved_accel:
+                current_speed = 0.0
+                displacement_accumulator = 0.0
+                displacement = 0
+            else:
+                displacement = resolved_speed
+
             while self.is_holding():
-                handler(EV_REL, code, resolved_speed)
+                # Cursors can only move by integers. To get smooth acceleration for
+                # small acceleration values, the cursor needs to move by a pixel every
+                # few iterations. This can be achieved by remembering the decimal
+                # places that were cast away, and using them for the next iteration.
+                if resolved_accel and current_speed < resolved_speed:
+                    current_speed += resolved_accel
+                    current_speed = min(current_speed, resolved_speed)
+                    displacement_accumulator += current_speed
+                    displacement = int(displacement_accumulator)
+                    displacement_accumulator -= displacement
+
+                handler(EV_REL, code, value * displacement)
                 await asyncio.sleep(1 / self.mapping.rel_rate)
 
         self.tasks.append(task)

readme/macros.md

@@ -124,16 +124,19 @@ Bear in mind that anti-cheat software might detect macros in games.
 ### mouse
 
 > Moves the mouse cursor
+> 
+> If `acceleration` is provided then the cursor will accelerate from zero to a maximum speed of `speed`. 
 >
 > ```c#
-> mouse(direction: str, speed: int)
+> mouse(direction: str, speed: int, acceleration: float | None)
 > ```
 >
 > Examples:
 >
 > ```c#
 > mouse(up, 1)
 > mouse(left, 2)
+> mouse(down, 10, 0.3)
 > ```
 
 ### wheel

tests/unit/test_macros.py

@@ -1012,6 +1012,20 @@ async def test_mouse(self):
             actual_wheel_hi_res_event_count, expected_wheel_hi_res_event_count * 1.1
         )
 
+    async def test_mouse_accel(self):
+        macro_1 = parse("mouse(up, 10, 0.9)", self.context, DummyMapping)
+        macro_1.press_trigger()
+        asyncio.ensure_future(macro_1.run(self.handler))
+
+        sleep = 0.1
+        await asyncio.sleep(sleep)
+        self.assertTrue(macro_1.is_holding())
+        macro_1.release_trigger()
+        self.assertEqual(
+            [(2, 1, 0), (2, 1, -2), (2, 1, -3), (2, 1, -4), (2, 1, -4), (2, 1, -5)],
+            self.result,
+        )
+
     async def test_event_1(self):
         macro = parse("e(EV_KEY, KEY_A, 1)", self.context, DummyMapping)
         a_code = system_mapping.get("a")