filter: apply the same factor for constant motion as for normal motion

Users that want a flat pointer acceleration want the input speed to
match 1:1 to the output speed, barring a fixed constant multiplier.
This will apply to things like button scrolling as well, so let's map
the constant accel function to the non-constant accel functions to the
speed setting applies to every movement.

This is applied to both the flat and the touchpad flat filter.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

src/filter-flat.c

@@ -65,11 +65,18 @@ accelerator_filter_noop_flat(struct motion_filter *filter,
 			     const struct device_float_coords *unaccelerated,
 			     void *data, uint64_t time)
 {
-	const struct normalized_coords normalized = {
+	/* We map the unaccelerated flat filter to have the same behavior as
-		.x = unaccelerated->x,
+	 * the "accelerated" flat filter.
-		.y = unaccelerated->y,
+	 * The filter by definition is flat, i.e. it does not actually
-	};
+	 * apply any acceleration (merely a constant factor) and we can assume
-	return normalized;
+	 * that a user wants all mouse movement to have the same speed, mapped
+	 * 1:1 to the input speed.
+	 *
+	 * Thus we apply the same factor to our non-accelerated motion - this way
+	 * things like button scrolling end up having the same movement as
+	 * pointer motion.
+	 */
+	return accelerator_filter_flat(filter, unaccelerated, data, time);
 }
 
 static bool

src/filter-touchpad-flat.c

@@ -69,15 +69,18 @@ accelerator_filter_noop_touchpad_flat(struct motion_filter *filter,
 				      const struct device_float_coords *unaccelerated,
 				      void *data, uint64_t time)
 {
-	struct touchpad_accelerator_flat *accel =
+	/* We map the unaccelerated flat filter to have the same behavior as
-		(struct touchpad_accelerator_flat *) filter;
+	 * the "accelerated" flat filter.
-	struct normalized_coords normalized;
+	 * The filter by definition is flat, i.e. it does not actually
-
+	 * apply any acceleration (merely a constant factor) and we can assume
-	normalized = normalize_for_dpi(unaccelerated, accel->dpi);
+	 * that a user wants all mouse movement to have the same speed, mapped
-	normalized.x = TP_MAGIC_SLOWDOWN_FLAT * normalized.x;
+	 * 1:1 to the input speed.
-	normalized.y = TP_MAGIC_SLOWDOWN_FLAT * normalized.y;
+	 *
-
+	 * Thus we apply the same factor to our non-accelerated motion - this way
-	return normalized;
+	 * things like gestures end up having the same movement as
+	 * pointer motion.
+	 */
+	return accelerator_filter_touchpad_flat(filter, unaccelerated, data, time);
 }
 
 static bool