2 files changed, 95 insertions, 9 deletions
diff --git a/include/input/AccelerationCurve.h b/include/input/AccelerationCurve.h
new file mode 100644
index 0000000000..0cf648a2f7
--- /dev/null
+++ b/include/input/AccelerationCurve.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <cstdint>
+#include <vector>
+
+namespace android {
+
+/**
+ * Describes a section of an acceleration curve as a function which outputs a scaling factor (gain)
+ * for the pointer movement, given the speed of the mouse or finger (in mm/s):
+ *
+ *     gain(input_speed_mm_per_s) = baseGain + reciprocal / input_speed_mm_per_s
+ */
+struct AccelerationCurveSegment {
+    /**
+     * The maximum pointer speed at which this segment should apply, in mm/s. The last segment in a
+     * curve should always set this to infinity.
+     */
+    double maxPointerSpeedMmPerS;
+    /** The gain for this segment before the reciprocal is taken into account. */
+    double baseGain;
+    /** The reciprocal part of the formula, which should be divided by the input speed. */
+    double reciprocal;
+};
+
+/**
+ * Creates an acceleration curve for the given pointer sensitivity value. The sensitivity value
+ * should be between -7 (for the lowest sensitivity) and 7, inclusive.
+ */
+std::vector<AccelerationCurveSegment> createAccelerationCurveForPointerSensitivity(
+        int32_t sensitivity);
+
+} // namespace android
diff --git a/include/input/VelocityControl.h b/include/input/VelocityControl.h
index b78f63e1ae..7c58c87f8b 100644
--- a/include/input/VelocityControl.h
+++ b/include/input/VelocityControl.h
@@ -16,7 +16,10 @@
 
 #pragma once
 
+#include <vector>
+
 #include <android-base/stringprintf.h>
+#include <input/AccelerationCurve.h>
 #include <input/Input.h>
 #include <input/VelocityTracker.h>
 #include <utils/Timers.h>
@@ -86,12 +89,7 @@ struct VelocityControlParameters {
 class VelocityControl {
 public:
     VelocityControl();
-
-    /* Gets the various parameters. */
-    const VelocityControlParameters& getParameters() const;
-
-    /* Sets the various parameters. */
-    void setParameters(const VelocityControlParameters& parameters);
+    virtual ~VelocityControl() {}
 
     /* Resets the current movement counters to zero.
      * This has the effect of nullifying any acceleration. */
@@ -101,16 +99,55 @@ public:
      * scaled / accelerated delta based on the current velocity. */
     void move(nsecs_t eventTime, float* deltaX, float* deltaY);
 
-private:
+protected:
+    virtual void scaleDeltas(float* deltaX, float* deltaY) = 0;
+
     // If no movements are received within this amount of time,
     // we assume the movement has stopped and reset the movement counters.
     static const nsecs_t STOP_TIME = 500 * 1000000; // 500 ms
 
-    VelocityControlParameters mParameters;
-
     nsecs_t mLastMovementTime;
     float mRawPositionX, mRawPositionY;
     VelocityTracker mVelocityTracker;
 };
 
+/**
+ * Velocity control using a simple acceleration curve where the acceleration factor increases
+ * linearly with movement speed, subject to minimum and maximum values.
+ */
+class SimpleVelocityControl : public VelocityControl {
+public:
+    /** Gets the various parameters. */
+    const VelocityControlParameters& getParameters() const;
+
+    /** Sets the various parameters. */
+    void setParameters(const VelocityControlParameters& parameters);
+
+protected:
+    virtual void scaleDeltas(float* deltaX, float* deltaY) override;
+
+private:
+    VelocityControlParameters mParameters;
+};
+
+/** Velocity control using a curve made up of multiple reciprocal segments. */
+class CurvedVelocityControl : public VelocityControl {
+public:
+    CurvedVelocityControl();
+
+    /** Sets the curve to be used for acceleration. */
+    void setCurve(const std::vector<AccelerationCurveSegment>& curve);
+
+    void setAccelerationEnabled(bool enabled);
+
+protected:
+    virtual void scaleDeltas(float* deltaX, float* deltaY) override;
+
+private:
+    const AccelerationCurveSegment& segmentForSpeed(float speedMmPerS);
+
+    bool mAccelerationEnabled = true;
+    std::vector<AccelerationCurveSegment> mCurveSegments;
+};
+
 } // namespace android