1 /*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #define LOG_TAG "VelocityControl"
18 //#define LOG_NDEBUG 0
19
20 // Log debug messages about acceleration.
21 static constexpr bool DEBUG_ACCELERATION = false;
22
23 #include <math.h>
24 #include <limits.h>
25
26 #include <input/VelocityControl.h>
27 #include <utils/BitSet.h>
28 #include <utils/Timers.h>
29
30 namespace android {
31
32 // --- VelocityControl ---
33
34 const nsecs_t VelocityControl::STOP_TIME;
35
VelocityControl()36 VelocityControl::VelocityControl() {
37 reset();
38 }
39
getParameters()40 VelocityControlParameters& VelocityControl::getParameters() {
41 return mParameters;
42 }
43
setParameters(const VelocityControlParameters & parameters)44 void VelocityControl::setParameters(const VelocityControlParameters& parameters) {
45 mParameters = parameters;
46 reset();
47 }
48
reset()49 void VelocityControl::reset() {
50 mLastMovementTime = LLONG_MIN;
51 mRawPositionX = 0;
52 mRawPositionY = 0;
53 mVelocityTracker.clear();
54 }
55
move(nsecs_t eventTime,float * deltaX,float * deltaY)56 void VelocityControl::move(nsecs_t eventTime, float* deltaX, float* deltaY) {
57 if ((deltaX && *deltaX) || (deltaY && *deltaY)) {
58 if (eventTime >= mLastMovementTime + STOP_TIME) {
59 if (DEBUG_ACCELERATION && mLastMovementTime != LLONG_MIN) {
60 ALOGD("VelocityControl: stopped, last movement was %0.3fms ago",
61 (eventTime - mLastMovementTime) * 0.000001f);
62 }
63 reset();
64 }
65
66 mLastMovementTime = eventTime;
67 if (deltaX) {
68 mRawPositionX += *deltaX;
69 }
70 if (deltaY) {
71 mRawPositionY += *deltaY;
72 }
73 mVelocityTracker.addMovement(eventTime, /*pointerId=*/0, AMOTION_EVENT_AXIS_X,
74 mRawPositionX);
75 mVelocityTracker.addMovement(eventTime, /*pointerId=*/0, AMOTION_EVENT_AXIS_Y,
76 mRawPositionY);
77
78 std::optional<float> vx = mVelocityTracker.getVelocity(AMOTION_EVENT_AXIS_X, 0);
79 std::optional<float> vy = mVelocityTracker.getVelocity(AMOTION_EVENT_AXIS_Y, 0);
80 float scale = mParameters.scale;
81 if (vx && vy) {
82 float speed = hypotf(*vx, *vy) * scale;
83 if (speed >= mParameters.highThreshold) {
84 // Apply full acceleration above the high speed threshold.
85 scale *= mParameters.acceleration;
86 } else if (speed > mParameters.lowThreshold) {
87 // Linearly interpolate the acceleration to apply between the low and high
88 // speed thresholds.
89 scale *= 1 + (speed - mParameters.lowThreshold)
90 / (mParameters.highThreshold - mParameters.lowThreshold)
91 * (mParameters.acceleration - 1);
92 }
93
94 if (DEBUG_ACCELERATION) {
95 ALOGD("VelocityControl(%0.3f, %0.3f, %0.3f, %0.3f): "
96 "vx=%0.3f, vy=%0.3f, speed=%0.3f, accel=%0.3f",
97 mParameters.scale, mParameters.lowThreshold, mParameters.highThreshold,
98 mParameters.acceleration, *vx, *vy, speed, scale / mParameters.scale);
99 }
100
101 } else {
102 if (DEBUG_ACCELERATION) {
103 ALOGD("VelocityControl(%0.3f, %0.3f, %0.3f, %0.3f): unknown velocity",
104 mParameters.scale, mParameters.lowThreshold, mParameters.highThreshold,
105 mParameters.acceleration);
106 }
107 }
108
109 if (deltaX) {
110 *deltaX *= scale;
111 }
112 if (deltaY) {
113 *deltaY *= scale;
114 }
115 }
116 }
117
118 } // namespace android
119