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 #define DEBUG_ACCELERATION 0
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
setParameters(const VelocityControlParameters & parameters)40 void VelocityControl::setParameters(const VelocityControlParameters& parameters) {
41 mParameters = parameters;
42 reset();
43 }
44
reset()45 void VelocityControl::reset() {
46 mLastMovementTime = LLONG_MIN;
47 mRawPosition.x = 0;
48 mRawPosition.y = 0;
49 mVelocityTracker.clear();
50 }
51
move(nsecs_t eventTime,float * deltaX,float * deltaY)52 void VelocityControl::move(nsecs_t eventTime, float* deltaX, float* deltaY) {
53 if ((deltaX && *deltaX) || (deltaY && *deltaY)) {
54 if (eventTime >= mLastMovementTime + STOP_TIME) {
55 #if DEBUG_ACCELERATION
56 ALOGD("VelocityControl: stopped, last movement was %0.3fms ago",
57 (eventTime - mLastMovementTime) * 0.000001f);
58 #endif
59 reset();
60 }
61
62 mLastMovementTime = eventTime;
63 if (deltaX) {
64 mRawPosition.x += *deltaX;
65 }
66 if (deltaY) {
67 mRawPosition.y += *deltaY;
68 }
69 mVelocityTracker.addMovement(eventTime, BitSet32(BitSet32::valueForBit(0)), &mRawPosition);
70
71 float vx, vy;
72 float scale = mParameters.scale;
73 if (mVelocityTracker.getVelocity(0, &vx, &vy)) {
74 float speed = hypotf(vx, vy) * scale;
75 if (speed >= mParameters.highThreshold) {
76 // Apply full acceleration above the high speed threshold.
77 scale *= mParameters.acceleration;
78 } else if (speed > mParameters.lowThreshold) {
79 // Linearly interpolate the acceleration to apply between the low and high
80 // speed thresholds.
81 scale *= 1 + (speed - mParameters.lowThreshold)
82 / (mParameters.highThreshold - mParameters.lowThreshold)
83 * (mParameters.acceleration - 1);
84 }
85
86 #if DEBUG_ACCELERATION
87 ALOGD("VelocityControl(%0.3f, %0.3f, %0.3f, %0.3f): "
88 "vx=%0.3f, vy=%0.3f, speed=%0.3f, accel=%0.3f",
89 mParameters.scale, mParameters.lowThreshold, mParameters.highThreshold,
90 mParameters.acceleration,
91 vx, vy, speed, scale / mParameters.scale);
92 #endif
93 } else {
94 #if DEBUG_ACCELERATION
95 ALOGD("VelocityControl(%0.3f, %0.3f, %0.3f, %0.3f): unknown velocity",
96 mParameters.scale, mParameters.lowThreshold, mParameters.highThreshold,
97 mParameters.acceleration);
98 #endif
99 }
100
101 if (deltaX) {
102 *deltaX *= scale;
103 }
104 if (deltaY) {
105 *deltaY *= scale;
106 }
107 }
108 }
109
110 } // namespace android
111