1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/widget/gonk/libui/VelocityControl.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,110 @@
1.4 +/*
1.5 + * Copyright (C) 2012 The Android Open Source Project
1.6 + *
1.7 + * Licensed under the Apache License, Version 2.0 (the "License");
1.8 + * you may not use this file except in compliance with the License.
1.9 + * You may obtain a copy of the License at
1.10 + *
1.11 + * http://www.apache.org/licenses/LICENSE-2.0
1.12 + *
1.13 + * Unless required by applicable law or agreed to in writing, software
1.14 + * distributed under the License is distributed on an "AS IS" BASIS,
1.15 + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
1.16 + * See the License for the specific language governing permissions and
1.17 + * limitations under the License.
1.18 + */
1.19 +
1.20 +#define LOG_TAG "VelocityControl"
1.21 +//#define LOG_NDEBUG 0
1.22 +
1.23 +// Log debug messages about acceleration.
1.24 +#define DEBUG_ACCELERATION 0
1.25 +
1.26 +#include <math.h>
1.27 +#include <limits.h>
1.28 +
1.29 +#include "VelocityControl.h"
1.30 +#include <utils/BitSet.h>
1.31 +#include <utils/Timers.h>
1.32 +
1.33 +namespace android {
1.34 +
1.35 +// --- VelocityControl ---
1.36 +
1.37 +const nsecs_t VelocityControl::STOP_TIME;
1.38 +
1.39 +VelocityControl::VelocityControl() {
1.40 + reset();
1.41 +}
1.42 +
1.43 +void VelocityControl::setParameters(const VelocityControlParameters& parameters) {
1.44 + mParameters = parameters;
1.45 + reset();
1.46 +}
1.47 +
1.48 +void VelocityControl::reset() {
1.49 + mLastMovementTime = LLONG_MIN;
1.50 + mRawPosition.x = 0;
1.51 + mRawPosition.y = 0;
1.52 + mVelocityTracker.clear();
1.53 +}
1.54 +
1.55 +void VelocityControl::move(nsecs_t eventTime, float* deltaX, float* deltaY) {
1.56 + if ((deltaX && *deltaX) || (deltaY && *deltaY)) {
1.57 + if (eventTime >= mLastMovementTime + STOP_TIME) {
1.58 +#if DEBUG_ACCELERATION
1.59 + ALOGD("VelocityControl: stopped, last movement was %0.3fms ago",
1.60 + (eventTime - mLastMovementTime) * 0.000001f);
1.61 +#endif
1.62 + reset();
1.63 + }
1.64 +
1.65 + mLastMovementTime = eventTime;
1.66 + if (deltaX) {
1.67 + mRawPosition.x += *deltaX;
1.68 + }
1.69 + if (deltaY) {
1.70 + mRawPosition.y += *deltaY;
1.71 + }
1.72 + mVelocityTracker.addMovement(eventTime, BitSet32(BitSet32::valueForBit(0)), &mRawPosition);
1.73 +
1.74 + float vx, vy;
1.75 + float scale = mParameters.scale;
1.76 + if (mVelocityTracker.getVelocity(0, &vx, &vy)) {
1.77 + float speed = hypotf(vx, vy) * scale;
1.78 + if (speed >= mParameters.highThreshold) {
1.79 + // Apply full acceleration above the high speed threshold.
1.80 + scale *= mParameters.acceleration;
1.81 + } else if (speed > mParameters.lowThreshold) {
1.82 + // Linearly interpolate the acceleration to apply between the low and high
1.83 + // speed thresholds.
1.84 + scale *= 1 + (speed - mParameters.lowThreshold)
1.85 + / (mParameters.highThreshold - mParameters.lowThreshold)
1.86 + * (mParameters.acceleration - 1);
1.87 + }
1.88 +
1.89 +#if DEBUG_ACCELERATION
1.90 + ALOGD("VelocityControl(%0.3f, %0.3f, %0.3f, %0.3f): "
1.91 + "vx=%0.3f, vy=%0.3f, speed=%0.3f, accel=%0.3f",
1.92 + mParameters.scale, mParameters.lowThreshold, mParameters.highThreshold,
1.93 + mParameters.acceleration,
1.94 + vx, vy, speed, scale / mParameters.scale);
1.95 +#endif
1.96 + } else {
1.97 +#if DEBUG_ACCELERATION
1.98 + ALOGD("VelocityControl(%0.3f, %0.3f, %0.3f, %0.3f): unknown velocity",
1.99 + mParameters.scale, mParameters.lowThreshold, mParameters.highThreshold,
1.100 + mParameters.acceleration);
1.101 +#endif
1.102 + }
1.103 +
1.104 + if (deltaX) {
1.105 + *deltaX *= scale;
1.106 + }
1.107 + if (deltaY) {
1.108 + *deltaY *= scale;
1.109 + }
1.110 + }
1.111 +}
1.112 +
1.113 +} // namespace android
