111 lines
3.5 KiB
C++
111 lines
3.5 KiB
C++
/*
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* Copyright (C) 2012 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#define LOG_TAG "VelocityControl"
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//#define LOG_NDEBUG 0
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// Log debug messages about acceleration.
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#define DEBUG_ACCELERATION 0
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#include <math.h>
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#include <limits.h>
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#include <input/VelocityControl.h>
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#include <utils/BitSet.h>
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#include <utils/Timers.h>
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namespace android {
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// --- VelocityControl ---
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const nsecs_t VelocityControl::STOP_TIME;
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VelocityControl::VelocityControl() {
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reset();
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}
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void VelocityControl::setParameters(const VelocityControlParameters& parameters) {
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mParameters = parameters;
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reset();
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}
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void VelocityControl::reset() {
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mLastMovementTime = LLONG_MIN;
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mRawPosition.x = 0;
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mRawPosition.y = 0;
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mVelocityTracker.clear();
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}
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void VelocityControl::move(nsecs_t eventTime, float* deltaX, float* deltaY) {
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if ((deltaX && *deltaX) || (deltaY && *deltaY)) {
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if (eventTime >= mLastMovementTime + STOP_TIME) {
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#if DEBUG_ACCELERATION
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ALOGD("VelocityControl: stopped, last movement was %0.3fms ago",
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(eventTime - mLastMovementTime) * 0.000001f);
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#endif
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reset();
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}
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mLastMovementTime = eventTime;
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if (deltaX) {
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mRawPosition.x += *deltaX;
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}
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if (deltaY) {
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mRawPosition.y += *deltaY;
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}
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mVelocityTracker.addMovement(eventTime, BitSet32(BitSet32::valueForBit(0)), &mRawPosition);
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float vx, vy;
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float scale = mParameters.scale;
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if (mVelocityTracker.getVelocity(0, &vx, &vy)) {
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float speed = hypotf(vx, vy) * scale;
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if (speed >= mParameters.highThreshold) {
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// Apply full acceleration above the high speed threshold.
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scale *= mParameters.acceleration;
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} else if (speed > mParameters.lowThreshold) {
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// Linearly interpolate the acceleration to apply between the low and high
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// speed thresholds.
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scale *= 1 + (speed - mParameters.lowThreshold)
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/ (mParameters.highThreshold - mParameters.lowThreshold)
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* (mParameters.acceleration - 1);
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}
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#if DEBUG_ACCELERATION
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ALOGD("VelocityControl(%0.3f, %0.3f, %0.3f, %0.3f): "
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"vx=%0.3f, vy=%0.3f, speed=%0.3f, accel=%0.3f",
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mParameters.scale, mParameters.lowThreshold, mParameters.highThreshold,
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mParameters.acceleration,
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vx, vy, speed, scale / mParameters.scale);
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#endif
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} else {
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#if DEBUG_ACCELERATION
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ALOGD("VelocityControl(%0.3f, %0.3f, %0.3f, %0.3f): unknown velocity",
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mParameters.scale, mParameters.lowThreshold, mParameters.highThreshold,
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mParameters.acceleration);
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#endif
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}
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if (deltaX) {
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*deltaX *= scale;
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}
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if (deltaY) {
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*deltaY *= scale;
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}
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}
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}
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} // namespace android
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