| Jeff Brown | 8a90e6e | 2012-05-11 12:24:35 -0700 | [diff] [blame] | 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 <androidfw/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 | |
| 36 | VelocityControl::VelocityControl() { |
| 37 | reset(); |
| 38 | } |
| 39 | |
| 40 | void VelocityControl::setParameters(const VelocityControlParameters& parameters) { |
| 41 | mParameters = parameters; |
| 42 | reset(); |
| 43 | } |
| 44 | |
| 45 | void VelocityControl::reset() { |
| 46 | mLastMovementTime = LLONG_MIN; |
| 47 | mRawPosition.x = 0; |
| 48 | mRawPosition.y = 0; |
| 49 | mVelocityTracker.clear(); |
| 50 | } |
| 51 | |
| 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 |