1 /* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 5 * in compliance with the License. You may obtain a copy of the License at 6 * 7 * http://www.apache.org/licenses/LICENSE-2.0 8 * 9 * Unless required by applicable law or agreed to in writing, software distributed under the License 10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 11 * or implied. See the License for the specific language governing permissions and limitations under 12 * the License. 13 */ 14 15 package com.android.inputmethod.keyboard.internal; 16 17 import android.content.res.TypedArray; 18 import android.util.Log; 19 20 import com.android.inputmethod.latin.InputPointers; 21 import com.android.inputmethod.latin.R; 22 import com.android.inputmethod.latin.ResizableIntArray; 23 import com.android.inputmethod.latin.ResourceUtils; 24 25 public class GestureStroke { 26 private static final String TAG = GestureStroke.class.getSimpleName(); 27 private static final boolean DEBUG = false; 28 private static final boolean DEBUG_SPEED = false; 29 30 public static final int DEFAULT_CAPACITY = 128; 31 32 private final int mPointerId; 33 private final ResizableIntArray mEventTimes = new ResizableIntArray(DEFAULT_CAPACITY); 34 private final ResizableIntArray mXCoordinates = new ResizableIntArray(DEFAULT_CAPACITY); 35 private final ResizableIntArray mYCoordinates = new ResizableIntArray(DEFAULT_CAPACITY); 36 37 private final GestureStrokeParams mParams; 38 39 private int mKeyWidth; // pixel 40 // Static threshold for starting gesture detection 41 private int mDetectFastMoveSpeedThreshold; // pixel /sec 42 private int mDetectFastMoveTime; 43 private int mDetectFastMoveX; 44 private int mDetectFastMoveY; 45 // Dynamic threshold for gesture after fast typing 46 private boolean mAfterFastTyping; 47 private int mGestureDynamicDistanceThresholdFrom; // pixel 48 private int mGestureDynamicDistanceThresholdTo; // pixel 49 // Variables for gesture sampling 50 private int mGestureSamplingMinimumDistance; // pixel 51 private long mLastMajorEventTime; 52 private int mLastMajorEventX; 53 private int mLastMajorEventY; 54 // Variables for gesture recognition 55 private int mGestureRecognitionSpeedThreshold; // pixel / sec 56 private int mIncrementalRecognitionSize; 57 private int mLastIncrementalBatchSize; 58 59 public static final class GestureStrokeParams { 60 // Static threshold for gesture after fast typing 61 public final int mStaticTimeThresholdAfterFastTyping; // msec 62 // Static threshold for starting gesture detection 63 public final float mDetectFastMoveSpeedThreshold; // keyWidth/sec 64 // Dynamic threshold for gesture after fast typing 65 public final int mDynamicThresholdDecayDuration; // msec 66 // Time based threshold values 67 public final int mDynamicTimeThresholdFrom; // msec 68 public final int mDynamicTimeThresholdTo; // msec 69 // Distance based threshold values 70 public final float mDynamicDistanceThresholdFrom; // keyWidth 71 public final float mDynamicDistanceThresholdTo; // keyWidth 72 // Parameters for gesture sampling 73 public final float mSamplingMinimumDistance; // keyWidth 74 // Parameters for gesture recognition 75 public final int mRecognitionMinimumTime; // msec 76 public final float mRecognitionSpeedThreshold; // keyWidth/sec 77 78 // Default GestureStroke parameters for test. 79 public static final GestureStrokeParams FOR_TEST = new GestureStrokeParams(); 80 public static final GestureStrokeParams DEFAULT = FOR_TEST; 81 82 private GestureStrokeParams() { 83 // These parameter values are default and intended for testing. 84 mStaticTimeThresholdAfterFastTyping = 350; // msec 85 mDetectFastMoveSpeedThreshold = 1.5f; // keyWidth / sec 86 mDynamicThresholdDecayDuration = 450; // msec 87 mDynamicTimeThresholdFrom = 300; // msec 88 mDynamicTimeThresholdTo = 20; // msec 89 mDynamicDistanceThresholdFrom = 6.0f; // keyWidth 90 mDynamicDistanceThresholdTo = 0.35f; // keyWidth 91 // The following parameters' change will affect the result of regression test. 92 mSamplingMinimumDistance = 1.0f / 6.0f; // keyWidth 93 mRecognitionMinimumTime = 100; // msec 94 mRecognitionSpeedThreshold = 5.5f; // keyWidth / sec 95 } 96 97 public GestureStrokeParams(final TypedArray mainKeyboardViewAttr) { 98 mStaticTimeThresholdAfterFastTyping = mainKeyboardViewAttr.getInt( 99 R.styleable.MainKeyboardView_gestureStaticTimeThresholdAfterFastTyping, 100 DEFAULT.mStaticTimeThresholdAfterFastTyping); 101 mDetectFastMoveSpeedThreshold = ResourceUtils.getFraction(mainKeyboardViewAttr, 102 R.styleable.MainKeyboardView_gestureDetectFastMoveSpeedThreshold, 103 DEFAULT.mDetectFastMoveSpeedThreshold); 104 mDynamicThresholdDecayDuration = mainKeyboardViewAttr.getInt( 105 R.styleable.MainKeyboardView_gestureDynamicThresholdDecayDuration, 106 DEFAULT.mDynamicThresholdDecayDuration); 107 mDynamicTimeThresholdFrom = mainKeyboardViewAttr.getInt( 108 R.styleable.MainKeyboardView_gestureDynamicTimeThresholdFrom, 109 DEFAULT.mDynamicTimeThresholdFrom); 110 mDynamicTimeThresholdTo = mainKeyboardViewAttr.getInt( 111 R.styleable.MainKeyboardView_gestureDynamicTimeThresholdTo, 112 DEFAULT.mDynamicTimeThresholdTo); 113 mDynamicDistanceThresholdFrom = ResourceUtils.getFraction(mainKeyboardViewAttr, 114 R.styleable.MainKeyboardView_gestureDynamicDistanceThresholdFrom, 115 DEFAULT.mDynamicDistanceThresholdFrom); 116 mDynamicDistanceThresholdTo = ResourceUtils.getFraction(mainKeyboardViewAttr, 117 R.styleable.MainKeyboardView_gestureDynamicDistanceThresholdTo, 118 DEFAULT.mDynamicDistanceThresholdTo); 119 mSamplingMinimumDistance = ResourceUtils.getFraction(mainKeyboardViewAttr, 120 R.styleable.MainKeyboardView_gestureSamplingMinimumDistance, 121 DEFAULT.mSamplingMinimumDistance); 122 mRecognitionMinimumTime = mainKeyboardViewAttr.getInt( 123 R.styleable.MainKeyboardView_gestureRecognitionMinimumTime, 124 DEFAULT.mRecognitionMinimumTime); 125 mRecognitionSpeedThreshold = ResourceUtils.getFraction(mainKeyboardViewAttr, 126 R.styleable.MainKeyboardView_gestureRecognitionSpeedThreshold, 127 DEFAULT.mRecognitionSpeedThreshold); 128 } 129 } 130 131 private static final int MSEC_PER_SEC = 1000; 132 133 public GestureStroke(final int pointerId, final GestureStrokeParams params) { 134 mPointerId = pointerId; 135 mParams = params; 136 } 137 138 public void setKeyboardGeometry(final int keyWidth) { 139 mKeyWidth = keyWidth; 140 // TODO: Find an appropriate base metric for these length. Maybe diagonal length of the key? 141 mDetectFastMoveSpeedThreshold = (int)(keyWidth * mParams.mDetectFastMoveSpeedThreshold); 142 mGestureDynamicDistanceThresholdFrom = 143 (int)(keyWidth * mParams.mDynamicDistanceThresholdFrom); 144 mGestureDynamicDistanceThresholdTo = (int)(keyWidth * mParams.mDynamicDistanceThresholdTo); 145 mGestureSamplingMinimumDistance = (int)(keyWidth * mParams.mSamplingMinimumDistance); 146 mGestureRecognitionSpeedThreshold = (int)(keyWidth * mParams.mRecognitionSpeedThreshold); 147 if (DEBUG) { 148 Log.d(TAG, String.format( 149 "[%d] setKeyboardGeometry: keyWidth=%3d tT=%3d >> %3d tD=%3d >> %3d", 150 mPointerId, keyWidth, 151 mParams.mDynamicTimeThresholdFrom, 152 mParams.mDynamicTimeThresholdTo, 153 mGestureDynamicDistanceThresholdFrom, 154 mGestureDynamicDistanceThresholdTo)); 155 } 156 } 157 158 public void onDownEvent(final int x, final int y, final long downTime, 159 final long gestureFirstDownTime, final long lastTypingTime) { 160 reset(); 161 final long elapsedTimeAfterTyping = downTime - lastTypingTime; 162 if (elapsedTimeAfterTyping < mParams.mStaticTimeThresholdAfterFastTyping) { 163 mAfterFastTyping = true; 164 } 165 if (DEBUG) { 166 Log.d(TAG, String.format("[%d] onDownEvent: dT=%3d%s", mPointerId, 167 elapsedTimeAfterTyping, mAfterFastTyping ? " afterFastTyping" : "")); 168 } 169 final int elapsedTimeFromFirstDown = (int)(downTime - gestureFirstDownTime); 170 addPoint(x, y, elapsedTimeFromFirstDown, true /* isMajorEvent */); 171 } 172 173 private int getGestureDynamicDistanceThreshold(final int deltaTime) { 174 if (!mAfterFastTyping || deltaTime >= mParams.mDynamicThresholdDecayDuration) { 175 return mGestureDynamicDistanceThresholdTo; 176 } 177 final int decayedThreshold = 178 (mGestureDynamicDistanceThresholdFrom - mGestureDynamicDistanceThresholdTo) 179 * deltaTime / mParams.mDynamicThresholdDecayDuration; 180 return mGestureDynamicDistanceThresholdFrom - decayedThreshold; 181 } 182 183 private int getGestureDynamicTimeThreshold(final int deltaTime) { 184 if (!mAfterFastTyping || deltaTime >= mParams.mDynamicThresholdDecayDuration) { 185 return mParams.mDynamicTimeThresholdTo; 186 } 187 final int decayedThreshold = 188 (mParams.mDynamicTimeThresholdFrom - mParams.mDynamicTimeThresholdTo) 189 * deltaTime / mParams.mDynamicThresholdDecayDuration; 190 return mParams.mDynamicTimeThresholdFrom - decayedThreshold; 191 } 192 193 public final boolean isStartOfAGesture() { 194 if (!hasDetectedFastMove()) { 195 return false; 196 } 197 final int size = mEventTimes.getLength(); 198 if (size <= 0) { 199 return false; 200 } 201 final int lastIndex = size - 1; 202 final int deltaTime = mEventTimes.get(lastIndex) - mDetectFastMoveTime; 203 if (deltaTime < 0) { 204 return false; 205 } 206 final int deltaDistance = getDistance( 207 mXCoordinates.get(lastIndex), mYCoordinates.get(lastIndex), 208 mDetectFastMoveX, mDetectFastMoveY); 209 final int distanceThreshold = getGestureDynamicDistanceThreshold(deltaTime); 210 final int timeThreshold = getGestureDynamicTimeThreshold(deltaTime); 211 final boolean isStartOfAGesture = deltaTime >= timeThreshold 212 && deltaDistance >= distanceThreshold; 213 if (DEBUG) { 214 Log.d(TAG, String.format("[%d] isStartOfAGesture: dT=%3d tT=%3d dD=%3d tD=%3d%s%s", 215 mPointerId, deltaTime, timeThreshold, 216 deltaDistance, distanceThreshold, 217 mAfterFastTyping ? " afterFastTyping" : "", 218 isStartOfAGesture ? " startOfAGesture" : "")); 219 } 220 return isStartOfAGesture; 221 } 222 223 protected void reset() { 224 mIncrementalRecognitionSize = 0; 225 mLastIncrementalBatchSize = 0; 226 mEventTimes.setLength(0); 227 mXCoordinates.setLength(0); 228 mYCoordinates.setLength(0); 229 mLastMajorEventTime = 0; 230 mDetectFastMoveTime = 0; 231 mAfterFastTyping = false; 232 } 233 234 private void appendPoint(final int x, final int y, final int time) { 235 mEventTimes.add(time); 236 mXCoordinates.add(x); 237 mYCoordinates.add(y); 238 } 239 240 private void updateMajorEvent(final int x, final int y, final int time) { 241 mLastMajorEventTime = time; 242 mLastMajorEventX = x; 243 mLastMajorEventY = y; 244 } 245 246 private final boolean hasDetectedFastMove() { 247 return mDetectFastMoveTime > 0; 248 } 249 250 private int detectFastMove(final int x, final int y, final int time) { 251 final int size = mEventTimes.getLength(); 252 final int lastIndex = size - 1; 253 final int lastX = mXCoordinates.get(lastIndex); 254 final int lastY = mYCoordinates.get(lastIndex); 255 final int dist = getDistance(lastX, lastY, x, y); 256 final int msecs = time - mEventTimes.get(lastIndex); 257 if (msecs > 0) { 258 final int pixels = getDistance(lastX, lastY, x, y); 259 final int pixelsPerSec = pixels * MSEC_PER_SEC; 260 if (DEBUG_SPEED) { 261 final float speed = (float)pixelsPerSec / msecs / mKeyWidth; 262 Log.d(TAG, String.format("[%d] detectFastMove: speed=%5.2f", mPointerId, speed)); 263 } 264 // Equivalent to (pixels / msecs < mStartSpeedThreshold / MSEC_PER_SEC) 265 if (!hasDetectedFastMove() && pixelsPerSec > mDetectFastMoveSpeedThreshold * msecs) { 266 if (DEBUG) { 267 final float speed = (float)pixelsPerSec / msecs / mKeyWidth; 268 Log.d(TAG, String.format( 269 "[%d] detectFastMove: speed=%5.2f T=%3d points=%3d fastMove", 270 mPointerId, speed, time, size)); 271 } 272 mDetectFastMoveTime = time; 273 mDetectFastMoveX = x; 274 mDetectFastMoveY = y; 275 } 276 } 277 return dist; 278 } 279 280 public void addPoint(final int x, final int y, final int time, final boolean isMajorEvent) { 281 final int size = mEventTimes.getLength(); 282 if (size <= 0) { 283 // Down event 284 appendPoint(x, y, time); 285 updateMajorEvent(x, y, time); 286 } else { 287 final int distance = detectFastMove(x, y, time); 288 if (distance > mGestureSamplingMinimumDistance) { 289 appendPoint(x, y, time); 290 } 291 } 292 if (isMajorEvent) { 293 updateIncrementalRecognitionSize(x, y, time); 294 updateMajorEvent(x, y, time); 295 } 296 } 297 298 private void updateIncrementalRecognitionSize(final int x, final int y, final int time) { 299 final int msecs = (int)(time - mLastMajorEventTime); 300 if (msecs <= 0) { 301 return; 302 } 303 final int pixels = getDistance(mLastMajorEventX, mLastMajorEventY, x, y); 304 final int pixelsPerSec = pixels * MSEC_PER_SEC; 305 // Equivalent to (pixels / msecs < mGestureRecognitionThreshold / MSEC_PER_SEC) 306 if (pixelsPerSec < mGestureRecognitionSpeedThreshold * msecs) { 307 mIncrementalRecognitionSize = mEventTimes.getLength(); 308 } 309 } 310 311 public final boolean hasRecognitionTimePast( 312 final long currentTime, final long lastRecognitionTime) { 313 return currentTime > lastRecognitionTime + mParams.mRecognitionMinimumTime; 314 } 315 316 public final void appendAllBatchPoints(final InputPointers out) { 317 appendBatchPoints(out, mEventTimes.getLength()); 318 } 319 320 public final void appendIncrementalBatchPoints(final InputPointers out) { 321 appendBatchPoints(out, mIncrementalRecognitionSize); 322 } 323 324 private void appendBatchPoints(final InputPointers out, final int size) { 325 final int length = size - mLastIncrementalBatchSize; 326 if (length <= 0) { 327 return; 328 } 329 out.append(mPointerId, mEventTimes, mXCoordinates, mYCoordinates, 330 mLastIncrementalBatchSize, length); 331 mLastIncrementalBatchSize = size; 332 } 333 334 private static int getDistance(final int x1, final int y1, final int x2, final int y2) { 335 final int dx = x1 - x2; 336 final int dy = y1 - y2; 337 // Note that, in recent versions of Android, FloatMath is actually slower than 338 // java.lang.Math due to the way the JIT optimizes java.lang.Math. 339 return (int)Math.sqrt(dx * dx + dy * dy); 340 } 341 } 342
