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| 1 // Copyright 2015 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 package org.chromium.chrome.browser.compositor.layouts.phone.stack; |
| 6 |
| 7 import android.content.Context; |
| 8 import android.hardware.SensorManager; |
| 9 import android.util.Log; |
| 10 import android.view.ViewConfiguration; |
| 11 |
| 12 /** |
| 13 * This class is vastly copied from {@link android.widget.OverScroller} but deco
uples the time |
| 14 * from the app time so it can be specified manually. |
| 15 */ |
| 16 public class StackScroller { |
| 17 private int mMode; |
| 18 |
| 19 private final SplineStackScroller mScrollerX; |
| 20 private final SplineStackScroller mScrollerY; |
| 21 |
| 22 private final boolean mFlywheel; |
| 23 |
| 24 private static final int SCROLL_MODE = 0; |
| 25 private static final int FLING_MODE = 1; |
| 26 |
| 27 private static float sViscousFluidScale; |
| 28 private static float sViscousFluidNormalize; |
| 29 |
| 30 /** |
| 31 * Creates an StackScroller with a viscous fluid scroll interpolator and fly
wheel. |
| 32 * @param context |
| 33 */ |
| 34 public StackScroller(Context context) { |
| 35 mFlywheel = true; |
| 36 mScrollerX = new SplineStackScroller(context); |
| 37 mScrollerY = new SplineStackScroller(context); |
| 38 initContants(); |
| 39 } |
| 40 |
| 41 private static void initContants() { |
| 42 // This controls the viscous fluid effect (how much of it) |
| 43 sViscousFluidScale = 8.0f; |
| 44 // must be set to 1.0 (used in viscousFluid()) |
| 45 sViscousFluidNormalize = 1.0f; |
| 46 sViscousFluidNormalize = 1.0f / viscousFluid(1.0f); |
| 47 } |
| 48 |
| 49 /** |
| 50 * |
| 51 * Returns whether the scroller has finished scrolling. |
| 52 * |
| 53 * @return True if the scroller has finished scrolling, false otherwise. |
| 54 */ |
| 55 public final boolean isFinished() { |
| 56 return mScrollerX.mFinished && mScrollerY.mFinished; |
| 57 } |
| 58 |
| 59 /** |
| 60 * Force the finished field to a particular value. Contrary to |
| 61 * {@link #abortAnimation()}, forcing the animation to finished |
| 62 * does NOT cause the scroller to move to the final x and y |
| 63 * position. |
| 64 * |
| 65 * @param finished The new finished value. |
| 66 */ |
| 67 public final void forceFinished(boolean finished) { |
| 68 mScrollerX.mFinished = mScrollerY.mFinished = finished; |
| 69 } |
| 70 |
| 71 /** |
| 72 * Returns the current X offset in the scroll. |
| 73 * |
| 74 * @return The new X offset as an absolute distance from the origin. |
| 75 */ |
| 76 public final int getCurrX() { |
| 77 return mScrollerX.mCurrentPosition; |
| 78 } |
| 79 |
| 80 /** |
| 81 * Returns the current Y offset in the scroll. |
| 82 * |
| 83 * @return The new Y offset as an absolute distance from the origin. |
| 84 */ |
| 85 public final int getCurrY() { |
| 86 return mScrollerY.mCurrentPosition; |
| 87 } |
| 88 |
| 89 /** |
| 90 * Returns where the scroll will end. Valid only for "fling" scrolls. |
| 91 * |
| 92 * @return The final X offset as an absolute distance from the origin. |
| 93 */ |
| 94 public final int getFinalX() { |
| 95 return mScrollerX.mFinal; |
| 96 } |
| 97 |
| 98 /** |
| 99 * Returns where the scroll will end. Valid only for "fling" scrolls. |
| 100 * |
| 101 * @return The final Y offset as an absolute distance from the origin. |
| 102 */ |
| 103 public final int getFinalY() { |
| 104 return mScrollerY.mFinal; |
| 105 } |
| 106 |
| 107 /** |
| 108 * Sets where the scroll will end. Valid only for "fling" scrolls. |
| 109 * |
| 110 * @param x The final X offset as an absolute distance from the origin. |
| 111 */ |
| 112 public final void setFinalX(int x) { |
| 113 mScrollerX.setFinalPosition(x); |
| 114 } |
| 115 |
| 116 private static float viscousFluid(float x) { |
| 117 x *= sViscousFluidScale; |
| 118 if (x < 1.0f) { |
| 119 x -= (1.0f - (float) Math.exp(-x)); |
| 120 } else { |
| 121 float start = 0.36787944117f; // 1/e == exp(-1) |
| 122 x = 1.0f - (float) Math.exp(1.0f - x); |
| 123 x = start + x * (1.0f - start); |
| 124 } |
| 125 x *= sViscousFluidNormalize; |
| 126 return x; |
| 127 } |
| 128 |
| 129 /** |
| 130 * Call this when you want to know the new location. If it returns true, the |
| 131 * animation is not yet finished. |
| 132 */ |
| 133 public boolean computeScrollOffset(long time) { |
| 134 if (isFinished()) { |
| 135 return false; |
| 136 } |
| 137 |
| 138 switch (mMode) { |
| 139 case SCROLL_MODE: |
| 140 // Any scroller can be used for time, since they were started |
| 141 // together in scroll mode. We use X here. |
| 142 final long elapsedTime = time - mScrollerX.mStartTime; |
| 143 |
| 144 final int duration = mScrollerX.mDuration; |
| 145 if (elapsedTime < duration) { |
| 146 float q = (float) (elapsedTime) / duration; |
| 147 q = viscousFluid(q); |
| 148 mScrollerX.updateScroll(q); |
| 149 mScrollerY.updateScroll(q); |
| 150 } else { |
| 151 abortAnimation(); |
| 152 } |
| 153 break; |
| 154 |
| 155 case FLING_MODE: |
| 156 if (!mScrollerX.mFinished) { |
| 157 if (!mScrollerX.update(time)) { |
| 158 if (!mScrollerX.continueWhenFinished(time)) { |
| 159 mScrollerX.finish(); |
| 160 } |
| 161 } |
| 162 } |
| 163 |
| 164 if (!mScrollerY.mFinished) { |
| 165 if (!mScrollerY.update(time)) { |
| 166 if (!mScrollerY.continueWhenFinished(time)) { |
| 167 mScrollerY.finish(); |
| 168 } |
| 169 } |
| 170 } |
| 171 |
| 172 break; |
| 173 |
| 174 default: |
| 175 break; |
| 176 } |
| 177 |
| 178 return true; |
| 179 } |
| 180 |
| 181 /** |
| 182 * Start scrolling by providing a starting point and the distance to travel. |
| 183 * |
| 184 * @param startX Starting horizontal scroll offset in pixels. Positive |
| 185 * numbers will scroll the content to the left. |
| 186 * @param startY Starting vertical scroll offset in pixels. Positive numbers |
| 187 * will scroll the content up. |
| 188 * @param dx Horizontal distance to travel. Positive numbers will scroll the |
| 189 * content to the left. |
| 190 * @param dy Vertical distance to travel. Positive numbers will scroll the |
| 191 * content up. |
| 192 * @param duration Duration of the scroll in milliseconds. |
| 193 */ |
| 194 public void startScroll(int startX, int startY, int dx, int dy, long startTi
me, int duration) { |
| 195 mMode = SCROLL_MODE; |
| 196 mScrollerX.startScroll(startX, dx, startTime, duration); |
| 197 mScrollerY.startScroll(startY, dy, startTime, duration); |
| 198 } |
| 199 |
| 200 /** |
| 201 * Call this when you want to 'spring back' into a valid coordinate range. |
| 202 * |
| 203 * @param startX Starting X coordinate |
| 204 * @param startY Starting Y coordinate |
| 205 * @param minX Minimum valid X value |
| 206 * @param maxX Maximum valid X value |
| 207 * @param minY Minimum valid Y value |
| 208 * @param maxY Minimum valid Y value |
| 209 * @return true if a springback was initiated, false if startX and startY we
re |
| 210 * already within the valid range. |
| 211 */ |
| 212 public boolean springBack( |
| 213 int startX, int startY, int minX, int maxX, int minY, int maxY, long
time) { |
| 214 mMode = FLING_MODE; |
| 215 |
| 216 // Make sure both methods are called. |
| 217 final boolean spingbackX = mScrollerX.springback(startX, minX, maxX, tim
e); |
| 218 final boolean spingbackY = mScrollerY.springback(startY, minY, maxY, tim
e); |
| 219 return spingbackX || spingbackY; |
| 220 } |
| 221 |
| 222 /** |
| 223 * Start scrolling based on a fling gesture. The distance traveled will |
| 224 * depend on the initial velocity of the fling. |
| 225 * |
| 226 * @param startX Starting point of the scroll (X) |
| 227 * @param startY Starting point of the scroll (Y) |
| 228 * @param velocityX Initial velocity of the fling (X) measured in pixels per
second. |
| 229 * @param velocityY Initial velocity of the fling (Y) measured in pixels per
second |
| 230 * @param minX Minimum X value. The scroller will not scroll past this point |
| 231 * unless overX > 0. If overfling is allowed, it will use minX as |
| 232 * a springback boundary. |
| 233 * @param maxX Maximum X value. The scroller will not scroll past this point |
| 234 * unless overX > 0. If overfling is allowed, it will use maxX as |
| 235 * a springback boundary. |
| 236 * @param minY Minimum Y value. The scroller will not scroll past this point |
| 237 * unless overY > 0. If overfling is allowed, it will use minY as |
| 238 * a springback boundary. |
| 239 * @param maxY Maximum Y value. The scroller will not scroll past this point |
| 240 * unless overY > 0. If overfling is allowed, it will use maxY as |
| 241 * a springback boundary. |
| 242 * @param overX Overfling range. If > 0, horizontal overfling in either |
| 243 * direction will be possible. |
| 244 * @param overY Overfling range. If > 0, vertical overfling in either |
| 245 * direction will be possible. |
| 246 */ |
| 247 public void fling(int startX, int startY, int velocityX, int velocityY, int
minX, int maxX, |
| 248 int minY, int maxY, int overX, int overY, long time) { |
| 249 // Continue a scroll or fling in progress |
| 250 if (mFlywheel && !isFinished()) { |
| 251 float oldVelocityX = mScrollerX.mCurrVelocity; |
| 252 float oldVelocityY = mScrollerY.mCurrVelocity; |
| 253 if (Math.signum(velocityX) == Math.signum(oldVelocityX) |
| 254 && Math.signum(velocityY) == Math.signum(oldVelocityY)) { |
| 255 velocityX += oldVelocityX; |
| 256 velocityY += oldVelocityY; |
| 257 } |
| 258 } |
| 259 |
| 260 mMode = FLING_MODE; |
| 261 mScrollerX.fling(startX, velocityX, minX, maxX, overX, time); |
| 262 mScrollerY.fling(startY, velocityY, minY, maxY, overY, time); |
| 263 } |
| 264 |
| 265 /** |
| 266 * Stops the animation. Contrary to {@link #forceFinished(boolean)}, |
| 267 * aborting the animating causes the scroller to move to the final x and y |
| 268 * positions. |
| 269 * |
| 270 * @see #forceFinished(boolean) |
| 271 */ |
| 272 public void abortAnimation() { |
| 273 mScrollerX.finish(); |
| 274 mScrollerY.finish(); |
| 275 } |
| 276 |
| 277 static class SplineStackScroller { |
| 278 // Initial position |
| 279 private int mStart; |
| 280 |
| 281 // Current position |
| 282 private int mCurrentPosition; |
| 283 |
| 284 // Final position |
| 285 private int mFinal; |
| 286 |
| 287 // Initial velocity |
| 288 private int mVelocity; |
| 289 |
| 290 // Current velocity |
| 291 private float mCurrVelocity; |
| 292 |
| 293 // Constant current deceleration |
| 294 private float mDeceleration; |
| 295 |
| 296 // Animation starting time, in system milliseconds |
| 297 private long mStartTime; |
| 298 |
| 299 // Animation duration, in milliseconds |
| 300 private int mDuration; |
| 301 |
| 302 // Duration to complete spline component of animation |
| 303 private int mSplineDuration; |
| 304 |
| 305 // Distance to travel along spline animation |
| 306 private int mSplineDistance; |
| 307 |
| 308 // Whether the animation is currently in progress |
| 309 private boolean mFinished; |
| 310 |
| 311 // The allowed overshot distance before boundary is reached. |
| 312 private int mOver; |
| 313 |
| 314 // Fling friction |
| 315 private final float mFlingFriction = ViewConfiguration.getScrollFriction
(); |
| 316 |
| 317 // Current state of the animation. |
| 318 private int mState = SPLINE; |
| 319 |
| 320 // Constant gravity value, used in the deceleration phase. |
| 321 private static final float GRAVITY = 2000.0f; |
| 322 |
| 323 // A context-specific coefficient adjusted to physical values. |
| 324 private final float mPhysicalCoeff; |
| 325 |
| 326 private static final float DECELERATION_RATE = (float) (Math.log(0.78) /
Math.log(0.9)); |
| 327 private static final float INFLEXION = 0.35f; // Tension lines cross at
(INFLEXION, 1) |
| 328 private static final float START_TENSION = 0.5f; |
| 329 private static final float END_TENSION = 1.0f; |
| 330 private static final float P1 = START_TENSION * INFLEXION; |
| 331 private static final float P2 = 1.0f - END_TENSION * (1.0f - INFLEXION); |
| 332 |
| 333 private static final int NB_SAMPLES = 100; |
| 334 private static final float[] SPLINE_POSITION = new float[NB_SAMPLES + 1]
; |
| 335 private static final float[] SPLINE_TIME = new float[NB_SAMPLES + 1]; |
| 336 |
| 337 private static final int SPLINE = 0; |
| 338 private static final int CUBIC = 1; |
| 339 private static final int BALLISTIC = 2; |
| 340 |
| 341 static { |
| 342 float xMin = 0.0f; |
| 343 float yMin = 0.0f; |
| 344 for (int i = 0; i < NB_SAMPLES; i++) { |
| 345 final float alpha = (float) i / NB_SAMPLES; |
| 346 |
| 347 float xMax = 1.0f; |
| 348 float x, tx, coef; |
| 349 while (true) { |
| 350 x = xMin + (xMax - xMin) / 2.0f; |
| 351 coef = 3.0f * x * (1.0f - x); |
| 352 tx = coef * ((1.0f - x) * P1 + x * P2) + x * x * x; |
| 353 if (Math.abs(tx - alpha) < 1E-5) break; |
| 354 if (tx > alpha) { |
| 355 xMax = x; |
| 356 } else { |
| 357 xMin = x; |
| 358 } |
| 359 } |
| 360 SPLINE_POSITION[i] = coef * ((1.0f - x) * START_TENSION + x) + x
* x * x; |
| 361 |
| 362 float yMax = 1.0f; |
| 363 float y, dy; |
| 364 while (true) { |
| 365 y = yMin + (yMax - yMin) / 2.0f; |
| 366 coef = 3.0f * y * (1.0f - y); |
| 367 dy = coef * ((1.0f - y) * START_TENSION + y) + y * y * y; |
| 368 if (Math.abs(dy - alpha) < 1E-5) break; |
| 369 if (dy > alpha) { |
| 370 yMax = y; |
| 371 } else { |
| 372 yMin = y; |
| 373 } |
| 374 } |
| 375 SPLINE_TIME[i] = coef * ((1.0f - y) * P1 + y * P2) + y * y * y; |
| 376 } |
| 377 SPLINE_POSITION[NB_SAMPLES] = SPLINE_TIME[NB_SAMPLES] = 1.0f; |
| 378 } |
| 379 |
| 380 SplineStackScroller(Context context) { |
| 381 mFinished = true; |
| 382 final float ppi = context.getResources().getDisplayMetrics().density
* 160.0f; |
| 383 mPhysicalCoeff = SensorManager.GRAVITY_EARTH // g (m/s^2) |
| 384 * 39.37f // inch/meter |
| 385 * ppi * 0.84f; // look and feel tuning |
| 386 } |
| 387 |
| 388 void updateScroll(float q) { |
| 389 mCurrentPosition = mStart + Math.round(q * (mFinal - mStart)); |
| 390 } |
| 391 |
| 392 /* |
| 393 * Get a signed deceleration that will reduce the velocity. |
| 394 */ |
| 395 private static float getDeceleration(int velocity) { |
| 396 return velocity > 0 ? -GRAVITY : GRAVITY; |
| 397 } |
| 398 |
| 399 /* |
| 400 * Modifies mDuration to the duration it takes to get from start to newF
inal using the |
| 401 * spline interpolation. The previous duration was needed to get to oldF
inal. |
| 402 */ |
| 403 private void adjustDuration(int start, int oldFinal, int newFinal) { |
| 404 final int oldDistance = oldFinal - start; |
| 405 final int newDistance = newFinal - start; |
| 406 final float x = Math.abs((float) newDistance / oldDistance); |
| 407 final int index = (int) (NB_SAMPLES * x); |
| 408 if (index < NB_SAMPLES) { |
| 409 final float xInf = (float) index / NB_SAMPLES; |
| 410 final float xSup = (float) (index + 1) / NB_SAMPLES; |
| 411 final float tInf = SPLINE_TIME[index]; |
| 412 final float tSup = SPLINE_TIME[index + 1]; |
| 413 final float timeCoef = tInf + (x - xInf) / (xSup - xInf) * (tSup
- tInf); |
| 414 mDuration *= timeCoef; |
| 415 } |
| 416 } |
| 417 |
| 418 void startScroll(int start, int distance, long startTime, int duration)
{ |
| 419 mFinished = false; |
| 420 |
| 421 mStart = start; |
| 422 mFinal = start + distance; |
| 423 |
| 424 mStartTime = startTime; |
| 425 mDuration = duration; |
| 426 |
| 427 // Unused |
| 428 mDeceleration = 0.0f; |
| 429 mVelocity = 0; |
| 430 } |
| 431 |
| 432 void finish() { |
| 433 mCurrentPosition = mFinal; |
| 434 // Not reset since WebView relies on this value for fast fling. |
| 435 // TODO: restore when WebView uses the fast fling implemented in thi
s class. |
| 436 // mCurrVelocity = 0.0f; |
| 437 mFinished = true; |
| 438 } |
| 439 |
| 440 void setFinalPosition(int position) { |
| 441 mFinal = position; |
| 442 mFinished = false; |
| 443 } |
| 444 |
| 445 boolean springback(int start, int min, int max, long time) { |
| 446 mFinished = true; |
| 447 |
| 448 mStart = mFinal = start; |
| 449 mVelocity = 0; |
| 450 |
| 451 mStartTime = time; |
| 452 mDuration = 0; |
| 453 |
| 454 if (start < min) { |
| 455 startSpringback(start, min, 0); |
| 456 } else if (start > max) { |
| 457 startSpringback(start, max, 0); |
| 458 } |
| 459 |
| 460 return !mFinished; |
| 461 } |
| 462 |
| 463 private void startSpringback(int start, int end, int velocity) { |
| 464 // mStartTime has been set |
| 465 mFinished = false; |
| 466 mState = CUBIC; |
| 467 mStart = start; |
| 468 mFinal = end; |
| 469 final int delta = start - end; |
| 470 mDeceleration = getDeceleration(delta); |
| 471 // TODO take velocity into account |
| 472 mVelocity = -delta; // only sign is used |
| 473 mOver = Math.abs(delta); |
| 474 mDuration = (int) (1000.0 * Math.sqrt(-2.0 * delta / mDeceleration))
; |
| 475 } |
| 476 |
| 477 void fling(int start, int velocity, int min, int max, int over, long tim
e) { |
| 478 mOver = over; |
| 479 mFinished = false; |
| 480 mCurrVelocity = mVelocity = velocity; |
| 481 mDuration = mSplineDuration = 0; |
| 482 mStartTime = time; |
| 483 mCurrentPosition = mStart = start; |
| 484 |
| 485 if (start > max || start < min) { |
| 486 startAfterEdge(start, min, max, velocity, time); |
| 487 return; |
| 488 } |
| 489 |
| 490 mState = SPLINE; |
| 491 double totalDistance = 0.0; |
| 492 |
| 493 if (velocity != 0) { |
| 494 mDuration = mSplineDuration = getSplineFlingDuration(velocity); |
| 495 totalDistance = getSplineFlingDistance(velocity); |
| 496 } |
| 497 |
| 498 mSplineDistance = (int) (totalDistance * Math.signum(velocity)); |
| 499 mFinal = start + mSplineDistance; |
| 500 |
| 501 // Clamp to a valid final position |
| 502 if (mFinal < min) { |
| 503 adjustDuration(mStart, mFinal, min); |
| 504 mFinal = min; |
| 505 } |
| 506 |
| 507 if (mFinal > max) { |
| 508 adjustDuration(mStart, mFinal, max); |
| 509 mFinal = max; |
| 510 } |
| 511 } |
| 512 |
| 513 private double getSplineDeceleration(int velocity) { |
| 514 return Math.log(INFLEXION * Math.abs(velocity) / (mFlingFriction * m
PhysicalCoeff)); |
| 515 } |
| 516 |
| 517 private double getSplineFlingDistance(int velocity) { |
| 518 final double l = getSplineDeceleration(velocity); |
| 519 final double decelMinusOne = DECELERATION_RATE - 1.0; |
| 520 return mFlingFriction * mPhysicalCoeff |
| 521 * Math.exp(DECELERATION_RATE / decelMinusOne * l); |
| 522 } |
| 523 |
| 524 /* Returns the duration, expressed in milliseconds */ |
| 525 private int getSplineFlingDuration(int velocity) { |
| 526 final double l = getSplineDeceleration(velocity); |
| 527 final double decelMinusOne = DECELERATION_RATE - 1.0; |
| 528 return (int) (1000.0 * Math.exp(l / decelMinusOne)); |
| 529 } |
| 530 |
| 531 private void fitOnBounceCurve(int start, int end, int velocity) { |
| 532 // Simulate a bounce that started from edge |
| 533 final float durationToApex = -velocity / mDeceleration; |
| 534 final float distanceToApex = velocity * velocity / 2.0f / Math.abs(m
Deceleration); |
| 535 final float distanceToEdge = Math.abs(end - start); |
| 536 final float totalDuration = (float) Math.sqrt( |
| 537 2.0 * (distanceToApex + distanceToEdge) / Math.abs(mDecelera
tion)); |
| 538 mStartTime -= (int) (1000.0f * (totalDuration - durationToApex)); |
| 539 mStart = end; |
| 540 mVelocity = (int) (-mDeceleration * totalDuration); |
| 541 } |
| 542 |
| 543 private void startBounceAfterEdge(int start, int end, int velocity) { |
| 544 mDeceleration = getDeceleration(velocity == 0 ? start - end : veloci
ty); |
| 545 fitOnBounceCurve(start, end, velocity); |
| 546 onEdgeReached(); |
| 547 } |
| 548 |
| 549 private void startAfterEdge(int start, int min, int max, int velocity, l
ong time) { |
| 550 if (start > min && start < max) { |
| 551 Log.e("StackScroller", "startAfterEdge called from a valid posit
ion"); |
| 552 mFinished = true; |
| 553 return; |
| 554 } |
| 555 final boolean positive = start > max; |
| 556 final int edge = positive ? max : min; |
| 557 final int overDistance = start - edge; |
| 558 boolean keepIncreasing = overDistance * velocity >= 0; |
| 559 if (keepIncreasing) { |
| 560 // Will result in a bounce or a to_boundary depending on velocit
y. |
| 561 startBounceAfterEdge(start, edge, velocity); |
| 562 } else { |
| 563 final double totalDistance = getSplineFlingDistance(velocity); |
| 564 if (totalDistance > Math.abs(overDistance)) { |
| 565 fling(start, velocity, positive ? min : start, positive ? st
art : max, mOver, |
| 566 time); |
| 567 } else { |
| 568 startSpringback(start, edge, velocity); |
| 569 } |
| 570 } |
| 571 } |
| 572 |
| 573 private void onEdgeReached() { |
| 574 // mStart, mVelocity and mStartTime were adjusted to their values wh
en edge was reached. |
| 575 float distance = mVelocity * mVelocity / (2.0f * Math.abs(mDecelerat
ion)); |
| 576 final float sign = Math.signum(mVelocity); |
| 577 |
| 578 if (distance > mOver) { |
| 579 // Default deceleration is not sufficient to slow us down before
boundary |
| 580 mDeceleration = -sign * mVelocity * mVelocity / (2.0f * mOver); |
| 581 distance = mOver; |
| 582 } |
| 583 |
| 584 mOver = (int) distance; |
| 585 mState = BALLISTIC; |
| 586 mFinal = mStart + (int) (mVelocity > 0 ? distance : -distance); |
| 587 mDuration = -(int) (1000.0f * mVelocity / mDeceleration); |
| 588 } |
| 589 |
| 590 boolean continueWhenFinished(long time) { |
| 591 switch (mState) { |
| 592 case SPLINE: |
| 593 // Duration from start to null velocity |
| 594 if (mDuration < mSplineDuration) { |
| 595 // If the animation was clamped, we reached the edge |
| 596 mStart = mFinal; |
| 597 // TODO Better compute speed when edge was reached |
| 598 mVelocity = (int) mCurrVelocity; |
| 599 mDeceleration = getDeceleration(mVelocity); |
| 600 mStartTime += mDuration; |
| 601 onEdgeReached(); |
| 602 } else { |
| 603 // Normal stop, no need to continue |
| 604 return false; |
| 605 } |
| 606 break; |
| 607 case BALLISTIC: |
| 608 mStartTime += mDuration; |
| 609 startSpringback(mFinal, mStart, 0); |
| 610 break; |
| 611 case CUBIC: |
| 612 return false; |
| 613 } |
| 614 |
| 615 update(time); |
| 616 return true; |
| 617 } |
| 618 |
| 619 /* |
| 620 * Update the current position and velocity for current time. Returns |
| 621 * true if update has been done and false if animation duration has been |
| 622 * reached. |
| 623 */ |
| 624 boolean update(long time) { |
| 625 final long currentTime = time - mStartTime; |
| 626 |
| 627 if (currentTime > mDuration) { |
| 628 return false; |
| 629 } |
| 630 |
| 631 double distance = 0.0; |
| 632 switch (mState) { |
| 633 case SPLINE: { |
| 634 final float t = (float) currentTime / mSplineDuration; |
| 635 final int index = (int) (NB_SAMPLES * t); |
| 636 float distanceCoef = 1.f; |
| 637 float velocityCoef = 0.f; |
| 638 if (index < NB_SAMPLES) { |
| 639 final float tInf = (float) index / NB_SAMPLES; |
| 640 final float tSup = (float) (index + 1) / NB_SAMPLES; |
| 641 final float dInf = SPLINE_POSITION[index]; |
| 642 final float dSup = SPLINE_POSITION[index + 1]; |
| 643 velocityCoef = (dSup - dInf) / (tSup - tInf); |
| 644 distanceCoef = dInf + (t - tInf) * velocityCoef; |
| 645 } |
| 646 |
| 647 distance = distanceCoef * mSplineDistance; |
| 648 mCurrVelocity = velocityCoef * mSplineDistance / mSplineDura
tion * 1000.0f; |
| 649 break; |
| 650 } |
| 651 |
| 652 case BALLISTIC: { |
| 653 final float t = currentTime / 1000.0f; |
| 654 mCurrVelocity = mVelocity + mDeceleration * t; |
| 655 distance = mVelocity * t + mDeceleration * t * t / 2.0f; |
| 656 break; |
| 657 } |
| 658 |
| 659 case CUBIC: { |
| 660 final float t = (float) (currentTime) / mDuration; |
| 661 final float t2 = t * t; |
| 662 final float sign = Math.signum(mVelocity); |
| 663 distance = sign * mOver * (3.0f * t2 - 2.0f * t * t2); |
| 664 mCurrVelocity = sign * mOver * 6.0f * (-t + t2); |
| 665 break; |
| 666 } |
| 667 } |
| 668 |
| 669 mCurrentPosition = mStart + (int) Math.round(distance); |
| 670 |
| 671 return true; |
| 672 } |
| 673 } |
| 674 } |
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