@@ -77,7 +77,9 @@ public static void setSlowMotion(boolean aSlowMotion) {
7777 private double initVelocity , friction ;
7878 private int lastReturnedValue ;
7979 private int [] previousLastReturnedValue = new int [3 ];
80+ private long [] previousLastReturnedValueTime = new long [3 ];
8081 private long currentMotionTime = -1 ;
82+ private long previousCurrentMotionTime = -1 ;
8183 private float p0 , p1 , p2 , p3 ;
8284
8385 /**
@@ -95,7 +97,8 @@ protected Motion(int sourceValue, int destinationValue, int duration) {
9597 if (slowMotion ) {
9698 this .duration *= 50 ;
9799 }
98- previousLastReturnedValue [0 ] = -1 ;
100+ previousLastReturnedValue [0 ] = -1 ;
101+ previousLastReturnedValueTime [0 ] = -1 ;
99102 }
100103
101104 /**
@@ -105,6 +108,7 @@ public void finish() {
105108 if (!isFinished ()) {
106109 startTime = System .currentTimeMillis () - duration ;
107110 currentMotionTime = -1 ;
111+ previousCurrentMotionTime = -1 ;
108112 }
109113 }
110114
@@ -120,15 +124,17 @@ protected Motion(int sourceValue, float initVelocity, float friction) {
120124 this .initVelocity = initVelocity ;
121125 this .friction = friction ;
122126 duration = (int ) ((Math .abs (initVelocity )) / friction );
123- previousLastReturnedValue [0 ] = -1 ;
127+ previousLastReturnedValue [0 ] = -1 ;
128+ previousLastReturnedValueTime [0 ] = -1 ;
124129 }
125130
126131 protected Motion (int sourceValue , double initVelocity , double friction ) {
127132 this .sourceValue = sourceValue ;
128133 this .initVelocity = initVelocity ;
129134 this .friction = friction ;
130135 duration = (int ) ((Math .abs (initVelocity )) / friction );
131- previousLastReturnedValue [0 ] = -1 ;
136+ previousLastReturnedValue [0 ] = -1 ;
137+ previousLastReturnedValueTime [0 ] = -1 ;
132138 }
133139
134140
@@ -265,6 +271,24 @@ public static Motion createDecelerationMotion(int sourceValue, int destinationVa
265271 deceleration .motionType = DECELERATION ;
266272 return deceleration ;
267273 }
274+
275+ /**
276+ * Creates a deceleration motion starting from the current position of another motion.
277+ *
278+ * @param motion the number from which we are starting (usually indicating animation start position)
279+ * @param maxDestinationValue The farthest position to allow motion to go.
280+ * @param maxDuration The longest that the duration is allowed to proceed for.
281+ * @return new motion object
282+ */
283+ public static Motion createDecelerationMotionFrom (Motion motion , int maxDestinationValue , int maxDuration ) {
284+ return createDecelerationMotion (
285+ motion .lastReturnedValue ,
286+ motion .destinationValue < motion .sourceValue
287+ ? Math .min (motion .destinationValue , maxDestinationValue )
288+ : Math .max (motion .destinationValue , maxDestinationValue ),
289+ (int )Math .min (maxDuration , motion .duration - (System .currentTimeMillis () - motion .startTime ))
290+ );
291+ }
268292
269293 /**
270294 * Creates a friction motion starting from source with initial speed and the friction
@@ -319,6 +343,7 @@ public long getCurrentMotionTime() {
319343 * @param currentMotionTime the time in milliseconds for the motion.
320344 */
321345 public void setCurrentMotionTime (long currentMotionTime ) {
346+ this .previousCurrentMotionTime = this .currentMotionTime ;
322347 this .currentMotionTime = currentMotionTime ;
323348
324349 // workaround allowing the motion to be restarted when manually setting the current time
@@ -327,6 +352,10 @@ public void setCurrentMotionTime(long currentMotionTime) {
327352 }
328353 }
329354
355+ public boolean isDecayMotion () {
356+ return motionType == EXPONENTIAL_DECAY ;
357+ }
358+
330359 /**
331360 * Sets the start time of the motion
332361 *
@@ -414,69 +443,6 @@ private int getCubicValue() {
414443 return current ;
415444 }
416445
417- // private int[] values = new int[1000];
418- // private int[] times = new int[1000];
419- // private int vOff;
420- //
421- // /**
422- // * Returns the value for the motion for the current clock time.
423- // * The value is dependent on the Motion type.
424- // *
425- // * @return a value that is relative to the source value
426- // */
427- // public int getValue() {
428- // int v = getValueImpl();
429- // if(isFinished() && vOff > 0) {
430- // System.out.println("initVelocity:\t"+initVelocity + "\tfriction:\t" + friction + "\tdestinationValue:\t" + destinationValue + "\tsourceValue:\t" + sourceValue);
431- // System.out.println("Value\tTime");
432- // for(int iter = 0 ; iter < vOff ; iter++) {
433- // System.out.println("" + values[iter] + "\t" + times[iter]);
434- // }
435- // vOff = 0;
436- // } else {
437- // values[vOff] = v;
438- // int time = (int) getCurrentMotionTime();
439- // times[vOff] = time;
440- //
441- // vOff++;
442- // }
443- //
444- // return v;
445- // }
446- //
447- // /**
448- // * Returns the value for the motion for the current clock time.
449- // * The value is dependent on the Motion type.
450- // *
451- // * @return a value that is relative to the source value
452- // */
453- // private int getValueImpl() {
454- // if(currentMotionTime > -1 && startTime > getCurrentMotionTime()) {
455- // return sourceValue;
456- // }
457- // switch(motionType) {
458- // case SPLINE:
459- // lastReturnedValue = getSplineValue();
460- // break;
461- // case CUBIC:
462- // lastReturnedValue = getCubicValue();
463- // break;
464- // case FRICTION:
465- // lastReturnedValue = getFriction();
466- // break;
467- // case DECELERATION:
468- // lastReturnedValue = getRubber();
469- // break;
470- // case COLOR_LINEAR:
471- // lastReturnedValue = getColorLinear();
472- // break;
473- // default:
474- // lastReturnedValue = getLinear();
475- // break;
476- // }
477- // return lastReturnedValue;
478- // }
479-
480446 /**
481447 * Returns the value for the motion for the current clock time.
482448 * The value is dependent on the Motion type.
@@ -489,8 +455,14 @@ public int getValue() {
489455 }
490456
491457 previousLastReturnedValue [0 ] = previousLastReturnedValue [1 ];
458+ previousLastReturnedValueTime [0 ] = previousLastReturnedValueTime [1 ];
492459 previousLastReturnedValue [1 ] = previousLastReturnedValue [2 ];
460+ previousLastReturnedValueTime [1 ] = previousLastReturnedValueTime [2 ];
493461 previousLastReturnedValue [2 ] = lastReturnedValue ;
462+ previousLastReturnedValueTime [2 ] = previousCurrentMotionTime ;
463+ if (previousCurrentMotionTime < 0 ) {
464+ previousCurrentMotionTime = getCurrentMotionTime ();
465+ }
494466 switch (motionType ) {
495467 case SPLINE :
496468 lastReturnedValue = getSplineValue ();
@@ -516,6 +488,55 @@ public int getValue() {
516488 }
517489 return lastReturnedValue ;
518490 }
491+
492+ /**
493+ * Gets an approximation of the current velocity in pixels per millisecond.
494+ *
495+ * <p>NOTE: If {@link #countAvailableVelocitySamplingPoints()} <= 1, then this method will always output {@literal 0}.
496+ * Therefore the output of this method only has meaning if {@link #countAvailableVelocitySamplingPoints()} > {@literal 0}</p>
497+ *
498+ * @return Current velocity in pixels per millisecond.
499+ * @since 8.0
500+ */
501+ public double getVelocity () {
502+ final long localCurrentMotionTime = getCurrentMotionTime ();
503+ final int lastReturnedValueLocal = lastReturnedValue ;
504+ double velocity = 0 ;
505+ boolean firstIteration = true ;
506+ for (int i =2 ; i >= 0 ; i --) {
507+ final long t = previousLastReturnedValueTime [i ];
508+ if (t <= 0 || localCurrentMotionTime == t ) {
509+ break ;
510+ }
511+ final int valueAtT = previousLastReturnedValue [i ];
512+ final double spotVelocity = (lastReturnedValueLocal - valueAtT ) / (double )(localCurrentMotionTime - t );
513+ velocity = firstIteration ? spotVelocity : (velocity + spotVelocity )/2.0 ;
514+ firstIteration = false ;
515+ }
516+
517+ return velocity ;
518+ }
519+
520+ /**
521+ * Gets the number of sampling points that can be used by {@link #getVelocity()}. A minimum of 2 sampling
522+ * points are required for the result of {@link #getVelocity()} to have any meaning.
523+ *
524+ * @since 8.0
525+ * @return The number of sampling points that can be used by {@link #getVelocity()}.
526+ */
527+ public int countAvailableVelocitySamplingPoints () {
528+ int count = 1 ;
529+ final long localCurrentMotionTime = getCurrentMotionTime ();
530+ for (int i =2 ; i >= 0 ; i --) {
531+ final long t = previousLastReturnedValueTime [i ];
532+ if (t <= 0 || localCurrentMotionTime == t ) {
533+ break ;
534+ }
535+ count ++;
536+ }
537+
538+ return count ;
539+ }
519540
520541 private int getLinear () {
521542 //make sure we reach the destination value.
@@ -600,9 +621,6 @@ private int getFriction() {
600621 }
601622
602623 private int getExponentialDecay () {
603- //amplitude = initialVelocity * scaleFactor;
604- //targetPosition = position + amplitude;
605- //timestamp = Date.now();
606624 double elapsed = getCurrentMotionTime ();
607625 double timeConstant = friction ;
608626 double amplitude = targetPosition - sourceValue ;
@@ -612,9 +630,7 @@ private int getExponentialDecay() {
612630 } else {
613631 return Math .max (position , destinationValue );
614632 }
615-
616633 }
617-
618634 private int getRubber () {
619635 if (isFinished ()){
620636 return destinationValue ;
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