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Merge "Use spring animation for stretch overscroll" into sc-dev

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This commit is contained in:
George Mount
2021-03-11 00:43:04 +00:00
committed by Android (Google) Code Review
parent 1bee4b7b6f 61324dbfcc
commit 73046dc2f6
1 changed files with 99 additions and 34 deletions
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133
core/java/android/widget/EdgeEffect.java
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@@ -102,6 +102,28 @@ public class EdgeEffect {
*/
public static final int TYPE_STRETCH = 1;
/**
* The velocity threshold before the spring animation is considered settled.
* The idea here is that velocity should be less than 1 pixel per frame (~16ms).
*/
private static final double VELOCITY_THRESHOLD = 1.0 / 0.016;
/**
* The value threshold before the spring animation is considered close enough to
* the destination to be settled. This should be around 1 pixel.
*/
private static final double VALUE_THRESHOLD = 1;
/**
* The natural frequency of the stretch spring.
*/
private static final double NATURAL_FREQUENCY = 14.4222;
/**
* The damping ratio of the stretch spring.
*/
private static final double DAMPING_RATIO = 0.875;
/** @hide */
@IntDef({TYPE_GLOW, TYPE_STRETCH})
@Retention(RetentionPolicy.SOURCE)
@@ -145,13 +167,12 @@ public class EdgeEffect {
@UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
private float mGlowScaleY;
private float mDistance;
private float mVelocity; // only for stretch animations
private float mGlowAlphaStart;
private float mGlowAlphaFinish;
private float mGlowScaleYStart;
private float mGlowScaleYFinish;
private float mDistanceStart;
private float mDistanceFinish;
private long mStartTime;
private float mDuration;
@@ -273,6 +294,8 @@ public class EdgeEffect {
*/
public void finish() {
mState = STATE_IDLE;
mDistance = 0;
mVelocity = 0;
}
/**
@@ -327,7 +350,8 @@ public class EdgeEffect {
mDuration = PULL_TIME;
mPullDistance += deltaDistance;
mDistanceStart = mDistanceFinish = mDistance = Math.max(0f, mPullDistance);
mDistance = Math.max(0f, mPullDistance);
mVelocity = 0;
final float absdd = Math.abs(deltaDistance);
mGlowAlpha = mGlowAlphaStart = Math.min(MAX_ALPHA,
@@ -421,11 +445,10 @@ public class EdgeEffect {
mState = STATE_RECEDE;
mGlowAlphaStart = mGlowAlpha;
mGlowScaleYStart = mGlowScaleY;
mDistanceStart = mDistance;
mGlowAlphaFinish = 0.f;
mGlowScaleYFinish = 0.f;
mDistanceFinish = 0.f;
mVelocity = 0.f;
mStartTime = AnimationUtils.currentAnimationTimeMillis();
mDuration = RECEDE_TIME;
@@ -442,30 +465,36 @@ public class EdgeEffect {
* @param velocity Velocity at impact in pixels per second.
*/
public void onAbsorb(int velocity) {
mState = STATE_ABSORB;
velocity = Math.min(Math.max(MIN_VELOCITY, Math.abs(velocity)), MAX_VELOCITY);
if (mEdgeEffectType == TYPE_STRETCH) {
mState = STATE_RECEDE;
mVelocity = velocity / mHeight;
mDistance = 0;
mStartTime = AnimationUtils.currentAnimationTimeMillis();
} else {
mState = STATE_ABSORB;
mVelocity = 0;
velocity = Math.min(Math.max(MIN_VELOCITY, Math.abs(velocity)), MAX_VELOCITY);
mStartTime = AnimationUtils.currentAnimationTimeMillis();
mDuration = 0.15f + (velocity * 0.02f);
mStartTime = AnimationUtils.currentAnimationTimeMillis();
mDuration = 0.15f + (velocity * 0.02f);
// The glow depends more on the velocity, and therefore starts out
// nearly invisible.
mGlowAlphaStart = GLOW_ALPHA_START;
mGlowScaleYStart = Math.max(mGlowScaleY, 0.f);
mDistanceStart = mDistance;
// The glow depends more on the velocity, and therefore starts out
// nearly invisible.
mGlowAlphaStart = GLOW_ALPHA_START;
mGlowScaleYStart = Math.max(mGlowScaleY, 0.f);
// Growth for the size of the glow should be quadratic to properly
// respond
// to a user's scrolling speed. The faster the scrolling speed, the more
// intense the effect should be for both the size and the saturation.
mGlowScaleYFinish = Math.min(0.025f + (velocity * (velocity / 100) * 0.00015f) / 2, 1.f);
// Alpha should change for the glow as well as size.
mGlowAlphaFinish = Math.max(
mGlowAlphaStart, Math.min(velocity * VELOCITY_GLOW_FACTOR * .00001f, MAX_ALPHA));
mTargetDisplacement = 0.5f;
// Use glow values to estimate the absorption for stretch distance.
mDistanceFinish = calculateDistanceFromGlowValues(mGlowScaleYFinish, mGlowAlphaFinish);
// Growth for the size of the glow should be quadratic to properly
// respond
// to a user's scrolling speed. The faster the scrolling speed, the more
// intense the effect should be for both the size and the saturation.
mGlowScaleYFinish = Math.min(0.025f + (velocity * (velocity / 100) * 0.00015f) / 2,
1.f);
// Alpha should change for the glow as well as size.
mGlowAlphaFinish = Math.max(
mGlowAlphaStart,
Math.min(velocity * VELOCITY_GLOW_FACTOR * .00001f, MAX_ALPHA));
mTargetDisplacement = 0.5f;
}
}
/**
@@ -573,8 +602,8 @@ public class EdgeEffect {
canvas.drawCircle(centerX, centerY, mRadius, mPaint);
canvas.restoreToCount(count);
} else if (canvas instanceof RecordingCanvas) {
if (mState != STATE_PULL) {
update();
if (mState == STATE_RECEDE) {
updateSpring();
}
RecordingCanvas recordingCanvas = (RecordingCanvas) canvas;
if (mTmpMatrix == null) {
@@ -631,7 +660,7 @@ public class EdgeEffect {
}
boolean oneLastFrame = false;
if (mState == STATE_RECEDE && mDistance == 0) {
if (mState == STATE_RECEDE && mDistance == 0 && mVelocity == 0) {
mState = STATE_IDLE;
oneLastFrame = true;
}
@@ -668,7 +697,7 @@ public class EdgeEffect {
mGlowAlpha = mGlowAlphaStart + (mGlowAlphaFinish - mGlowAlphaStart) * interp;
mGlowScaleY = mGlowScaleYStart + (mGlowScaleYFinish - mGlowScaleYStart) * interp;
mDistance = mDistanceStart + (mDistanceFinish - mDistanceStart) * interp;
mDistance = calculateDistanceFromGlowValues(mGlowScaleY, mGlowAlpha);
mDisplacement = (mDisplacement + mTargetDisplacement) / 2;
if (t >= 1.f - EPSILON) {
@@ -680,12 +709,10 @@ public class EdgeEffect {
mGlowAlphaStart = mGlowAlpha;
mGlowScaleYStart = mGlowScaleY;
mDistanceStart = mDistance;
// After absorb, the glow should fade to nothing.
mGlowAlphaFinish = 0.f;
mGlowScaleYFinish = 0.f;
mDistanceFinish = 0.f;
break;
case STATE_PULL:
mState = STATE_PULL_DECAY;
@@ -694,12 +721,10 @@ public class EdgeEffect {
mGlowAlphaStart = mGlowAlpha;
mGlowScaleYStart = mGlowScaleY;
mDistanceStart = mDistance;
// After pull, the glow should fade to nothing.
mGlowAlphaFinish = 0.f;
mGlowScaleYFinish = 0.f;
mDistanceFinish = 0.f;
break;
case STATE_PULL_DECAY:
mState = STATE_RECEDE;
@@ -711,6 +736,35 @@ public class EdgeEffect {
}
}
private void updateSpring() {
final long time = AnimationUtils.currentAnimationTimeMillis();
final float deltaT = (time - mStartTime) / 1000f; // Convert from millis to seconds
if (deltaT < 0.001f) {
return; // Must have at least 1 ms difference
}
final double mDampedFreq = NATURAL_FREQUENCY * Math.sqrt(1 - DAMPING_RATIO * DAMPING_RATIO);
// We're always underdamped, so we can use only those equations:
double cosCoeff = mDistance;
double sinCoeff = (1 / mDampedFreq) * (DAMPING_RATIO * NATURAL_FREQUENCY
* mDistance + mVelocity);
double distance = Math.pow(Math.E, -DAMPING_RATIO * NATURAL_FREQUENCY * deltaT)
* (cosCoeff * Math.cos(mDampedFreq * deltaT)
+ sinCoeff * Math.sin(mDampedFreq * deltaT));
double velocity = distance * (-NATURAL_FREQUENCY) * DAMPING_RATIO
+ Math.pow(Math.E, -DAMPING_RATIO * NATURAL_FREQUENCY * deltaT)
* (-mDampedFreq * cosCoeff * Math.sin(mDampedFreq * deltaT)
+ mDampedFreq * sinCoeff * Math.cos(mDampedFreq * deltaT));
mDistance = (float) distance;
mVelocity = (float) velocity;
mStartTime = time;
if (isAtEquilibrium()) {
mState = STATE_IDLE;
mDistance = 0;
mVelocity = 0;
}
}
/**
* @return The estimated pull distance as calculated from mGlowScaleY.
*/
@@ -726,4 +780,15 @@ public class EdgeEffect {
}
return alpha / PULL_DISTANCE_ALPHA_GLOW_FACTOR;
}
/**
* @return true if the spring used for calculating the stretch animation is
* considered at rest or false if it is still animating.
*/
private boolean isAtEquilibrium() {
double velocity = mVelocity * mHeight; // in pixels/second
double displacement = mDistance * mHeight; // in pixels
return Math.abs(velocity) < VELOCITY_THRESHOLD
&& Math.abs(displacement) < VALUE_THRESHOLD;
}
}