Merge "Adding support for building a "spring like animation" with precomputed values" into ub-launcher3-qt-qpr1-dev

quickstep/recents_ui_overrides/src/com/android/launcher3/LauncherAppTransitionManagerImpl.java

@@ -18,16 +18,11 @@ package com.android.launcher3;
 
 import static com.android.launcher3.LauncherAnimUtils.VIEW_TRANSLATE_X;
 import static com.android.launcher3.LauncherState.NORMAL;
-import static com.android.launcher3.allapps.AllAppsTransitionController.ALL_APPS_PROGRESS;
 import static com.android.launcher3.anim.Interpolators.AGGRESSIVE_EASE;
 import static com.android.launcher3.anim.Interpolators.LINEAR;
 import static com.android.quickstep.TaskViewUtils.findTaskViewToLaunch;
 import static com.android.quickstep.TaskViewUtils.getRecentsWindowAnimator;
 
-import static androidx.dynamicanimation.animation.DynamicAnimation.MIN_VISIBLE_CHANGE_PIXELS;
-import static androidx.dynamicanimation.animation.SpringForce.DAMPING_RATIO_MEDIUM_BOUNCY;
-import static androidx.dynamicanimation.animation.SpringForce.STIFFNESS_MEDIUM;
-
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.animation.AnimatorSet;
@@ -35,18 +30,17 @@ import android.animation.ObjectAnimator;
 import android.content.Context;
 import android.view.View;
 
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
-
-import com.android.launcher3.allapps.AllAppsTransitionController;
 import com.android.launcher3.anim.AnimatorPlaybackController;
 import com.android.launcher3.anim.Interpolators;
-import com.android.launcher3.anim.SpringObjectAnimator;
+import com.android.launcher3.anim.SpringAnimationBuilder;
 import com.android.quickstep.util.ClipAnimationHelper;
 import com.android.quickstep.views.RecentsView;
 import com.android.quickstep.views.TaskView;
 import com.android.systemui.shared.system.RemoteAnimationTargetCompat;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
 /**
  * A {@link QuickstepAppTransitionManagerImpl} that also implements recents transitions from
  * {@link RecentsView}.
@@ -156,8 +150,11 @@ public final class LauncherAppTransitionManagerImpl extends QuickstepAppTransiti
                 return ObjectAnimator.ofFloat(mLauncher.getOverviewPanel(),
                         RecentsView.CONTENT_ALPHA, values);
             case INDEX_RECENTS_TRANSLATE_X_ANIM:
-                return new SpringObjectAnimator<>(mLauncher.getOverviewPanel(),
-                        VIEW_TRANSLATE_X, MIN_VISIBLE_CHANGE_PIXELS, 0.8f, 250, values);
+                return new SpringAnimationBuilder<>(mLauncher.getOverviewPanel(), VIEW_TRANSLATE_X)
+                        .setDampingRatio(0.8f)
+                        .setStiffness(250)
+                        .setValues(values)
+                        .build(mLauncher);
             default:
                 return super.createStateElementAnimation(index, values);
         }

src/com/android/launcher3/anim/SpringAnimationBuilder.java

@@ -0,0 +1,229 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.launcher3.anim;
+
+import android.animation.Animator;
+import android.animation.ObjectAnimator;
+import android.content.Context;
+import android.util.FloatProperty;
+
+import com.android.launcher3.util.DefaultDisplay;
+
+import androidx.annotation.FloatRange;
+import androidx.dynamicanimation.animation.SpringForce;
+
+/**
+ * Utility class to build an object animator which follows the same path as a spring animation for
+ * an underdamped spring.
+ */
+public class SpringAnimationBuilder<T> extends FloatProperty<T> {
+
+    private final T mTarget;
+    private final FloatProperty<T> mProperty;
+
+    private float mStartValue;
+    private float mEndValue;
+    private float mVelocity = 0;
+
+    private float mStiffness = SpringForce.STIFFNESS_MEDIUM;
+    private float mDampingRatio = SpringForce.DAMPING_RATIO_MEDIUM_BOUNCY;
+    private float mMinVisibleChange = 1;
+
+    // Multiplier to the min visible change value for value threshold
+    private static final float THRESHOLD_MULTIPLIER = 0.65f;
+
+    /**
+     * The spring equation is given as
+     *   x = e^(-beta*t/2) * (a cos(gamma * t) + b sin(gamma * t)
+     *   v = e^(-beta*t/2) * ((2 * a * gamma + beta * b) * sin(gamma * t)
+     *                  + (a * beta - 2 * b * gamma) * cos(gamma * t)) / 2
+     *
+     *   a = x(0)
+     *   b = beta * x(0) / (2 * gamma) + v(0) / gamma
+     */
+    private double beta;
+    private double gamma;
+
+    private double a, b;
+    private double va, vb;
+
+    // Threshold for velocity and value to determine when it's reasonable to assume that the spring
+    // is approximately at rest.
+    private double mValueThreshold;
+    private double mVelocityThreshold;
+
+    private float mCurrentTime = 0;
+
+    public SpringAnimationBuilder(T target, FloatProperty<T> property) {
+        super("dynamic-spring-property");
+        mTarget = target;
+        mProperty = property;
+
+        mStartValue = mProperty.get(target);
+    }
+
+    public SpringAnimationBuilder<T> setEndValue(float value) {
+        mEndValue = value;
+        return this;
+    }
+
+    public SpringAnimationBuilder<T> setStartValue(float value) {
+        mStartValue = value;
+        return this;
+    }
+
+    public SpringAnimationBuilder<T> setValues(float... values) {
+        if (values.length > 1) {
+            mStartValue = values[0];
+            mEndValue = values[values.length - 1];
+        } else {
+            mEndValue = values[0];
+        }
+        return this;
+    }
+
+    public SpringAnimationBuilder<T> setStiffness(
+            @FloatRange(from = 0.0, fromInclusive = false) float stiffness) {
+        if (stiffness <= 0) {
+            throw new IllegalArgumentException("Spring stiffness constant must be positive.");
+        }
+        mStiffness = stiffness;
+        return this;
+    }
+
+    public SpringAnimationBuilder<T> setDampingRatio(
+            @FloatRange(from = 0.0, to = 1.0, fromInclusive = false, toInclusive = false)
+                    float dampingRatio) {
+        if (dampingRatio <= 0 || dampingRatio >= 1) {
+            throw new IllegalArgumentException("Damping ratio must be between 0 and 1");
+        }
+        mDampingRatio = dampingRatio;
+        return this;
+    }
+
+    public SpringAnimationBuilder<T> setMinimumVisibleChange(
+            @FloatRange(from = 0.0, fromInclusive = false) float minimumVisibleChange) {
+        if (minimumVisibleChange <= 0) {
+            throw new IllegalArgumentException("Minimum visible change must be positive.");
+        }
+        mMinVisibleChange = minimumVisibleChange;
+        return this;
+    }
+
+    public SpringAnimationBuilder<T> setStartVelocity(float startVelocity) {
+        mVelocity = startVelocity;
+        return this;
+    }
+
+    @Override
+    public void setValue(T object, float time) {
+        mCurrentTime = time;
+        mProperty.setValue(
+                object, (float) (exponentialComponent(time) * cosSinX(time)) + mEndValue);
+    }
+
+    @Override
+    public Float get(T t) {
+        return mCurrentTime;
+    }
+
+    public ObjectAnimator build(Context context) {
+        int singleFrameMs = DefaultDisplay.getSingleFrameMs(context);
+        double naturalFreq = Math.sqrt(mStiffness);
+        double dampedFreq = naturalFreq * Math.sqrt(1 - mDampingRatio * mDampingRatio);
+
+        // All the calculations assume the stable position to be 0, shift the values accordingly.
+        beta = 2 * mDampingRatio * naturalFreq;
+        gamma = dampedFreq;
+        a =  mStartValue - mEndValue;
+        b = beta * a / (2 * gamma) + mVelocity / gamma;
+
+        va = a * beta / 2 - b * gamma;
+        vb = a * gamma + beta * b / 2;
+
+        mValueThreshold = mMinVisibleChange * THRESHOLD_MULTIPLIER;
+
+        // This multiplier is used to calculate the velocity threshold given a certain value
+        // threshold. The idea is that if it takes >= 1 frame to move the value threshold amount,
+        // then the velocity is a reasonable threshold.
+        mVelocityThreshold = mValueThreshold * 1000.0 / singleFrameMs;
+
+        // Find the duration (in seconds) for the spring to reach equilibrium.
+        // equilibrium is reached when x = 0
+        double duration = Math.atan2(-a, b) / gamma;
+
+        // Keep moving ahead until the velocity reaches equilibrium.
+        double piByG = Math.PI / gamma;
+        while (duration < 0 || Math.abs(exponentialComponent(duration) * cosSinV(duration))
+                >= mVelocityThreshold) {
+            duration += piByG;
+        }
+
+        // Find the shortest time
+        double edgeTime = Math.max(0, duration - piByG / 2);
+        double minDiff = singleFrameMs / 2000.0;    // Half frame time in seconds
+
+        do {
+            if ((duration - edgeTime) < minDiff) {
+                break;
+            }
+            double mid = (edgeTime + duration) / 2;
+            if (isAtEquilibrium(mid)) {
+                duration = mid;
+            } else {
+                edgeTime = mid;
+            }
+        } while (true);
+
+
+        long durationMs = (long) (1000.0 * duration);
+        ObjectAnimator animator = ObjectAnimator.ofFloat(mTarget, this, 0, (float) duration);
+        animator.setDuration(durationMs).setInterpolator(Interpolators.LINEAR);
+        animator.addListener(new AnimationSuccessListener() {
+            @Override
+            public void onAnimationSuccess(Animator animator) {
+                mProperty.setValue(mTarget, mEndValue);
+            }
+        });
+        return animator;
+    }
+
+    private boolean isAtEquilibrium(double t) {
+        double ec = exponentialComponent(t);
+
+        if (Math.abs(ec * cosSinX(t)) >= mValueThreshold) {
+            return false;
+        }
+        return Math.abs(ec * cosSinV(t)) < mVelocityThreshold;
+    }
+
+    private double exponentialComponent(double t) {
+        return Math.pow(Math.E, - beta * t / 2);
+    }
+
+    private double cosSinX(double t) {
+        return cosSin(t, a, b);
+    }
+
+    private double cosSinV(double t) {
+        return cosSin(t, va, vb);
+    }
+
+    private double cosSin(double t, double cosFactor, double sinFactor) {
+        double angle = t * gamma;
+        return cosFactor * Math.cos(angle) + sinFactor * Math.sin(angle);
+    }
+}