Add physics motion to items in all apps.

Motion applied to:
- Icons
- Prediction icons
- Prediction divider

Bug: 38349031
Change-Id: I376e6e39080c8c80463a0ce8b104b05e4d576f17

1 files changed, 247 insertions, 0 deletions

diff --git a/src/com/android/launcher3/anim/SpringAnimationHandler.java b/src/com/android/launcher3/anim/SpringAnimationHandler.java
new file mode 100644
index 000000000..5792127d0
--- /dev/null
+++ b/src/com/android/launcher3/anim/SpringAnimationHandler.java
@@ -0,0 +1,247 @@
+/*
+ * Copyright (C) 2017 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.support.animation.DynamicAnimation;
+import android.support.animation.SpringAnimation;
+import android.support.animation.SpringForce;
+import android.support.annotation.IntDef;
+import android.util.Log;
+import android.view.MotionEvent;
+import android.view.VelocityTracker;
+import android.view.View;
+
+import com.android.launcher3.Utilities;
+import com.android.launcher3.allapps.AlphabeticalAppsList;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.util.ArrayList;
+
+/**
+ * Handler class that manages springs for a set of views that should all move based on the same
+ * {@link MotionEvent}s.
+ *
+ * Supports using physics for X or Y translations.
+ */
+public class SpringAnimationHandler {
+
+    private static final String TAG = "SpringAnimationHandler";
+    private static final boolean DEBUG = false;
+
+    private static final float DEFAULT_MAX_VALUE = 100;
+    private static final float DEFAULT_MIN_VALUE = -DEFAULT_MAX_VALUE;
+
+    private static final float SPRING_DAMPING_RATIO = 0.55f;
+    private static final float MIN_SPRING_STIFFNESS = 580f;
+    private static final float MAX_SPRING_STIFFNESS = 900f;
+
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef({Y_DIRECTION, X_DIRECTION})
+    public @interface Direction {}
+    public static final int Y_DIRECTION = 0;
+    public static final int X_DIRECTION = 1;
+    private int mDirection;
+
+    private VelocityTracker mVelocityTracker;
+    private float mCurrentVelocity = 0;
+    private boolean mShouldComputeVelocity = false;
+
+    private ArrayList<SpringAnimation> mAnimations = new ArrayList<>();
+
+    public SpringAnimationHandler(@Direction int direction) {
+        mDirection = direction;
+        mVelocityTracker = VelocityTracker.obtain();
+    }
+
+    public SpringAnimation add(View view, int position, AlphabeticalAppsList apps, int appsPerRow,
+            SpringAnimation recycle) {
+        int numPredictedApps = Math.min(appsPerRow, apps.getPredictedApps().size());
+        int appPosition = getAppPosition(position, numPredictedApps, appsPerRow);
+
+        int col = appPosition % appsPerRow;
+        int row = appPosition / appsPerRow;
+
+        int numTotalRows = apps.getNumAppRows() - 1; // zero offset
+        if (row > (numTotalRows / 2)) {
+            // Mirror the rows so that the top row acts the same as the bottom row.
+            row = Math.abs(numTotalRows - row);
+        }
+
+        // We manipulate the stiffness, min, and max values based on the items distance to the first
+        // row and the items distance to the center column to create the ^-shaped motion effect.
+        float rowFactor = (1 + row) * 0.5f;
+        float colFactor = getColumnFactor(col, appsPerRow);
+
+        float minValue = DEFAULT_MIN_VALUE * (rowFactor + colFactor);
+        float maxValue = DEFAULT_MAX_VALUE * (rowFactor + colFactor);
+
+        float stiffness = Utilities.boundToRange(MAX_SPRING_STIFFNESS - (row * 50f),
+                MIN_SPRING_STIFFNESS, MAX_SPRING_STIFFNESS);
+
+        SpringAnimation animation = (recycle != null ? recycle : createSpringAnimation(view))
+                .setStartVelocity(mCurrentVelocity)
+                .setMinValue(minValue)
+                .setMaxValue(maxValue);
+        animation.getSpring().setStiffness(stiffness);
+
+        mAnimations.add(animation);
+        return animation;
+    }
+
+    public SpringAnimation remove(SpringAnimation animation) {
+        animation.skipToEnd();
+        mAnimations.remove(animation);
+        return animation;
+    }
+
+    public void addMovement(MotionEvent event) {
+        int action = event.getActionMasked();
+        if (DEBUG) Log.d(TAG, "addMovement#action=" + action);
+        switch (action) {
+            case MotionEvent.ACTION_CANCEL:
+            case MotionEvent.ACTION_DOWN:
+                reset();
+                break;
+        }
+
+        getVelocityTracker().addMovement(event);
+        mShouldComputeVelocity = true;
+    }
+
+    public void animateToFinalPosition(float position) {
+        if (DEBUG) Log.d(TAG, "animateToFinalPosition#computeVelocity=" + mShouldComputeVelocity);
+
+        if (mShouldComputeVelocity) {
+            computeVelocity();
+            setStartVelocity(mCurrentVelocity);
+        }
+
+        int size = mAnimations.size();
+        for (int i = 0; i < size; ++i) {
+            mAnimations.get(i).animateToFinalPosition(position);
+        }
+
+        reset();
+    }
+
+    public void skipToEnd() {
+        if (DEBUG) Log.d(TAG, "setStartVelocity#skipToEnd");
+        if (DEBUG) Log.v(TAG, "setStartVelocity#skipToEnd", new Exception());
+
+        int size = mAnimations.size();
+        for (int i = 0; i < size; ++i) {
+            mAnimations.get(i).skipToEnd();
+        }
+    }
+
+    public void reset() {
+        if (mVelocityTracker != null) {
+            mVelocityTracker.recycle();
+            mVelocityTracker = null;
+        }
+        mCurrentVelocity = 0;
+    }
+
+    private void setStartVelocity(float velocity) {
+        int size = mAnimations.size();
+        for (int i = 0; i < size; ++i) {
+            mAnimations.get(i).setStartVelocity(velocity);
+        }
+    }
+
+    private void computeVelocity() {
+        getVelocityTracker().computeCurrentVelocity(300);
+
+        mCurrentVelocity = isVerticalDirection()
+                ? getVelocityTracker().getYVelocity()
+                : getVelocityTracker().getXVelocity();
+        mShouldComputeVelocity = false;
+
+        if (DEBUG) Log.d(TAG, "computeVelocity=" + mCurrentVelocity);
+    }
+
+    private boolean isVerticalDirection() {
+        return mDirection == Y_DIRECTION;
+    }
+
+    private SpringAnimation createSpringAnimation(View view) {
+        DynamicAnimation.ViewProperty property = isVerticalDirection()
+                ? DynamicAnimation.TRANSLATION_Y
+                : DynamicAnimation.TRANSLATION_X;
+
+        return new SpringAnimation(view, property, 0)
+                .setStartValue(1f)
+                .setSpring(new SpringForce(0)
+                .setDampingRatio(SPRING_DAMPING_RATIO));
+    }
+
+    /**
+     * @return The app position is the position of the app in the Adapter if we ignored all other
+     * view types.
+     *
+     * ie. The first predicted app is at position 0, and the first app of all apps is
+     *     at {@param appsPerRow}.
+     */
+    private int getAppPosition(int position, int numPredictedApps, int appsPerRow) {
+        int appPosition = position;
+        int numDividerViews = 1 + (numPredictedApps == 0 ? 0 : 1);
+
+        int allAppsStartAt = numDividerViews + numPredictedApps;
+        if (numDividerViews == 1 || position < allAppsStartAt) {
+            appPosition -= 1;
+        } else {
+            // We cannot assume that the predicted row will always be full.
+            int numPredictedAppsOffset = appsPerRow - numPredictedApps;
+            appPosition = position + numPredictedAppsOffset - numDividerViews;
+        }
+
+        return appPosition;
+    }
+
+    /**
+     * Increase the column factor as the distance increases between the column and the center
+     * column(s).
+     */
+    private float getColumnFactor(int col, int numCols) {
+        float centerColumn = numCols / 2;
+        int distanceToCenter = (int) Math.abs(col - centerColumn);
+
+        boolean evenNumberOfColumns = numCols % 2 == 0;
+        if (evenNumberOfColumns && col < centerColumn) {
+            distanceToCenter -= 1;
+        }
+
+        float factor = 0;
+        while (distanceToCenter > 0) {
+            if (distanceToCenter == 1) {
+                factor += 0.2f;
+            } else {
+                factor += 0.1f;
+            }
+            --distanceToCenter;
+        }
+
+        return factor;
+    }
+
+    private VelocityTracker getVelocityTracker() {
+        if (mVelocityTracker == null) {
+            mVelocityTracker = VelocityTracker.obtain();
+        }
+        return mVelocityTracker;
+    }
+}