src/com/android/launcher3/LauncherStateTransitionAnimation.java

/*
 * Copyright (C) 2015 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;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.animation.PropertyValuesHolder;
import android.animation.TimeInterpolator;
import android.annotation.SuppressLint;
import android.content.res.Resources;
import android.util.Log;
import android.view.View;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.DecelerateInterpolator;

import com.android.launcher3.allapps.AllAppsContainerView;
import com.android.launcher3.util.UiThreadCircularReveal;
import com.android.launcher3.util.Thunk;
import com.android.launcher3.widget.WidgetsContainerView;

import java.util.HashMap;

/**
 * TODO: figure out what kind of tests we can write for this
 *
 * Things to test when changing the following class.
 *   - Home from workspace
 *          - from center screen
 *          - from other screens
 *   - Home from all apps
 *          - from center screen
 *          - from other screens
 *   - Back from all apps
 *          - from center screen
 *          - from other screens
 *   - Launch app from workspace and quit
 *          - with back
 *          - with home
 *   - Launch app from all apps and quit
 *          - with back
 *          - with home
 *   - Go to a screen that's not the default, then all
 *     apps, and launch and app, and go back
 *          - with back
 *          -with home
 *   - On workspace, long press power and go back
 *          - with back
 *          - with home
 *   - On all apps, long press power and go back
 *          - with back
 *          - with home
 *   - On workspace, power off
 *   - On all apps, power off
 *   - Launch an app and turn off the screen while in that app
 *          - Go back with home key
 *          - Go back with back key  TODO: make this not go to workspace
 *          - From all apps
 *          - From workspace
 *   - Enter and exit car mode (becuase it causes an extra configuration changed)
 *          - From all apps
 *          - From the center workspace
 *          - From another workspace
 */
public class LauncherStateTransitionAnimation {

    /**
     * Private callbacks made during transition setup.
     */
    static abstract class PrivateTransitionCallbacks {
        float getMaterialRevealViewFinalAlpha(View revealView) {
            return 0;
        }
        float getMaterialRevealViewStartFinalRadius() {
            return 0;
        }
        AnimatorListenerAdapter getMaterialRevealViewAnimatorListener(View revealView,
                View buttonView) {
            return null;
        }
        void onTransitionComplete() {}
    }

    public static final String TAG = "LauncherStateTransitionAnimation";

    // Flags to determine how to set the layers on views before the transition animation
    public static final int BUILD_LAYER = 0;
    public static final int BUILD_AND_SET_LAYER = 1;
    public static final int SINGLE_FRAME_DELAY = 16;

    @Thunk Launcher mLauncher;
    @Thunk AnimatorSet mCurrentAnimation;

    public LauncherStateTransitionAnimation(Launcher l) {
        mLauncher = l;
    }

    /**
     * Starts an animation to the apps view.
     *
     * @param startSearchAfterTransition Immediately starts app search after the transition to
     *                                   All Apps is completed.
     */
    public void startAnimationToAllApps(final Workspace.State fromWorkspaceState,
            final boolean animated, final boolean startSearchAfterTransition) {
        final AllAppsContainerView toView = mLauncher.getAppsView();
        final View buttonView = mLauncher.getAllAppsButton();
        PrivateTransitionCallbacks cb = new PrivateTransitionCallbacks() {
            @Override
            public float getMaterialRevealViewFinalAlpha(View revealView) {
                return 1f;
            }
            @Override
            public float getMaterialRevealViewStartFinalRadius() {
                int allAppsButtonSize = mLauncher.getDeviceProfile().allAppsButtonVisualSize;
                return allAppsButtonSize / 2;
            }
            @Override
            public AnimatorListenerAdapter getMaterialRevealViewAnimatorListener(
                    final View revealView, final View allAppsButtonView) {
                return new AnimatorListenerAdapter() {
                    public void onAnimationStart(Animator animation) {
                        allAppsButtonView.setVisibility(View.INVISIBLE);
                    }
                    public void onAnimationEnd(Animator animation) {
                        allAppsButtonView.setVisibility(View.VISIBLE);
                    }
                };
            }
            @Override
            void onTransitionComplete() {
                if (startSearchAfterTransition) {
                    toView.startAppsSearch();
                }
            }
        };
        // Only animate the search bar if animating from spring loaded mode back to all apps
        mCurrentAnimation = startAnimationToOverlay(fromWorkspaceState,
                Workspace.State.NORMAL_HIDDEN, buttonView, toView, toView.getContentView(),
                toView.getRevealView(), toView.getSearchBarView(), animated, cb);
    }

    /**
     * Starts an animation to the widgets view.
     */
    public void startAnimationToWidgets(final Workspace.State fromWorkspaceState,
            final boolean animated) {
        final WidgetsContainerView toView = mLauncher.getWidgetsView();
        final View buttonView = mLauncher.getWidgetsButton();

        PrivateTransitionCallbacks cb = new PrivateTransitionCallbacks() {
            @Override
            public float getMaterialRevealViewFinalAlpha(View revealView) {
                return 0.3f;
            }
        };
        mCurrentAnimation = startAnimationToOverlay(fromWorkspaceState,
                Workspace.State.OVERVIEW_HIDDEN, buttonView, toView, toView.getContentView(),
                toView.getRevealView(), null, animated, cb);
    }

    /**
     * Starts and animation to the workspace from the current overlay view.
     */
    public void startAnimationToWorkspace(final Launcher.State fromState,
            final Workspace.State fromWorkspaceState, final Workspace.State toWorkspaceState,
            final int toWorkspacePage, final boolean animated, final Runnable onCompleteRunnable) {
        if (toWorkspaceState != Workspace.State.NORMAL &&
                toWorkspaceState != Workspace.State.SPRING_LOADED &&
                toWorkspaceState != Workspace.State.OVERVIEW) {
            Log.e(TAG, "Unexpected call to startAnimationToWorkspace");
        }

        if (fromState == Launcher.State.APPS || fromState == Launcher.State.APPS_SPRING_LOADED) {
            startAnimationToWorkspaceFromAllApps(fromWorkspaceState, toWorkspaceState, toWorkspacePage,
                    animated, onCompleteRunnable);
        } else {
            startAnimationToWorkspaceFromWidgets(fromWorkspaceState, toWorkspaceState, toWorkspacePage,
                    animated, onCompleteRunnable);
        }
    }

    /**
     * Creates and starts a new animation to a particular overlay view.
     */
    @SuppressLint("NewApi")
    private AnimatorSet startAnimationToOverlay(final Workspace.State fromWorkspaceState,
            final Workspace.State toWorkspaceState, final View buttonView, final View toView,
            final View contentView, final View revealView, final View overlaySearchBarView,
            final boolean animated, final PrivateTransitionCallbacks pCb) {
        final AnimatorSet animation = LauncherAnimUtils.createAnimatorSet();
        final Resources res = mLauncher.getResources();
        final boolean material = Utilities.isLmpOrAbove();
        final int revealDuration = res.getInteger(R.integer.config_overlayRevealTime);
        final int itemsAlphaStagger =
                res.getInteger(R.integer.config_overlayItemsAlphaStagger);

        final View fromView = mLauncher.getWorkspace();

        final HashMap<View, Integer> layerViews = new HashMap<>();

        // If for some reason our views aren't initialized, don't animate
        boolean initialized = buttonView != null;

        // Cancel the current animation
        cancelAnimation();

        // Create the workspace animation.
        // NOTE: this call apparently also sets the state for the workspace if !animated
        Animator workspaceAnim = mLauncher.startWorkspaceStateChangeAnimation(toWorkspaceState, -1,
                animated, layerViews);

        // Animate the search bar
        startWorkspaceSearchBarAnimation(animation, fromWorkspaceState, toWorkspaceState,
                animated ? revealDuration : 0, overlaySearchBarView);

        if (animated && initialized) {
            // Setup the reveal view animation
            int width = revealView.getMeasuredWidth();
            int height = revealView.getMeasuredHeight();
            float revealRadius = (float) Math.hypot(width / 2, height / 2);
            revealView.setVisibility(View.VISIBLE);
            revealView.setAlpha(0f);
            revealView.setTranslationY(0f);
            revealView.setTranslationX(0f);

            // Calculate the final animation values
            final float revealViewToAlpha;
            final float revealViewToXDrift;
            final float revealViewToYDrift;
            if (material) {
                int[] buttonViewToPanelDelta = Utilities.getCenterDeltaInScreenSpace(revealView,
                        buttonView, null);
                revealViewToAlpha = pCb.getMaterialRevealViewFinalAlpha(revealView);
                revealViewToYDrift = buttonViewToPanelDelta[1];
                revealViewToXDrift = buttonViewToPanelDelta[0];
            } else {
                revealViewToAlpha = 0f;
                revealViewToYDrift = 2 * height / 3;
                revealViewToXDrift = 0;
            }

            // Create the animators
            PropertyValuesHolder panelAlpha =
                    PropertyValuesHolder.ofFloat("alpha", revealViewToAlpha, 1f);
            PropertyValuesHolder panelDriftY =
                    PropertyValuesHolder.ofFloat("translationY", revealViewToYDrift, 0);
            PropertyValuesHolder panelDriftX =
                    PropertyValuesHolder.ofFloat("translationX", revealViewToXDrift, 0);
            ObjectAnimator panelAlphaAndDrift = ObjectAnimator.ofPropertyValuesHolder(revealView,
                    panelAlpha, panelDriftY, panelDriftX);
            panelAlphaAndDrift.setDuration(revealDuration);
            panelAlphaAndDrift.setInterpolator(new LogDecelerateInterpolator(100, 0));

            // Play the animation
            layerViews.put(revealView, BUILD_AND_SET_LAYER);
            animation.play(panelAlphaAndDrift);

            if (overlaySearchBarView != null) {
                overlaySearchBarView.setAlpha(0f);
                ObjectAnimator searchBarAlpha = ObjectAnimator.ofFloat(overlaySearchBarView, "alpha", 0f, 1f);
                searchBarAlpha.setDuration(100);
                searchBarAlpha.setInterpolator(new AccelerateInterpolator(1.5f));
                layerViews.put(overlaySearchBarView, BUILD_AND_SET_LAYER);
                animation.play(searchBarAlpha);
            }

            // Setup the animation for the content view
            contentView.setVisibility(View.VISIBLE);
            contentView.setAlpha(0f);
            contentView.setTranslationY(revealViewToYDrift);
            layerViews.put(contentView, BUILD_AND_SET_LAYER);

            // Create the individual animators
            ObjectAnimator pageDrift = ObjectAnimator.ofFloat(contentView, "translationY",
                    revealViewToYDrift, 0);
            pageDrift.setDuration(revealDuration);
            pageDrift.setInterpolator(new LogDecelerateInterpolator(100, 0));
            pageDrift.setStartDelay(itemsAlphaStagger);
            animation.play(pageDrift);

            ObjectAnimator itemsAlpha = ObjectAnimator.ofFloat(contentView, "alpha", 0f, 1f);
            itemsAlpha.setDuration(revealDuration);
            itemsAlpha.setInterpolator(new AccelerateInterpolator(1.5f));
            itemsAlpha.setStartDelay(itemsAlphaStagger);
            animation.play(itemsAlpha);

            if (material) {
                float startRadius = pCb.getMaterialRevealViewStartFinalRadius();
                AnimatorListenerAdapter listener = pCb.getMaterialRevealViewAnimatorListener(
                        revealView, buttonView);
                Animator reveal = UiThreadCircularReveal.createCircularReveal(revealView, width / 2,
                        height / 2, startRadius, revealRadius);
                reveal.setDuration(revealDuration);
                reveal.setInterpolator(new LogDecelerateInterpolator(100, 0));
                if (listener != null) {
                    reveal.addListener(listener);
                }
                animation.play(reveal);
            }

            animation.addListener(new AnimatorListenerAdapter() {
                @Override
                public void onAnimationEnd(Animator animation) {
                    dispatchOnLauncherTransitionEnd(fromView, animated, false);
                    dispatchOnLauncherTransitionEnd(toView, animated, false);

                    // Hide the reveal view
                    revealView.setVisibility(View.INVISIBLE);

                    // Disable all necessary layers
                    for (View v : layerViews.keySet()) {
                        if (layerViews.get(v) == BUILD_AND_SET_LAYER) {
                            v.setLayerType(View.LAYER_TYPE_NONE, null);
                        }
                    }

                    // This can hold unnecessary references to views.
                    cleanupAnimation();
                    pCb.onTransitionComplete();
                }

            });

            // Play the workspace animation
            if (workspaceAnim != null) {
                animation.play(workspaceAnim);
            }

            // Dispatch the prepare transition signal
            dispatchOnLauncherTransitionPrepare(fromView, animated, false);
            dispatchOnLauncherTransitionPrepare(toView, animated, false);


            final AnimatorSet stateAnimation = animation;
            final Runnable startAnimRunnable = new Runnable() {
                public void run() {
                    // Check that mCurrentAnimation hasn't changed while
                    // we waited for a layout/draw pass
                    if (mCurrentAnimation != stateAnimation)
                        return;
                    dispatchOnLauncherTransitionStart(fromView, animated, false);
                    dispatchOnLauncherTransitionStart(toView, animated, false);

                    // Enable all necessary layers
                    boolean isLmpOrAbove = Utilities.isLmpOrAbove();
                    for (View v : layerViews.keySet()) {
                        if (layerViews.get(v) == BUILD_AND_SET_LAYER) {
                            v.setLayerType(View.LAYER_TYPE_HARDWARE, null);
                        }
                        if (isLmpOrAbove && Utilities.isViewAttachedToWindow(v)) {
                            v.buildLayer();
                        }
                    }

                    // Focus the new view
                    toView.requestFocus();

                    stateAnimation.start();
                }
            };
            toView.bringToFront();
            toView.setVisibility(View.VISIBLE);
            toView.post(startAnimRunnable);

            return animation;
        } else {
            toView.setTranslationX(0.0f);
            toView.setTranslationY(0.0f);
            toView.setScaleX(1.0f);
            toView.setScaleY(1.0f);
            toView.setVisibility(View.VISIBLE);
            toView.bringToFront();

            // Show the content view
            contentView.setVisibility(View.VISIBLE);

            dispatchOnLauncherTransitionPrepare(fromView, animated, false);
            dispatchOnLauncherTransitionStart(fromView, animated, false);
            dispatchOnLauncherTransitionEnd(fromView, animated, false);
            dispatchOnLauncherTransitionPrepare(toView, animated, false);
            dispatchOnLauncherTransitionStart(toView, animated, false);
            dispatchOnLauncherTransitionEnd(toView, animated, false);
            pCb.onTransitionComplete();

            return null;
        }
    }

    /**
     * Starts and animation to the workspace from the apps view.
     */
    private void startAnimationToWorkspaceFromAllApps(final Workspace.State fromWorkspaceState,
            final Workspace.State toWorkspaceState, final int toWorkspacePage,
            final boolean animated, final Runnable onCompleteRunnable) {
        AllAppsContainerView appsView = mLauncher.getAppsView();
        PrivateTransitionCallbacks cb = new PrivateTransitionCallbacks() {
            @Override
            float getMaterialRevealViewFinalAlpha(View revealView) {
                // No alpha anim from all apps
                return 1f;
            }
            @Override
            float getMaterialRevealViewStartFinalRadius() {
                int allAppsButtonSize = mLauncher.getDeviceProfile().allAppsButtonVisualSize;
                return allAppsButtonSize / 2;
            }
            @Override
            public AnimatorListenerAdapter getMaterialRevealViewAnimatorListener(
                    final View revealView, final View allAppsButtonView) {
                return new AnimatorListenerAdapter() {
                    public void onAnimationStart(Animator animation) {
                        // We set the alpha instead of visibility to ensure that the focus does not
                        // get taken from the all apps view
                        allAppsButtonView.setVisibility(View.VISIBLE);
                        allAppsButtonView.setAlpha(0f);
                    }
                    public void onAnimationEnd(Animator animation) {
                        // Hide the reveal view
                        revealView.setVisibility(View.INVISIBLE);

                        // Show the all apps button, and focus it
                        allAppsButtonView.setAlpha(1f);
                    }
                };
            }
        };
        // Only animate the search bar if animating to spring loaded mode from all apps
        mCurrentAnimation = startAnimationToWorkspaceFromOverlay(fromWorkspaceState, toWorkspaceState,
                toWorkspacePage, mLauncher.getAllAppsButton(), appsView, appsView.getContentView(),
                appsView.getRevealView(), appsView.getSearchBarView(), animated,
                onCompleteRunnable, cb);
    }

    /**
     * Starts and animation to the workspace from the widgets view.
     */
    private void startAnimationToWorkspaceFromWidgets(final Workspace.State fromWorkspaceState,
            final Workspace.State toWorkspaceState, final int toWorkspacePage,
            final boolean animated, final Runnable onCompleteRunnable) {
        final WidgetsContainerView widgetsView = mLauncher.getWidgetsView();
        PrivateTransitionCallbacks cb = new PrivateTransitionCallbacks() {
            @Override
            float getMaterialRevealViewFinalAlpha(View revealView) {
                return 0.3f;
            }
            @Override
            public AnimatorListenerAdapter getMaterialRevealViewAnimatorListener(
                    final View revealView, final View widgetsButtonView) {
                return new AnimatorListenerAdapter() {
                    public void onAnimationEnd(Animator animation) {
                        // Hide the reveal view
                        revealView.setVisibility(View.INVISIBLE);
                    }
                };
            }
        };
        mCurrentAnimation = startAnimationToWorkspaceFromOverlay(fromWorkspaceState,
                toWorkspaceState, toWorkspacePage, mLauncher.getWidgetsButton(), widgetsView,
                widgetsView.getContentView(), widgetsView.getRevealView(), null, animated,
                onCompleteRunnable, cb);
    }

    /**
     * Creates and starts a new animation to the workspace.
     */
    private AnimatorSet startAnimationToWorkspaceFromOverlay(final Workspace.State fromWorkspaceState,
            final Workspace.State toWorkspaceState, final int toWorkspacePage, final View buttonView,
            final View fromView, final View contentView, final View revealView,
            final View overlaySearchBarView, final boolean animated, final Runnable onCompleteRunnable,
            final PrivateTransitionCallbacks pCb) {
        final AnimatorSet animation = LauncherAnimUtils.createAnimatorSet();
        final Resources res = mLauncher.getResources();
        final boolean material = Utilities.isLmpOrAbove();
        final int revealDuration = res.getInteger(R.integer.config_overlayRevealTime);
        final int itemsAlphaStagger =
                res.getInteger(R.integer.config_overlayItemsAlphaStagger);

        final View toView = mLauncher.getWorkspace();

        final HashMap<View, Integer> layerViews = new HashMap<>();

        // If for some reason our views aren't initialized, don't animate
        boolean initialized = buttonView != null;

        // Cancel the current animation
        cancelAnimation();

        // Create the workspace animation.
        // NOTE: this call apparently also sets the state for the workspace if !animated
        Animator workspaceAnim = mLauncher.startWorkspaceStateChangeAnimation(toWorkspaceState,
                toWorkspacePage, animated, layerViews);

        // Animate the search bar
        startWorkspaceSearchBarAnimation(animation, fromWorkspaceState, toWorkspaceState,
                animated ? revealDuration : 0, overlaySearchBarView);

        if (animated && initialized) {
            // Play the workspace animation
            if (workspaceAnim != null) {
                animation.play(workspaceAnim);
            }

            // hideAppsCustomizeHelper is called in some cases when it is already hidden
            // don't perform all these no-op animations. In particularly, this was causing
            // the all-apps button to pop in and out.
            if (fromView.getVisibility() == View.VISIBLE) {
                int width = revealView.getMeasuredWidth();
                int height = revealView.getMeasuredHeight();
                float revealRadius = (float) Math.hypot(width / 2, height / 2);
                revealView.setVisibility(View.VISIBLE);
                revealView.setAlpha(1f);
                revealView.setTranslationY(0);
                layerViews.put(revealView, BUILD_AND_SET_LAYER);

                // Calculate the final animation values
                final float revealViewToXDrift;
                final float revealViewToYDrift;
                if (material) {
                    int[] buttonViewToPanelDelta = Utilities.getCenterDeltaInScreenSpace(revealView,
                            buttonView, null);
                    revealViewToYDrift = buttonViewToPanelDelta[1];
                    revealViewToXDrift = buttonViewToPanelDelta[0];
                } else {
                    revealViewToYDrift = 2 * height / 3;
                    revealViewToXDrift = 0;
                }

                // The vertical motion of the apps panel should be delayed by one frame
                // from the conceal animation in order to give the right feel. We correspondingly
                // shorten the duration so that the slide and conceal end at the same time.
                TimeInterpolator decelerateInterpolator = material ?
                        new LogDecelerateInterpolator(100, 0) :
                        new DecelerateInterpolator(1f);
                ObjectAnimator panelDriftY = ObjectAnimator.ofFloat(revealView, "translationY",
                        0, revealViewToYDrift);
                panelDriftY.setDuration(revealDuration - SINGLE_FRAME_DELAY);
                panelDriftY.setStartDelay(itemsAlphaStagger + SINGLE_FRAME_DELAY);
                panelDriftY.setInterpolator(decelerateInterpolator);
                animation.play(panelDriftY);

                ObjectAnimator panelDriftX = ObjectAnimator.ofFloat(revealView, "translationX",
                        0, revealViewToXDrift);
                panelDriftX.setDuration(revealDuration - SINGLE_FRAME_DELAY);
                panelDriftX.setStartDelay(itemsAlphaStagger + SINGLE_FRAME_DELAY);
                panelDriftX.setInterpolator(decelerateInterpolator);
                animation.play(panelDriftX);

                // Setup animation for the reveal panel alpha
                final float revealViewToAlpha = !material ? 0f :
                        pCb.getMaterialRevealViewFinalAlpha(revealView);
                if (revealViewToAlpha != 1f) {
                    ObjectAnimator panelAlpha = ObjectAnimator.ofFloat(revealView, "alpha",
                            1f, revealViewToAlpha);
                    panelAlpha.setDuration(material ? revealDuration : 150);
                    panelAlpha.setStartDelay(material ? 0 : itemsAlphaStagger + SINGLE_FRAME_DELAY);
                    panelAlpha.setInterpolator(decelerateInterpolator);
                    animation.play(panelAlpha);
                }

                // Setup the animation for the content view
                layerViews.put(contentView, BUILD_AND_SET_LAYER);

                // Create the individual animators
                ObjectAnimator pageDrift = ObjectAnimator.ofFloat(contentView, "translationY",
                        0, revealViewToYDrift);
                contentView.setTranslationY(0);
                pageDrift.setDuration(revealDuration - SINGLE_FRAME_DELAY);
                pageDrift.setInterpolator(decelerateInterpolator);
                pageDrift.setStartDelay(itemsAlphaStagger + SINGLE_FRAME_DELAY);
                animation.play(pageDrift);

                contentView.setAlpha(1f);
                ObjectAnimator itemsAlpha = ObjectAnimator.ofFloat(contentView, "alpha", 1f, 0f);
                itemsAlpha.setDuration(100);
                itemsAlpha.setInterpolator(decelerateInterpolator);
                animation.play(itemsAlpha);

                if (overlaySearchBarView != null) {
                    overlaySearchBarView.setAlpha(1f);
                    ObjectAnimator searchAlpha = ObjectAnimator.ofFloat(overlaySearchBarView, "alpha", 1f, 0f);
                    searchAlpha.setDuration(material ? 100 : 150);
                    searchAlpha.setInterpolator(decelerateInterpolator);
                    searchAlpha.setStartDelay(material ? 0 : itemsAlphaStagger + SINGLE_FRAME_DELAY);
                    layerViews.put(overlaySearchBarView, BUILD_AND_SET_LAYER);
                    animation.play(searchAlpha);
                }

                if (material) {
                    // Animate the all apps button
                    float finalRadius = pCb.getMaterialRevealViewStartFinalRadius();
                    AnimatorListenerAdapter listener =
                            pCb.getMaterialRevealViewAnimatorListener(revealView, buttonView);
                    Animator reveal = UiThreadCircularReveal.createCircularReveal(revealView, width / 2,
                            height / 2, revealRadius, finalRadius);
                    reveal.setInterpolator(new LogDecelerateInterpolator(100, 0));
                    reveal.setDuration(revealDuration);
                    reveal.setStartDelay(itemsAlphaStagger);
                    if (listener != null) {
                        reveal.addListener(listener);
                    }
                    animation.play(reveal);
                }

                dispatchOnLauncherTransitionPrepare(fromView, animated, true);
                dispatchOnLauncherTransitionPrepare(toView, animated, true);
            }

            animation.addListener(new AnimatorListenerAdapter() {
                @Override
                public void onAnimationEnd(Animator animation) {
                    fromView.setVisibility(View.GONE);
                    dispatchOnLauncherTransitionEnd(fromView, animated, true);
                    dispatchOnLauncherTransitionEnd(toView, animated, true);

                    // Run any queued runnables
                    if (onCompleteRunnable != null) {
                        onCompleteRunnable.run();
                    }

                    // Disable all necessary layers
                    for (View v : layerViews.keySet()) {
                        if (layerViews.get(v) == BUILD_AND_SET_LAYER) {
                            v.setLayerType(View.LAYER_TYPE_NONE, null);
                        }
                    }

                    // Reset page transforms
                    if (contentView != null) {
                        contentView.setTranslationX(0);
                        contentView.setTranslationY(0);
                        contentView.setAlpha(1);
                    }
                    if (overlaySearchBarView != null) {
                        overlaySearchBarView.setAlpha(1f);
                    }

                    // This can hold unnecessary references to views.
                    cleanupAnimation();
                    pCb.onTransitionComplete();
                }
            });

            final AnimatorSet stateAnimation = animation;
            final Runnable startAnimRunnable = new Runnable() {
                public void run() {
                    // Check that mCurrentAnimation hasn't changed while
                    // we waited for a layout/draw pass
                    if (mCurrentAnimation != stateAnimation)
                        return;

                    dispatchOnLauncherTransitionStart(fromView, animated, false);
                    dispatchOnLauncherTransitionStart(toView, animated, false);

                    // Enable all necessary layers
                    boolean isLmpOrAbove = Utilities.isLmpOrAbove();
                    for (View v : layerViews.keySet()) {
                        if (layerViews.get(v) == BUILD_AND_SET_LAYER) {
                            v.setLayerType(View.LAYER_TYPE_HARDWARE, null);
                        }
                        if (isLmpOrAbove && Utilities.isViewAttachedToWindow(v)) {
                            v.buildLayer();
                        }
                    }
                    stateAnimation.start();
                }
            };
            fromView.post(startAnimRunnable);

            return animation;
        } else {
            fromView.setVisibility(View.GONE);
            dispatchOnLauncherTransitionPrepare(fromView, animated, true);
            dispatchOnLauncherTransitionStart(fromView, animated, true);
            dispatchOnLauncherTransitionEnd(fromView, animated, true);
            dispatchOnLauncherTransitionPrepare(toView, animated, true);
            dispatchOnLauncherTransitionStart(toView, animated, true);
            dispatchOnLauncherTransitionEnd(toView, animated, true);
            pCb.onTransitionComplete();

            // Run any queued runnables
            if (onCompleteRunnable != null) {
                onCompleteRunnable.run();
            }

            return null;
        }
    }

    /**
     * Coordinates the workspace search bar animation along with the launcher state animation.
     */
    private void startWorkspaceSearchBarAnimation(AnimatorSet animation,
            final Workspace.State fromWorkspaceState, final Workspace.State toWorkspaceState, int duration,
            View overlaySearchBar) {
        final SearchDropTargetBar.State toSearchBarState =
                toWorkspaceState.getSearchDropTargetBarState();

        if (overlaySearchBar != null) {
            if ((toWorkspaceState == Workspace.State.NORMAL) &&
                    (fromWorkspaceState == Workspace.State.NORMAL_HIDDEN)) {
                // If we are transitioning from the overlay to the workspace, then show the
                // workspace search bar immediately and let the overlay search bar fade out on top
                mLauncher.getSearchDropTargetBar().animateToState(toSearchBarState, 0);
            } else if (fromWorkspaceState == Workspace.State.NORMAL) {
                // If we are transitioning from the workspace to the overlay, then keep the
                // workspace search bar visible until the overlay search bar fades in on top
                animation.addListener(new AnimatorListenerAdapter() {
                    @Override
                    public void onAnimationEnd(Animator animation) {
                        mLauncher.getSearchDropTargetBar().animateToState(toSearchBarState, 0);
                    }
                });
            } else {
                // Otherwise, then just animate the workspace search bar normally
                mLauncher.getSearchDropTargetBar().animateToState(toSearchBarState, duration);
            }
        } else {
            // If there is no overlay search bar, then just animate the workspace search bar
            mLauncher.getSearchDropTargetBar().animateToState(toSearchBarState, duration);
        }
    }

    /**
     * Dispatches the prepare-transition event to suitable views.
     */
    void dispatchOnLauncherTransitionPrepare(View v, boolean animated, boolean toWorkspace) {
        if (v instanceof LauncherTransitionable) {
            ((LauncherTransitionable) v).onLauncherTransitionPrepare(mLauncher, animated,
                    toWorkspace);
        }
    }

    /**
     * Dispatches the start-transition event to suitable views.
     */
    void dispatchOnLauncherTransitionStart(View v, boolean animated, boolean toWorkspace) {
        if (v instanceof LauncherTransitionable) {
            ((LauncherTransitionable) v).onLauncherTransitionStart(mLauncher, animated,
                    toWorkspace);
        }

        // Update the workspace transition step as well
        dispatchOnLauncherTransitionStep(v, 0f);
    }

    /**
     * Dispatches the step-transition event to suitable views.
     */
    void dispatchOnLauncherTransitionStep(View v, float t) {
        if (v instanceof LauncherTransitionable) {
            ((LauncherTransitionable) v).onLauncherTransitionStep(mLauncher, t);
        }
    }

    /**
     * Dispatches the end-transition event to suitable views.
     */
    void dispatchOnLauncherTransitionEnd(View v, boolean animated, boolean toWorkspace) {
        if (v instanceof LauncherTransitionable) {
            ((LauncherTransitionable) v).onLauncherTransitionEnd(mLauncher, animated,
                    toWorkspace);
        }

        // Update the workspace transition step as well
        dispatchOnLauncherTransitionStep(v, 1f);
    }

    /**
     * Cancels the current animation.
     */
    private void cancelAnimation() {
        if (mCurrentAnimation != null) {
            mCurrentAnimation.setDuration(0);
            mCurrentAnimation.cancel();
            mCurrentAnimation = null;
        }
    }

    @Thunk void cleanupAnimation() {
        mCurrentAnimation = null;
    }
}