本文介绍安卓动画系统中的过渡动画流程。

过渡动画简介

一般过渡动画有在system_server进程中执行的本地动画和在例如systemui等进程执行的远程动画两种情况。

常见的本地动画：App内切换Activity等。

常见的远程动画：从桌面进入App，从App回到桌面，从Notification悬浮窗进入Activity等。

本地动画

从窗口布局流程中RootWindowContainer的performSurfacePlacement方法开始：

    void performSurfacePlacement() {Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "performSurfacePlacement");try {performSurfacePlacementNoTrace();} finally {Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);}}// "Something has changed!  Let's make it correct now."// TODO: Super crazy long method that should be broken down...void performSurfacePlacementNoTrace() {if (DEBUG_WINDOW_TRACE) Slog.v(TAG, "performSurfacePlacementInner: entry. Called by "+ Debug.getCallers(3));int i;if (mWmService.mFocusMayChange) {mWmService.mFocusMayChange = false;mWmService.updateFocusedWindowLocked(UPDATE_FOCUS_WILL_PLACE_SURFACES, false /*updateInputWindows*/);}// Initialize state of exiting tokens.final int numDisplays = mChildren.size();for (int displayNdx = 0; displayNdx < numDisplays; ++displayNdx) {final DisplayContent displayContent = mChildren.get(displayNdx);displayContent.setExitingTokensHasVisible(false);}mHoldScreen = null;mScreenBrightnessOverride = PowerManager.BRIGHTNESS_INVALID_FLOAT;mUserActivityTimeout = -1;mObscureApplicationContentOnSecondaryDisplays = false;mSustainedPerformanceModeCurrent = false;mWmService.mTransactionSequence++;// TODO(multi-display): recents animation & wallpaper need support multi-display.final DisplayContent defaultDisplay = mWmService.getDefaultDisplayContentLocked();final WindowSurfacePlacer surfacePlacer = mWmService.mWindowPlacerLocked;if (SHOW_LIGHT_TRANSACTIONS) Slog.i(TAG,">>> OPEN TRANSACTION performLayoutAndPlaceSurfaces");Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "applySurfaceChanges");mWmService.openSurfaceTransaction();try {applySurfaceChangesTransaction();} catch (RuntimeException e) {Slog.wtf(TAG, "Unhandled exception in Window Manager", e);} finally {mWmService.closeSurfaceTransaction("performLayoutAndPlaceSurfaces");Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);if (SHOW_LIGHT_TRANSACTIONS) Slog.i(TAG,"<<< CLOSE TRANSACTION performLayoutAndPlaceSurfaces");}mWmService.mAnimator.executeAfterPrepareSurfacesRunnables();checkAppTransitionReady(surfacePlacer);// Defer starting the recents animation until the wallpaper has drawnfinal RecentsAnimationController recentsAnimationController =mWmService.getRecentsAnimationController();if (recentsAnimationController != null) {recentsAnimationController.checkAnimationReady(defaultDisplay.mWallpaperController);}for (int displayNdx = 0; displayNdx < numDisplays; ++displayNdx) {final DisplayContent displayContent = mChildren.get(displayNdx);if (displayContent.mWallpaperMayChange) {if (DEBUG_WALLPAPER_LIGHT) Slog.v(TAG, "Wallpaper may change!  Adjusting");displayContent.pendingLayoutChanges |= FINISH_LAYOUT_REDO_WALLPAPER;if (DEBUG_LAYOUT_REPEATS) {surfacePlacer.debugLayoutRepeats("WallpaperMayChange",displayContent.pendingLayoutChanges);}}}if (mWmService.mFocusMayChange) {mWmService.mFocusMayChange = false;mWmService.updateFocusedWindowLocked(UPDATE_FOCUS_PLACING_SURFACES,false /*updateInputWindows*/);}if (isLayoutNeeded()) {defaultDisplay.pendingLayoutChanges |= FINISH_LAYOUT_REDO_LAYOUT;if (DEBUG_LAYOUT_REPEATS) surfacePlacer.debugLayoutRepeats("mLayoutNeeded",defaultDisplay.pendingLayoutChanges);}handleResizingWindows();if (mWmService.mDisplayFrozen) {ProtoLog.v(WM_DEBUG_ORIENTATION,"With display frozen, orientationChangeComplete=%b",mOrientationChangeComplete);}if (mOrientationChangeComplete) {if (mWmService.mWindowsFreezingScreen != WINDOWS_FREEZING_SCREENS_NONE) {mWmService.mWindowsFreezingScreen = WINDOWS_FREEZING_SCREENS_NONE;mWmService.mLastFinishedFreezeSource = mLastWindowFreezeSource;mWmService.mH.removeMessages(WINDOW_FREEZE_TIMEOUT);}mWmService.stopFreezingDisplayLocked();}// Destroy the surface of any windows that are no longer visible.i = mWmService.mDestroySurface.size();if (i > 0) {do {i--;WindowState win = mWmService.mDestroySurface.get(i);win.mDestroying = false;final DisplayContent displayContent = win.getDisplayContent();if (displayContent.mInputMethodWindow == win) {displayContent.setInputMethodWindowLocked(null);}if (displayContent.mWallpaperController.isWallpaperTarget(win)) {displayContent.pendingLayoutChanges |= FINISH_LAYOUT_REDO_WALLPAPER;}win.destroySurfaceUnchecked();win.mWinAnimator.destroyPreservedSurfaceLocked();} while (i > 0);mWmService.mDestroySurface.clear();}// Time to remove any exiting tokens?for (int displayNdx = 0; displayNdx < numDisplays; ++displayNdx) {final DisplayContent displayContent = mChildren.get(displayNdx);displayContent.removeExistingTokensIfPossible();}for (int displayNdx = 0; displayNdx < numDisplays; ++displayNdx) {final DisplayContent displayContent = mChildren.get(displayNdx);if (displayContent.pendingLayoutChanges != 0) {displayContent.setLayoutNeeded();}}mWmService.setHoldScreenLocked(mHoldScreen);if (!mWmService.mDisplayFrozen) {final float brightnessOverride = mScreenBrightnessOverride < PowerManager.BRIGHTNESS_MIN|| mScreenBrightnessOverride > PowerManager.BRIGHTNESS_MAX? PowerManager.BRIGHTNESS_INVALID_FLOAT : mScreenBrightnessOverride;int brightnessFloatAsIntBits = Float.floatToIntBits(brightnessOverride);// Post these on a handler such that we don't call into power manager service while// holding the window manager lock to avoid lock contention with power manager lock.mHandler.obtainMessage(SET_SCREEN_BRIGHTNESS_OVERRIDE, brightnessFloatAsIntBits,0).sendToTarget();mHandler.obtainMessage(SET_USER_ACTIVITY_TIMEOUT, mUserActivityTimeout).sendToTarget();}if (mSustainedPerformanceModeCurrent != mSustainedPerformanceModeEnabled) {mSustainedPerformanceModeEnabled = mSustainedPerformanceModeCurrent;mWmService.mPowerManagerInternal.powerHint(PowerHint.SUSTAINED_PERFORMANCE,(mSustainedPerformanceModeEnabled ? 1 : 0));}if (mUpdateRotation) {ProtoLog.d(WM_DEBUG_ORIENTATION, "Performing post-rotate rotation");mUpdateRotation = updateRotationUnchecked();}if (!mWmService.mWaitingForDrawnCallbacks.isEmpty()|| (mOrientationChangeComplete && !isLayoutNeeded()&& !mUpdateRotation)) {mWmService.checkDrawnWindowsLocked();}final int N = mWmService.mPendingRemove.size();if (N > 0) {if (mWmService.mPendingRemoveTmp.length < N) {mWmService.mPendingRemoveTmp = new WindowState[N + 10];}mWmService.mPendingRemove.toArray(mWmService.mPendingRemoveTmp);mWmService.mPendingRemove.clear();ArrayList<DisplayContent> displayList = new ArrayList();for (i = 0; i < N; i++) {final WindowState w = mWmService.mPendingRemoveTmp[i];w.removeImmediately();final DisplayContent displayContent = w.getDisplayContent();if (displayContent != null && !displayList.contains(displayContent)) {displayList.add(displayContent);}}for (int j = displayList.size() - 1; j >= 0; --j) {final DisplayContent dc = displayList.get(j);dc.assignWindowLayers(true /*setLayoutNeeded*/);}}forAllDisplays(dc -> {dc.getInputMonitor().updateInputWindowsLw(true /*force*/);dc.updateSystemGestureExclusion();dc.updateTouchExcludeRegion();});// Check to see if we are now in a state where the screen should// be enabled, because the window obscured flags have changed.mWmService.enableScreenIfNeededLocked();mWmService.scheduleAnimationLocked();// Send any pending task-info changes that were queued-up during a layout defermentmWmService.mAtmService.mTaskOrganizerController.dispatchPendingTaskInfoChanges();if (DEBUG_WINDOW_TRACE) Slog.e(TAG, "performSurfacePlacementInner exit");}

调用了RootWindowContainer的checkAppTransitionReady方法：

    private void checkAppTransitionReady(WindowSurfacePlacer surfacePlacer) {// Trace all displays app transition by Z-order for pending layout change.for (int i = mChildren.size() - 1; i >= 0; --i) {final DisplayContent curDisplay = mChildren.get(i);// If we are ready to perform an app transition, check through all of the app tokens// to be shown and see if they are ready to go.if (curDisplay.mAppTransition.isReady()) {// handleAppTransitionReady may modify curDisplay.pendingLayoutChanges.curDisplay.mAppTransitionController.handleAppTransitionReady();if (DEBUG_LAYOUT_REPEATS) {surfacePlacer.debugLayoutRepeats("after handleAppTransitionReady",curDisplay.pendingLayoutChanges);}}if (curDisplay.mAppTransition.isRunning() && !curDisplay.isAppTransitioning()) {// We have finished the animation of an app transition. To do this, we have// delayed a lot of operations like showing and hiding apps, moving apps in// Z-order, etc.// The app token list reflects the correct Z-order, but the window list may now// be out of sync with it. So here we will just rebuild the entire app window// list. Fun!curDisplay.handleAnimatingStoppedAndTransition();if (DEBUG_LAYOUT_REPEATS) {surfacePlacer.debugLayoutRepeats("after handleAnimStopAndXitionLock",curDisplay.pendingLayoutChanges);}}}}

调用了AppTransitionController的handleAppTransitionReady方法：

    /*** Handle application transition for given display.*/void handleAppTransitionReady() {mTempTransitionReasons.clear();if (!transitionGoodToGo(mDisplayContent.mOpeningApps, mTempTransitionReasons)|| !transitionGoodToGo(mDisplayContent.mChangingContainers,mTempTransitionReasons)) {return;}Trace.traceBegin(Trace.TRACE_TAG_WINDOW_MANAGER, "AppTransitionReady");ProtoLog.v(WM_DEBUG_APP_TRANSITIONS, "**** GOOD TO GO");final AppTransition appTransition = mDisplayContent.mAppTransition;int transit = appTransition.getAppTransition();if (mDisplayContent.mSkipAppTransitionAnimation && !isKeyguardGoingAwayTransit(transit)) {transit = WindowManager.TRANSIT_UNSET;}mDisplayContent.mSkipAppTransitionAnimation = false;mDisplayContent.mNoAnimationNotifyOnTransitionFinished.clear();appTransition.removeAppTransitionTimeoutCallbacks();mDisplayContent.mWallpaperMayChange = false;int appCount = mDisplayContent.mOpeningApps.size();for (int i = 0; i < appCount; ++i) {// Clearing the mAnimatingExit flag before entering animation. It's set to true if app// window is removed, or window relayout to invisible. This also affects window// visibility. We need to clear it *before* maybeUpdateTransitToWallpaper() as the// transition selection depends on wallpaper target visibility.mDisplayContent.mOpeningApps.valueAtUnchecked(i).clearAnimatingFlags();}appCount = mDisplayContent.mChangingContainers.size();for (int i = 0; i < appCount; ++i) {// Clearing for same reason as above.final ActivityRecord activity = getAppFromContainer(mDisplayContent.mChangingContainers.valueAtUnchecked(i));if (activity != null) {activity.clearAnimatingFlags();}}// Adjust wallpaper before we pull the lower/upper target, since pending changes// (like the clearAnimatingFlags() above) might affect wallpaper target result.// Or, the opening app window should be a wallpaper target.mWallpaperControllerLocked.adjustWallpaperWindowsForAppTransitionIfNeeded(mDisplayContent.mOpeningApps);// Determine if closing and opening app token sets are wallpaper targets, in which case// special animations are needed.final boolean hasWallpaperTarget = mWallpaperControllerLocked.getWallpaperTarget() != null;final boolean openingAppHasWallpaper = canBeWallpaperTarget(mDisplayContent.mOpeningApps)&& hasWallpaperTarget;final boolean closingAppHasWallpaper = canBeWallpaperTarget(mDisplayContent.mClosingApps)&& hasWallpaperTarget;transit = maybeUpdateTransitToTranslucentAnim(transit);transit = maybeUpdateTransitToWallpaper(transit, openingAppHasWallpaper,closingAppHasWallpaper);// Find the layout params of the top-most application window in the tokens, which is// what will control the animation theme. If all closing windows are obscured, then there is// no need to do an animation. This is the case, for example, when this transition is being// done behind a dream window.final ArraySet<Integer> activityTypes = collectActivityTypes(mDisplayContent.mOpeningApps,mDisplayContent.mClosingApps, mDisplayContent.mChangingContainers);final ActivityRecord animLpActivity = findAnimLayoutParamsToken(transit, activityTypes);final ActivityRecord topOpeningApp =getTopApp(mDisplayContent.mOpeningApps, false /* ignoreHidden */);final ActivityRecord topClosingApp =getTopApp(mDisplayContent.mClosingApps, false /* ignoreHidden */);final ActivityRecord topChangingApp =getTopApp(mDisplayContent.mChangingContainers, false /* ignoreHidden */);final WindowManager.LayoutParams animLp = getAnimLp(animLpActivity);overrideWithRemoteAnimationIfSet(animLpActivity, transit, activityTypes);final boolean voiceInteraction = containsVoiceInteraction(mDisplayContent.mOpeningApps)|| containsVoiceInteraction(mDisplayContent.mOpeningApps);final int layoutRedo;mService.mSurfaceAnimationRunner.deferStartingAnimations();try {applyAnimations(mDisplayContent.mOpeningApps, mDisplayContent.mClosingApps, transit,animLp, voiceInteraction);handleClosingApps();handleOpeningApps();handleChangingApps(transit);appTransition.setLastAppTransition(transit, topOpeningApp,topClosingApp, topChangingApp);final int flags = appTransition.getTransitFlags();layoutRedo = appTransition.goodToGo(transit, topOpeningApp,mDisplayContent.mOpeningApps);handleNonAppWindowsInTransition(transit, flags);appTransition.postAnimationCallback();appTransition.clear();} finally {mService.mSurfaceAnimationRunner.continueStartingAnimations();}mService.mTaskSnapshotController.onTransitionStarting(mDisplayContent);mDisplayContent.mOpeningApps.clear();mDisplayContent.mClosingApps.clear();mDisplayContent.mChangingContainers.clear();mDisplayContent.mUnknownAppVisibilityController.clear();// This has changed the visibility of windows, so perform// a new layout to get them all up-to-date.mDisplayContent.setLayoutNeeded();mDisplayContent.computeImeTarget(true /* updateImeTarget */);mService.mAtmService.mStackSupervisor.getActivityMetricsLogger().notifyTransitionStarting(mTempTransitionReasons);if (transit == TRANSIT_SHOW_SINGLE_TASK_DISPLAY) {mService.mAnimator.addAfterPrepareSurfacesRunnable(() -> {mService.mAtmInternal.notifySingleTaskDisplayDrawn(mDisplayContent.getDisplayId());});}Trace.traceEnd(Trace.TRACE_TAG_WINDOW_MANAGER);mDisplayContent.pendingLayoutChanges |=layoutRedo | FINISH_LAYOUT_REDO_LAYOUT | FINISH_LAYOUT_REDO_CONFIG;}

其中调用了AppTransitionController的applyAnimations方法：

    /*** Apply an app transition animation based on a set of {@link ActivityRecord}** @param openingApps The list of opening apps to which an app transition animation applies.* @param closingApps The list of closing apps to which an app transition animation applies.* @param transit The current transition type.* @param animLp Layout parameters in which an app transition animation runs.* @param voiceInteraction {@code true} if one of the apps in this transition belongs to a voice*                         interaction session driving task.*/private void applyAnimations(ArraySet<ActivityRecord> openingApps,ArraySet<ActivityRecord> closingApps, @TransitionType int transit,LayoutParams animLp, boolean voiceInteraction) {if (transit == WindowManager.TRANSIT_UNSET|| (openingApps.isEmpty() && closingApps.isEmpty())) {return;}final ArraySet<WindowContainer> openingWcs = getAnimationTargets(openingApps, closingApps, true /* visible */);final ArraySet<WindowContainer> closingWcs = getAnimationTargets(openingApps, closingApps, false /* visible */);applyAnimations(openingWcs, openingApps, transit, true /* visible */, animLp,voiceInteraction);applyAnimations(closingWcs, closingApps, transit, false /* visible */, animLp,voiceInteraction);final AccessibilityController accessibilityController =mDisplayContent.mWmService.mAccessibilityController;if (accessibilityController != null) {accessibilityController.onAppWindowTransitionLocked(mDisplayContent.getDisplayId(), transit);}}/*** Apply animation to the set of window containers.** @param wcs The list of {@link WindowContainer}s to which an app transition animation applies.* @param apps The list of {@link ActivityRecord}s being transitioning.* @param transit The current transition type.* @param visible {@code true} if the apps becomes visible, {@code false} if the apps becomes*                invisible.* @param animLp Layout parameters in which an app transition animation runs.* @param voiceInteraction {@code true} if one of the apps in this transition belongs to a voice*                         interaction session driving task.*/private void applyAnimations(ArraySet<WindowContainer> wcs, ArraySet<ActivityRecord> apps,@TransitionType int transit, boolean visible, LayoutParams animLp,boolean voiceInteraction) {final int wcsCount = wcs.size();for (int i = 0; i < wcsCount; i++) {final WindowContainer wc = wcs.valueAt(i);// If app transition animation target is promoted to higher level, SurfaceAnimator// triggers WC#onAnimationFinished only on the promoted target. So we need to take care// of triggering AR#onAnimationFinished on each ActivityRecord which is a part of the// app transition.final ArrayList<ActivityRecord> transitioningDescendants = new ArrayList<>();for (int j = 0; j < apps.size(); ++j) {final ActivityRecord app = apps.valueAt(j);if (app.isDescendantOf(wc)) {transitioningDescendants.add(app);}}wc.applyAnimation(animLp, transit, visible, voiceInteraction, transitioningDescendants);}}

调用了WindowContainer的applyAnimation方法：

    /*** Applies the app transition animation according the given the layout properties in the* window hierarchy.** @param lp The layout parameters of the window.* @param transit The app transition type indicates what kind of transition to be applied.* @param enter Whether the app transition is entering transition or not.* @param isVoiceInteraction Whether the container is participating in voice interaction or not.* @param sources {@link ActivityRecord}s which causes this app transition animation.** @return {@code true} when the container applied the app transition, {@code false} if the*         app transition is disabled or skipped.** @see #getAnimationAdapter*/boolean applyAnimation(WindowManager.LayoutParams lp, int transit, boolean enter,boolean isVoiceInteraction, @Nullable ArrayList<WindowContainer> sources) {if (mWmService.mDisableTransitionAnimation) {ProtoLog.v(WM_DEBUG_APP_TRANSITIONS_ANIM,"applyAnimation: transition animation is disabled or skipped. "+ "container=%s", this);cancelAnimation();return false;}// Only apply an animation if the display isn't frozen. If it is frozen, there is no reason// to animate and it can cause strange artifacts when we unfreeze the display if some// different animation is running.try {Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "WC#applyAnimation");if (okToAnimate()) {applyAnimationUnchecked(lp, enter, transit, isVoiceInteraction, sources);} else {cancelAnimation();}} finally {Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);}return isAnimating();}

调用了WindowContainer的applyAnimationUnchecked方法：

    protected void applyAnimationUnchecked(WindowManager.LayoutParams lp, boolean enter,int transit, boolean isVoiceInteraction,@Nullable ArrayList<WindowContainer> sources) {final Pair<AnimationAdapter, AnimationAdapter> adapters = getAnimationAdapter(lp,transit, enter, isVoiceInteraction);AnimationAdapter adapter = adapters.first;AnimationAdapter thumbnailAdapter = adapters.second;if (adapter != null) {if (sources != null) {mSurfaceAnimationSources.addAll(sources);}startAnimation(getPendingTransaction(), adapter, !isVisible(),ANIMATION_TYPE_APP_TRANSITION);if (adapter.getShowWallpaper()) {getDisplayContent().pendingLayoutChanges |= FINISH_LAYOUT_REDO_WALLPAPER;}if (thumbnailAdapter != null) {mSurfaceFreezer.mSnapshot.startAnimation(getPendingTransaction(),thumbnailAdapter, ANIMATION_TYPE_APP_TRANSITION, (type, anim) -> { });}}}

首先调用了WindowContainer的getAnimationAdapter方法：

    /*** Gets the {@link AnimationAdapter} according the given window layout properties in the window* hierarchy.** @return The return value will always contain two elements, one for normal animations and the*         other for thumbnail animation, both can be {@code null}.** @See com.android.server.wm.RemoteAnimationController.RemoteAnimationRecord* @See LocalAnimationAdapter*/Pair<AnimationAdapter, AnimationAdapter> getAnimationAdapter(WindowManager.LayoutParams lp,int transit, boolean enter, boolean isVoiceInteraction) {final Pair<AnimationAdapter, AnimationAdapter> resultAdapters;......if (controller != null && !mSurfaceAnimator.isAnimationStartDelayed()) {......} else if (isChanging) {......} else {mNeedsAnimationBoundsLayer = (appStackClipMode == STACK_CLIP_AFTER_ANIM);final Animation a = loadAnimation(lp, transit, enter, isVoiceInteraction);if (a != null) {// Only apply corner radius to animation if we're not in multi window mode.// We don't want rounded corners when in pip or split screen.final float windowCornerRadius = !inMultiWindowMode()? getDisplayContent().getWindowCornerRadius(): 0;AnimationAdapter adapter = new LocalAnimationAdapter(new WindowAnimationSpec(a, mTmpPoint, mTmpRect,getDisplayContent().mAppTransition.canSkipFirstFrame(),appStackClipMode, true /* isAppAnimation */, windowCornerRadius),getSurfaceAnimationRunner());resultAdapters = new Pair<>(adapter, null);mNeedsZBoost = a.getZAdjustment() == Animation.ZORDER_TOP|| AppTransition.isClosingTransit(transit);mTransit = transit;mTransitFlags = getDisplayContent().mAppTransition.getTransitFlags();} else {resultAdapters = new Pair<>(null, null);}}return resultAdapters;}

创建了LocalAnimationAdapter作为AnimationAdapter。

WindowContainer的applyAnimationUnchecked后面还调用了WindowContainer的startAnimation方法：

    void startAnimation(Transaction t, AnimationAdapter anim, boolean hidden,@AnimationType int type) {startAnimation(t, anim, hidden, type, null /* animationFinishedCallback */);}/*** Starts an animation on the container.** @param anim The animation to run.* @param hidden Whether our container is currently hidden. TODO This should use isVisible at*               some point but the meaning is too weird to work for all containers.* @param type The type of animation defined as {@link AnimationType}.* @param animationFinishedCallback The callback being triggered when the animation finishes.*/void startAnimation(Transaction t, AnimationAdapter anim, boolean hidden,@AnimationType int type,@Nullable OnAnimationFinishedCallback animationFinishedCallback) {if (DEBUG_ANIM) {Slog.v(TAG, "Starting animation on " + this + ": type=" + type + ", anim=" + anim);}// TODO: This should use isVisible() but because isVisible has a really weird meaning at// the moment this doesn't work for all animatable window containers.mSurfaceAnimator.startAnimation(t, anim, hidden, type, animationFinishedCallback,mSurfaceFreezer);}

最后在SurfaceAnimator的startAnimation方法中创建Leash并调用Animatable（WindowContainer）的onAnimationLeashCreated方法和AnimationAdapter（LocalAnimationAdapter）的startAnimation方法来开始执行动画。

远程动画

以在桌面点击悬浮窗形式的Notification打开Activity为例，整个动画流程是这样的：

1 在systemui进程中接收点击事件，创建RemoteAnimationAdapter

从StatusBarNotificationActivityStarter的onNotificationClicked方法开始：

    /*** Called when a notification is clicked.** @param sbn notification that was clicked* @param row row for that notification*/@Overridepublic void onNotificationClicked(StatusBarNotification sbn, ExpandableNotificationRow row) {......ActivityStarter.OnDismissAction postKeyguardAction =() -> handleNotificationClickAfterKeyguardDismissed(sbn, row, controller, intent,isActivityIntent, wasOccluded, showOverLockscreen);if (showOverLockscreen) {mIsCollapsingToShowActivityOverLockscreen = true;postKeyguardAction.onDismiss();} else {mActivityStarter.dismissKeyguardThenExecute(postKeyguardAction, null /* cancel */, afterKeyguardGone);}}

在Keyguard消失后会调用StatusBarNotificationActivityStarter的handleNotificationClickAfterKeyguardDismissed方法：

    private boolean handleNotificationClickAfterKeyguardDismissed(StatusBarNotification sbn,ExpandableNotificationRow row,RemoteInputController controller,PendingIntent intent,boolean isActivityIntent,boolean wasOccluded,boolean showOverLockscreen) {......final Runnable runnable = () -> handleNotificationClickAfterPanelCollapsed(sbn, row, controller, intent,isActivityIntent, wasOccluded, parentToCancelFinal);if (showOverLockscreen) {mShadeController.addPostCollapseAction(runnable);mShadeController.collapsePanel(true /* animate */);} else if (mKeyguardStateController.isShowing()&& mStatusBar.isOccluded()) {mStatusBarKeyguardViewManager.addAfterKeyguardGoneRunnable(runnable);mShadeController.collapsePanel();} else {mBackgroundHandler.postAtFrontOfQueue(runnable);}return !mNotificationPanel.isFullyCollapsed();}

最终会调用StatusBarNotificationActivityStarter的handleNotificationClickAfterPanelCollapsed方法：

    private void handleNotificationClickAfterPanelCollapsed(StatusBarNotification sbn,ExpandableNotificationRow row,RemoteInputController controller,PendingIntent intent,boolean isActivityIntent,boolean wasOccluded,NotificationEntry parentToCancelFinal) {......startNotificationIntent(intent, fillInIntent, entry, row, wasOccluded, isActivityIntent);......}

调用了StatusBarNotificationActivityStarter的startNotificationIntent方法：

    private void startNotificationIntent(PendingIntent intent,Intent fillInIntent,NotificationEntry entry,View row,boolean wasOccluded,boolean isActivityIntent) {RemoteAnimationAdapter adapter = mActivityLaunchAnimator.getLaunchAnimation(row,wasOccluded);mLogger.logStartNotificationIntent(entry.getKey(), intent);try {if (adapter != null) {ActivityTaskManager.getService().registerRemoteAnimationForNextActivityStart(intent.getCreatorPackage(), adapter);}int launchResult = intent.sendAndReturnResult(mContext, 0, fillInIntent, null,null, null, getActivityOptions(adapter));mMainThreadHandler.post(() -> {mActivityLaunchAnimator.setLaunchResult(launchResult, isActivityIntent);});} catch (RemoteException | PendingIntent.CanceledException e) {// the stack trace isn't very helpful here.// Just log the exception message.mLogger.logSendingIntentFailed(e);// TODO: Dismiss Keyguard.}}

调用了ActivityLaunchAnimator的getLaunchAnimation方法：

    public RemoteAnimationAdapter getLaunchAnimation(View sourceView, boolean occluded) {if (!(sourceView instanceof ExpandableNotificationRow)|| !mCallback.areLaunchAnimationsEnabled() || occluded) {return null;}AnimationRunner animationRunner = new AnimationRunner((ExpandableNotificationRow) sourceView);return new RemoteAnimationAdapter(animationRunner, ANIMATION_DURATION,ANIMATION_DURATION - 150 /* statusBarTransitionDelay */);}

其中AnimationRunner是ActivityLaunchAnimator的内部类，其继承了IRemoteAnimationRunner.Stub：

    class AnimationRunner extends IRemoteAnimationRunner.Stub {private final ExpandableNotificationRow mSourceNotification;private final ExpandAnimationParameters mParams;private final Rect mWindowCrop = new Rect();private final float mNotificationCornerRadius;private float mCornerRadius;private boolean mIsFullScreenLaunch = true;private final SyncRtSurfaceTransactionApplier mSyncRtTransactionApplier;public AnimationRunner(ExpandableNotificationRow sourceNofitication) {mSourceNotification = sourceNofitication;mParams = new ExpandAnimationParameters();mSyncRtTransactionApplier = new SyncRtSurfaceTransactionApplier(mSourceNotification);mNotificationCornerRadius = Math.max(mSourceNotification.getCurrentTopRoundness(),mSourceNotification.getCurrentBottomRoundness());}@Overridepublic void onAnimationStart(RemoteAnimationTarget[] remoteAnimationTargets,RemoteAnimationTarget[] remoteAnimationWallpaperTargets,IRemoteAnimationFinishedCallback iRemoteAnimationFinishedCallback)throws RemoteException {mMainExecutor.execute(() -> {RemoteAnimationTarget primary = getPrimaryRemoteAnimationTarget(remoteAnimationTargets);if (primary == null) {setAnimationPending(false);invokeCallback(iRemoteAnimationFinishedCallback);mNotificationPanel.collapse(false /* delayed */, 1.0f /* speedUpFactor */);return;}setExpandAnimationRunning(true);mIsFullScreenLaunch = primary.position.y == 0&& primary.sourceContainerBounds.height()>= mNotificationPanel.getHeight();if (!mIsFullScreenLaunch) {mNotificationPanel.collapseWithDuration(ANIMATION_DURATION);}ValueAnimator anim = ValueAnimator.ofFloat(0, 1);mParams.startPosition = mSourceNotification.getLocationOnScreen();mParams.startTranslationZ = mSourceNotification.getTranslationZ();mParams.startClipTopAmount = mSourceNotification.getClipTopAmount();if (mSourceNotification.isChildInGroup()) {int parentClip = mSourceNotification.getNotificationParent().getClipTopAmount();mParams.parentStartClipTopAmount = parentClip;// We need to calculate how much the child is clipped by the parent// because children always have 0 clipTopAmountif (parentClip != 0) {float childClip = parentClip- mSourceNotification.getTranslationY();if (childClip > 0.0f) {mParams.startClipTopAmount = (int) Math.ceil(childClip);}}}int targetWidth = primary.sourceContainerBounds.width();// If the notification panel is collapsed, the clip may be larger than the height.int notificationHeight = Math.max(mSourceNotification.getActualHeight()- mSourceNotification.getClipBottomAmount(), 0);int notificationWidth = mSourceNotification.getWidth();anim.setDuration(ANIMATION_DURATION);anim.setInterpolator(Interpolators.LINEAR);anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {@Overridepublic void onAnimationUpdate(ValueAnimator animation) {mParams.linearProgress = animation.getAnimatedFraction();float progress = Interpolators.FAST_OUT_SLOW_IN.getInterpolation(mParams.linearProgress);int newWidth = (int) MathUtils.lerp(notificationWidth,targetWidth, progress);mParams.left = (int) ((targetWidth - newWidth) / 2.0f);mParams.right = mParams.left + newWidth;mParams.top = (int) MathUtils.lerp(mParams.startPosition[1],primary.position.y, progress);mParams.bottom = (int) MathUtils.lerp(mParams.startPosition[1]+ notificationHeight,primary.position.y + primary.sourceContainerBounds.bottom,progress);mCornerRadius = MathUtils.lerp(mNotificationCornerRadius,mWindowCornerRadius, progress);applyParamsToWindow(primary);applyParamsToNotification(mParams);applyParamsToNotificationShade(mParams);}});anim.addListener(new AnimatorListenerAdapter() {@Overridepublic void onAnimationEnd(Animator animation) {setExpandAnimationRunning(false);invokeCallback(iRemoteAnimationFinishedCallback);}});anim.start();setAnimationPending(false);});}private void invokeCallback(IRemoteAnimationFinishedCallback callback) {try {callback.onAnimationFinished();} catch (RemoteException e) {e.printStackTrace();}}private RemoteAnimationTarget getPrimaryRemoteAnimationTarget(RemoteAnimationTarget[] remoteAnimationTargets) {RemoteAnimationTarget primary = null;for (RemoteAnimationTarget app : remoteAnimationTargets) {if (app.mode == RemoteAnimationTarget.MODE_OPENING) {primary = app;break;}}return primary;}private void setExpandAnimationRunning(boolean running) {mNotificationPanel.setLaunchingNotification(running);mSourceNotification.setExpandAnimationRunning(running);mNotificationShadeWindowViewController.setExpandAnimationRunning(running);mNotificationContainer.setExpandingNotification(running ? mSourceNotification : null);mAnimationRunning = running;if (!running) {mCallback.onExpandAnimationFinished(mIsFullScreenLaunch);applyParamsToNotification(null);applyParamsToNotificationShade(null);}}private void applyParamsToNotificationShade(ExpandAnimationParameters params) {mNotificationContainer.applyExpandAnimationParams(params);mNotificationPanel.applyExpandAnimationParams(params);mDepthController.setNotificationLaunchAnimationParams(params);}private void applyParamsToNotification(ExpandAnimationParameters params) {mSourceNotification.applyExpandAnimationParams(params);}private void applyParamsToWindow(RemoteAnimationTarget app) {Matrix m = new Matrix();m.postTranslate(0, (float) (mParams.top - app.position.y));mWindowCrop.set(mParams.left, 0, mParams.right, mParams.getHeight());SurfaceParams params = new SurfaceParams.Builder(app.leash).withAlpha(1f).withMatrix(m).withWindowCrop(mWindowCrop).withLayer(app.prefixOrderIndex).withCornerRadius(mCornerRadius).withVisibility(true).build();mSyncRtTransactionApplier.scheduleApply(params);}@Overridepublic void onAnimationCancelled() throws RemoteException {mMainExecutor.execute(() -> {setAnimationPending(false);mCallback.onLaunchAnimationCancelled();});}};

在StatusBarNotificationActivityStarter的startNotificationIntent方法中，创建好了RemoteAnimationAdapter后，通过binder调用了ActivityTaskManagerService的registerRemoteAnimationForNextActivityStart方法：

    @Overridepublic void registerRemoteAnimationForNextActivityStart(String packageName,RemoteAnimationAdapter adapter) {mAmInternal.enforceCallingPermission(CONTROL_REMOTE_APP_TRANSITION_ANIMATIONS,"registerRemoteAnimationForNextActivityStart");adapter.setCallingPidUid(Binder.getCallingPid(), Binder.getCallingUid());synchronized (mGlobalLock) {final long origId = Binder.clearCallingIdentity();try {getActivityStartController().registerRemoteAnimationForNextActivityStart(packageName, adapter);} finally {Binder.restoreCallingIdentity(origId);}}}

调用了ActivityStartController的registerRemoteAnimationForNextActivityStart方法：

    void registerRemoteAnimationForNextActivityStart(String packageName,RemoteAnimationAdapter adapter) {mPendingRemoteAnimationRegistry.addPendingAnimation(packageName, adapter);}

调用了PendingRemoteAnimationRegistry的addPendingAnimation方法：

    private final ArrayMap<String, Entry> mEntries = new ArrayMap<>();/*** Adds a remote animation to be run for all activity starts originating from a certain package.*/void addPendingAnimation(String packageName, RemoteAnimationAdapter adapter) {mEntries.put(packageName, new Entry(packageName, adapter));}

最终将RemoteAnimationAdapter保存到了ActivityTaskManagerService.mActivityStartController.mPendingRemoteAnimationRegistry.mEntries中。

2 在ActivityStarter启动Activity时，将RemoteAnimationAdapter保存在ActivityOptions中

在ActivityStarter的executeRequest方法中：

    /*** Executing activity start request and starts the journey of starting an activity. Here* begins with performing several preliminary checks. The normally activity launch flow will* go through {@link #startActivityUnchecked} to {@link #startActivityInner}.*/private int executeRequest(Request request) {......if (request.allowPendingRemoteAnimationRegistryLookup) {checkedOptions = mService.getActivityStartController().getPendingRemoteAnimationRegistry().overrideOptionsIfNeeded(callingPackage, checkedOptions);}......final ActivityRecord r = new ActivityRecord(mService, callerApp, callingPid, callingUid,callingPackage, callingFeatureId, intent, resolvedType, aInfo,mService.getGlobalConfiguration(), resultRecord, resultWho, requestCode,request.componentSpecified, voiceSession != null, mSupervisor, checkedOptions,sourceRecord);......}

调用了PendingRemoteAnimationRegistry的overrideOptionsIfNeeded方法：

    /*** Overrides the activity options with a registered remote animation for a certain calling* package if such a remote animation is registered.*/ActivityOptions overrideOptionsIfNeeded(String callingPackage,@Nullable ActivityOptions options) {final Entry entry = mEntries.get(callingPackage);if (entry == null) {return options;}if (options == null) {options = ActivityOptions.makeRemoteAnimation(entry.adapter);} else {options.setRemoteAnimationAdapter(entry.adapter);}mEntries.remove(callingPackage);return options;}

将RemoteAnimationAdapter保存在了ActivityOptions中。

在ActivityStarter的executeRequest方法后面还调用了ActivityRecord的构造器：

    ActivityRecord(ActivityTaskManagerService _service, WindowProcessController _caller,int _launchedFromPid, int _launchedFromUid, String _launchedFromPackage,@Nullable String _launchedFromFeature, Intent _intent, String _resolvedType,ActivityInfo aInfo, Configuration _configuration, ActivityRecord _resultTo,String _resultWho, int _reqCode, boolean _componentSpecified,boolean _rootVoiceInteraction, ActivityStackSupervisor supervisor,ActivityOptions options, ActivityRecord sourceRecord) {......if (options != null) {pendingOptions = options;......}

将这个ActivityOptions保存在了ActivityRecord的成员变量pendingOptions中。

3 ATMS将桌面Pause后，要对新的Activity进行Resume前，检查ActivityOptions时，将RemoteAnimationAdapter保存在了AppTransition的RemoteAnimationController中

先看ActivityTaskManagerService的activityPaused方法：

    @Overridepublic final void activityPaused(IBinder token) {final long origId = Binder.clearCallingIdentity();synchronized (mGlobalLock) {Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "activityPaused");final ActivityRecord r = ActivityRecord.forTokenLocked(token);if (r != null) {r.activityPaused(false);}Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);}Binder.restoreCallingIdentity(origId);}

其中r就是桌面的ActivityRecord，调用了其activityPaused方法：

    void activityPaused(boolean timeout) {if (DEBUG_PAUSE) Slog.v(TAG_PAUSE,"Activity paused: token=" + appToken + ", timeout=" + timeout);final ActivityStack stack = getStack();if (stack != null) {removePauseTimeout();if (stack.mPausingActivity == this) {if (DEBUG_STATES) Slog.v(TAG_STATES, "Moving to PAUSED: " + this+ (timeout ? " (due to timeout)" : " (pause complete)"));mAtmService.deferWindowLayout();try {stack.completePauseLocked(true /* resumeNext */, null /* resumingActivity */);} finally {mAtmService.continueWindowLayout();}return;} else {EventLogTags.writeWmFailedToPause(mUserId, System.identityHashCode(this),shortComponentName, stack.mPausingActivity != null? stack.mPausingActivity.shortComponentName : "(none)");if (isState(PAUSING)) {callServiceTrackeronActivityStatechange(PAUSED, true);setState(PAUSED, "activityPausedLocked");if (finishing) {if (DEBUG_PAUSE) Slog.v(TAG,"Executing finish of failed to pause activity: " + this);completeFinishing("activityPausedLocked");}}}}mRootWindowContainer.ensureActivitiesVisible(null, 0, !PRESERVE_WINDOWS);}

又调用了其ActivityStack的completePauseLocked方法：

    @VisibleForTestingvoid completePauseLocked(boolean resumeNext, ActivityRecord resuming) {ActivityRecord prev = mPausingActivity;......if (resumeNext) {final ActivityStack topStack = mRootWindowContainer.getTopDisplayFocusedStack();if (topStack != null && !topStack.shouldSleepOrShutDownActivities()) {mRootWindowContainer.resumeFocusedStacksTopActivities(topStack, prev, null);}......}......}

调用了RootWindowContainer的resumeFocusedStacksTopActivities方法：

    boolean resumeFocusedStacksTopActivities(ActivityStack targetStack, ActivityRecord target, ActivityOptions targetOptions) {......if (targetStack != null && (targetStack.isTopStackInDisplayArea()|| getTopDisplayFocusedStack() == targetStack)) {result = targetStack.resumeTopActivityUncheckedLocked(target, targetOptions);}......}

调用了ActivityStack的resumeTopActivityUncheckedLocked方法：

    /*** Ensure that the top activity in the stack is resumed.** @param prev The previously resumed activity, for when in the process* of pausing; can be null to call from elsewhere.* @param options Activity options.** @return Returns true if something is being resumed, or false if* nothing happened.** NOTE: It is not safe to call this method directly as it can cause an activity in a*       non-focused stack to be resumed.*       Use {@link RootWindowContainer#resumeFocusedStacksTopActivities} to resume the*       right activity for the current system state.*/@GuardedBy("mService")boolean resumeTopActivityUncheckedLocked(ActivityRecord prev, ActivityOptions options) {......try {......result = resumeTopActivityInnerLocked(prev, options);......}......}

调用了ActivityStack的resumeTopActivityInnerLocked方法：

    @GuardedBy("mService")private boolean resumeTopActivityInnerLocked(ActivityRecord prev, ActivityOptions options) {......if (anim) {next.applyOptionsLocked();}......}

其中next是要启动的Activity的ActivityRecord，调用了其applyOptionsLocked方法：

    void applyOptionsLocked() {if (pendingOptions != null&& pendingOptions.getAnimationType() != ANIM_SCENE_TRANSITION) {......applyOptionsLocked(pendingOptions, intent);......}}/*** Apply override app transition base on options & animation type.*/void applyOptionsLocked(ActivityOptions pendingOptions, Intent intent) {final int animationType = pendingOptions.getAnimationType();final DisplayContent displayContent = getDisplayContent();switch (animationType) {......case ANIM_REMOTE_ANIMATION:displayContent.mAppTransition.overridePendingAppTransitionRemote(pendingOptions.getRemoteAnimationAdapter());break;......}}

根据上一步可知，这里的pendingOptions中保存了systemui进程传来的RemoteAnimationAdapter。

最后调用了AppTransition的overridePendingAppTransitionRemote方法：

    void overridePendingAppTransitionRemote(RemoteAnimationAdapter remoteAnimationAdapter) {ProtoLog.i(WM_DEBUG_APP_TRANSITIONS, "Override pending remote transitionSet=%b adapter=%s",isTransitionSet(), remoteAnimationAdapter);if (isTransitionSet()) {clear();mNextAppTransitionType = NEXT_TRANSIT_TYPE_REMOTE;mRemoteAnimationController = new RemoteAnimationController(mService,remoteAnimationAdapter, mHandler);}}

在这里创建了RemoteAnimationController，其中保存了RemoteAnimationAdapter。

4 在app过渡动画流程中，使用RemoteAnimationAdapterWrapper作为AnimationAdapter

在WindowContainer的applyAnimationUnchecked方法中调用了WindowContainer的getAnimationAdapter方法：

    /*** Gets the {@link AnimationAdapter} according the given window layout properties in the window* hierarchy.** @return The return value will always contain two elements, one for normal animations and the*         other for thumbnail animation, both can be {@code null}.** @See com.android.server.wm.RemoteAnimationController.RemoteAnimationRecord* @See LocalAnimationAdapter*/Pair<AnimationAdapter, AnimationAdapter> getAnimationAdapter(WindowManager.LayoutParams lp,int transit, boolean enter, boolean isVoiceInteraction) {final Pair<AnimationAdapter, AnimationAdapter> resultAdapters;......final RemoteAnimationController controller =getDisplayContent().mAppTransition.getRemoteAnimationController();......// Delaying animation start isn't compatible with remote animations at all.if (controller != null && !mSurfaceAnimator.isAnimationStartDelayed()) {final Rect localBounds = new Rect(mTmpRect);localBounds.offsetTo(mTmpPoint.x, mTmpPoint.y);final RemoteAnimationController.RemoteAnimationRecord adapters =controller.createRemoteAnimationRecord(this, mTmpPoint, localBounds,screenBounds, (isChanging ? mSurfaceFreezer.mFreezeBounds : null));resultAdapters = new Pair<>(adapters.mAdapter, adapters.mThumbnailAdapter);}......return resultAdapters;}

其中调用了RemoteAnimationController的createRemoteAnimationRecord方法：

    /*** Creates an animation record for each individual {@link WindowContainer}.** @param windowContainer The windows to animate.* @param position The position app bounds, in screen coordinates.* @param localBounds The bounds of the app relative to its parent.* @param stackBounds The stack bounds of the app relative to position.* @param startBounds The stack bounds before the transition, in screen coordinates* @return The record representing animation(s) to run on the app.*/RemoteAnimationRecord createRemoteAnimationRecord(WindowContainer windowContainer,Point position, Rect localBounds, Rect stackBounds, Rect startBounds) {ProtoLog.d(WM_DEBUG_REMOTE_ANIMATIONS, "createAnimationAdapter(): container=%s",windowContainer);final RemoteAnimationRecord adapters = new RemoteAnimationRecord(windowContainer, position,localBounds, stackBounds, startBounds);mPendingAnimations.add(adapters);return adapters;}

RemoteAnimationRecord是RemoteAnimationController的内部类：

    /*** Contains information about a remote-animation for one WindowContainer. This keeps track of,* potentially, multiple animating surfaces (AdapterWrappers) associated with one* Window/Transition. For example, a change transition has an adapter controller for the* main window and an adapter controlling the start-state snapshot.* <p>* This can be thought of as a bridge between the information that the remote animator sees (via* {@link RemoteAnimationTarget}) and what the server sees (the* {@link RemoteAnimationAdapterWrapper}(s) interfacing with the moving surfaces).*/public class RemoteAnimationRecord {RemoteAnimationAdapterWrapper mAdapter;RemoteAnimationAdapterWrapper mThumbnailAdapter = null;RemoteAnimationTarget mTarget;final WindowContainer mWindowContainer;final Rect mStartBounds;RemoteAnimationRecord(WindowContainer windowContainer, Point endPos, Rect localBounds,Rect endBounds, Rect startBounds) {mWindowContainer = windowContainer;mAdapter = new RemoteAnimationAdapterWrapper(this, endPos, localBounds, endBounds);if (startBounds != null) {mStartBounds = new Rect(startBounds);mTmpRect.set(startBounds);mTmpRect.offsetTo(0, 0);if (mRemoteAnimationAdapter.getChangeNeedsSnapshot()) {mThumbnailAdapter =new RemoteAnimationAdapterWrapper(this, new Point(0, 0), localBounds,mTmpRect);}} else {mStartBounds = null;}}RemoteAnimationTarget createRemoteAnimationTarget() {if (mAdapter == null|| mAdapter.mCapturedFinishCallback == null|| mAdapter.mCapturedLeash == null) {return null;}mTarget = mWindowContainer.createRemoteAnimationTarget(this);return mTarget;}int getMode() {final DisplayContent dc = mWindowContainer.getDisplayContent();final ActivityRecord topActivity = mWindowContainer.getTopMostActivity();// Note that opening/closing transitions are per-activity while changing transitions// are per-task.if (dc.mOpeningApps.contains(topActivity)) {return RemoteAnimationTarget.MODE_OPENING;} else if (dc.mChangingContainers.contains(mWindowContainer)) {return RemoteAnimationTarget.MODE_CHANGING;} else {return RemoteAnimationTarget.MODE_CLOSING;}}}

RemoteAnimationAdapterWrapper是RemoteAnimationController的内部类，其实现了AnimationAdapter接口：

    class RemoteAnimationAdapterWrapper implements AnimationAdapter {private final RemoteAnimationRecord mRecord;SurfaceControl mCapturedLeash;private OnAnimationFinishedCallback mCapturedFinishCallback;private @AnimationType int mAnimationType;final Point mPosition = new Point();final Rect mLocalBounds;final Rect mStackBounds = new Rect();RemoteAnimationAdapterWrapper(RemoteAnimationRecord record, Point position,Rect localBounds, Rect stackBounds) {mRecord = record;mPosition.set(position.x, position.y);mLocalBounds = localBounds;mStackBounds.set(stackBounds);}@Overridepublic boolean getShowWallpaper() {return false;}@Overridepublic void startAnimation(SurfaceControl animationLeash, Transaction t,@AnimationType int type, OnAnimationFinishedCallback finishCallback) {ProtoLog.d(WM_DEBUG_REMOTE_ANIMATIONS, "startAnimation");// Restore position and stack crop until client has a chance to modify it.if (mRecord.mStartBounds != null) {t.setPosition(animationLeash, mRecord.mStartBounds.left, mRecord.mStartBounds.top);t.setWindowCrop(animationLeash, mRecord.mStartBounds.width(),mRecord.mStartBounds.height());} else {t.setPosition(animationLeash, mPosition.x, mPosition.y);t.setWindowCrop(animationLeash, mStackBounds.width(), mStackBounds.height());}mCapturedLeash = animationLeash;mCapturedFinishCallback = finishCallback;mAnimationType = type;}@Overridepublic void onAnimationCancelled(SurfaceControl animationLeash) {if (mRecord.mAdapter == this) {mRecord.mAdapter = null;} else {mRecord.mThumbnailAdapter = null;}if (mRecord.mAdapter == null && mRecord.mThumbnailAdapter == null) {mPendingAnimations.remove(mRecord);}if (mPendingAnimations.isEmpty()) {cancelAnimation("allAppAnimationsCanceled");}}@Overridepublic long getDurationHint() {return mRemoteAnimationAdapter.getDuration();}@Overridepublic long getStatusBarTransitionsStartTime() {return SystemClock.uptimeMillis()+ mRemoteAnimationAdapter.getStatusBarTransitionDelay();}@Overridepublic void dump(PrintWriter pw, String prefix) {pw.print(prefix); pw.print("container="); pw.println(mRecord.mWindowContainer);if (mRecord.mTarget != null) {pw.print(prefix); pw.println("Target:");mRecord.mTarget.dump(pw, prefix + "  ");} else {pw.print(prefix); pw.println("Target: null");}}@Overridepublic void dumpDebug(ProtoOutputStream proto) {final long token = proto.start(REMOTE);if (mRecord.mTarget != null) {mRecord.mTarget.dumpDebug(proto, TARGET);}proto.end(token);}}

5 调用IRemoteAnimationRunner的onAnimationStart方法开始进行远程动画

在AppTransitionController的handleAppTransitionReady方法后面还调用了AppTransition的goodToGo方法：

    /*** @return bit-map of WindowManagerPolicy#FINISH_LAYOUT_REDO_* to indicate whether another*         layout pass needs to be done*/int goodToGo(int transit, ActivityRecord topOpeningApp, ArraySet<ActivityRecord> openingApps) {......if (mRemoteAnimationController != null) {mRemoteAnimationController.goodToGo();}......}

调用了RemoteAnimationController的goodToGo方法：

    /*** Called when the transition is ready to be started, and all leashes have been set up.*/void goodToGo() {ProtoLog.d(WM_DEBUG_REMOTE_ANIMATIONS, "goodToGo()");if (mPendingAnimations.isEmpty() || mCanceled) {ProtoLog.d(WM_DEBUG_REMOTE_ANIMATIONS,"goodToGo(): Animation finished already, canceled=%s mPendingAnimations=%d",mCanceled, mPendingAnimations.size());onAnimationFinished();return;}// Scale the timeout with the animator scale the controlling app is using.mHandler.postDelayed(mTimeoutRunnable,(long) (TIMEOUT_MS * mService.getCurrentAnimatorScale()));mFinishedCallback = new FinishedCallback(this);// Create the app targetsfinal RemoteAnimationTarget[] appTargets = createAppAnimations();if (appTargets.length == 0) {ProtoLog.d(WM_DEBUG_REMOTE_ANIMATIONS, "goodToGo(): No apps to animate");onAnimationFinished();return;}// Create the remote wallpaper animation targets (if any)final RemoteAnimationTarget[] wallpaperTargets = createWallpaperAnimations();mService.mAnimator.addAfterPrepareSurfacesRunnable(() -> {try {linkToDeathOfRunner();mRemoteAnimationAdapter.getRunner().onAnimationStart(appTargets, wallpaperTargets,mFinishedCallback);} catch (RemoteException e) {Slog.e(TAG, "Failed to start remote animation", e);onAnimationFinished();}if (ProtoLogImpl.isEnabled(WM_DEBUG_REMOTE_ANIMATIONS)) {ProtoLog.d(WM_DEBUG_REMOTE_ANIMATIONS, "startAnimation(): Notify animation start:");writeStartDebugStatement();}});setRunningRemoteAnimation(true);}

最终调用了IRemoteAnimationRunner的onAnimationStart方法开始进行远程动画。

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