Android P ActivityManagerService（六） startActivity的第四小部分
ActivityStarter中，生成ActivityRecord之后startActivity方法；
private int startActivity(final ActivityRecord r, ActivityRecord sourceRecord,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
int startFlags, boolean doResume, ActivityOptions options, TaskRecord inTask,
ActivityRecord[] outActivity) {
int result = START_CANCELED;
try {
mService.mWindowManager.deferSurfaceLayout();
result = startActivityUnchecked(r, sourceRecord, voiceSession, voiceInteractor,
startFlags, doResume, options, inTask, outActivity);
} finally {
// If we are not able to proceed, disassociate the activity from the task. Leaving an
// activity in an incomplete state can lead to issues, such as performing operations
// without a window container.
final ActivityStack stack = mStartActivity.getStack();
if (!ActivityManager.isStartResultSuccessful(result) && stack != null) {
stack.finishActivityLocked(mStartActivity, RESULT_CANCELED,
null /* intentResultData */, "startActivity", true /* oomAdj */);
}
mService.mWindowManager.continueSurfaceLayout();
}
postStartActivityProcessing(r, result, mTargetStack);
return result;
}在AMS的初始化中，SystemServer的startOtherServices方法内，AMS通过setWindowManager方法获得了WindowManagerService；即这里的mService.mWindowManager；
public void setWindowManager(WindowManagerService wm) {
synchronized (this) {
mWindowManager = wm;
mStackSupervisor.setWindowManager(wm);
mLockTaskController.setWindowManager(wm);
}
}WindowManagerService的deferSurfaceLayout方法；通知暂停布局；
/**
* Starts deferring layout passes. Useful when doing multiple changes but to optimize
* performance, only one layout pass should be done. This can be called multiple times, and
* layouting will be resumed once the last caller has called {@link #continueSurfaceLayout}
*/
public void deferSurfaceLayout() {
synchronized (mWindowMap) {
mWindowPlacerLocked.deferLayout();
}
}continueSurfaceLayout方法；恢复暂停的布局；
/**
* Resumes layout passes after deferring them. See {@link #deferSurfaceLayout()}
*/
public void continueSurfaceLayout() {
synchronized (mWindowMap) {
mWindowPlacerLocked.continueLayout();
}
}这两个方法中间，是启动Activity的关键方法；startActivityUnchecked；Unchecked这个词很关键，表示再也不会像之前一样，检查个300行代码了；然后这个启动的代码，也有260行之多；
// Note: This method should only be called from {@link startActivity}.
private int startActivityUnchecked(final ActivityRecord r, ActivityRecord sourceRecord,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
int startFlags, boolean doResume, ActivityOptions options, TaskRecord inTask,
ActivityRecord[] outActivity) {
setInitialState(r, options, inTask, doResume, startFlags, sourceRecord, voiceSession,
voiceInteractor);
computeLaunchingTaskFlags();
computeSourceStack();
mIntent.setFlags(mLaunchFlags);
ActivityRecord reusedActivity = getReusableIntentActivity();
int preferredWindowingMode = WINDOWING_MODE_UNDEFINED;
int preferredLaunchDisplayId = DEFAULT_DISPLAY;
if (mOptions != null) {
preferredWindowingMode = mOptions.getLaunchWindowingMode();
preferredLaunchDisplayId = mOptions.getLaunchDisplayId();
}
// windowing mode and preferred launch display values from {@link LaunchParams} take
// priority over those specified in {@link ActivityOptions}.
if (!mLaunchParams.isEmpty()) {
if (mLaunchParams.hasPreferredDisplay()) {
preferredLaunchDisplayId = mLaunchParams.mPreferredDisplayId;
}
if (mLaunchParams.hasWindowingMode()) {
preferredWindowingMode = mLaunchParams.mWindowingMode;
}
}
if (reusedActivity != null) {
// When the flags NEW_TASK and CLEAR_TASK are set, then the task gets reused but
// still needs to be a lock task mode violation since the task gets cleared out and
// the device would otherwise leave the locked task.
if (mService.getLockTaskController().isLockTaskModeViolation(reusedActivity.getTask(),
(mLaunchFlags & (FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TASK))
== (FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TASK))) {
Slog.e(TAG, "startActivityUnchecked: Attempt to violate Lock Task Mode");
return START_RETURN_LOCK_TASK_MODE_VIOLATION;
}
// True if we are clearing top and resetting of a standard (default) launch mode
// ({@code LAUNCH_MULTIPLE}) activity. The existing activity will be finished.
final boolean clearTopAndResetStandardLaunchMode =
(mLaunchFlags & (FLAG_ACTIVITY_CLEAR_TOP | FLAG_ACTIVITY_RESET_TASK_IF_NEEDED))
== (FLAG_ACTIVITY_CLEAR_TOP | FLAG_ACTIVITY_RESET_TASK_IF_NEEDED)
&& mLaunchMode == LAUNCH_MULTIPLE;
// If mStartActivity does not have a task associated with it, associate it with the
// reused activity's task. Do not do so if we're clearing top and resetting for a
// standard launchMode activity.
if (mStartActivity.getTask() == null && !clearTopAndResetStandardLaunchMode) {
mStartActivity.setTask(reusedActivity.getTask());
}
if (reusedActivity.getTask().intent == null) {
// This task was started because of movement of the activity based on affinity...
// Now that we are actually launching it, we can assign the base intent.
reusedActivity.getTask().setIntent(mStartActivity);
}
// This code path leads to delivering a new intent, we want to make sure we schedule it
// as the first operation, in case the activity will be resumed as a result of later
// operations.
if ((mLaunchFlags & FLAG_ACTIVITY_CLEAR_TOP) != 0
|| isDocumentLaunchesIntoExisting(mLaunchFlags)
|| isLaunchModeOneOf(LAUNCH_SINGLE_INSTANCE, LAUNCH_SINGLE_TASK)) {
final TaskRecord task = reusedActivity.getTask();
// In this situation we want to remove all activities from the task up to the one
// being started. In most cases this means we are resetting the task to its initial
// state.
final ActivityRecord top = task.performClearTaskForReuseLocked(mStartActivity,
mLaunchFlags);
// The above code can remove {@code reusedActivity} from the task, leading to the
// the {@code ActivityRecord} removing its reference to the {@code TaskRecord}. The
// task reference is needed in the call below to
// {@link setTargetStackAndMoveToFrontIfNeeded}.
if (reusedActivity.getTask() == null) {
reusedActivity.setTask(task);
}
if (top != null) {
if (top.frontOfTask) {
// Activity aliases may mean we use different intents for the top activity,
// so make sure the task now has the identity of the new intent.
top.getTask().setIntent(mStartActivity);
}
deliverNewIntent(top);
}
}
mSupervisor.sendPowerHintForLaunchStartIfNeeded(false /* forceSend */, reusedActivity);
reusedActivity = setTargetStackAndMoveToFrontIfNeeded(reusedActivity);
final ActivityRecord outResult =
outActivity != null && outActivity.length > 0 ? outActivity[0] : null;
// When there is a reused activity and the current result is a trampoline activity,
// set the reused activity as the result.
if (outResult != null && (outResult.finishing || outResult.noDisplay)) {
outActivity[0] = reusedActivity;
}
if ((mStartFlags & START_FLAG_ONLY_IF_NEEDED) != 0) {
// We don't need to start a new activity, and the client said not to do anything
// if that is the case, so this is it! And for paranoia, make sure we have
// correctly resumed the top activity.
resumeTargetStackIfNeeded();
return START_RETURN_INTENT_TO_CALLER;
}
if (reusedActivity != null) {
setTaskFromIntentActivity(reusedActivity);
if (!mAddingToTask && mReuseTask == null) {
// We didn't do anything... but it was needed (a.k.a., client don't use that
// intent!) And for paranoia, make sure we have correctly resumed the top activity.
resumeTargetStackIfNeeded();
if (outActivity != null && outActivity.length > 0) {
outActivity[0] = reusedActivity;
}
return mMovedToFront ? START_TASK_TO_FRONT : START_DELIVERED_TO_TOP;
}
}
}
if (mStartActivity.packageName == null) {
final ActivityStack sourceStack = mStartActivity.resultTo != null
? mStartActivity.resultTo.getStack() : null;
if (sourceStack != null) {
sourceStack.sendActivityResultLocked(-1 /* callingUid */, mStartActivity.resultTo,
mStartActivity.resultWho, mStartActivity.requestCode, RESULT_CANCELED,
null /* data */);
}
ActivityOptions.abort(mOptions);
return START_CLASS_NOT_FOUND;
}
// If the activity being launched is the same as the one currently at the top, then
// we need to check if it should only be launched once.
final ActivityStack topStack = mSupervisor.mFocusedStack;
final ActivityRecord topFocused = topStack.getTopActivity();
final ActivityRecord top = topStack.topRunningNonDelayedActivityLocked(mNotTop);
final boolean dontStart = top != null && mStartActivity.resultTo == null
&& top.realActivity.equals(mStartActivity.realActivity)
&& top.userId == mStartActivity.userId
&& top.app != null && top.app.thread != null
&& ((mLaunchFlags & FLAG_ACTIVITY_SINGLE_TOP) != 0
|| isLaunchModeOneOf(LAUNCH_SINGLE_TOP, LAUNCH_SINGLE_TASK));
if (dontStart) {
// For paranoia, make sure we have correctly resumed the top activity.
topStack.mLastPausedActivity = null;
if (mDoResume) {
mSupervisor.resumeFocusedStackTopActivityLocked();
}
ActivityOptions.abort(mOptions);
if ((mStartFlags & START_FLAG_ONLY_IF_NEEDED) != 0) {
// We don't need to start a new activity, and the client said not to do
// anything if that is the case, so this is it!
return START_RETURN_INTENT_TO_CALLER;
}
deliverNewIntent(top);
// Don't use mStartActivity.task to show the toast. We're not starting a new activity
// but reusing 'top'. Fields in mStartActivity may not be fully initialized.
mSupervisor.handleNonResizableTaskIfNeeded(top.getTask(), preferredWindowingMode,
preferredLaunchDisplayId, topStack);
return START_DELIVERED_TO_TOP;
}
boolean newTask = false;
final TaskRecord taskToAffiliate = (mLaunchTaskBehind && mSourceRecord != null)
? mSourceRecord.getTask() : null;
// Should this be considered a new task?
int result = START_SUCCESS;
if (mStartActivity.resultTo == null && mInTask == null && !mAddingToTask
&& (mLaunchFlags & FLAG_ACTIVITY_NEW_TASK) != 0) {
newTask = true;
result = setTaskFromReuseOrCreateNewTask(taskToAffiliate, topStack);
} else if (mSourceRecord != null) {
result = setTaskFromSourceRecord();
} else if (mInTask != null) {
result = setTaskFromInTask();
} else {
// This not being started from an existing activity, and not part of a new task...
// just put it in the top task, though these days this case should never happen.
setTaskToCurrentTopOrCreateNewTask();
}
if (result != START_SUCCESS) {
return result;
}
mService.grantUriPermissionFromIntentLocked(mCallingUid, mStartActivity.packageName,
mIntent, mStartActivity.getUriPermissionsLocked(), mStartActivity.userId);
mService.grantEphemeralAccessLocked(mStartActivity.userId, mIntent,
mStartActivity.appInfo.uid, UserHandle.getAppId(mCallingUid));
if (newTask) {
EventLog.writeEvent(EventLogTags.AM_CREATE_TASK, mStartActivity.userId,
mStartActivity.getTask().taskId);
}
ActivityStack.logStartActivity(
EventLogTags.AM_CREATE_ACTIVITY, mStartActivity, mStartActivity.getTask());
mTargetStack.mLastPausedActivity = null;
mSupervisor.sendPowerHintForLaunchStartIfNeeded(false /* forceSend */, mStartActivity);
mTargetStack.startActivityLocked(mStartActivity, topFocused, newTask, mKeepCurTransition,
mOptions);
if (mDoResume) {
final ActivityRecord topTaskActivity =
mStartActivity.getTask().topRunningActivityLocked();
if (!mTargetStack.isFocusable()
|| (topTaskActivity != null && topTaskActivity.mTaskOverlay
&& mStartActivity != topTaskActivity)) {
// If the activity is not focusable, we can't resume it, but still would like to
// make sure it becomes visible as it starts (this will also trigger entry
// animation). An example of this are PIP activities.
// Also, we don't want to resume activities in a task that currently has an overlay
// as the starting activity just needs to be in the visible paused state until the
// over is removed.
mTargetStack.ensureActivitiesVisibleLocked(null, 0, !PRESERVE_WINDOWS);
// Go ahead and tell window manager to execute app transition for this activity
// since the app transition will not be triggered through the resume channel.
mService.mWindowManager.executeAppTransition();
} else {
// If the target stack was not previously focusable (previous top running activity
// on that stack was not visible) then any prior calls to move the stack to the
// will not update the focused stack. If starting the new activity now allows the
// task stack to be focusable, then ensure that we now update the focused stack
// accordingly.
if (mTargetStack.isFocusable() && !mSupervisor.isFocusedStack(mTargetStack)) {
mTargetStack.moveToFront("startActivityUnchecked");
}
mSupervisor.resumeFocusedStackTopActivityLocked(mTargetStack, mStartActivity,
mOptions);
}
} else if (mStartActivity != null) {
mSupervisor.mRecentTasks.add(mStartActivity.getTask());
}
mSupervisor.updateUserStackLocked(mStartActivity.userId, mTargetStack);
mSupervisor.handleNonResizableTaskIfNeeded(mStartActivity.getTask(), preferredWindowingMode,
preferredLaunchDisplayId, mTargetStack);
return START_SUCCESS;
}代码太长；只能一段段分开看；
1. 启动参数的初始化；里面是对一个参数和Flag的设置；
setInitialState(r, options, inTask, doResume, startFlags, sourceRecord, voiceSession,
voiceInteractor);2. 计算LaunchingTask和一些LaunchMode；
computeLaunchingTaskFlags();3. 拿到mSourceStack；这里会对正在关闭的source做特殊处理；
computeSourceStack();4. 设置LaunchFlags；FLAG_ACTIVITY_NEW_TASK、FLAG_ACTIVITY_MULTIPLE_TASK等Flags；
mIntent.setFlags(mLaunchFlags);5. 判断是否应将新Activity插入现有task；如果不是，则返回null；如果是，则返回包含要添加新Activity的task的ActivityRecord；
ActivityRecord reusedActivity = getReusableIntentActivity();6. window mode和dispaly id；window mode定义在WindowConfiguration，包括WINDOWING_MODE_UNDEFINED、WINDOWING_MODE_FULLSCREEN、WINDOWING_MODE_PINNED等；display id相关定义在Display中，每个dispay都有一个唯一的id；
int preferredWindowingMode = WINDOWING_MODE_UNDEFINED;
int preferredLaunchDisplayId = DEFAULT_DISPLAY;
if (mOptions != null) {
preferredWindowingMode = mOptions.getLaunchWindowingMode();
preferredLaunchDisplayId = mOptions.getLaunchDisplayId();
}
// windowing mode and preferred launch display values from {@link LaunchParams} take
// priority over those specified in {@link ActivityOptions}.
if (!mLaunchParams.isEmpty()) {
if (mLaunchParams.hasPreferredDisplay()) {
preferredLaunchDisplayId = mLaunchParams.mPreferredDisplayId;
}
if (mLaunchParams.hasWindowingMode()) {
preferredWindowingMode = mLaunchParams.mWindowingMode;
}
}
7. 重用Activity；符合条件就直接重用；不走后面的代码；
if (reusedActivity != null) {
// When the flags NEW_TASK and CLEAR_TASK are set, then the task gets reused but
// still needs to be a lock task mode violation since the task gets cleared out and
// the device would otherwise leave the locked task.
if (mService.getLockTaskController().isLockTaskModeViolation(reusedActivity.getTask(),
(mLaunchFlags & (FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TASK))
== (FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TASK))) {
Slog.e(TAG, "startActivityUnchecked: Attempt to violate Lock Task Mode");
return START_RETURN_LOCK_TASK_MODE_VIOLATION;
}
// True if we are clearing top and resetting of a standard (default) launch mode
// ({@code LAUNCH_MULTIPLE}) activity. The existing activity will be finished.
final boolean clearTopAndResetStandardLaunchMode =
(mLaunchFlags & (FLAG_ACTIVITY_CLEAR_TOP | FLAG_ACTIVITY_RESET_TASK_IF_NEEDED))
== (FLAG_ACTIVITY_CLEAR_TOP | FLAG_ACTIVITY_RESET_TASK_IF_NEEDED)
&& mLaunchMode == LAUNCH_MULTIPLE;
// If mStartActivity does not have a task associated with it, associate it with the
// reused activity's task. Do not do so if we're clearing top and resetting for a
// standard launchMode activity.
if (mStartActivity.getTask() == null && !clearTopAndResetStandardLaunchMode) {
mStartActivity.setTask(reusedActivity.getTask());
}
if (reusedActivity.getTask().intent == null) {
// This task was started because of movement of the activity based on affinity...
// Now that we are actually launching it, we can assign the base intent.
reusedActivity.getTask().setIntent(mStartActivity);
}
// This code path leads to delivering a new intent, we want to make sure we schedule it
// as the first operation, in case the activity will be resumed as a result of later
// operations.
if ((mLaunchFlags & FLAG_ACTIVITY_CLEAR_TOP) != 0
|| isDocumentLaunchesIntoExisting(mLaunchFlags)
|| isLaunchModeOneOf(LAUNCH_SINGLE_INSTANCE, LAUNCH_SINGLE_TASK)) {
final TaskRecord task = reusedActivity.getTask();
// In this situation we want to remove all activities from the task up to the one
// being started. In most cases this means we are resetting the task to its initial
// state.
final ActivityRecord top = task.performClearTaskForReuseLocked(mStartActivity,
mLaunchFlags);
// The above code can remove {@code reusedActivity} from the task, leading to the
// the {@code ActivityRecord} removing its reference to the {@code TaskRecord}. The
// task reference is needed in the call below to
// {@link setTargetStackAndMoveToFrontIfNeeded}.
if (reusedActivity.getTask() == null) {
reusedActivity.setTask(task);
}
if (top != null) {
if (top.frontOfTask) {
// Activity aliases may mean we use different intents for the top activity,
// so make sure the task now has the identity of the new intent.
top.getTask().setIntent(mStartActivity);
}
deliverNewIntent(top);
}
}
mSupervisor.sendPowerHintForLaunchStartIfNeeded(false /* forceSend */, reusedActivity);
reusedActivity = setTargetStackAndMoveToFrontIfNeeded(reusedActivity);
final ActivityRecord outResult =
outActivity != null && outActivity.length > 0 ? outActivity[0] : null;
// When there is a reused activity and the current result is a trampoline activity,
// set the reused activity as the result.
if (outResult != null && (outResult.finishing || outResult.noDisplay)) {
outActivity[0] = reusedActivity;
}
if ((mStartFlags & START_FLAG_ONLY_IF_NEEDED) != 0) {
// We don't need to start a new activity, and the client said not to do anything
// if that is the case, so this is it! And for paranoia, make sure we have
// correctly resumed the top activity.
resumeTargetStackIfNeeded();
return START_RETURN_INTENT_TO_CALLER;
}
if (reusedActivity != null) {
setTaskFromIntentActivity(reusedActivity);
if (!mAddingToTask && mReuseTask == null) {
// We didn't do anything... but it was needed (a.k.a., client don't use that
// intent!) And for paranoia, make sure we have correctly resumed the top activity.
resumeTargetStackIfNeeded();
if (outActivity != null && outActivity.length > 0) {
outActivity[0] = reusedActivity;
}
return mMovedToFront ? START_TASK_TO_FRONT : START_DELIVERED_TO_TOP;
}
}
}8. 检查class not found；
if (mStartActivity.packageName == null) {
final ActivityStack sourceStack = mStartActivity.resultTo != null
? mStartActivity.resultTo.getStack() : null;
if (sourceStack != null) {
sourceStack.sendActivityResultLocked(-1 /* callingUid */, mStartActivity.resultTo,
mStartActivity.resultWho, mStartActivity.requestCode, RESULT_CANCELED,
null /* data */);
}
ActivityOptions.abort(mOptions);
return START_CLASS_NOT_FOUND;
}
9. 对SINGLE_TOP做的CASE处理；
// If the activity being launched is the same as the one currently at the top, then
// we need to check if it should only be launched once.
final ActivityStack topStack = mSupervisor.mFocusedStack;
final ActivityRecord topFocused = topStack.getTopActivity();
final ActivityRecord top = topStack.topRunningNonDelayedActivityLocked(mNotTop);
final boolean dontStart = top != null && mStartActivity.resultTo == null
&& top.realActivity.equals(mStartActivity.realActivity)
&& top.userId == mStartActivity.userId
&& top.app != null && top.app.thread != null
&& ((mLaunchFlags & FLAG_ACTIVITY_SINGLE_TOP) != 0
|| isLaunchModeOneOf(LAUNCH_SINGLE_TOP, LAUNCH_SINGLE_TASK));
if (dontStart) {
// For paranoia, make sure we have correctly resumed the top activity.
topStack.mLastPausedActivity = null;
if (mDoResume) {
mSupervisor.resumeFocusedStackTopActivityLocked();
}
ActivityOptions.abort(mOptions);
if ((mStartFlags & START_FLAG_ONLY_IF_NEEDED) != 0) {
// We don't need to start a new activity, and the client said not to do
// anything if that is the case, so this is it!
return START_RETURN_INTENT_TO_CALLER;
}
deliverNewIntent(top);
// Don't use mStartActivity.task to show the toast. We're not starting a new activity
// but reusing 'top'. Fields in mStartActivity may not be fully initialized.
mSupervisor.handleNonResizableTaskIfNeeded(top.getTask(), preferredWindowingMode,
preferredLaunchDisplayId, topStack);
return START_DELIVERED_TO_TOP;
}
10. 根据情况选择task，并将其带到前台；如果是new task，就需要创建新的；
boolean newTask = false;
final TaskRecord taskToAffiliate = (mLaunchTaskBehind && mSourceRecord != null)
? mSourceRecord.getTask() : null;
// Should this be considered a new task?
int result = START_SUCCESS;
if (mStartActivity.resultTo == null && mInTask == null && !mAddingToTask
&& (mLaunchFlags & FLAG_ACTIVITY_NEW_TASK) != 0) {
newTask = true;
result = setTaskFromReuseOrCreateNewTask(taskToAffiliate, topStack);
} else if (mSourceRecord != null) {
result = setTaskFromSourceRecord();
} else if (mInTask != null) {
result = setTaskFromInTask();
} else {
// This not being started from an existing activity, and not part of a new task...
// just put it in the top task, though these days this case should never happen.
setTaskToCurrentTopOrCreateNewTask();
}
if (result != START_SUCCESS) {
return result;
}
11. 给予UriPermission；
mService.grantUriPermissionFromIntentLocked(mCallingUid, mStartActivity.packageName,
mIntent, mStartActivity.getUriPermissionsLocked(), mStartActivity.userId);12. emmm
mService.grantEphemeralAccessLocked(mStartActivity.userId, mIntent,
mStartActivity.appInfo.uid, UserHandle.getAppId(mCallingUid));13. 打LOG
if (newTask) {
EventLog.writeEvent(EventLogTags.AM_CREATE_TASK, mStartActivity.userId,
mStartActivity.getTask().taskId);
}
ActivityStack.logStartActivity(
EventLogTags.AM_CREATE_ACTIVITY, mStartActivity, mStartActivity.getTask());14. 将mLastPausedActivity 置为null；
mTargetStack.mLastPausedActivity = null;/**
* This is the last activity that we put into the paused state. This is
* used to determine if we need to do an activity transition while sleeping,
* when we normally hold the top activity paused.
*/
ActivityRecord mLastPausedActivity = null;15. emmmm
mSupervisor.sendPowerHintForLaunchStartIfNeeded(false /* forceSend */, mStartActivity);16. 启动Activity
mTargetStack.startActivityLocked(mStartActivity, topFocused, newTask, mKeepCurTransition,
mOptions);17. Resume
if (mDoResume) {
final ActivityRecord topTaskActivity =
mStartActivity.getTask().topRunningActivityLocked();
if (!mTargetStack.isFocusable()
|| (topTaskActivity != null && topTaskActivity.mTaskOverlay
&& mStartActivity != topTaskActivity)) {
// If the activity is not focusable, we can't resume it, but still would like to
// make sure it becomes visible as it starts (this will also trigger entry
// animation). An example of this are PIP activities.
// Also, we don't want to resume activities in a task that currently has an overlay
// as the starting activity just needs to be in the visible paused state until the
// over is removed.
mTargetStack.ensureActivitiesVisibleLocked(null, 0, !PRESERVE_WINDOWS);
// Go ahead and tell window manager to execute app transition for this activity
// since the app transition will not be triggered through the resume channel.
mService.mWindowManager.executeAppTransition();
} else {
// If the target stack was not previously focusable (previous top running activity
// on that stack was not visible) then any prior calls to move the stack to the
// will not update the focused stack. If starting the new activity now allows the
// task stack to be focusable, then ensure that we now update the focused stack
// accordingly.
if (mTargetStack.isFocusable() && !mSupervisor.isFocusedStack(mTargetStack)) {
mTargetStack.moveToFront("startActivityUnchecked");
}
mSupervisor.resumeFocusedStackTopActivityLocked(mTargetStack, mStartActivity,
mOptions);
}
} else if (mStartActivity != null) {
mSupervisor.mRecentTasks.add(mStartActivity.getTask());
}
18. 更新stack的userId
mSupervisor.updateUserStackLocked(mStartActivity.userId, mTargetStack);/**
* Update the last used stack id for non-current user (current user's last
* used stack is the focused stack)
*/
void updateUserStackLocked(int userId, ActivityStack stack) {
if (userId != mCurrentUser) {
mUserStackInFront.put(userId, stack != null ? stack.getStackId() : mHomeStack.mStackId);
}
}19. 处理分屏
mSupervisor.handleNonResizableTaskIfNeeded(mStartActivity.getTask(), preferredWindowingMode,
preferredLaunchDisplayId, mTargetStack);
startActivityUnchecked的内容很多；后面再摘取有趣的部分深入的阅读；
mSupervisor.resumeFocusedStackTopActivityLocked(mTargetStack, mStartActivity,
mOptions);targetStack.resumeTopActivityUncheckedLocked(target, targetOptions);
mFocusedStack.resumeTopActivityUncheckedLocked(null, null);
private boolean resumeTopActivityInnerLocked(ActivityRecord prev, ActivityOptions options)mStackSupervisor.startSpecificActivityLocked(next, true, true);
final boolean realStartActivityLocked(ActivityRecord r, ProcessRecord app,
boolean andResume, boolean checkConfig) throws RemoteException