具体请看下面的表格：
|
|
public void overridePendingTransition(int enterAnim, int exitAnim) { try { ActivityManagerNative.getDefault().overridePendingTransition( mToken, getPackageName(), enterAnim, exitAnim); } catch (RemoteException e) { } } |
♠ frameworks/base/core/java/android/app/ActivityManagerNative.java
| § ActivityManagerNative.getDefault() 很简单，获取gDefault |
|
|
static public IActivityManager getDefault() { return gDefault.get(); } |
|
| § gDefault 一个静态变量，是ActivityManagerService 的代理对象 |
|
|
private static final Singleton<IActivityManager> gDefault = new Singleton<IActivityManager>() { protected IActivityManager create() { IBinder b = ServiceManager.getService("activity"); if (false) { Log.v("ActivityManager", "default service binder = " + b); } IActivityManager am = asInterface(b); if (false) { Log.v("ActivityManager", "default service = " + am); } return am; } }; |
|
♠ frameworks/base/services/java/com/android/server/am/ActivityManagerService.java
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 |
@Override public void overridePendingTransition(IBinder token, String packageName, int enterAnim, int exitAnim) { synchronized(this) { ActivityRecord self = ActivityRecord.isInStackLocked(token); if (self == null) { return; } final long origId = Binder.clearCallingIdentity(); if (self.state == ActivityState.RESUMED || self.state == ActivityState.PAUSING) { mWindowManager.overridePendingAppTransition(packageName, enterAnim, exitAnim, null); } Binder.restoreCallingIdentity(origId); } } |
| ActivityRecord.isInStackLocked(token); 查询当前Activity是否还在Activity栈中？ |
|
|
static ActivityRecord isInStackLocked(IBinder token) { final ActivityRecord r = ActivityRecord.forToken(token); if (r != null) { return r.task.stack.isInStackLocked(token); } return null; } |
|
| 如果还在继续执行Binder.clearCallingIdentity();保存此Activity在Binder中的id，稍候就会使用overridePendingAppTransition执行恢复的操作。 |
| 如果当前Activity的状态是活动状态或者将要暂停状态，执行WindowManagerService的overridePendingAppTransition |
♠ frameworks/base/services/java/com/android/server/wm/WindowManagerService.java
|
|
@Override public void overridePendingAppTransition(String packageName, int enterAnim, int exitAnim, IRemoteCallback startedCallback) { synchronized(mWindowMap) { mAppTransition.overridePendingAppTransition(packageName, enterAnim, exitAnim, startedCallback); } } |
| 调用AppTransition的overridePendingAppTransition方法（将动画的设置信息都放在AppTransition中了） |
|
|
void overridePendingAppTransition(String packageName, int enterAnim, int exitAnim, IRemoteCallback startedCallback) { if (isTransitionSet()) { mNextAppTransitionType = NEXT_TRANSIT_TYPE_CUSTOM; mNextAppTransitionPackage = packageName; mNextAppTransitionThumbnail = null; mNextAppTransitionEnter = enterAnim; mNextAppTransitionExit = exitAnim; postAnimationCallback(); mNextAppTransitionCallback = startedCallback; } else { postAnimationCallback(); } } |
|
| 然后WindowManagerService在进行Activity切换的时候就会根据AppTransition的动画设置来显示切换动画了。 |
总结：
1. 执行overridePendingTransition时的调用顺序ActivityManageService->WindowManageService
2. 最终设置的是WindowManagerService的overridePendingAppTransition
3. 和Windows编程中显示模式窗口不同，执行startActivity时并没有立即暂停当前Activity，而是通过Handler在下一个MessageQueue的处理中暂停的当前Activity
