How can I get screenshot's from “Recent opened apps”?

问题

Is possible to get full app screenshot from "Recent opened apps"?
I want to make MeeGo or Symbian similar task manager for Android.

回答1:

I doubt this is possible without running on a rooted phone.

The system recent tasks panel gets the thumbnails via this code:

final ActivityManager am = (ActivityManager)
mContext.getSystemService(Context.ACTIVITY_SERVICE);
ActivityManager.TaskThumbnails thumbs = am.getTaskThumbnails(td.persistentTaskId);

But it seems getTaskThumbnails is a private method and only allowed to be accessed with system privileges.

Source: http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/4.0.1_r1/com/android/systemui/recent/RecentTasksLoader.java#RecentTasksLoader

Another option would be to use ActivityManager.getRunningTaks() to get the list of running tasks, then use RunningTaskInfo.thumbnail to get a thumbnail of the app. However, it seems that always returns null.

回答2:

You could get the list of running tasks using AvtivityManager.getRunningTasks and use this to take the screenshots. Refer this project: http://androidexample.com/Check_Current_Running_Activity_%7C_Task_%7C_Application_-_Android_Example/index.php?view=article_discription&aid=111&aaid=133

来源：https://stackoverflow.com/questions/21796543/how-can-i-get-screenshots-from-recent-opened-apps