Develop Reference

Flutter Launcher: Go back to the HomeScreen when Home Button is pressed

I am trying to make a launcher using flutter. I have made multiple screens for doing specific tasks like HomeScreen. AppDrawerScreen and so on. The problem I am facing is whenever I go to say AppDrawerScreen and press on the Home Button, I am not redirected to the HomeScreen. How can I handle this scenario?

I've had the same problem. I guess the only solution is to listen to the Home button, and there go to the first screen. there is a plugin called hardware_buttons, and about the Back button you can use the WillPopScope() widget.

You can achieve this by adding WidgetsBindingObserver mixing to your StatefulWidget class.
And then you can invoke didChangeAppLifecycleState() method where you can listen to the AppLifeCycleState changes like :
inactive
paused
resume and soon
But in your case since you want to navigate to HomeScreen when Android Home Button is pressed so you need to check if AppLifeCycleState.inactive is true (which means you have pressed the Android Home Button and app is running in background) and there you can add your code to Navigate to HomeScreen.
Also you can refer to this documentation for more information.

Changing Activity screen when the app is not running

How can i change the screen of an activity when pressing any button on an android phone that takes one away from the running app.
I'm trying to get a blank screen to show up on the "recents" screen, instead of a snapshot of the app.

You can use this option and check if it helps you meet your need.
android:excludeFromRecents="true"
Add this to your activities in the application manifest if you do not want the app to be shown in the recent apps list. One drawback is that you would not be able to resume the app from the Recents list. Not sure if this is what you need.
The other way is to have a 'Blank Activity', which you start when your actual activity pauses. You can then finish the 'Blank Activity' on its Resume. This way, you will have your app shown on the Recents list, but with a blank screen.

You can call finish() for activity but that will kill activity. I think that will leave blank screen. Or destroy(). Try both respond with results.

you might want to change the onpause() or onclose() functions of your app. they are the last thing android execute before leaving,therefor you can change the aspect off your app just before you leave it
EDIT :
Maybe if you create PopupWindow and set it to full screen, and color black when exiting no preview would be shown, but app would still be running (idea of user DjDexter5GH) in the onpause() and onclose() functions. therefgor,when you leave,a black(or whatever you want) screen is pushed in front
you can then close it in the onrestart(is it called this?)

Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED|Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET

When these two flags are added(or set) to a new activity A, A becomes the top of task's back stack and is shown on the screen. Here HOME is pressed, and the screen shows home.
What I want: Then let's go to launcher and select the app's icon, the app comes alive again, the A is gone.
What I am confused: Then let's long press HOME and select the app, the app comes alive again, A is still THERE.
I want A disappeared, however from Launcher or from Recent. How can I make it?

I don't think there is any easy way to do this. You can either exclude your app from the Recent list or save a flag in activity A that if true call finish() in onCreate.

Killing activities before they stack, so recalling an activity doesn't cause an overflow

I have read into the finish(); commands and the FLAG_ACTIVITY_CLEAR_TOP commands and also checked out Common Ware's answer on killing app, but I am not sure how to put this into my app.
Basically, I have a user click a button that takes them to the camera. The user then snaps a photo and it brings them to a layout view. The user then clicks a button that takes them to one of 2 views, depending on a some conditions.
The user is then allowed to either retake a photo, or go to the main menu (depending). My problem is, if the user goes back to the main menu, and snaps another, then another, etc...the activities stack, so when I click the 'Main Menu' button the app goes back through eached stack activity until finally it goes back to the main menu. Is there a way to kill each activity with one of these lines, so even if a user retakes a photo, they will only need to go back once to get to the main menu?
Thanks!

I use the noHistory parameter in the manifest to accomplish this. Here is an example of a manifest entry for a Activity that should not be placed in the history stack:
<activity android:name=".MyActivity"
android:label="MyActivityTitle"
android:noHistory="true" />

how to go on previous screen from current screen in Android app

How do I go to previous screen from current screen in Android app? I know there is a back button on phone, but it takes me to beginning screen of my app and I want my buttons on app to work for going back to previous screen.

Back button indeed takes you to previously seen activity on screen, that launched the current one (not by means of back button). If back button takes you to beggining screen of your app means that navigation to your last activity was done from it. Try launching an activity from another one different from start activity.
What really can be problematic is ending application once at start activity by pressing back button and discovering the application switching to activity that lauched start activity (not by means of back button). In this case you should just call finish() inside onDestroy() listener method of your start activity.