Android :: Handling Orientation Changes That Occur In Another Activity
Jun 3, 2010
I am having an interesting problem and would appreciate any advice. My app uses WebView as its primary view. Using a javascript hook, it can launch the camera so the user can take a picture. The camera is launched using: Intent i = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
When the camera starts, it makes sense to use landscape mode, so the user naturally turns the phone on its side. After the user takes a picture, control returns to my launching Activity (actually, my Acitivity gets restarted because it usually gets destroyed to free up memory for the camera on my Moto Droid). When my WebView gets recreated, I restore its state from the Bundle I saved in onSaveInstanceState().
Now everything looks ok, except the phone is still in landscape mode. However, when the user turns the phone upright bringing back into portrait mode, my WebView takes up only half of the screen. Somewhere along the way, the scale of my WebView got lost. This seems like such a minor issue, but it is driving me crazy.
Does anyone have an idea why this might be happening? What is the correct way to preserve the scale of my WebView? I am hesitant to hard code any scale factors because what looks good on my device may not be the same for another.
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Mar 12, 2010
I'm trying to find a way to properly handle setting up an activity where its orientation is determined from data in the intent that launched it. This is for a game where the user can choose levels, some of which are int portrait orientation and some are landscape orientation. The problem I'm facing is that setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE) doesn't take effect until the activity is fully loaded. This is a problem for me because I do some loading and image processing during startup, which I'd like to only have to do once.
Currently, if the user chose a landscape level:
the activity starts onCreate(), defaulting to portrait discovers from analysing its launching Intent that it should be in landscape orientation continues regardless all the way to onResume(), loading information and performing other setup tasks at this point setRequestedOrientation kicks in so the application runs through onPause() to onDestroy() it then again starts up from onCreate() and runs to onResume() repeating the setup from earlier
Is there a way to avoid that and have it not perform the loading twice? For example, ideally, the activity would know before even onCreate was called whether it should be landscape or portrait depending on some property of the launching intent, but unless I've missed something that isn't possible. I've managed to hack together a way to avoid repeating the loading by checking a boolean before the time-consuming loading steps, but that doesn't seem like the right way of doing it. I imagine I could override onSaveInstanceState, but that would require a lot of additional coding. Is there a simple way to do this?
Solution:
As per Daniel's answer, this was actually quite easy to fix. I just needed to make a few small changes. In my 'menu' Activity, where the player would choose which level to play, I just had to add an if/else check to choose which class would be started by my Intent. This was done with a simple int representing portrait or landscape, determined when the player selected a level. I then created a second class extending my 'GameLogic' class; this is the class which contained most of the code for the game itself, rather than the menus, instructions, etc.
public class GameLandscape extends GameLogic{}
Literally that simple and completely empty. That way it inherited all the code from my previous activity where I had already coded it to handle things differently depending on the orientation. Lastly I just had to add a line to the manifest stating that GameLandscape would always run in landscape, and GameLogic would always run in portrait.
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Jun 3, 2010
From the documentation regarding the android:configChanges='orientation' attribute of the activity tag in the manifest:
Using this attribute should be avoided and used only as a last-resort. Please read Handling Runtime Changes for more information about how to properly handle a restart due to a configuration change.
Why does it say this?
In the case of threads and networking requests via a service API library, a request could be made with a reference to the original Activity, and then an orientation change could occur, leaving the thread pointing to the old Activity.
While this can be fixed, it's tedious and ugly compared to just handling the configuration changes yourself.
Why should it be avoided?
I guess I should also ask: would this be an acceptable reason for doing the orientation configuration changes yourself?
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Apr 18, 2010
We have created an AppWidget that takes user inputted text into an EditText and displays a calculated amount of text inside a TextView on the Home Screen. We calculate the amount of text based on the AppWidgetInfo.minWidth, minHeight attributes. We do this to simulate scrolling; we cut up the user-inputted text into chunks that will fit into the widget and swap them based on button clicks.
When we save the widget with the device in Landscape mode, it calculates the appropriate amount of text for Landscape mode and displays it in the widget. The problem is when the user changes orientation of the device to Portrait mode (without opening the widget and resaving the text), the calculated amount of text for Landscape mode is still displayed. This also happens in the vice versa case (the user is in Portrait and saves, etc.)
How can we tell our AppWidget to recalculate the amount of text displayed on screen orientation change? Is this possible? How would you solve this problem?
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Jul 6, 2010
My project is working fine when i hold my HTC device vertical.But the moment i rotate my screen 90degrees , it throws a force close error.Starts all over again, runs fine until i again change the orientation.How do i handle it ?
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Jun 16, 2009
Just started working with the webview. The issue is performance following rotation. The WebView has to reload the page, which can be a bit tedious.What's the best of of handling an orientation change without reloading the page from source each time?
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May 31, 2009
Some of the content in my widget is based on custom drawing routines. is there any event i can listen for so i redraw and update this custom area when the orientation changes? currently my widget looks pretty screwed until the next widget update is requested.
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Feb 1, 2010
I have EditText in my application. While entering the text i am changing the portrait mode to landscape mode. Not the entered text is resetting. how do i handle this? Like if i change the orientation what ever entered text should be remain as it is.
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Apr 27, 2010
When a TabWidget is using intents to designate the target Activity for each tab, is there any special handling of those Activities on the Activity Stack outside of the default operation? For Instance, if my app has tabs A, B, and C, and I click them in this order--A, B, A, C, A, B--how will the Activity stack change? My understanding of the default operation, if startActivity() is called each time on the intent, would have the Stack keep loading up new instances of the activities: A, AB, ABA, ABAC, ABACA, ABACAB It's hard to believe that's how it works though... Seems like it would be a waste of resources and could be endless. Can anyone tell me how this will actually work?
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May 14, 2009
I have created an activity for my game which handles all orientation changes by itself and has a fixed "portrait" layout. Actually it uses the accelerometer and is rendered using 2D canvas methods. If the level has been completed I show up a highscore dialog in which the user can enter his name. The dialog is floating above the underlying level screen which gets blurred out nicely. This generally works.
Problem is that the dialog does not get rotated if the orientation of the phone changes. So even if the keyboard is exposed the dialog is shown in portrait mode instead of landscape. I have tried to use an activity with dialog theme instead but the behavior didn't change. After several tries it seems that I have found the reason for this: Once there's an activity with fixed orientation in the activity stack then all subsequent activities keep this orientation, too. They will not react on orientation changes anymore (e.g. if the keyboard gets exposed).
After upgrading to 1.5 SDK the described behavior changed a little bit. Now at subactivities indead react on orientation changes like expected. However, the need to have an opaque background! That means that neither dialogs nor activities with dialog theme will work. Those will stick with the orientation of the underlaying activity. So my workaround is to first start a sub-activity with an opaque black background. This activity then shows my highscore dialog on top. It looks quite okay but I wonder if there's a better solution? Is it possible to show a dialog above a fixed portrait or landscape activity which automatically adapts to orientation changes?
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Oct 27, 2010
I have a ViewGroup that gets inflated dynamically. I have set Id's to all the inflated views. I am still not able to retain the inflated ViewGroup whenever the orientation is changed. Any particular check that i am missing here ?
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Jun 19, 2010
My main application screen uses a GridView to display a grid of icons. Each icon has an image, name, and Intent. I have the Activity set to handle orientation changes so I can change the background. The onCreate method sets up the GridView with 3 test icons that don't do anything and a preferences icon which opens a PreferencesActivity:............
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Jan 13, 2010
I'm using Wakelock in my application to prevent the phone from sleeping when the app is visible. The problem comes when there is an orientation change and the system destroys and re-creates the app in landscape mode. If the wakelock timer has expired in the background the system takes the release of wakelock as an opportunity to switch off the screen.
Edit: I should mention that I am setting Wakelock onResume, and releasing onPause - as I understand it, it's necessary to release then to prevent the app from leaking the wakelock. I need wakelock to continue through the orientation change. Below I've outlined a solution to this. Is this the preferred way to handle it, and are there any alternatives?
Create a service which holds wakelock (rather than the activity) and when the activity unbinds the service starts a countdown timer (for say 10 seconds) in which it will release wakelock when the timer expires if the activity does not rebind. If it was a simple orientation change the activity will rebind within that 10 seconds and so maintain wakelock, if it doesn't, wakelock will be released.
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Jan 21, 2010
When views with different type have same id and screen orientation changes,
either java.lang.ClassCastException: android.view.AbsSavedState$1 or java.lang.IllegalArgumentException: Wrong state class -- expecting View State will occur. (depends on the view's order)
Because View.dispatchRestoreInstanceState() checks id only.
You may wonder why anyone would make views with different type to have same id.
But it can happen when you use tab activity.
Imagine you have tab activity with two children activity.
Tab1 is ListActivity and Tab2 is ExpandableListActivity.
Both activity have id of "@android:id/list" but the type of view is different.
This means we cannot use ListActivity & ExpandableListActivit at the same in one tab activity.
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Nov 2, 2010
I have a TabActivity, and each Tab corresponds to its own Activity. In one of them, in the onCreate method, I use startActivityForResult to show a dialog (specifically, Bump's BumpAPI activity).
code:...............
The problem is that when the screen orientation changes, it tries to create the tab's activity again which makes another BumpAPI dialog, resulting in multiple stacked on top of each other. Do I have a hook into the started activity to cancel the previous one when the orientation changes?
A workaround seems to be to add a button that when clicked, starts the second activity, but that adds an unnecessary step.
Also, I can't fix the screen orientation for the entire tabActivity because some of them require typing and users may want to use their physical keyboards.
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Aug 9, 2010
I am writing an activity, that loads data from a server and displays it as a list using ArrayAdapter. For that I'm showing a progress dialog i.e loading, while it loads all data from the server. Then i dismiss the dialog in a handler. My problem is that when ever i change the orientation, the progress dialog is again shown, which is not needed, because all the data is displayed already?
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Sep 20, 2010
How does my android activity know (is there a callback) when there is a change in screen orientation?
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Aug 16, 2010
I know on screen orientation changes activity restarted, but suppose i don't want to restart the activity then what should I do? I had tried it by adding in manifest.xml. android:configChanges="keyboardHidden|orientation"
and override public void onConfigurationChanged(Configuration newConfig) { super.onConfigurationChanged(newConfig); }
But still activity restarted each time when I change screen orientation.
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Jul 7, 2009
I finally got to the point where I was ready to deploy my app to my G1 and test it out and the first thing I noticed was that when I change my phone to landscape view my main activity restarts and resets all of my variables to their default settings. How can I avoid this?
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Aug 31, 2010
My main activity has some code that makes some database changes that should not be interrupted. I'm doing the heavy lifting in another thread, and using a progress dialog which I set as non-cancellable. However, I noticed that if I rotate my phone it restarts the activity which is REALLY bad for the process that was running, and I get a Force Close.
What I want to do is programatically disable screen orientation changes until my process completes, at which time orientation changes are enabled.
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Nov 24, 2010
It is possible to set the orientation of an activity in the manifest file. but is it also possible to do it from code? if so, how?
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May 6, 2010
I m currently working on landscape mode for android app in which i want to know how to maintain the state of the activity and views displayed on orientation change i.e from portrait mode to landscape mode ?
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Apr 5, 2010
I am working on a MVC implementation for Android (to be subsequently hosted on SF and/or GC).
It works like this:
Activity (View) <=> Application (Controller) <=> Data (Model) <=> Persistence (DB/Network etc)
The scenario is:
1. Activity launch (main/launcher)
2. Notifies Application about performing a data transaction
3. Upon receipt of data response, controller devices which Activity to launch (or update existing)
4. Application has overridden the method onConfigurationChange
Problem: When the orientation is changed, the Application is notified about onConfigurationChange but:
a) The "current" activity is Destroyed and recreated -- which is fine to some extent b) The new instance which is created is automatically => onCreate, onPause, onStop, onDestroy.... now that's catastrophic.
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Sep 11, 2010
My MainActivity (the one that is started by the android application) is a TabActivity which contains several tabs (which are implemented as activities as well). In a certain tab/activity I want to prevent the change of orientation/rotation when the phone is turned. What is the easiest way to achieve this?
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Apr 6, 2010
i've developed an android app that's fetches an xml file and displays this data via several markers on the map. This works fine so far. The problem right now is that when i switch the orientation of the phone (portrait->landscape or vice versa) the markers disappear for a small moment, the xml processing is started again and then they reappear. Is there a way to prevent this re-loading of the file? It only takes about 2-3 seconds.
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May 26, 2010
Can I temporarily disable automatic orientation changes in my Activity? I want to do this when my app does some background internet communication.
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Apr 7, 2010
I have Activity with ListView inside it and in the onCreate method of the Activity I have code for populating the Data of the ListView this Data is a server based and so populating includes calling Network URLs. I have the ArrayAdapter of the ListView in the Same Activity Class.
Now the Issue I'am facing is that, in Rest all scenarios my Activity is behaving in a proper way but when the Orientation [ Portrait to Landscaped or other way round] is taking place the Data is Getting lost and Newer Data calls are Required to Populate the Same Old Data now this is something that is not intended out the code how should I deal with it.
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Jun 7, 2010
I have an Android Activity with a RelativeLayout and I have implemented the following method to prevent the activity from being recreated on change of Orientation:
CODE:..............
I am obviously not doing anything in this method, but it worked perfect when using a LinearLayout. Now however, using RelativeLayout, my layout is all messed up when changing to landscape orientation.
What is the most efficient way to have the screen redraw correctly without having the activity restarted again with a call to onCreate?
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Aug 3, 2009
I have a requirement where I have to read/parse some data from the server(using HTTPConnection) and then display it on to the screen. To avoid ANR issue I used AsyncTask to perform the above. Now in order to avoid application crash in case the activity gets destroyed(either by OS or if orientation changes or say on any incoming call-->where user stays on the phone for long and for some reason OS destroys/recreates the activity). Currently, I hols the reference of AsyncTask in my activity and then provide a callback(the activity itself) to AsyncTask so that I can pos back message to activity(like closing progress dialog box).In order to avoid memory leaks on onPause I nullify this activity reference in AsyncTask.Before onPause I save the AsyncTask instance using onSaveInstanceState method but I have to use putSerializable for that. I have read on the forums that serialization method is slow, so my question is should I use parcelable approach(and whether the converting AsyncTask to parcelable will be same as creating any other object parcelable). or both these approaches are totally wrong i.e...............
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Aug 13, 2010
It seems when screen orientation changes, the activity's onCreate() method is called. In my onCreate() method, I have an AlertDialog which pops up when the activity is called. The problem is when I switch the screen sideways, the popup is displayed again. How can I avoid this?
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