I have an Activity with a fixed orientation, android:screenOrientation="portrait" in my manifest. I noticed that when pressing Cntl-F11 on the emulator and when a user slides out the keyboard on a device the Activity is destroyed and onCreate is called.
Yet when I use a non-slide out keyboard device the Activity is never destroyed, simply because it is locked to portrait.
Why is there a difference in behavior between devices? Why is an Activity that is locked to portrait, invoking a configuration change? This is really irritating.
Edit: I also experimented with android:configChanges="orientation without any noticeable difference.
You can probably prevent this by telling Android you want to handle the configuration changes yourself via the configChanges attribute.
However, doesn't this point out why it is a bad idea to force the app to be in portrait? That is really annoying on phones with a keyboard.
Related
I got an app that is locked in landscape orientation. Now, when I change the devices settings to set its orientation locked to portrait, some problems occur.
After a bit of testing, it seems that for each Activity that is started, the onCreate is called twice.
First time for portrait orientation, second time as an orientationChange with orientation set to landscape. The first orientation is wrong, and probably has something to do with the device being locked to portrait.
In the app, the orientation is forced to landscape programmatically (using setRequestedOrientation), and I prefer to keep it that way, if possible, for various reasons.
Any ideas about how to avoid this behavior?
Thanks in advance!
Ok, I found a solution myself.
After a lot of searching and digging in the code, the solution was fairly simple.
All I had to do was add:
android:configChanges="orientation|screenSize"
... to all my Activities in the manifest file.
This tells the app that I will handle configuration changes myself in the code. Instead of doing this, I didn't add any handlers for these config changes. This way, my Activities aren't recreated when the orientation change happens at the creation of those Activities. I can do it this way, because my app is locked in a certain orientation.
This post came closest to my problem, but it's solution didn't work for me:
Android: set activity orientation BEFORE onCreate, but not in manifest (HDMI plugged in issue)
This post gave me the answer:
http://www.acnenomor.com/1053172p1/oncreate-were-called-twice-after-implementing-setrequestedorientation
Try setting up the orientation directly in the manifest instead of programmatically. Under your activity tag in AndroidManifest.xml add android:screenOrientation="landscape".
This should force the activity to be directly created in the correct orientation.
I have stumbled on a problem, that, when the screen turns off while being in LANDSCAPE orientation, certain devices "rotate" the app back to PORTRAIT position (because the lockscreen is PORTRAIT only or something like that). I did a little research before posting this, and most popular work-around is to modify app's configuration change process to prevent activity being recreated after the configuration has changed.
But disabling activity recreation is not a solution for me, because my app supports both orientations with sepparate layout's etc.
So i would like to find out, is it possible to disable the configuration change only in special cases (Screen turned off and orientation is landscape)? Or is the right way to override onConfigurationChanged() then manually manage activity recreation inside that function (i guess simply setting different layout resources when orientation is changed simply wont cut it)?
Or is the right way to override onConfigurationChanged() then manually manage activity recreation inside that function?
Yes to an extent.
You cannot set the configChanges attribute programmatically. I guess it's to do with the way an Activity is created. They're created from the XML first and then the overridden methods in your activity implementation are invoked. There's nothing in the API that lets you change the configChanges attribute.
Now in your case it doesn't sound like you need to. If you support both orientations, then if the user locks the device and it rotates back why does it matter? From a UX perspective we know it's in portrait mode again. So should your app when it opens back up.
Background
Each time the device is being rotated, Android will destroy the current activity and re-create it with the new configuration.
An easy way to avoid activity re-creation is by adding "configChanges" values to the manifest ("screenSize" and "orientation" as I recall).
The problem
If you use the "configChanges" attribute, the app won't respect the orientation lock feature that some (or all?) Android devices have, which prevent anything from being rotated when the screen is being rotated.
What I've tried
I tried playing with the "screenOrientation" attribute values, yet none of them achieved what I wanted.
The question
How can I prevent the activity from being re-created when the screen changes its orientation, while also respecting the user preference of orientation-lock?
Is it perhaps possible to get the value of this preference, so that I could let the activity lock its orientation when it's being set?
OK, never mind. I think I just missed the correct one:
android:screenOrientation="user"
Together with the other configChanges values, this works perfectly.
How to test the landscape mode on Android Emulator (Mac) ?
When I press ctrl+fn+11 the emulator turns into landscape mode, but the activity screen remains in portrait orientation. What should I do?
Does your activity have android:configChanges="orientation" in its manifest entry? That would explain the behavior, since you are then responsible for overriding onConfigurationChanged() and redrawing your views yourself.
If you don't need to handle it explicitly, just remove the configChanges attribute and your activity will be destroyed and recreated (you might need to save and restore custom state in this case).
I am using android HTC HERO 2.1 version.
The activity I write :
<activity android:name=".gogogo"
android:label="#string/app_name"
android:theme="#style/Theme.mine"
android:screenOrientation="landscape"
android:configChanges="orientation">
let my orientation change to landscape.
However, I figured out that every time I pressed "power" button and then come back to my activity, it always start at portrait.
I tried the game : TEETER , which was written not by me. Has the same problem too, any one know how to fix it??
Edit: it always start at portrait. --> I mean, if you come back from power, you have to scroll down to do everything, there is something like screen lock.
You can see that there is a "status bar" at the top of the screen and at this time, the orientation is "portrait". So after You scroll the "screen lock" a little bit down, you can see the activity (such as TEETER) is at "portrait" state. When you scroll all the way down, the activity's orientation will suddenly change to the state "landscape".
So the conclusion is : My activity is forced to orient once. And I really want to know how to fix it!
Hai Steven Shih:
Pls go through this page of developer guide.
http://developer.android.com/guide/topics/manifest/activity-element.html
and try this line
android:windowSoftInputMode="stateUnspecified|adjustPan"
Not sure if it's the same problem, but here is the problem I had :
I force the orientation as landscape in the manifest
My activity has a two surfaceviews ( a camera preview and a layer on top of it )
After pressing the power button and coming back, my views were suddenly in the wrong orientation
It seems to be the same problem as another question : Disable orientation but detect orientation
I think the problem is that once you press the power button, the lock screen forces the orientation as portrait. In the onConfigurationChanged I get an orientation change right when I press the power button, which was unexpected because I told to explicitly lock the orientation. The fact is that when another activity which comes in front forces the orientation, the other activities get notified of the orientation change, even if they asked for an explicit orientation.
Here's my workaround :
in onPause, detach the views with removeView ( my application has programmatically created views, not an xml layout )
in onResume , first check if the orientation is the one you requested ( getResources().getConfiguration().orientation ). If it's the case, reattach the views ( addContentView or whatever ).
if the orientation is not the one you expect, call setRequestedOrientation
onConfigurationChanged will be called to tell the orientation has been changed to the one you requested. At this point you can reattach the views with setContentView.
Seems a bit complicated, but that's what I had to go through in my particular case, since my views are created dynamically and directly attach to the default FrameLayout of the activity. Maybe I then missed some default behaviors because of that, but this way I could achieve the reactivity I was looking for.
Not sure whether this can be called a fix, but it's kind of a work-around.
#Override
public void onWindowFocusChanged(boolean hasFocus) {
if (hasFocus)
setContentView(mGameView);
else
setContentView(mEmptyView);
}
Where mGameView is your ordinary content and mEmptyView is just a simple View object. The activity will still be drawn in portrait for a frame or two, but it will not be visible to the user.
I've tested this with HTC Hero and Nexus S.