Bug 38227 - Can't use style.xml anymore - No custom theming
Summary: Can't use style.xml anymore - No custom theming
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 2.0.0
Hardware: PC Windows
: --- normal
Target Milestone: ---
Assignee: Bugzilla
Depends on:
Reported: 2016-01-31 05:54 UTC by adrianknight89
Modified: 2016-03-11 22:02 UTC (History)
5 users (show)

Is this bug a regression?: ---
Last known good build:

style.xml can't be used (46.02 KB, application/zip)
2016-01-31 05:54 UTC, adrianknight89

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Description adrianknight89 2016-01-31 05:54:52 UTC
Created attachment 14816 [details]
style.xml can't be used

<package id="Xamarin.Forms" version="" targetFramework="monoandroid60" />

Compile using Android version: Use Latest Platform (Android 6.0 Marshmallow)
Minimum Android to target; Android 4.0.3 (API Level 15)
Target Android version: Use Compile using SDK version

Compiling this on VS2015 / Win10
Xamarin (413372c)
Xamarin.Android (e98e962)

Application errors out on launch at LoadApplication(new App()); in MainActivity.cs with the following error:

01-31 07:07:08.315 I/MonoDroid(26231): UNHANDLED EXCEPTION:
01-31 07:07:08.315 I/MonoDroid(26231): System.NullReferenceException: Object reference not set to an instance of an object
01-31 07:07:08.315 I/MonoDroid(26231):   at Xamarin.Forms.Platform.Android.Platform.UpdateActionBarHomeAsUp (Android.App.ActionBar actionBar) [0x0001d] in <filename unknown>:0 
01-31 07:07:08.315 I/MonoDroid(26231):   at Xamarin.Forms.Platform.Android.Platform.HideActionBar () [0x0000d] in <filename unknown>:0 
01-31 07:07:08.315 I/MonoDroid(26231):   at Xamarin.Forms.Platform.Android.Platform.UpdateActionBar () [0x000a0] in <filename unknown>:0 
01-31 07:07:08.315 I/MonoDroid(26231):   at Xamarin.Forms.Platform.Android.Platform.SetPage (Xamarin.Forms.Page newRoot) [0x000bd] in <filename unknown>:0 
01-31 07:07:08.315 I/MonoDroid(26231):   at Xamarin.Forms.Platform.Android.FormsApplicationActivity.InternalSetPage (Xamarin.Forms.Page page) [0x000b7] in <filename unknown>:0 
01-31 07:07:08.315 I/MonoDroid(26231):   at Xamarin.Forms.Platform.Android.FormsApplicationActivity.SetMainPage () [0x0000c] in <filename unknown>:0 
01-31 07:07:08.315 I/MonoDroid(26231):   at Xamarin.Forms.Platform.Android.FormsApplicationActivity.LoadApplication (Xamarin.Forms.Application application) [0x0002d] in <filename unknown>:0 
01-31 07:07:08.325 I/MonoDroid(26231):   at App23.Droid.MainActivity.OnCreate (Android.OS.Bundle bundle) [0x00020] in C:\Users\xyz\Documents\Visual Studio 2015\Projects\App23\App23\App23.Droid\MainActivity.cs:24 
01-31 07:07:08.325 I/MonoDroid(26231):   at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_ (IntPtr jnienv, IntPtr native__this, IntPtr native_savedInstanceState) [0x00011] in /Users/builder/data/lanes/2692/e98e9627/source/monodroid/src/Mono.Android/platforms/android-23/src/generated/Android.App.Activity.cs:2857 
01-31 07:07:08.325 I/MonoDroid(26231):   at (wrapper dynamic-method) System.Object:0d4ea3af-d627-4c79-af83-fd09d236a7f1 (intptr,intptr,intptr)
01-31 07:07:08.335 W/art     (26231): JNI RegisterNativeMethods: attempt to register 0 native methods for md52ce486a14f4bcd95899665e9d932190b.JavaProxyThrowable

I noticed Xamarin.Android works fine, so this must be a Forms issue.

Please see repro.

Also created a thread: http://forums.xamarin.com/discussion/60091/updating-xamarin-to-the-latest-stable-seems-to-have-broken-android-custom-styles-for-xf#latest
Comment 1 adrianknight89 2016-01-31 06:11:43 UTC
This issue is happening on both Visual Studio and Xamarin Studio.
Comment 2 adrianknight89 2016-02-02 00:53:21 UTC
I rolled back to the following versions, however the issue still persists:

Comment 3 Jonathan Pryor 2016-02-02 10:55:40 UTC
Based on the stack trace, I'm going to surmise that the exception happens because Activity.ActionBar is null.

Based on that assumption, observe $ANDROID_SDK_PATH/platforms/android-23/data/res/values/themes.xml:

      <style name="Theme">
        <!-- ... -->
        <item name="windowActionBar">false</item>
      <!-- ... -->

      <!-- Default theme with an Action Bar. -->
      <style name="Theme.WithActionBar">
        <item name="windowActionBar">true</item>

i.e. the default android:Theme resource does NOT support the ActionBar, and thus (I assume) Activity.ActionBar returns null.

If you need the action bar -- and presumably Xamarin.Forms requires the action bar -- then use a style which supports it:

    <style name="MyTheme" parent="android:Theme.WithActionBar">

Please try that.
Comment 4 adrianknight89 2016-02-02 15:14:16 UTC
Jonathan, I do not need the action bar or the status bar. I want to go full screen. If, however, Xamarin Forms requires an ActionBar, then I can use another theme and hide it programmatically at startup. I'll try your suggestion later today and get back with you. I remember android:Theme working for me before I upgraded Xamarin. I just can't remember what version of Xamarin I was using before.
Comment 5 adrianknight89 2016-02-02 18:41:40 UTC
Theme.WithActionBar did not work for me. I think the problem is using any theme throws an error. Did you test run the repro I submitted? Did it work for you? Please suggest a reason as to why this bug's status was changed to "NEEDINFO".
Comment 6 adrianknight89 2016-02-03 14:50:02 UTC
Please suggest a reason as to why this bug's status was changed to "NEEDINFO". I'd like to understand if my repro is producible on your end.
Comment 7 adrianknight89 2016-02-14 04:26:39 UTC
I noticed the problem is with these two lines:

<item name="android:windowNoTitle">true</item>
<item name="android:windowActionBar">false</item>

These are throwing the exception whether I set my theme to android:Theme or android:Theme.WithActionBar. They used to work before.
Comment 8 adrianknight89 2016-03-11 22:02:17 UTC
This could be closed as I figured out a way to hide the title bar properly. I believe I was approaching things from the wrong perspective.