[Xamarin.Android.Build.Tasks] fix for aapt2 and $(AndroidResgenArgs)

[jonathanpeppers]

Fixes: #3314

Create a new Xamarin.Forms project using aapt2, you will encounter a
crash on startup for API 19 devices:

android.content.res.Resources$NotFoundException: File res/drawable/abc_vector_test.xml from drawable resource ID #0x7f080058
at android.content.res.Resources.loadDrawable(Resources.java:2096)
at android.content.res.Resources.getDrawable(Resources.java:700)
at android.support.v4.content.ContextCompat.getDrawable(ContextCompat.java:360)
at android.support.v7.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:198)
at android.support.v7.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:186)
at android.support.v7.widget.AppCompatDrawableManager.checkVectorDrawableSetup(AppCompatDrawableManager.java:753)
at android.support.v7.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:191)
at android.support.v7.widget.TintTypedArray.getDrawableIfKnown(TintTypedArray.java:85)
at android.support.v7.app.AppCompatDelegateImplBase.(AppCompatDelegateImplBase.java:128)
at android.support.v7.app.AppCompatDelegateImplV9.(AppCompatDelegateImplV9.java:149)
at android.support.v7.app.AppCompatDelegateImplV11.(AppCompatDelegateImplV11.java:29)
at android.support.v7.app.AppCompatDelegateImplV14.(AppCompatDelegateImplV14.java:54)
at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:202)
at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:183)
at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:519)
at android.support.v7.app.AppCompatActivity.onCreate(AppCompatActivity.java:70)
at com.taphome.offline.SplashActivity.n_onCreate(Native Method)
at com.taphome.offline.SplashActivity.onCreate(SplashActivity.java:29)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)
at dalvik.system.NativeStart.main(Native Method)
Java.Lang.RuntimeException: File res/drawable/abc_vector_test.xml from drawable resource ID #0x7f080058 --->
Org.XmlPull.V1.XmlPullParserException: Binary XML file line #15: invalid drawable tag vector

Reviewing the logs, there was a missing --no-version-vectors flag?

The Xamarin.Android.Support.Vector.Drawable NuGet was setting this
value:

Target _XamarinAndroidSupportVectorDrawableArgs
AndroidResgenExtraArgs = --no-version-vectors

Unfortunately the logic for passing this flag to aapt2 was happening
too soon, at this point $(AndroidResgenExtraArgs) is blank:

<AndroidAapt2LinkExtraArgs Condition=" '$(_AndroidUseAapt2)' == 'True' And $(AndroidResgenExtraArgs.Contains('--no-version-vectors')) And !($(AndroidAapt2LinkExtraArgs.Contains('--no-version-vectors'))) ">--no-version-vectors $(AndroidAapt2LinkExtraArgs) </AndroidAapt2LinkExtraArgs>

The simple solution here is to move this property at the beginning of
_UpdateAndroidResgen and the problem is solved.

I added a test verifying that we are getting the
--no-version-vectors flag for both aapt and aapt2.

[jonathanpeppers]

There were some really weird byte-order marks that VS removed:

Apparently three of them?

[jonpryor]

The BOM in UTF-8 is 3 bytes: 0xEF, 0xBB, 0xBF. This is thus "expected."

What isn't "expected" is the removal of the BOM in the first place. Why was the BOM removed?

[jonathanpeppers]

@jonpryor our .editorconfig is set to remove BOMs: https://github.com/xamarin/xamarin-android/blob/0b79ab6653a4364f837d513453567485c535c611/.editorconfig#L9

I can change this to charset = utf-8-bom, and it will add BOMs by default.

However, I think it is pretty useful to remove the BOMs for proguard and java files.

[dellis1972]

Can that config file not set that setting per file type?

[jonathanpeppers]

The utf-8-bom setting does this:

Which still appears to be different than what was in this file. But it matches other files?

We can change the BOM setting on a per-extension basis, if that is what we want to do.

[dellis1972]

This looks ok. The Designer tests are not running it seems though?

[jonathanpeppers]

The Github status checks are messed up, but you can go view the build: https://dev.azure.com/DevDiv/DevDiv/_build/results?buildId=2831202

The only test failed is the lint one -- which is known to have an issue right now.