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It seems that 9-patch images in Xamarin may have regressed in the recent past. 9-patch images are quite special to the "aapt" tooling and it seems that we do not treat them as special as they need to be.
var d = Resources.GetDrawable(Resource.Drawable.abc_textfield_default_mtrl_alpha);
d will be a type of: Android.Graphics.Drawables.BitmapDrawable
Now this already sounds really fishy to me because consuming a 9-patch image in this fashion will result in the following error:
11-11 08:18:39.991 I/MonoDroid( 3554): UNHANDLED EXCEPTION:
11-11 08:18:39.995 I/MonoDroid( 3554): Android.Views.InflateException: Binary XML file line #1: Error inflating class EditText ---> Android.Content.Res.Resources+NotFoundException: File res/drawable-v21/abc_edit_text_material.xml from drawable resource ID #0x7f020015 ---> Org.XmlPull.V1.XmlPullParserException: Binary XML file line #24: <nine-patch> requires a valid 9-patch source image
The kicker here is that this is a resource coming directly from the AppCompat v7 library. More specifically it is trying to use a <nine-patch> above:
So the error message is telling us that our <nine-patch> srcs are invalid. Well that seems fair enough because they are invalid in terms of what actual `type` is returned when getting this resource.
Now let's jump into normal Android:
Drawable d = AppCompatResources.getDrawable(this, R.drawable.abc_textfield_default_mtrl_alpha);
Class c = d.getClass();
d will be a type of: android.graphics.drawable.NinePatchDrawable
This is correct behavior as it not only returns the correct type back, but it also does not throw an error when accessing a <nine-patch>.
1. Download https://github.com/xamarinhq/app-acquaint
2. Open up App/Acquaint.Native.sln
3. Run the Droid project on API 21 (Note: This is the easiest way to reproduce the failure since Lollipop uses these <nine-patch> items in a drawable as noted above - res/drawable-v21/abc_edit_text_material.xml.
4. You should run into an unhandled exception like above on the following line of the SetupActivity.cs:
_MainLayout = LayoutInflater.Inflate(Resource.Layout.Setup, null);
If you'd like to test the native Android side for behavior differences, you can simply create a new project with the "Navigation Drawer Activity" template as it will contain this resource. You can then add the two lines of code from above to get the drawable class type.
Xamarin - 184.108.40.206
I would be interested to see if you can attach the pre and post processed 9 patch file. This would narrow down is this is a problem with the build system or the binding. A post build 9 patch should have an extra chunk in it which identify it as a 9 patch image.
Created attachment 19160 [details]
Before: The 9-patch named "abc_textfield_default_mtrl_alpha" found in the `AppData/Local/Xamarin/Xamarin.Android.Support.v7.AppCompat`
After: The 9-patch named "abc_textfield_default_mtrl_alpha" found in the .apk's res/ folder
From my initial comparisons, they seem to be the exact same file(with no added bits). I'm not sure if these are the correct locations to grab them from, but please let me know if there's anything else I can do.
Created attachment 19161 [details]
Android Studio 9-Patches
Doing the same comparison with Android Studio and the same bitmap, I'm seeing that the pre/post processed 9 patch files are different:
(In reply to Jon Douglas from comment #3)
> Created attachment 19161 [details]
> Android Studio 9-Patches
> Doing the same comparison with Android Studio and the same bitmap, I'm
> seeing that the pre/post processed 9 patch files are different:
Please note that I used the Android Studio paths of:
Before: NinePatchExample\app\src\main\res\ (Inside the application resources)
After: NinePatchExample\app\build\outputs\apk\app-debug\res\ (Inside of the .apk)
I just tried this on the very latest master of monodroid.
New project, updated the nuget packages to the latest. Built then added the following
var d = Resources.GetDrawable (Resource.Drawable.abc_textfield_default_mtrl_alpha);
if (d == null)
throw new Exception ("error d should exist");
var nine = d as Android.Graphics.Drawables.NinePatchDrawable;
if (nine == null)
throw new Exception ("error d should be a NinePatchDrawable");
And it works. d is a NinePatchDrawable object.
So it I think this is working. I will see if I can add a runtime test to our suite though.
Perfect! I think a test would be very helpful here so these types of errors don't pop up every now and then.
I can still reproduce with the latest stable release tools & NuGet packages. I've created a minimum viable reproduction project and will attach it.
Created attachment 21029 [details]
Sample Reproduction Project
Open the sample project in Visual Studio, build, deploy, & run on an Android 5.0.x (API 21) emulator or device.
Looks like someone added
to the project.
This stops the crunching of .png files as part of the app build process. But crunching is also what processes the 9 patch files. So if you switch it off.. the 9 patch files don't get processed. Hence this issue.
So I'm gonna mark this as answered.