Bug 51664 - View.PerformAccessibilityAction and other AccessibilityAction methods map to the incorrect enum?
Summary: View.PerformAccessibilityAction and other AccessibilityAction methods map to ...
Status: VERIFIED FIXED
Alias: None
Product: Android
Classification: Xamarin
Component: General ()
Version: 7.1 (C9)
Hardware: PC Windows
: Highest major
Target Milestone: 15.5
Assignee: Atsushi Eno
URL:
Depends on:
Blocks:
 
Reported: 2017-01-20 16:35 UTC by Jon Douglas [MSFT]
Modified: 2017-11-13 10:37 UTC (History)
4 users (show)

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

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Status:
VERIFIED FIXED

Description Jon Douglas [MSFT] 2017-01-20 16:35:11 UTC
*Description:

Based on the current Android documentation for View.performAccessibilityAction, it has a parameter of type "int" named "action". However I believe this mapping might be incorrect.

https://developer.android.com/reference/android/view/View.html#performAccessibilityAction(int, android.os.Bundle)

In the documentation it notes that a default implementation will delegate ACTION_SCROLL_BACKWARD(https://developer.android.com/reference/android/view/accessibility/AccessibilityNodeInfo.html#ACTION_SCROLL_BACKWARD) and ACTION_SCROLL_FORWARD(https://developer.android.com/reference/android/view/accessibility/AccessibilityNodeInfo.html#ACTION_SCROLL_FORWARD) to the nested scrolling parents if nested scrolling is enabled on the view. This is clue #1 that this parameter of "int action" should be of C# type "Action" (https://developer.xamarin.com/api/type/Android.Views.Accessibility.Action/)

Instead the same method based on the docs expects an enum of type "GlobalAction"

https://developer.xamarin.com/api/member/Android.Views.View.PerformAccessibilityAction/p/Android.AccessibilityServices.GlobalAction/Android.OS.Bundle/

https://developer.xamarin.com/api/type/Android.AccessibilityServices.GlobalAction/

The reason why this seems off is that the source code of this method in Android seems to specifically have a switch case on these "Action" items.

http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/5.1.1_r1/android/view/View.java#View.performAccessibilityActionInternal%28int%2Candroid.os.Bundle%29

I believe the culprit is the method mapping here:

https://github.com/xamarin/xamarin-android/blob/1889b58257130b1db5e01104ab59183e5bdf67a7/src/Mono.Android/methodmap.csv#L1344

I believe that not only this method is wrong, but other methods as well such as 

https://developer.android.com/reference/android/view/View.AccessibilityDelegate.html#performAccessibilityAction(android.view.View, int, android.os.Bundle)

https://developer.android.com/reference/android/view/accessibility/AccessibilityEvent.html#getAction()

https://developer.android.com/reference/android/view/accessibility/AccessibilityEvent.html#setAction(int)

https://developer.android.com/reference/android/view/accessibility/AccessibilityNodeProvider.html#performAction(int, int, android.os.Bundle)

I believe the correct mappings here would be https://developer.xamarin.com/api/type/Android.Views.Accessibility.Action/ for these methods. Please correct me if I'm wrong or if this is intended behavior.


*Version:

I believe this is the same scenario up to the current master of https://github.com/xamarin/xamarin-android
Comment 2 Tom Opgenorth 2017-06-26 20:23:56 UTC
I agree with Jon Douglas - this is a broken API implementation; the current mapping in Xamarin.Android is incorrect. The int values of GlobalAction don't match the values expected by the Android APIs.

For example,  AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD is 8192 and AccessbilityNodeInfo.ACTION_SCROLL_FORWARD is 4096. GlobalAction only has values in the range of 1 - 7.
Comment 3 Atsushi Eno 2017-09-14 17:16:37 UTC
This kind of mismatching enumification happens at any time due to lack of Android documentation at early phase or anything that *might* be passed via Intent where more than one enum types could apply to one single int.
The only alternative is to totally dump the idea of using enums (which I believe is the way to go).

https://github.com/xamarin/xamarin-android/pull/859 introduces some workarounds and fixes. Old incorrect members cannot be removed for compatiblity. We add method overloads that take the right enums, and introduce getter/setter methods with the right enum for the wrong property (whose type cannot be changed for comparibility).
Comment 4 Atsushi Eno 2017-09-19 11:27:17 UTC
The PR is merged.
Comment 5 Sarang Kanchalwar 2017-11-13 10:37:02 UTC
While verifying the bug, I tried using AccessibilityNodeInfo.ActionScrollBackward.
As the intellisense tool tip shows that AccessibilityNodeInfo.ActionScrollBackward is obsolete & will be removed in future. I am using Android.Views.Accessibility.Action.ScrollBackward as mentioned in tool tip. Also did the same for rest constants/enums.
Expected values for comparison taken from-
https://developer.android.com/reference/android/view/accessibility/AccessibilityNodeInfo.html#ACTION_SCROLL_BACKWARD


I found the expected results.
ACTION_SCROLL_BACKWARD = Action.ScrollBackward = 8192
ACTION_SCROLL_FORWARD = Action.ScrollForward = 4096
ACTION_SELECT = Action.Select = 4
ACTION_SET_SELECTION = Action.SetSelection = 131072
ACTION_SET_TEXT = Action.SetText = 2097152


Following are the build details:
Microsoft Visual Studio Enterprise 2017 
Version 15.5.0 [27109.1.d15rel]
VisualStudio.15.Release.Int/15.5.0+27109.1.d15rel
Microsoft .NET Framework
Version 4.7.02046
Installed Version: Enterprise
Xamarin   4.8.0.744 (a773aca)
Xamarin Designer   4.8.152 (5e0da2967)
Xamarin.Android SDK   8.1.0.23 (HEAD/f65f87747)
Xamarin.iOS and Xamarin.Mac SDK   11.4.0.214 (c4240f3)

Complete Build Details:
https://gist.github.com/ksarang2009/6cd2e5cdc720c160dba34fbf6a76ee1c

Screencast: 
https://www.screencast.com/t/QEWroPO8aFvj