Add View.setUsageHint() to describe click actions for TalkBack users

[ataulm]

Usage hints are used by TalkBack to describe the action that will be triggered on click or long click, e.g.:

"The Matrix... <pause>... Double tap to start playing movie"

where "The Matrix" is the content description and "Double tap to start playing movie" is the usage hint.

Without a custom hint set, it will read: "The Matrix... <pause>... Double tap to activate".

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Java implementation:

    ...
    setUsageHint(movieItemView, "start playing movie", null);
}

private static void setUsageHint(View view, @Nullable CharSequence clickLabel, @Nullable CharSequence longClickLabel) {
    ViewCompat.setAccessibilityDelegate(
        this, new AccessibilityDelegateCompat() {
            @Override
            public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) {
                super.onInitializeAccessibilityNodeInfo(host, info);

                if (host.isClickable()) {
                    info.addAction(new AccessibilityNodeInfoCompat.AccessibilityActionCompat(ACTION_CLICK, clickLabel));
                }

                if (host.isLongClickable()) {
                    info.addAction(new AccessibilityNodeInfoCompat.AccessibilityActionCompat(ACTION_LONG_CLICK, longClickLabel));
                }
            }
        }
    );
}

with Kotlin-ktx:

movieItemView.setUsageHint("start playing movie")

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There are many more combinations of tests I can add but I dunno if it's too much. I am concerned that View.kt and consequently ViewTest.kt will get very large - is there some strategy to mitigate this or is it not considered an issue?

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On pre-Lollipop, this behaviour is a no-op (handled by ViewCompat's implementation of AccessibilityDelegate under the hood).

[ataulm]

⚠️ Note: ViewCompat comes from the support library.

This functionality is possible without ViewCompat, since View also has setAccessibilityDelegate but would require RequiresSdk annotations. I don't mind either.

[ataulm]

Is there something I could answer or change to get this merged in?

If it's not suitable for this library, could we close the PR?