My Android app contains a custom slider control based on the SeekBar, and I want to attach a custom text phrase to my control to explain its use for Accessibility.
I have done this successfully using View.setContentDescription(text), and TalkBack correctly speaks the phrase when I request focus on my slider control from Activity.onCreate.
So far, so good. However, when I touch the control, which I believe sets the AccessibilityFocus on my Android API 16 test device, extra words are being added to the spoken phrase, i.e. '...seek control. 0 per cent'. I want to remove these additional words.
I have tried to eliminate them using event.getText().clear() in View.onInitializeAccessibilityEvent(event) without success. Echoing the event to LogCat reports the correct phrase in event.contentDescription and no entries in event.text, but the extra words appear both in the audio output from the device hardware and in the on-screen debug text displayed by Menu->Settings->Accessibility->TalkBack->Settings->Developer Settings->Display Speech Output.
Please can anyone suggest where the extra words are being added, and how to eliminate them?
Any constructive suggestions would be welcomed. Thanks.
Update
I can see that some Explore By Touch (initial single-tap) event on my custom control does not pass through either its onInitializeAccessibilityEvent or dispatchPopulateAccessibilityEvent methods as I am deliberately calling event.setContentDescription(null). Despite this, there is an AccessibilityEvent being generated with my custom control's ContentDescription, set in Activity.onCreate in code, plus the extra words I'm trying to eliminate.
I've also set an AccessibilityDelegate on my custom control's parent ViewGroup to give visibility of its onRequestSendAccessibilityEvent calls. This confirms that no event containing my ContentDescription is passing through.
This is very puzzling, and happens on both the emulator and real hardware with API 16. Any ideas?
You also need to override http://developer.android.com/reference/android/view/View.html#onInitializeAccessibilityNodeInfo(android.view.accessibility.AccessibilityNodeInfo)
and set the contentDescription there.
If you want to remove the 0%, I would try to change the class in AccessibilityNodeInfo/AccessibilityEvent: http://developer.android.com/reference/android/view/accessibility/AccessibilityNodeInfo.html#setClassName(java.lang.CharSequence)
I believe that this is a bug in TalkBack, and have raised Google Eyes-Free issue #375, including example code.
Update: Google have now archived this. Link moved to: http://code.google.com/archive/p/eyes-free/issues/375
来源：https://stackoverflow.com/questions/25001069/android-how-to-eliminate-spoken-text-from-accessibilityevents-when-extending-se