fix: talkback read display value on scroll value change (#373)

* When TalkBack is enabled, read new values while scrolling a wheel

* Support for reading displayed value instead index value (IosClone)

* Add comments and small refactoring

* Small refactor

android/src/main/java/com/henninghall/date_picker/pickers/IosClone.java

@@ -6,22 +6,41 @@ import android.util.AttributeSet;
 import android.view.View;
 import android.view.MotionEvent;
 
-import com.henninghall.date_picker.ui.Accessibility;
-
 import cn.carbswang.android.numberpickerview.library.NumberPickerView;
 
+import com.henninghall.date_picker.ui.Accessibility;
+
 public class IosClone extends NumberPickerView implements Picker {
+    private Picker.OnValueChangeListenerInScrolling mOnValueChangeListenerInScrolling;
 
     public IosClone(Context context) {
         super(context);
+        initSetOnValueChangeListenerInScrolling();
     }
 
     public IosClone(Context context, AttributeSet attrs) {
         super(context, attrs);
+        initSetOnValueChangeListenerInScrolling();
     }
 
     public IosClone(Context context, AttributeSet attrs, int defStyleAttr) {
         super(context, attrs, defStyleAttr);
+        initSetOnValueChangeListenerInScrolling();
+    }
+
+    private void initSetOnValueChangeListenerInScrolling() {
+        final Picker self = this;
+        super.setOnValueChangeListenerInScrolling(new NumberPickerView.OnValueChangeListenerInScrolling() {
+            @Override
+
+            public void onValueChangeInScrolling(NumberPickerView picker, int oldVal, int newVal) {
+                Accessibility.announceNumberPickerValue(picker, newVal);
+
+                if (mOnValueChangeListenerInScrolling != null) {
+                    mOnValueChangeListenerInScrolling.onValueChangeInScrolling(self, oldVal, newVal);
+                }
+            }
+        });
     }
 
     @Override
@@ -34,13 +53,7 @@ public class IosClone extends NumberPickerView implements Picker {
 
     @Override
     public void setOnValueChangeListenerInScrolling(final Picker.OnValueChangeListenerInScrolling listener) {
-        final Picker self = this;
-        super.setOnValueChangeListenerInScrolling(new NumberPickerView.OnValueChangeListenerInScrolling() {
-            @Override
-            public void onValueChangeInScrolling(NumberPickerView picker, int oldVal, int newVal) {
-                listener.onValueChangeInScrolling(self, oldVal, newVal);
-            }
-        });
+        this.mOnValueChangeListenerInScrolling = listener;
     }
 
     @Override

android/src/main/java/com/henninghall/date_picker/ui/Accessibility.java

@@ -5,6 +5,8 @@ import android.os.Build;
 import android.view.View;
 import android.view.accessibility.AccessibilityEvent;
 import android.view.accessibility.AccessibilityManager;
+import android.accessibilityservice.AccessibilityServiceInfo;
+import cn.carbswang.android.numberpickerview.library.NumberPickerView;
 
 import com.henninghall.date_picker.DatePickerManager;
 import com.henninghall.date_picker.State;
@@ -13,6 +15,8 @@ import com.henninghall.date_picker.wheelFunctions.WheelFunction;
 import com.henninghall.date_picker.wheels.Wheel;
 
 import java.util.Locale;
+import java.util.Arrays;
+import java.util.List;
 
 public class Accessibility {
 
@@ -85,6 +89,60 @@ public class Accessibility {
         picker.picker.getView().setContentDescription(descriptionPrefix + ", "+ descriptionPostFix + " "+ selectedDateString);
     }
 
+    /**
+     * Checks if the accessibility service responsible of spoken feedback is active
+     */
+    public static boolean isSpokenFeedbackEnabled() {
+        return hasAccessibilityFeatureTypeEnabled(AccessibilityServiceInfo.FEEDBACK_SPOKEN);
+    }
+
+    /**
+     * Get a list of accessibility services currently active
+     */
+    private static boolean hasAccessibilityFeatureTypeEnabled(int type) {
+
+        List<AccessibilityServiceInfo> enabledServices =
+                systemManager.getEnabledAccessibilityServiceList(type);
+
+        return enabledServices != null && enabledServices.size() > 0;
+    }
+
+    /**
+     * Read a message out loud when spoken feedback is active
+     */
+    public static void announce(String message) {
+        if (systemManager == null || !isSpokenFeedbackEnabled()) {
+            return;
+          }
+
+          AccessibilityEvent event = AccessibilityEvent.obtain(AccessibilityEvent.TYPE_ANNOUNCEMENT);
+          event.getText().add(message);
+          systemManager.sendAccessibilityEvent(event);
+    }
+
+    /**
+     * Get NumberPickerView displayValue from value.
+     */
+    private static String numberPickerValueToDisplayedValue(NumberPickerView numberPicker, int value) {
+        final String[] displayValues = numberPicker.getDisplayedValues();
+
+        final String displayValue = displayValues[value];
+
+        if (displayValue != null) {
+            return displayValue;
+        }
+
+        return String.valueOf(value);
+    }
+
+    /**
+     * Read NumberPickerView displayed value.
+     * For TalkBack to read dates etc. correctly, make sure they are in localised format.
+     */
+    public static void announceNumberPickerValue(NumberPickerView numberPicker, int newValue) {
+        announce(numberPickerValueToDisplayedValue(numberPicker, newValue));
+    }
+
     private String getAccessibleTextForSelectedDate() {
         String accessibleText;
         switch(state.getMode()) {