Fix: Two-finger scroll issue when TalkBack is active (#370)

* Fix: Two-finger scroll issue when TalkBack is active

* refactor: move accessibility related code to accessibility class

* cleanup imports

Co-authored-by: Henning Hall <henning.hall@hotmail.com>

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

@@ -4,6 +4,10 @@ import android.content.Context;
 import android.graphics.Color;
 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;
 
 public class IosClone extends NumberPickerView implements Picker {
@@ -58,4 +62,13 @@ public class IosClone extends NumberPickerView implements Picker {
     public boolean isSpinning() {
         return super.isScrolling();
     }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent event) {
+        if(Accessibility.shouldAllowScroll(this)){
+            super.onTouchEvent(event);
+            return true;
+        }
+        return false;
+    }
 }

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

@@ -1,8 +1,12 @@
 package com.henninghall.date_picker.ui;
 
+import android.content.Context;
+import android.os.Build;
 import android.view.View;
 import android.view.accessibility.AccessibilityEvent;
+import android.view.accessibility.AccessibilityManager;
 
+import com.henninghall.date_picker.DatePickerManager;
 import com.henninghall.date_picker.State;
 import com.henninghall.date_picker.Utils;
 import com.henninghall.date_picker.wheelFunctions.WheelFunction;
@@ -12,6 +16,30 @@ import java.util.Locale;
 
 public class Accessibility {
 
+    private final static AccessibilityManager systemManager =
+            (AccessibilityManager) DatePickerManager.context
+                    .getApplicationContext()
+                    .getSystemService(Context.ACCESSIBILITY_SERVICE);
+
+    /**
+      When TalkBack is active, user can use one finger to explore the screen
+      and set focus to elements. Then user can proceed to use second finger
+      to scroll contents of focused element.
+      When there's multiple pickers next to each other horizontally,
+      it's easy to accidentally scroll more than one picker at a time.
+      Following code aims to fix this issue.
+    */
+    public static boolean shouldAllowScroll(View view){
+        // If TalkBack isn't active, always proceed without suppressing touch events
+        if (!systemManager.isTouchExplorationEnabled()) {
+            return true;
+        }
+        if (Build.VERSION.SDK_INT >= 21) {
+            return view.isAccessibilityFocused();
+        }
+        return false;
+    }
+
     public static class SetAccessibilityDelegate implements WheelFunction {
 
         private final Locale locale;