[Fingerprint] Fix link accessibility

Copied ExploreByTouchHelper, LinkAccessibilityHelper and LinkTextView
from setup wizard and switched fingerprint_settings_footer to use
LinkTextView, so that users can navigate to the link in TalkBack
mode.

Bug: 24343933
Change-Id: I0ff0c054510dfef4263ea223cb0044a4bddf321f

res/layout/fingerprint_settings_footer.xml

@@ -14,7 +14,7 @@
   ~ See the License for the specific language governing permissions and
   ~ limitations under the License
   -->
-<TextView
+<com.android.settings.widget.LinkTextView
     xmlns:android="http://schemas.android.com/apk/res/android"
     style="@android:style/TextAppearance.Material.Body1"
     android:layout_width="wrap_content"
@@ -23,5 +23,4 @@
     android:paddingTop="32dp"
     android:paddingStart="16dp"
     android:paddingEnd="16dp"
-    android:selectable="false">
+    android:selectable="false" />
-</TextView>

src/com/android/settings/widget/ExploreByTouchHelper.java

@@ -0,0 +1,724 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.widget;
+
+import android.content.Context;
+import android.graphics.Rect;
+import android.os.Bundle;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.ViewParent;
+import android.view.accessibility.AccessibilityEvent;
+import android.view.accessibility.AccessibilityManager;
+import android.view.accessibility.AccessibilityNodeInfo;
+import android.view.accessibility.AccessibilityNodeProvider;
+
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * Copied from setup wizard, which is in turn a modified copy of
+ * com.android.internal.ExploreByTouchHelper with the following modifications:
+ *
+ * - Make accessibility calls to the views, instead of to the accessibility delegate directly to
+ *   make sure those methods for View subclasses are called.
+ *
+ * ExploreByTouchHelper is a utility class for implementing accessibility
+ * support in custom {@link android.view.View}s that represent a collection of View-like
+ * logical items. It extends {@link android.view.accessibility.AccessibilityNodeProvider} and
+ * simplifies many aspects of providing information to accessibility services
+ * and managing accessibility focus. This class does not currently support
+ * hierarchies of logical items.
+ * <p>
+ * This should be applied to the parent view using
+ * {@link android.view.View#setAccessibilityDelegate}:
+ *
+ * <pre>
+ * mAccessHelper = ExploreByTouchHelper.create(someView, mAccessHelperCallback);
+ * ViewCompat.setAccessibilityDelegate(someView, mAccessHelper);
+ * </pre>
+ */
+public abstract class ExploreByTouchHelper extends View.AccessibilityDelegate {
+    /** Virtual node identifier value for invalid nodes. */
+    public static final int INVALID_ID = Integer.MIN_VALUE;
+
+    /** Default class name used for virtual views. */
+    private static final String DEFAULT_CLASS_NAME = View.class.getName();
+
+    // Temporary, reusable data structures.
+    private final Rect mTempScreenRect = new Rect();
+    private final Rect mTempParentRect = new Rect();
+    private final Rect mTempVisibleRect = new Rect();
+    private final int[] mTempGlobalRect = new int[2];
+
+    /** View's context **/
+    private Context mContext;
+
+    /** System accessibility manager, used to check state and send events. */
+    private final AccessibilityManager mManager;
+
+    /** View whose internal structure is exposed through this helper. */
+    private final View mView;
+
+    /** Node provider that handles creating nodes and performing actions. */
+    private ExploreByTouchNodeProvider mNodeProvider;
+
+    /** Virtual view id for the currently focused logical item. */
+    private int mFocusedVirtualViewId = INVALID_ID;
+
+    /** Virtual view id for the currently hovered logical item. */
+    private int mHoveredVirtualViewId = INVALID_ID;
+
+    /**
+     * Factory method to create a new {@link com.google.android.setupwizard.util.ExploreByTouchHelper}.
+     *
+     * @param forView View whose logical children are exposed by this helper.
+     */
+    public ExploreByTouchHelper(View forView) {
+        if (forView == null) {
+            throw new IllegalArgumentException("View may not be null");
+        }
+
+        mView = forView;
+        mContext = forView.getContext();
+        mManager = (AccessibilityManager) mContext.getSystemService(Context.ACCESSIBILITY_SERVICE);
+    }
+
+    /**
+     * Returns the {@link android.view.accessibility.AccessibilityNodeProvider} for this helper.
+     *
+     * @param host View whose logical children are exposed by this helper.
+     * @return The accessibility node provider for this helper.
+     */
+    @Override
+    public AccessibilityNodeProvider getAccessibilityNodeProvider(View host) {
+        if (mNodeProvider == null) {
+            mNodeProvider = new ExploreByTouchNodeProvider();
+        }
+        return mNodeProvider;
+    }
+
+    /**
+     * Dispatches hover {@link android.view.MotionEvent}s to the virtual view hierarchy when
+     * the Explore by Touch feature is enabled.
+     * <p>
+     * This method should be called by overriding
+     * {@link android.view.View#dispatchHoverEvent}:
+     *
+     * <pre>&#64;Override
+     * public boolean dispatchHoverEvent(MotionEvent event) {
+     *   if (mHelper.dispatchHoverEvent(this, event) {
+     *     return true;
+     *   }
+     *   return super.dispatchHoverEvent(event);
+     * }
+     * </pre>
+     *
+     * @param event The hover event to dispatch to the virtual view hierarchy.
+     * @return Whether the hover event was handled.
+     */
+    public boolean dispatchHoverEvent(MotionEvent event) {
+        if (!mManager.isEnabled() || !mManager.isTouchExplorationEnabled()) {
+            return false;
+        }
+
+        switch (event.getAction()) {
+            case MotionEvent.ACTION_HOVER_MOVE:
+            case MotionEvent.ACTION_HOVER_ENTER:
+                final int virtualViewId = getVirtualViewAt(event.getX(), event.getY());
+                updateHoveredVirtualView(virtualViewId);
+                return (virtualViewId != INVALID_ID);
+            case MotionEvent.ACTION_HOVER_EXIT:
+                if (mFocusedVirtualViewId != INVALID_ID) {
+                    updateHoveredVirtualView(INVALID_ID);
+                    return true;
+                }
+                return false;
+            default:
+                return false;
+        }
+    }
+
+    /**
+     * Populates an event of the specified type with information about an item
+     * and attempts to send it up through the view hierarchy.
+     * <p>
+     * You should call this method after performing a user action that normally
+     * fires an accessibility event, such as clicking on an item.
+     *
+     * <pre>public void performItemClick(T item) {
+     *   ...
+     *   sendEventForVirtualViewId(item.id, AccessibilityEvent.TYPE_VIEW_CLICKED);
+     * }
+     * </pre>
+     *
+     * @param virtualViewId The virtual view id for which to send an event.
+     * @param eventType The type of event to send.
+     * @return true if the event was sent successfully.
+     */
+    public boolean sendEventForVirtualView(int virtualViewId, int eventType) {
+        if ((virtualViewId == INVALID_ID) || !mManager.isEnabled()) {
+            return false;
+        }
+
+        final ViewParent parent = mView.getParent();
+        if (parent == null) {
+            return false;
+        }
+
+        final AccessibilityEvent event = createEvent(virtualViewId, eventType);
+        return parent.requestSendAccessibilityEvent(mView, event);
+    }
+
+    /**
+     * Notifies the accessibility framework that the properties of the parent
+     * view have changed.
+     * <p>
+     * You <b>must</b> call this method after adding or removing items from the
+     * parent view.
+     */
+    public void invalidateRoot() {
+        invalidateVirtualView(View.NO_ID);
+    }
+
+    /**
+     * Notifies the accessibility framework that the properties of a particular
+     * item have changed.
+     * <p>
+     * You <b>must</b> call this method after changing any of the properties set
+     * in {@link #onPopulateNodeForVirtualView}.
+     *
+     * @param virtualViewId The virtual view id to invalidate.
+     */
+    public void invalidateVirtualView(int virtualViewId) {
+        sendEventForVirtualView(virtualViewId, AccessibilityEvent.TYPE_WINDOW_CONTENT_CHANGED);
+    }
+
+    /**
+     * Returns the virtual view id for the currently focused item,
+     *
+     * @return A virtual view id, or {@link #INVALID_ID} if no item is
+     *         currently focused.
+     */
+    public int getFocusedVirtualView() {
+        return mFocusedVirtualViewId;
+    }
+
+    /**
+     * Sets the currently hovered item, sending hover accessibility events as
+     * necessary to maintain the correct state.
+     *
+     * @param virtualViewId The virtual view id for the item currently being
+     *            hovered, or {@link #INVALID_ID} if no item is hovered within
+     *            the parent view.
+     */
+    private void updateHoveredVirtualView(int virtualViewId) {
+        if (mHoveredVirtualViewId == virtualViewId) {
+            return;
+        }
+
+        final int previousVirtualViewId = mHoveredVirtualViewId;
+        mHoveredVirtualViewId = virtualViewId;
+
+        // Stay consistent with framework behavior by sending ENTER/EXIT pairs
+        // in reverse order. This is accurate as of API 18.
+        sendEventForVirtualView(virtualViewId, AccessibilityEvent.TYPE_VIEW_HOVER_ENTER);
+        sendEventForVirtualView(previousVirtualViewId, AccessibilityEvent.TYPE_VIEW_HOVER_EXIT);
+    }
+
+    /**
+     * Constructs and returns an {@link android.view.accessibility.AccessibilityEvent} for the specified
+     * virtual view id, which includes the host view ({@link android.view.View#NO_ID}).
+     *
+     * @param virtualViewId The virtual view id for the item for which to
+     *            construct an event.
+     * @param eventType The type of event to construct.
+     * @return An {@link android.view.accessibility.AccessibilityEvent} populated with information about
+     *         the specified item.
+     */
+    private AccessibilityEvent createEvent(int virtualViewId, int eventType) {
+        switch (virtualViewId) {
+            case View.NO_ID:
+                return createEventForHost(eventType);
+            default:
+                return createEventForChild(virtualViewId, eventType);
+        }
+    }
+
+    /**
+     * Constructs and returns an {@link android.view.accessibility.AccessibilityEvent} for the host node.
+     *
+     * @param eventType The type of event to construct.
+     * @return An {@link android.view.accessibility.AccessibilityEvent} populated with information about
+     *         the specified item.
+     */
+    private AccessibilityEvent createEventForHost(int eventType) {
+        final AccessibilityEvent event = AccessibilityEvent.obtain(eventType);
+        mView.onInitializeAccessibilityEvent(event);
+        return event;
+    }
+
+    /**
+     * Constructs and returns an {@link android.view.accessibility.AccessibilityEvent} populated with
+     * information about the specified item.
+     *
+     * @param virtualViewId The virtual view id for the item for which to
+     *            construct an event.
+     * @param eventType The type of event to construct.
+     * @return An {@link android.view.accessibility.AccessibilityEvent} populated with information about
+     *         the specified item.
+     */
+    private AccessibilityEvent createEventForChild(int virtualViewId, int eventType) {
+        final AccessibilityEvent event = AccessibilityEvent.obtain(eventType);
+        event.setEnabled(true);
+        event.setClassName(DEFAULT_CLASS_NAME);
+
+        // Allow the client to populate the event.
+        onPopulateEventForVirtualView(virtualViewId, event);
+
+        // Make sure the developer is following the rules.
+        if (event.getText().isEmpty() && (event.getContentDescription() == null)) {
+            throw new RuntimeException("Callbacks must add text or a content description in "
+                    + "populateEventForVirtualViewId()");
+        }
+
+        // Don't allow the client to override these properties.
+        event.setPackageName(mView.getContext().getPackageName());
+        event.setSource(mView, virtualViewId);
+
+        return event;
+    }
+
+    /**
+     * Constructs and returns an {@link android.view.accessibility.AccessibilityNodeInfo} for the
+     * specified virtual view id, which includes the host view
+     * ({@link android.view.View#NO_ID}).
+     *
+     * @param virtualViewId The virtual view id for the item for which to
+     *            construct a node.
+     * @return An {@link android.view.accessibility.AccessibilityNodeInfo} populated with information
+     *         about the specified item.
+     */
+    private AccessibilityNodeInfo createNode(int virtualViewId) {
+        switch (virtualViewId) {
+            case View.NO_ID:
+                return createNodeForHost();
+            default:
+                return createNodeForChild(virtualViewId);
+        }
+    }
+
+    /**
+     * Constructs and returns an {@link android.view.accessibility.AccessibilityNodeInfo} for the
+     * host view populated with its virtual descendants.
+     *
+     * @return An {@link android.view.accessibility.AccessibilityNodeInfo} for the parent node.
+     */
+    private AccessibilityNodeInfo createNodeForHost() {
+        final AccessibilityNodeInfo node = AccessibilityNodeInfo.obtain(mView);
+        mView.onInitializeAccessibilityNodeInfo(node);
+
+        // Add the virtual descendants.
+        final LinkedList<Integer> virtualViewIds = new LinkedList<Integer>();
+        getVisibleVirtualViews(virtualViewIds);
+
+        for (Integer childVirtualViewId : virtualViewIds) {
+            node.addChild(mView, childVirtualViewId);
+        }
+
+        return node;
+    }
+
+    /**
+     * Constructs and returns an {@link android.view.accessibility.AccessibilityNodeInfo} for the
+     * specified item. Automatically manages accessibility focus actions.
+     * <p>
+     * Allows the implementing class to specify most node properties, but
+     * overrides the following:
+     * <ul>
+     * <li>{@link android.view.accessibility.AccessibilityNodeInfo#setPackageName}
+     * <li>{@link android.view.accessibility.AccessibilityNodeInfo#setClassName}
+     * <li>{@link android.view.accessibility.AccessibilityNodeInfo#setParent(android.view.View)}
+     * <li>{@link android.view.accessibility.AccessibilityNodeInfo#setSource(android.view.View, int)}
+     * <li>{@link android.view.accessibility.AccessibilityNodeInfo#setVisibleToUser}
+     * <li>{@link android.view.accessibility.AccessibilityNodeInfo#setBoundsInScreen(android.graphics.Rect)}
+     * </ul>
+     * <p>
+     * Uses the bounds of the parent view and the parent-relative bounding
+     * rectangle specified by
+     * {@link android.view.accessibility.AccessibilityNodeInfo#getBoundsInParent} to automatically
+     * update the following properties:
+     * <ul>
+     * <li>{@link android.view.accessibility.AccessibilityNodeInfo#setVisibleToUser}
+     * <li>{@link android.view.accessibility.AccessibilityNodeInfo#setBoundsInParent}
+     * </ul>
+     *
+     * @param virtualViewId The virtual view id for item for which to construct
+     *            a node.
+     * @return An {@link android.view.accessibility.AccessibilityNodeInfo} for the specified item.
+     */
+    private AccessibilityNodeInfo createNodeForChild(int virtualViewId) {
+        final AccessibilityNodeInfo node = AccessibilityNodeInfo.obtain();
+
+        // Ensure the client has good defaults.
+        node.setEnabled(true);
+        node.setClassName(DEFAULT_CLASS_NAME);
+
+        // Allow the client to populate the node.
+        onPopulateNodeForVirtualView(virtualViewId, node);
+
+        // Make sure the developer is following the rules.
+        if ((node.getText() == null) && (node.getContentDescription() == null)) {
+            throw new RuntimeException("Callbacks must add text or a content description in "
+                    + "populateNodeForVirtualViewId()");
+        }
+
+        node.getBoundsInParent(mTempParentRect);
+        if (mTempParentRect.isEmpty()) {
+            throw new RuntimeException("Callbacks must set parent bounds in "
+                    + "populateNodeForVirtualViewId()");
+        }
+
+        final int actions = node.getActions();
+        if ((actions & AccessibilityNodeInfo.ACTION_ACCESSIBILITY_FOCUS) != 0) {
+            throw new RuntimeException("Callbacks must not add ACTION_ACCESSIBILITY_FOCUS in "
+                    + "populateNodeForVirtualViewId()");
+        }
+        if ((actions & AccessibilityNodeInfo.ACTION_CLEAR_ACCESSIBILITY_FOCUS) != 0) {
+            throw new RuntimeException("Callbacks must not add ACTION_CLEAR_ACCESSIBILITY_FOCUS in "
+                    + "populateNodeForVirtualViewId()");
+        }
+
+        // Don't allow the client to override these properties.
+        node.setPackageName(mView.getContext().getPackageName());
+        node.setSource(mView, virtualViewId);
+        node.setParent(mView);
+
+        // Manage internal accessibility focus state.
+        if (mFocusedVirtualViewId == virtualViewId) {
+            node.setAccessibilityFocused(true);
+            node.addAction(AccessibilityNodeInfo.ACTION_CLEAR_ACCESSIBILITY_FOCUS);
+        } else {
+            node.setAccessibilityFocused(false);
+            node.addAction(AccessibilityNodeInfo.ACTION_ACCESSIBILITY_FOCUS);
+        }
+
+        // Set the visibility based on the parent bound.
+        if (intersectVisibleToUser(mTempParentRect)) {
+            node.setVisibleToUser(true);
+            node.setBoundsInParent(mTempParentRect);
+        }
+
+        // Calculate screen-relative bound.
+        mView.getLocationOnScreen(mTempGlobalRect);
+        final int offsetX = mTempGlobalRect[0];
+        final int offsetY = mTempGlobalRect[1];
+        mTempScreenRect.set(mTempParentRect);
+        mTempScreenRect.offset(offsetX, offsetY);
+        node.setBoundsInScreen(mTempScreenRect);
+
+        return node;
+    }
+
+    private boolean performAction(int virtualViewId, int action, Bundle arguments) {
+        switch (virtualViewId) {
+            case View.NO_ID:
+                return performActionForHost(action, arguments);
+            default:
+                return performActionForChild(virtualViewId, action, arguments);
+        }
+    }
+
+    private boolean performActionForHost(int action, Bundle arguments) {
+        return mView.performAccessibilityAction(action, arguments);
+    }
+
+    private boolean performActionForChild(int virtualViewId, int action, Bundle arguments) {
+        switch (action) {
+            case AccessibilityNodeInfo.ACTION_ACCESSIBILITY_FOCUS:
+            case AccessibilityNodeInfo.ACTION_CLEAR_ACCESSIBILITY_FOCUS:
+                return manageFocusForChild(virtualViewId, action, arguments);
+            default:
+                return onPerformActionForVirtualView(virtualViewId, action, arguments);
+        }
+    }
+
+    private boolean manageFocusForChild(int virtualViewId, int action, Bundle arguments) {
+        switch (action) {
+            case AccessibilityNodeInfo.ACTION_ACCESSIBILITY_FOCUS:
+                return requestAccessibilityFocus(virtualViewId);
+            case AccessibilityNodeInfo.ACTION_CLEAR_ACCESSIBILITY_FOCUS:
+                return clearAccessibilityFocus(virtualViewId);
+            default:
+                return false;
+        }
+    }
+
+    /**
+     * Computes whether the specified {@link android.graphics.Rect} intersects with the visible
+     * portion of its parent {@link android.view.View}. Modifies {@code localRect} to contain
+     * only the visible portion.
+     *
+     * @param localRect A rectangle in local (parent) coordinates.
+     * @return Whether the specified {@link android.graphics.Rect} is visible on the screen.
+     */
+    private boolean intersectVisibleToUser(Rect localRect) {
+        // Missing or empty bounds mean this view is not visible.
+        if ((localRect == null) || localRect.isEmpty()) {
+            return false;
+        }
+
+        // Attached to invisible window means this view is not visible.
+        if (mView.getWindowVisibility() != View.VISIBLE) {
+            return false;
+        }
+
+        // An invisible predecessor means that this view is not visible.
+        ViewParent viewParent = mView.getParent();
+        while (viewParent instanceof View) {
+            final View view = (View) viewParent;
+            if ((view.getAlpha() <= 0) || (view.getVisibility() != View.VISIBLE)) {
+                return false;
+            }
+            viewParent = view.getParent();
+        }
+
+        // A null parent implies the view is not visible.
+        if (viewParent == null) {
+            return false;
+        }
+
+        // If no portion of the parent is visible, this view is not visible.
+        if (!mView.getLocalVisibleRect(mTempVisibleRect)) {
+            return false;
+        }
+
+        // Check if the view intersects the visible portion of the parent.
+        return localRect.intersect(mTempVisibleRect);
+    }
+
+    /**
+     * Returns whether this virtual view is accessibility focused.
+     *
+     * @return True if the view is accessibility focused.
+     */
+    private boolean isAccessibilityFocused(int virtualViewId) {
+        return (mFocusedVirtualViewId == virtualViewId);
+    }
+
+    /**
+     * Attempts to give accessibility focus to a virtual view.
+     * <p>
+     * A virtual view will not actually take focus if
+     * {@link android.view.accessibility.AccessibilityManager#isEnabled()} returns false,
+     * {@link android.view.accessibility.AccessibilityManager#isTouchExplorationEnabled()} returns false,
+     * or the view already has accessibility focus.
+     *
+     * @param virtualViewId The id of the virtual view on which to place
+     *            accessibility focus.
+     * @return Whether this virtual view actually took accessibility focus.
+     */
+    private boolean requestAccessibilityFocus(int virtualViewId) {
+        final AccessibilityManager accessibilityManager =
+                (AccessibilityManager) mContext.getSystemService(Context.ACCESSIBILITY_SERVICE);
+
+        if (!mManager.isEnabled()
+                || !accessibilityManager.isTouchExplorationEnabled()) {
+            return false;
+        }
+        // TODO: Check virtual view visibility.
+        if (!isAccessibilityFocused(virtualViewId)) {
+            mFocusedVirtualViewId = virtualViewId;
+            // TODO: Only invalidate virtual view bounds.
+            mView.invalidate();
+            sendEventForVirtualView(virtualViewId,
+                    AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUSED);
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Attempts to clear accessibility focus from a virtual view.
+     *
+     * @param virtualViewId The id of the virtual view from which to clear
+     *            accessibility focus.
+     * @return Whether this virtual view actually cleared accessibility focus.
+     */
+    private boolean clearAccessibilityFocus(int virtualViewId) {
+        if (isAccessibilityFocused(virtualViewId)) {
+            mFocusedVirtualViewId = INVALID_ID;
+            mView.invalidate();
+            sendEventForVirtualView(virtualViewId,
+                    AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUS_CLEARED);
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Provides a mapping between view-relative coordinates and logical
+     * items.
+     *
+     * @param x The view-relative x coordinate
+     * @param y The view-relative y coordinate
+     * @return virtual view identifier for the logical item under
+     *         coordinates (x,y)
+     */
+    protected abstract int getVirtualViewAt(float x, float y);
+
+    /**
+     * Populates a list with the view's visible items. The ordering of items
+     * within {@code virtualViewIds} specifies order of accessibility focus
+     * traversal.
+     *
+     * @param virtualViewIds The list to populate with visible items
+     */
+    protected abstract void getVisibleVirtualViews(List<Integer> virtualViewIds);
+
+    /**
+     * Populates an {@link android.view.accessibility.AccessibilityEvent} with information about the
+     * specified item.
+     * <p>
+     * Implementations <b>must</b> populate the following required fields:
+     * <ul>
+     * <li>event text, see {@link android.view.accessibility.AccessibilityEvent#getText} or
+     * {@link android.view.accessibility.AccessibilityEvent#setContentDescription}
+     * </ul>
+     * <p>
+     * The helper class automatically populates the following fields with
+     * default values, but implementations may optionally override them:
+     * <ul>
+     * <li>item class name, set to android.view.View, see
+     * {@link android.view.accessibility.AccessibilityEvent#setClassName}
+     * </ul>
+     * <p>
+     * The following required fields are automatically populated by the
+     * helper class and may not be overridden:
+     * <ul>
+     * <li>package name, set to the package of the host view's
+     * {@link android.content.Context}, see {@link android.view.accessibility.AccessibilityEvent#setPackageName}
+     * <li>event source, set to the host view and virtual view identifier,
+     * see {@link android.view.accessibility.AccessibilityRecord#setSource(android.view.View, int)}
+     * </ul>
+     *
+     * @param virtualViewId The virtual view id for the item for which to
+     *            populate the event
+     * @param event The event to populate
+     */
+    protected abstract void onPopulateEventForVirtualView(
+            int virtualViewId, AccessibilityEvent event);
+
+    /**
+     * Populates an {@link android.view.accessibility.AccessibilityNodeInfo} with information
+     * about the specified item.
+     * <p>
+     * Implementations <b>must</b> populate the following required fields:
+     * <ul>
+     * <li>event text, see {@link android.view.accessibility.AccessibilityNodeInfo#setText} or
+     * {@link android.view.accessibility.AccessibilityNodeInfo#setContentDescription}
+     * <li>bounds in parent coordinates, see
+     * {@link android.view.accessibility.AccessibilityNodeInfo#setBoundsInParent}
+     * </ul>
+     * <p>
+     * The helper class automatically populates the following fields with
+     * default values, but implementations may optionally override them:
+     * <ul>
+     * <li>enabled state, set to true, see
+     * {@link android.view.accessibility.AccessibilityNodeInfo#setEnabled}
+     * <li>item class name, identical to the class name set by
+     * {@link #onPopulateEventForVirtualView}, see
+     * {@link android.view.accessibility.AccessibilityNodeInfo#setClassName}
+     * </ul>
+     * <p>
+     * The following required fields are automatically populated by the
+     * helper class and may not be overridden:
+     * <ul>
+     * <li>package name, identical to the package name set by
+     * {@link #onPopulateEventForVirtualView}, see
+     * {@link android.view.accessibility.AccessibilityNodeInfo#setPackageName}
+     * <li>node source, identical to the event source set in
+     * {@link #onPopulateEventForVirtualView}, see
+     * {@link android.view.accessibility.AccessibilityNodeInfo#setSource(android.view.View, int)}
+     * <li>parent view, set to the host view, see
+     * {@link android.view.accessibility.AccessibilityNodeInfo#setParent(android.view.View)}
+     * <li>visibility, computed based on parent-relative bounds, see
+     * {@link android.view.accessibility.AccessibilityNodeInfo#setVisibleToUser}
+     * <li>accessibility focus, computed based on internal helper state, see
+     * {@link android.view.accessibility.AccessibilityNodeInfo#setAccessibilityFocused}
+     * <li>bounds in screen coordinates, computed based on host view bounds,
+     * see {@link android.view.accessibility.AccessibilityNodeInfo#setBoundsInScreen}
+     * </ul>
+     * <p>
+     * Additionally, the helper class automatically handles accessibility
+     * focus management by adding the appropriate
+     * {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_ACCESSIBILITY_FOCUS} or
+     * {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_CLEAR_ACCESSIBILITY_FOCUS}
+     * action. Implementations must <b>never</b> manually add these actions.
+     * <p>
+     * The helper class also automatically modifies parent- and
+     * screen-relative bounds to reflect the portion of the item visible
+     * within its parent.
+     *
+     * @param virtualViewId The virtual view identifier of the item for
+     *            which to populate the node
+     * @param node The node to populate
+     */
+    protected abstract void onPopulateNodeForVirtualView(
+            int virtualViewId, AccessibilityNodeInfo node);
+
+    /**
+     * Performs the specified accessibility action on the item associated
+     * with the virtual view identifier. See
+     * {@link android.view.accessibility.AccessibilityNodeInfo#performAction(int, android.os.Bundle)} for
+     * more information.
+     * <p>
+     * Implementations <b>must</b> handle any actions added manually in
+     * {@link #onPopulateNodeForVirtualView}.
+     * <p>
+     * The helper class automatically handles focus management resulting
+     * from {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_ACCESSIBILITY_FOCUS}
+     * and
+     * {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_CLEAR_ACCESSIBILITY_FOCUS}
+     * actions.
+     *
+     * @param virtualViewId The virtual view identifier of the item on which
+     *            to perform the action
+     * @param action The accessibility action to perform
+     * @param arguments (Optional) A bundle with additional arguments, or
+     *            null
+     * @return true if the action was performed
+     */
+    protected abstract boolean onPerformActionForVirtualView(
+            int virtualViewId, int action, Bundle arguments);
+
+    /**
+     * Exposes a virtual view hierarchy to the accessibility framework. Only
+     * used in API 16+.
+     */
+    private class ExploreByTouchNodeProvider extends AccessibilityNodeProvider {
+        @Override
+        public AccessibilityNodeInfo createAccessibilityNodeInfo(int virtualViewId) {
+            return ExploreByTouchHelper.this.createNode(virtualViewId);
+        }
+
+        @Override
+        public boolean performAction(int virtualViewId, int action, Bundle arguments) {
+            return ExploreByTouchHelper.this.performAction(virtualViewId, action, arguments);
+        }
+    }
+}

src/com/android/settings/widget/LinkAccessibilityHelper.java

@@ -0,0 +1,169 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.widget;
+
+import android.graphics.Rect;
+import android.os.Bundle;
+import android.text.Layout;
+import android.text.Spanned;
+import android.text.style.ClickableSpan;
+import android.util.Log;
+import android.view.accessibility.AccessibilityEvent;
+import android.view.accessibility.AccessibilityNodeInfo;
+import android.widget.TextView;
+
+import java.util.List;
+
+/**
+ * Copied from setup wizard.
+ */
+public class LinkAccessibilityHelper extends ExploreByTouchHelper {
+
+    private static final String TAG = "LinkAccessibilityHelper";
+
+    private final TextView mView;
+    private final Rect mTempRect = new Rect();
+
+    public LinkAccessibilityHelper(TextView view) {
+        super(view);
+        mView = view;
+    }
+
+    @Override
+    protected int getVirtualViewAt(float x, float y) {
+        final CharSequence text = mView.getText();
+        if (text instanceof Spanned) {
+            final Spanned spannedText = (Spanned) text;
+            final int offset = mView.getOffsetForPosition(x, y);
+            ClickableSpan[] linkSpans = spannedText.getSpans(offset, offset, ClickableSpan.class);
+            if (linkSpans.length == 1) {
+                ClickableSpan linkSpan = linkSpans[0];
+                return spannedText.getSpanStart(linkSpan);
+            }
+        }
+        return INVALID_ID;
+    }
+
+    @Override
+    protected void getVisibleVirtualViews(List<Integer> virtualViewIds) {
+        final CharSequence text = mView.getText();
+        if (text instanceof Spanned) {
+            final Spanned spannedText = (Spanned) text;
+            ClickableSpan[] linkSpans = spannedText.getSpans(0, spannedText.length(),
+                    ClickableSpan.class);
+            for (ClickableSpan span : linkSpans) {
+                virtualViewIds.add(spannedText.getSpanStart(span));
+            }
+        }
+    }
+
+    @Override
+    protected void onPopulateEventForVirtualView(int virtualViewId, AccessibilityEvent event) {
+        final ClickableSpan span = getSpanForOffset(virtualViewId);
+        if (span != null) {
+            event.setContentDescription(getTextForSpan(span));
+        } else {
+            Log.e(TAG, "ClickableSpan is null for offset: " + virtualViewId);
+            event.setContentDescription(mView.getText());
+        }
+    }
+
+    @Override
+    protected void onPopulateNodeForVirtualView(int virtualViewId, AccessibilityNodeInfo info) {
+        final ClickableSpan span = getSpanForOffset(virtualViewId);
+        if (span != null) {
+            info.setContentDescription(getTextForSpan(span));
+        } else {
+            Log.e(TAG, "ClickableSpan is null for offset: " + virtualViewId);
+            info.setContentDescription(mView.getText());
+        }
+        info.setFocusable(true);
+        info.setClickable(true);
+        getBoundsForSpan(span, mTempRect);
+        if (!mTempRect.isEmpty()) {
+            info.setBoundsInParent(getBoundsForSpan(span, mTempRect));
+        } else {
+            Log.e(TAG, "LinkSpan bounds is empty for: " + virtualViewId);
+            mTempRect.set(0, 0, 1, 1);
+            info.setBoundsInParent(mTempRect);
+        }
+        info.addAction(AccessibilityNodeInfo.ACTION_CLICK);
+    }
+
+    @Override
+    protected boolean onPerformActionForVirtualView(int virtualViewId, int action,
+            Bundle arguments) {
+        if (action == AccessibilityNodeInfo.ACTION_CLICK) {
+            ClickableSpan span = getSpanForOffset(virtualViewId);
+            if (span != null) {
+                span.onClick(mView);
+                return true;
+            } else {
+                Log.e(TAG, "LinkSpan is null for offset: " + virtualViewId);
+            }
+        }
+        return false;
+    }
+
+    private ClickableSpan getSpanForOffset(int offset) {
+        CharSequence text = mView.getText();
+        if (text instanceof Spanned) {
+            Spanned spannedText = (Spanned) text;
+            ClickableSpan[] spans = spannedText.getSpans(offset, offset, ClickableSpan.class);
+            if (spans.length == 1) {
+                return spans[0];
+            }
+        }
+        return null;
+    }
+
+    private CharSequence getTextForSpan(ClickableSpan span) {
+        CharSequence text = mView.getText();
+        if (text instanceof Spanned) {
+            Spanned spannedText = (Spanned) text;
+            return spannedText.subSequence(spannedText.getSpanStart(span),
+                    spannedText.getSpanEnd(span));
+        }
+        return text;
+    }
+
+    // Find the bounds of a span. If it spans multiple lines, it will only return the bounds for the
+    // section on the first line.
+    private Rect getBoundsForSpan(ClickableSpan span, Rect outRect) {
+        CharSequence text = mView.getText();
+        outRect.setEmpty();
+        if (text instanceof Spanned) {
+            Spanned spannedText = (Spanned) text;
+            final int spanStart = spannedText.getSpanStart(span);
+            final int spanEnd = spannedText.getSpanEnd(span);
+            final Layout layout = mView.getLayout();
+            final float xStart = layout.getPrimaryHorizontal(spanStart);
+            final float xEnd = layout.getPrimaryHorizontal(spanEnd);
+            final int lineStart = layout.getLineForOffset(spanStart);
+            final int lineEnd = layout.getLineForOffset(spanEnd);
+            layout.getLineBounds(lineStart, outRect);
+            outRect.left = (int) xStart;
+            if (lineEnd == lineStart) {
+                outRect.right = (int) xEnd;
+            } // otherwise just leave it at the end of the start line
+
+            // Offset for padding
+            outRect.offset(mView.getTotalPaddingLeft(), mView.getTotalPaddingTop());
+        }
+        return outRect;
+    }
+}

src/com/android/settings/widget/LinkTextView.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.widget;
+
+import android.content.Context;
+import android.support.annotation.NonNull;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.widget.TextView;
+
+/**
+ * Copied from setup wizard.
+ */
+public class LinkTextView extends TextView {
+
+    private LinkAccessibilityHelper mAccessibilityHelper;
+
+    public LinkTextView(Context context) {
+        this(context, null);
+    }
+
+    public LinkTextView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        mAccessibilityHelper = new LinkAccessibilityHelper(this);
+        setAccessibilityDelegate(mAccessibilityHelper);
+    }
+
+    @Override
+    protected boolean dispatchHoverEvent(@NonNull MotionEvent event) {
+        if (mAccessibilityHelper.dispatchHoverEvent(event)) {
+            return true;
+        }
+        return super.dispatchHoverEvent(event);
+    }
+}