/*
* Copyright (C) 2012 Google Inc.
*
* 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.utils;
import android.annotation.TargetApi;
import android.graphics.Rect;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.view.ViewCompat;
import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat;
import android.support.v4.view.accessibility.AccessibilityRecordCompat;
import android.view.View;
import android.view.accessibility.AccessibilityEvent;
import java.util.LinkedList;
import java.util.List;
/**
* Extension of {@link ExploreByTouchHelper} for custom views that rely on a
* single class for logical units.
* <p>
* This should be applied to the parent view using
* {@link ViewCompat#setAccessibilityDelegate}:
*
* <pre>
* mHelper = new ExploreByTouchHelper(context, someView);
* ViewCompat.setAccessibilityDelegate(someView, mHelper);
* </pre>
*/
public abstract class ExploreByTouchObjectHelper<T> extends ExploreByTouchHelper {
/**
* Constructs a new object-based Explore by Touch helper.
*
* @param parentView The view whose virtual hierarchy is exposed by this
* helper.
*/
public ExploreByTouchObjectHelper(View parentView) {
super(parentView);
}
/**
* 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) {
* ...
* sendEventForItem(item, AccessibilityEvent.TYPE_VIEW_CLICKED);
* }
* </pre>
*
* @param item The item for which to send an event.
* @param eventType The type of event to send.
* @return {@code true} if the event was sent successfully.
*/
public boolean sendEventForItem(T item, int eventType) {
final int virtualViewId = getVirtualViewIdForItem(item);
return sendEventForVirtualViewId(virtualViewId, eventType);
}
@Override
protected final boolean performActionForVirtualViewId(int virtualViewId, int action) {
final T item = getItemForVirtualViewId(virtualViewId);
return item != null && performActionForItem(item, action);
}
@Override
protected final void populateEventForVirtualViewId(int virtualViewId, AccessibilityEvent event) {
final T item = getItemForVirtualViewId(virtualViewId);
if (item == null) {
return;
}
populateEventForItem(item, event);
event.setClassName(item.getClass().getName());
}
@Override
protected final void populateNodeForVirtualViewId(
int virtualViewId, AccessibilityNodeInfoCompat node) {
final T item = getItemForVirtualViewId(virtualViewId);
if (item == null) {
return;
}
populateNodeForItem(item, node);
node.setClassName(item.getClass().getName());
}
@Override
protected final void getVisibleVirtualViewIds(List<Integer> virtualViewIds) {
final List<T> items = new LinkedList<>();
getVisibleItems(items);
for (T item : items) {
final int virtualViewId = getVirtualViewIdForItem(item);
virtualViewIds.add(virtualViewId);
}
}
@Override
protected final int getVirtualViewIdAt(float x, float y) {
final T item = getItemAt(x, y);
if (item == null) {
return INVALID_ID;
}
return getVirtualViewIdForItem(item);
}
/**
* Performs an accessibility action on the specified item. See
* {@link AccessibilityNodeInfoCompat#performAction(int, Bundle)}.
* <p>
* Developers <b>must</b> handle any actions added manually in
* {@link #populateNodeForItem}.
* <p>
* The helper class automatically handles focus management resulting from
* {@link AccessibilityNodeInfoCompat#ACTION_ACCESSIBILITY_FOCUS} and
* {@link AccessibilityNodeInfoCompat#ACTION_CLEAR_ACCESSIBILITY_FOCUS}.
*
* @param item The item on which to perform the action.
* @param action The accessibility action to perform.
* @return {@code true} if the action was performed successfully.
*/
protected abstract boolean performActionForItem(T item, int action);
/**
* Populates an event with information about the specified item.
* <p>
* Developers <b>must</b> populate the following required fields:
* <ul>
* <li>event content, see {@link AccessibilityEvent#getText()} or
* {@link AccessibilityEvent#setContentDescription}
* </ul>
* <p>
* The helper class automatically populates some required fields:
* <ul>
* <li>package name, see {@link AccessibilityEvent#setPackageName}
* <li>item class name, see {@link AccessibilityEvent#setClassName}
* <li>event source, see
* {@link AccessibilityRecordCompat#setSource(View, int)}
* </ul>
*
* @param item The item for which to populate the event.
* @param event The event to populate.
*/
protected abstract void populateEventForItem(T item, AccessibilityEvent event);
/**
* Populates a node with information about the specified item.
* <p>
* Developers <b>must</b> populate the following required fields:
* <ul>
* <li>node content, see {@link AccessibilityNodeInfoCompat#setText} or
* {@link AccessibilityNodeInfoCompat#setContentDescription}
* <li>parent-relative bounds, see
* {@link AccessibilityNodeInfoCompat#setBoundsInParent}
* </ul>
* <p>
* The helper class automatically populates some required fields:
* <ul>
* <li>package name, see {@link AccessibilityNodeInfoCompat#setPackageName}
* <li>item class name, see {@link AccessibilityNodeInfoCompat#setClassName}
* <li>parent view, see {@link AccessibilityNodeInfoCompat#setParent(View)}
* <li>node source, see
* {@link AccessibilityNodeInfoCompat#setSource(View, int)}
* <li>visibility, see {@link AccessibilityNodeInfoCompat#setVisibleToUser}
* <li>screen-relative bounds, see
* {@link AccessibilityNodeInfoCompat#setBoundsInScreen(Rect)}
* </ul>
* <p>
* The helper class also automatically handles accessibility focus
* management by adding one of:
* <ul>
* <li>{@link AccessibilityNodeInfoCompat#ACTION_ACCESSIBILITY_FOCUS}
* <li>{@link AccessibilityNodeInfoCompat#ACTION_CLEAR_ACCESSIBILITY_FOCUS}
* </ul>
*
* @param item The item for which to populate the node.
* @param node The node to populate.
*/
protected abstract void populateNodeForItem(T item, AccessibilityNodeInfoCompat node);
/**
* Populates a list with the parent view's visible items.
*
* @param items The list to populate with visible items.
*/
protected abstract void getVisibleItems(List<T> items);
/**
* Returns the item under the specified parent-relative coordinates.
*
* @param x The parent-relative x coordinate.
* @param y The parent-relative y coordinate.
* @return The item under coordinates (x,y).
*/
protected abstract T getItemAt(float x, float y);
/**
* Returns the unique identifier for an item. If the specified item does not
* exist, returns {@link #INVALID_ID}.
* <p>
* Developers <b>must</b> provide a one-to-one mapping consistent with
* the result of {@link #getItemForVirtualViewId}.
*
* @param item The item whose identifier to return.
* @return A unique identifier, or {@link #INVALID_ID}.
*/
protected abstract int getVirtualViewIdForItem(T item);
/**
* Returns the item for a unique identifier. If the specified item does not
* exist, or if the specified identifier is {@link #INVALID_ID}, returns
* {@code null}.
* <p>
* Developers <b>must</b> provide a one-to-one mapping consistent with the
* result of {@link #getVirtualViewIdForItem}.
*
* @param id The identifier for the item to return.
* @return An item, or {@code null}.
*/
protected abstract T getItemForVirtualViewId(int id);
}