Java tutorial
/* * 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); }