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Commit 2994491d authored by Alan Viverette's avatar Alan Viverette
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Switch calendar accessibility to use new ExploreByTouchHelper. 

Change-Id: Idc2e268cdaa68524f7a5e7abf7276d8afec8dbba
parent d461f9bf
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Showing with 73 additions and 568 deletions
src/com/android/datetimepicker/date/SimpleMonthView.java
View file @ 2994491d
......@@ -27,10 +27,10 @@ import android.graphics.Typeface;
import android.os.Bundle;
import android.support.v4.view.ViewCompat;
import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat;
import android.support.v4.widget.ExploreByTouchHelper;
import android.text.format.DateFormat;
import android.text.format.DateUtils;
import android.text.format.Time;
import android.util.SparseArray;
import android.view.MotionEvent;
import android.view.View;
import android.view.accessibility.AccessibilityEvent;
......@@ -39,7 +39,6 @@ import android.view.accessibility.AccessibilityNodeInfo;
import com.android.datetimepicker.R;
import com.android.datetimepicker.Utils;
import com.android.datetimepicker.date.SimpleMonthAdapter.CalendarDay;
import com.googlecode.eyesfree.utils.TouchExplorationHelper;
import java.security.InvalidParameterException;
import java.util.Calendar;
......@@ -169,7 +168,7 @@ public class SimpleMonthView extends View {
private final Calendar mCalendar;
private final Calendar mDayLabelCalendar;
private final MonthViewNodeProvider mNodeProvider;
private final MonthViewTouchHelper mTouchHelper;
private int mNumRows = DEFAULT_NUM_ROWS;
......@@ -213,8 +212,8 @@ public class SimpleMonthView extends View {
- MONTH_HEADER_SIZE) / MAX_NUM_ROWS;
// Set up accessibility components.
mNodeProvider = new MonthViewNodeProvider(context, this);
ViewCompat.setAccessibilityDelegate(this, mNodeProvider.getAccessibilityDelegate());
mTouchHelper = new MonthViewTouchHelper(this);
ViewCompat.setAccessibilityDelegate(this, mTouchHelper);
ViewCompat.setImportantForAccessibility(this, ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_YES);
mLockAccessibilityDelegate = true;
......@@ -236,20 +235,20 @@ public class SimpleMonthView extends View {
}
@Override
public boolean onHoverEvent(MotionEvent event) {
public boolean dispatchHoverEvent(MotionEvent event) {
// First right-of-refusal goes the touch exploration helper.
if (mNodeProvider.onHover(this, event)) {
if (mTouchHelper.dispatchHoverEvent(event)) {
return true;
}
return super.onHoverEvent(event);
return super.dispatchHoverEvent(event);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_UP:
final CalendarDay day = getDayFromLocation(event.getX(), event.getY());
if (day != null) {
final int day = getDayFromLocation(event.getX(), event.getY());
if (day >= 0) {
onDayClick(day);
}
break;
......@@ -321,7 +320,6 @@ public class SimpleMonthView extends View {
*
* @param params A map of the new parameters, see
* {@link #VIEW_PARAMS_HEIGHT}
* @param tz The time zone this view should reference times in
*/
public void setMonthParams(HashMap<String, Integer> params) {
if (!params.containsKey(VIEW_PARAMS_MONTH) && !params.containsKey(VIEW_PARAMS_YEAR)) {
......@@ -371,7 +369,7 @@ public class SimpleMonthView extends View {
mNumRows = calculateNumRows();
// Invalidate cached accessibility information.
mNodeProvider.invalidateParent();
mTouchHelper.invalidateRoot();
}
public void reuse() {
......@@ -403,7 +401,7 @@ public class SimpleMonthView extends View {
mWidth = w;
// Invalidate cached accessibility information.
mNodeProvider.invalidateParent();
mTouchHelper.invalidateRoot();
}
private String getMonthAndYearString() {
......@@ -475,16 +473,15 @@ public class SimpleMonthView extends View {
/**
* Calculates the day that the given x position is in, accounting for week
* number. Returns a Time referencing that day or null if
* number. Returns the day or -1 if the position wasn't in a day.
*
* @param x The x position of the touch event
* @return A time object for the tapped day or null if the position wasn't
* in a day
* @return The day number, or -1 if the position wasn't in a day
*/
public CalendarDay getDayFromLocation(float x, float y) {
public int getDayFromLocation(float x, float y) {
int dayStart = mPadding;
if (x < dayStart || x > mWidth - mPadding) {
return null;
return -1;
}
// Selection is (x - start) / (pixels/day) == (x -s) * day / pixels
int row = (int) (y - MONTH_HEADER_SIZE) / mRowHeight;
......@@ -493,24 +490,24 @@ public class SimpleMonthView extends View {
int day = column - findDayOffset() + 1;
day += row * mNumDays;
if (day < 1 || day > mNumCells) {
return null;
return -1;
}
return new CalendarDay(mYear, mMonth, day);
return day;
}
/**
* Called when the user clicks on a day. Handles callbacks to the
* {@link OnDayClickListener} if one is set.
*
* @param day A time object representing the day that was clicked
* @param day The day that was clicked
*/
private void onDayClick(CalendarDay day) {
private void onDayClick(int day) {
if (mOnDayClickListener != null) {
mOnDayClickListener.onDayClick(this, day);
mOnDayClickListener.onDayClick(this, new CalendarDay(mYear, mMonth, day));
}
// This is a no-op if accessibility is turned off.
mNodeProvider.sendEventForItem(day, AccessibilityEvent.TYPE_VIEW_CLICKED);
mTouchHelper.sendEventForVirtualView(day, AccessibilityEvent.TYPE_VIEW_CLICKED);
}
/**
......@@ -518,7 +515,11 @@ public class SimpleMonthView extends View {
* has focus
*/
public CalendarDay getAccessibilityFocus() {
return mNodeProvider.getFocusedItem();
final int day = mTouchHelper.getFocusedVirtualView();
if (day >= 0) {
return new CalendarDay(mYear, mMonth, day);
}
return null;
}
/**
......@@ -526,7 +527,7 @@ public class SimpleMonthView extends View {
* contain accessibility focus.
*/
public void clearAccessibilityFocus() {
mNodeProvider.clearFocusedItem();
mTouchHelper.clearFocusedVirtualView();
}
/**
......@@ -540,8 +541,7 @@ public class SimpleMonthView extends View {
if ((day.year != mYear) || (day.month != mMonth) || (day.day > mNumCells)) {
return false;
}
mNodeProvider.setFocusedItem(day);
mTouchHelper.setFocusedVirtualView(day.day);
return true;
}
......@@ -549,104 +549,87 @@ public class SimpleMonthView extends View {
* Provides a virtual view hierarchy for interfacing with an accessibility
* service.
*/
private class MonthViewNodeProvider extends TouchExplorationHelper<CalendarDay> {
private final SparseArray<CalendarDay> mCachedItems = new SparseArray<CalendarDay>();
private class MonthViewTouchHelper extends ExploreByTouchHelper {
private static final String DATE_FORMAT = "dd MMMM yyyy";
private final Rect mTempRect = new Rect();
private final Calendar mTempCalendar = Calendar.getInstance();
Calendar recycle;
public MonthViewTouchHelper(View host) {
super(host);
}
public MonthViewNodeProvider(Context context, View parent) {
super(context, parent);
public void setFocusedVirtualView(int virtualViewId) {
getAccessibilityNodeProvider(SimpleMonthView.this).performAction(
virtualViewId, AccessibilityNodeInfoCompat.ACTION_ACCESSIBILITY_FOCUS, null);
}
@Override
public void invalidateItem(CalendarDay item) {
super.invalidateItem(item);
mCachedItems.delete(getIdForItem(item));
public void clearFocusedVirtualView() {
final int focusedVirtualView = getFocusedVirtualView();
if (focusedVirtualView != ExploreByTouchHelper.INVALID_ID) {
getAccessibilityNodeProvider(SimpleMonthView.this).performAction(
focusedVirtualView, AccessibilityNodeInfoCompat.ACTION_CLEAR_ACCESSIBILITY_FOCUS, null);
}
}
@Override
public void invalidateParent() {
super.invalidateParent();
mCachedItems.clear();
protected int getVirtualViewAt(float x, float y) {
final int day = getDayFromLocation(x, y);
if (day >= 0) {
return day;
}
return ExploreByTouchHelper.INVALID_ID;
}
@Override
protected boolean performActionForItem(CalendarDay item, int action, Bundle arguments) {
switch (action) {
case AccessibilityNodeInfo.ACTION_CLICK:
onDayClick(item);
return true;
protected void getVisibleVirtualViews(List<Integer> virtualViewIds) {
for (int day = 1; day <= mNumCells; day++) {
virtualViewIds.add(day);
}
return false;
}
@Override
protected void populateEventForItem(CalendarDay item, AccessibilityEvent event) {
event.setContentDescription(getItemDescription(item));
protected void onPopulateEventForVirtualView(int virtualViewId, AccessibilityEvent event) {
event.setContentDescription(getItemDescription(virtualViewId));
}
@Override
protected void populateNodeForItem(CalendarDay item, AccessibilityNodeInfoCompat node) {
getItemBounds(item, mTempRect);
protected void onPopulateNodeForVirtualView(int virtualViewId, AccessibilityNodeInfoCompat node) {
getItemBounds(virtualViewId, mTempRect);
node.setContentDescription(getItemDescription(item));
node.setContentDescription(getItemDescription(virtualViewId));
node.setBoundsInParent(mTempRect);
node.addAction(AccessibilityNodeInfo.ACTION_CLICK);
if (item.day == mSelectedDay) {
if (virtualViewId == mSelectedDay) {
node.setSelected(true);
}
}
@Override
protected void getVisibleItems(List<CalendarDay> items) {
// TODO: Optimize, only return items visible within parent bounds.
for (int day = 1; day <= mNumCells; day++) {
items.add(getItemForId(day));
}
}
@Override
protected CalendarDay getItemAt(float x, float y) {
return getDayFromLocation(x, y);
}
@Override
protected int getIdForItem(CalendarDay item) {
return item.day;
}
@Override
protected CalendarDay getItemForId(int id) {
if ((id < 1) || (id > mNumCells)) {
return null;
}
final CalendarDay item;
if (mCachedItems.indexOfKey(id) >= 0) {
item = mCachedItems.get(id);
} else {
item = new CalendarDay(mYear, mMonth, id);
mCachedItems.put(id, item);
protected boolean onPerformActionForVirtualView(int virtualViewId, int action, Bundle arguments) {
switch (action) {
case AccessibilityNodeInfo.ACTION_CLICK:
onDayClick(virtualViewId);
return true;
}
return item;
return false;
}
/**
* Calculates the bounding rectangle of a given time object.
*
* @param item The time object to calculate bounds for
* @param day The day to calculate bounds for
* @param rect The rectangle in which to store the bounds
*/
private void getItemBounds(CalendarDay item, Rect rect) {
private void getItemBounds(int day, Rect rect) {
final int offsetX = mPadding;
final int offsetY = MONTH_HEADER_SIZE;
final int cellHeight = mRowHeight;
final int cellWidth = ((mWidth - (2 * mPadding)) / mNumDays);
final int index = ((item.day - 1) + findDayOffset());
final int index = ((day - 1) + findDayOffset());
final int row = (index / mNumDays);
final int column = (index % mNumDays);
final int x = (offsetX + (column * cellWidth));
......@@ -660,17 +643,14 @@ public class SimpleMonthView extends View {
* description will be spoken, the components are ordered by descending
* specificity as DAY MONTH YEAR.
*
* @param item The time object to generate a description for
* @param day The day to generate a description for
* @return A description of the time object
*/
private CharSequence getItemDescription(CalendarDay item) {
if (recycle == null) {
recycle = Calendar.getInstance();
}
recycle.set(item.year, item.month, item.day);
CharSequence date = DateFormat.format("dd MMMM yyyy", recycle.getTimeInMillis());
private CharSequence getItemDescription(int day) {
mTempCalendar.set(mYear, mMonth, day);
final CharSequence date = DateFormat.format(DATE_FORMAT, mTempCalendar.getTimeInMillis());
if (item.day == mSelectedDay) {
if (day == mSelectedDay) {
return getContext().getString(R.string.item_is_selected, date);
}
......
src/com/googlecode/eyesfree/utils/TouchExplorationHelper.java deleted 100644 → 0
View file @ d461f9bf
/*
* 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.googlecode.eyesfree.utils;
import android.content.Context;
import android.graphics.Rect;
import android.os.Bundle;
import android.support.v4.view.AccessibilityDelegateCompat;
import android.support.v4.view.ViewCompat;
import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat;
import android.support.v4.view.accessibility.AccessibilityNodeProviderCompat;
import android.support.v4.view.accessibility.AccessibilityRecordCompat;
import android.text.TextUtils;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityManager;
import java.util.LinkedList;
import java.util.List;
public abstract class TouchExplorationHelper<T> extends AccessibilityNodeProviderCompat
implements View.OnHoverListener {
/** Virtual node identifier value for invalid nodes. */
public static final int INVALID_ID = Integer.MIN_VALUE;
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];
private final AccessibilityManager mManager;
private View mParentView;
private int mFocusedItemId = INVALID_ID;
private T mCurrentItem = null;
/**
* Constructs a new touch exploration helper.
*
* @param context The parent context.
*/
public TouchExplorationHelper(Context context, View parentView) {
mManager = (AccessibilityManager) context.getSystemService(Context.ACCESSIBILITY_SERVICE);
mParentView = parentView;
}
/**
* @return The current accessibility focused item, or {@code null} if no
* item is focused.
*/
public T getFocusedItem() {
return getItemForId(mFocusedItemId);
}
/**
* Clears the current accessibility focused item.
*/
public void clearFocusedItem() {
final int itemId = mFocusedItemId;
if (itemId == INVALID_ID) {
return;
}
performAction(itemId, AccessibilityNodeInfoCompat.ACTION_CLEAR_ACCESSIBILITY_FOCUS, null);
}
/**
* Requests accessibility focus be placed on the specified item.
*
* @param item The item to place focus on.
*/
public void setFocusedItem(T item) {
final int itemId = getIdForItem(item);
if (itemId == INVALID_ID) {
return;
}
performAction(itemId, AccessibilityNodeInfoCompat.ACTION_ACCESSIBILITY_FOCUS, null);
}
/**
* Invalidates cached information about the parent view.
* <p>
* You <b>must</b> call this method after adding or removing items from the
* parent view.
* </p>
*/
public void invalidateParent() {
mParentView.sendAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_CONTENT_CHANGED);
}
/**
* Invalidates cached information for a particular item.
* <p>
* You <b>must</b> call this method when any of the properties set in
* {@link #populateNodeForItem(Object, AccessibilityNodeInfoCompat)} have
* changed.
* </p>
*
* @param item
*/
public void invalidateItem(T item) {
sendEventForItem(item, AccessibilityEvent.TYPE_WINDOW_CONTENT_CHANGED);
}
/**
* Populates an event of the specified type with information about an item
* and attempts to send it up through the view hierarchy.
*
* @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) {
if (!mManager.isEnabled()) {
return false;
}
final AccessibilityEvent event = getEventForItem(item, eventType);
final ViewGroup group = (ViewGroup) mParentView.getParent();
return group.requestSendAccessibilityEvent(mParentView, event);
}
@Override
public AccessibilityNodeInfoCompat createAccessibilityNodeInfo(int virtualViewId) {
if (virtualViewId == View.NO_ID) {
return getNodeForParent();
}
final T item = getItemForId(virtualViewId);
if (item == null) {
return null;
}
final AccessibilityNodeInfoCompat node = AccessibilityNodeInfoCompat.obtain();
populateNodeForItemInternal(item, node);
return node;
}
@Override
public boolean performAction(int virtualViewId, int action, Bundle arguments) {
if (virtualViewId == View.NO_ID) {
return ViewCompat.performAccessibilityAction(mParentView, action, arguments);
}
final T item = getItemForId(virtualViewId);
if (item == null) {
return false;
}
boolean handled = false;
switch (action) {
case AccessibilityNodeInfoCompat.ACTION_ACCESSIBILITY_FOCUS:
if (mFocusedItemId != virtualViewId) {
mFocusedItemId = virtualViewId;
sendEventForItem(item, AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUSED);
handled = true;
}
break;
case AccessibilityNodeInfoCompat.ACTION_CLEAR_ACCESSIBILITY_FOCUS:
if (mFocusedItemId == virtualViewId) {
mFocusedItemId = INVALID_ID;
sendEventForItem(item, AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUS_CLEARED);
handled = true;
}
break;
}
handled |= performActionForItem(item, action, arguments);
return handled;
}
@Override
public boolean onHover(View view, MotionEvent event) {
if (!mManager.isTouchExplorationEnabled()) {
return false;
}
switch (event.getAction()) {
case MotionEvent.ACTION_HOVER_ENTER:
case MotionEvent.ACTION_HOVER_MOVE:
final T item = getItemAt(event.getX(), event.getY());
setCurrentItem(item);
return true;
case MotionEvent.ACTION_HOVER_EXIT:
setCurrentItem(null);
return true;
}
return false;
}
private void setCurrentItem(T item) {
if (mCurrentItem == item) {
return;
}
if (mCurrentItem != null) {
sendEventForItem(mCurrentItem, AccessibilityEvent.TYPE_VIEW_HOVER_EXIT);
}
mCurrentItem = item;
if (mCurrentItem != null) {
sendEventForItem(mCurrentItem, AccessibilityEvent.TYPE_VIEW_HOVER_ENTER);
}
}
private AccessibilityEvent getEventForItem(T item, int eventType) {
final AccessibilityEvent event = AccessibilityEvent.obtain(eventType);
final AccessibilityRecordCompat record = new AccessibilityRecordCompat(event);
final int virtualDescendantId = getIdForItem(item);
// Ensure the client has good defaults.
event.setEnabled(true);
// Allow the client to populate the event.
populateEventForItem(item, event);
if (event.getText().isEmpty() && TextUtils.isEmpty(event.getContentDescription())) {
throw new RuntimeException(
"You must add text or a content description in populateEventForItem()");
}
// Don't allow the client to override these properties.
event.setClassName(item.getClass().getName());
event.setPackageName(mParentView.getContext().getPackageName());
record.setSource(mParentView, virtualDescendantId);
return event;
}
private AccessibilityNodeInfoCompat getNodeForParent() {
final AccessibilityNodeInfoCompat info = AccessibilityNodeInfoCompat.obtain(mParentView);
ViewCompat.onInitializeAccessibilityNodeInfo(mParentView, info);
final LinkedList<T> items = new LinkedList<T>();
getVisibleItems(items);
for (T item : items) {
final int virtualDescendantId = getIdForItem(item);
info.addChild(mParentView, virtualDescendantId);
}
return info;
}
private AccessibilityNodeInfoCompat populateNodeForItemInternal(
T item, AccessibilityNodeInfoCompat node) {
final int virtualDescendantId = getIdForItem(item);
// Ensure the client has good defaults.
node.setEnabled(true);
// Allow the client to populate the node.
populateNodeForItem(item, node);
if (TextUtils.isEmpty(node.getText()) && TextUtils.isEmpty(node.getContentDescription())) {
throw new RuntimeException(
"You must add text or a content description in populateNodeForItem()");
}
// Don't allow the client to override these properties.
node.setPackageName(mParentView.getContext().getPackageName());
node.setClassName(item.getClass().getName());
node.setParent(mParentView);
node.setSource(mParentView, virtualDescendantId);
if (mFocusedItemId == virtualDescendantId) {
node.addAction(AccessibilityNodeInfoCompat.ACTION_CLEAR_ACCESSIBILITY_FOCUS);
} else {
node.addAction(AccessibilityNodeInfoCompat.ACTION_ACCESSIBILITY_FOCUS);
}
node.getBoundsInParent(mTempParentRect);
if (mTempParentRect.isEmpty()) {
throw new RuntimeException("You must set parent bounds in populateNodeForItem()");
}
// Set the visibility based on the parent bound.
if (intersectVisibleToUser(mTempParentRect)) {
node.setVisibleToUser(true);
node.setBoundsInParent(mTempParentRect);
}
// Calculate screen-relative bound.
mParentView.getLocationOnScreen(mTempGlobalRect);
final int offsetX = mTempGlobalRect[0];
final int offsetY = mTempGlobalRect[1];
mTempScreenRect.set(mTempParentRect);
mTempScreenRect.offset(offsetX, offsetY);
node.setBoundsInScreen(mTempScreenRect);
return node;
}
/**
* Computes whether the specified {@link Rect} intersects with the visible
* portion of its parent {@link View}. Modifies {@code localRect} to
* contain only the visible portion.
*
* @param localRect A rectangle in local (parent) coordinates.
* @return Whether the specified {@link 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 (mParentView.getWindowVisibility() != View.VISIBLE) {
return false;
}
// An invisible predecessor or one with alpha zero means
// that this view is not visible to the user.
Object current = this;
while (current instanceof View) {
final View view = (View) current;
// We have attach info so this view is attached and there is no
// need to check whether we reach to ViewRootImpl on the way up.
if ((view.getAlpha() <= 0) || (view.getVisibility() != View.VISIBLE)) {
return false;
}
current = view.getParent();
}
// If no portion of the parent is visible, this view is not visible.
if (!mParentView.getLocalVisibleRect(mTempVisibleRect)) {
return false;
}
// Check if the view intersects the visible portion of the parent.
return localRect.intersect(mTempVisibleRect);
}
public AccessibilityDelegateCompat getAccessibilityDelegate() {
return mDelegate;
}
private final AccessibilityDelegateCompat mDelegate = new AccessibilityDelegateCompat() {
@Override
public void onInitializeAccessibilityEvent(View view, AccessibilityEvent event) {
super.onInitializeAccessibilityEvent(view, event);
event.setClassName(view.getClass().getName());
}
@Override
public void onInitializeAccessibilityNodeInfo(View view, AccessibilityNodeInfoCompat info) {
super.onInitializeAccessibilityNodeInfo(view, info);
info.setClassName(view.getClass().getName());
}
@Override
public AccessibilityNodeProviderCompat getAccessibilityNodeProvider(View host) {
return TouchExplorationHelper.this;
}
};
/**
* Performs an accessibility action on the specified item. See
* {@link AccessibilityNodeInfoCompat#performAction(int, Bundle)}.
* <p>
* The helper class automatically handles focus management resulting from
* {@link AccessibilityNodeInfoCompat#ACTION_ACCESSIBILITY_FOCUS} and
* {@link AccessibilityNodeInfoCompat#ACTION_CLEAR_ACCESSIBILITY_FOCUS}, so
* typically a developer only needs to handle actions added manually in the
* {{@link #populateNodeForItem(Object, AccessibilityNodeInfoCompat)}
* method.
* </p>
*
* @param item The item on which to perform the action.
* @param action The accessibility action to perform.
* @param arguments Arguments for the action, or optionally {@code null}.
* @return {@code true} if the action was performed successfully.
*/
protected abstract boolean performActionForItem(T item, int action, Bundle arguments);
/**
* Populates an event with information about the specified item.
* <p>
* At a minimum, a developer must populate the event text by doing one of
* the following:
* <ul>
* <li>appending text to {@link AccessibilityEvent#getText()}</li>
* <li>populating a description with
* {@link AccessibilityEvent#setContentDescription(CharSequence)}</li>
* </ul>
* </p>
*
* @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>
* At a minimum, a developer must:
* <ul>
* <li>populate the event text using
* {@link AccessibilityNodeInfoCompat#setText(CharSequence)} or
* {@link AccessibilityNodeInfoCompat#setContentDescription(CharSequence)}
* </li>
* <li>set the item's parent-relative bounds using
* {@link AccessibilityNodeInfoCompat#setBoundsInParent(Rect)}
* </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.
* <p>
* The result of this method is cached until the developer calls
* {@link #invalidateParent()}.
* </p>
*
* @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>
* This result of this method must be consistent with
* {@link #getItemForId(int)}.
* </p>
*
* @param item The item whose identifier to return.
* @return A unique identifier, or {@link #INVALID_ID}.
*/
protected abstract int getIdForItem(T item);
/**
* Returns the item for a unique identifier. If the specified item does not
* exist, returns {@code null}.
*
* @param id The identifier for the item to return.
* @return An item, or {@code null}.
*/
protected abstract T getItemForId(int id);
}
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