/*
* Copyright (C) 2006 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 android.view;
import com.android.internal.R;
import com.android.internal.view.menu.MenuBuilder;
import android.content.Context;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Interpolator;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.Point;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.Region;
import android.graphics.Shader;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.Parcel;
import android.os.Parcelable;
import android.os.RemoteException;
import android.os.SystemClock;
import android.os.SystemProperties;
import android.util.AttributeSet;
import android.util.Config;
import android.util.EventLog;
import android.util.Log;
import android.util.Pool;
import android.util.Poolable;
import android.util.PoolableManager;
import android.util.Pools;
import android.util.SparseArray;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityEventSource;
import android.view.accessibility.AccessibilityManager;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.inputmethod.EditorInfo;
import android.view.inputmethod.InputConnection;
import android.view.inputmethod.InputMethodManager;
import android.widget.ScrollBarDrawable;
import java.lang.ref.SoftReference;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.WeakHashMap;
/**
* <p>
* This class represents the basic building block for user interface components. A View
* occupies a rectangular area on the screen and is responsible for drawing and
* event handling. View is the base class for <em>widgets</em>, which are
* used to create interactive UI components (buttons, text fields, etc.). The
* {@link android.view.ViewGroup} subclass is the base class for <em>layouts</em>, which
* are invisible containers that hold other Views (or other ViewGroups) and define
* their layout properties.
* </p>
*
* <div class="special">
* <p>For an introduction to using this class to develop your
* application's user interface, read the Developer Guide documentation on
* <strong><a href="{@docRoot}guide/topics/ui/index.html">User Interface</a></strong>. Special topics
* include:
* <br/><a href="{@docRoot}guide/topics/ui/declaring-layout.html">Declaring Layout</a>
* <br/><a href="{@docRoot}guide/topics/ui/menus.html">Creating Menus</a>
* <br/><a href="{@docRoot}guide/topics/ui/layout-objects.html">Common Layout Objects</a>
* <br/><a href="{@docRoot}guide/topics/ui/binding.html">Binding to Data with AdapterView</a>
* <br/><a href="{@docRoot}guide/topics/ui/ui-events.html">Handling UI Events</a>
* <br/><a href="{@docRoot}guide/topics/ui/themes.html">Applying Styles and Themes</a>
* <br/><a href="{@docRoot}guide/topics/ui/custom-components.html">Building Custom Components</a>
* <br/><a href="{@docRoot}guide/topics/ui/how-android-draws.html">How Android Draws Views</a>.
* </p>
* </div>
*
* <a name="Using"></a>
* <h3>Using Views</h3>
* <p>
* All of the views in a window are arranged in a single tree. You can add views
* either from code or by specifying a tree of views in one or more XML layout
* files. There are many specialized subclasses of views that act as controls or
* are capable of displaying text, images, or other content.
* </p>
* <p>
* Once you have created a tree of views, there are typically a few types of
* common operations you may wish to perform:
* <ul>
* <li><strong>Set properties:</strong> for example setting the text of a
* {@link android.widget.TextView}. The available properties and the methods
* that set them will vary among the different subclasses of views. Note that
* properties that are known at build time can be set in the XML layout
* files.</li>
* <li><strong>Set focus:</strong> The framework will handled moving focus in
* response to user input. To force focus to a specific view, call
* {@link #requestFocus}.</li>
* <li><strong>Set up listeners:</strong> Views allow clients to set listeners
* that will be notified when something interesting happens to the view. For
* example, all views will let you set a listener to be notified when the view
* gains or loses focus. You can register such a listener using
* {@link #setOnFocusChangeListener}. Other view subclasses offer more
* specialized listeners. For example, a Button exposes a listener to notify
* clients when the button is clicked.</li>
* <li><strong>Set visibility:</strong> You can hide or show views using
* {@link #setVisibility}.</li>
* </ul>
* </p>
* <p><em>
* Note: The Android framework is responsible for measuring, laying out and
* drawing views. You should not call methods that perform these actions on
* views yourself unless you are actually implementing a
* {@link android.view.ViewGroup}.
* </em></p>
*
* <a name="Lifecycle"></a>
* <h3>Implementing a Custom View</h3>
*
* <p>
* To implement a custom view, you will usually begin by providing overrides for
* some of the standard methods that the framework calls on all views. You do
* not need to override all of these methods. In fact, you can start by just
* overriding {@link #onDraw(android.graphics.Canvas)}.
* <table border="2" width="85%" align="center" cellpadding="5">
* <thead>
* <tr><th>Category</th> <th>Methods</th> <th>Description</th></tr>
* </thead>
*
* <tbody>
* <tr>
* <td rowspan="2">Creation</td>
* <td>Constructors</td>
* <td>There is a form of the constructor that are called when the view
* is created from code and a form that is called when the view is
* inflated from a layout file. The second form should parse and apply
* any attributes defined in the layout file.
* </td>
* </tr>
* <tr>
* <td><code>{@link #onFinishInflate()}</code></td>
* <td>Called after a view and all of its children has been inflated
* from XML.</td>
* </tr>
*
* <tr>
* <td rowspan="3">Layout</td>
* <td><code>{@link #onMeasure}</code></td>
* <td>Called to determine the size requirements for this view and all
* of its children.
* </td>
* </tr>
* <tr>
* <td><code>{@link #onLayout}</code></td>
* <td>Called when this view should assign a size and position to all
* of its children.
* </td>
* </tr>
* <tr>
* <td><code>{@link #onSizeChanged}</code></td>
* <td>Called when the size of this view has changed.
* </td>
* </tr>
*
* <tr>
* <td>Drawing</td>
* <td><code>{@link #onDraw}</code></td>
* <td>Called when the view should render its content.
* </td>
* </tr>
*
* <tr>
* <td rowspan="4">Event processi