Java tutorial
/* * 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.widget; import android.annotation.UnsupportedAppUsage; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.content.res.TypedArray; import android.os.Message; import android.util.AttributeSet; import android.util.Log; import android.widget.RemoteViews.RemoteView; /** * Simple {@link ViewAnimator} that will animate between two or more views * that have been added to it. Only one child is shown at a time. If * requested, can automatically flip between each child at a regular interval. * * @attr ref android.R.styleable#ViewFlipper_flipInterval * @attr ref android.R.styleable#ViewFlipper_autoStart */ @RemoteView public class ViewFlipper extends ViewAnimator { private static final String TAG = "ViewFlipper"; private static final boolean LOGD = false; private static final int DEFAULT_INTERVAL = 3000; private int mFlipInterval = DEFAULT_INTERVAL; private boolean mAutoStart = false; private boolean mRunning = false; private boolean mStarted = false; private boolean mVisible = false; @UnsupportedAppUsage private boolean mUserPresent = true; public ViewFlipper(Context context) { super(context); } public ViewFlipper(Context context, AttributeSet attrs) { super(context, attrs); TypedArray a = context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.ViewFlipper); mFlipInterval = a.getInt(com.android.internal.R.styleable.ViewFlipper_flipInterval, DEFAULT_INTERVAL); mAutoStart = a.getBoolean(com.android.internal.R.styleable.ViewFlipper_autoStart, false); a.recycle(); } private final BroadcastReceiver mReceiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { final String action = intent.getAction(); if (Intent.ACTION_SCREEN_OFF.equals(action)) { mUserPresent = false; updateRunning(); } else if (Intent.ACTION_USER_PRESENT.equals(action)) { mUserPresent = true; updateRunning(false); } } }; @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); // Listen for broadcasts related to user-presence final IntentFilter filter = new IntentFilter(); filter.addAction(Intent.ACTION_SCREEN_OFF); filter.addAction(Intent.ACTION_USER_PRESENT); // OK, this is gross but needed. This class is supported by the // remote views machanism and as a part of that the remote views // can be inflated by a context for another user without the app // having interact users permission - just for loading resources. // For exmaple, when adding widgets from a user profile to the // home screen. Therefore, we register the receiver as the current // user not the one the context is for. getContext().registerReceiverAsUser(mReceiver, android.os.Process.myUserHandle(), filter, null, getHandler()); if (mAutoStart) { // Automatically start when requested startFlipping(); } } @Override protected void onDetachedFromWindow() { super.onDetachedFromWindow(); mVisible = false; getContext().unregisterReceiver(mReceiver); updateRunning(); } @Override protected void onWindowVisibilityChanged(int visibility) { super.onWindowVisibilityChanged(visibility); mVisible = visibility == VISIBLE; updateRunning(false); } /** * How long to wait before flipping to the next view * * @param milliseconds * time in milliseconds */ @android.view.RemotableViewMethod public void setFlipInterval(int milliseconds) { mFlipInterval = milliseconds; } /** * Start a timer to cycle through child views */ public void startFlipping() { mStarted = true; updateRunning(); } /** * No more flips */ public void stopFlipping() { mStarted = false; updateRunning(); } @Override public CharSequence getAccessibilityClassName() { return ViewFlipper.class.getName(); } /** * Internal method to start or stop dispatching flip {@link Message} based * on {@link #mRunning} and {@link #mVisible} state. */ private void updateRunning() { updateRunning(true); } /** * Internal method to start or stop dispatching flip {@link Message} based * on {@link #mRunning} and {@link #mVisible} state. * * @param flipNow Determines whether or not to execute the animation now, in * addition to queuing future flips. If omitted, defaults to * true. */ @UnsupportedAppUsage private void updateRunning(boolean flipNow) { boolean running = mVisible && mStarted && mUserPresent; if (running != mRunning) { if (running) { showOnly(mWhichChild, flipNow); postDelayed(mFlipRunnable, mFlipInterval); } else { removeCallbacks(mFlipRunnable); } mRunning = running; } if (LOGD) { Log.d(TAG, "updateRunning() mVisible=" + mVisible + ", mStarted=" + mStarted + ", mUserPresent=" + mUserPresent + ", mRunning=" + mRunning); } } /** * Returns true if the child views are flipping. */ public boolean isFlipping() { return mStarted; } /** * Set if this view automatically calls {@link #startFlipping()} when it * becomes attached to a window. */ public void setAutoStart(boolean autoStart) { mAutoStart = autoStart; } /** * Returns true if this view automatically calls {@link #startFlipping()} * when it becomes attached to a window. */ public boolean isAutoStart() { return mAutoStart; } private final Runnable mFlipRunnable = new Runnable() { @Override public void run() { if (mRunning) { showNext(); postDelayed(mFlipRunnable, mFlipInterval); } } }; }