关于android4.0.4中彩蛋的实现

情况：

在android4.0.4的系统设置-关于手机-Android版本，连续快速点击几下，就会出现一个机器人，长按住机器人不放，机器人会一直变大，然后出现一堆机器从屏幕上飞过

觉得有点意思，于是想看看是怎么实现的，电脑上有android4.0的代码。

系统设置-关于手机的代码：

packages/apps/Settings/src/com/android/settings/DeviceInfoSettings.java

其中，点击选项的处理如下：

long [] mHits =  new   long [ 3 ];  

 @Override
 public boolean onPreferenceTreeClick(PreferenceScreen preferenceScreen, Preference preference) {
     if (preference.getKey().equals(KEY_FIRMWARE_VERSION)) {
         System.arraycopy(mHits, 1, mHits, 0, mHits.length-1);
         mHits[mHits.length-1] = SystemClock.uptimeMillis();
         if (mHits[0] >= (SystemClock.uptimeMillis()-500)) {
             Intent intent = new Intent(Intent.ACTION_MAIN);
             intent.setClassName("android",
                     com.android.internal.app.PlatLogoActivity.class.getName());
             try {
                 startActivity(intent);
             } catch (Exception e) {
                 Log.e(LOG_TAG, "Unable to start activity " + intent.toString());
             }
         }
     }
     return super.onPreferenceTreeClick(preferenceScreen, preference);
 }

这里可以看到对固件版本选项有特殊处理：

if (preference.getKey().equals(KEY_FIRMWARE_VERSION)) {

    //如果点击的是固件版本，则记录下最近三次点击的时间；

    //如果三次点击的总时间少于500ms，则启动com.android.internal.app.PlatLogoActivity

}

再看PlatLogoActivity的实现：

 public class PlatLogoActivity extends Activity {
     Toast mToast;
     ImageView mContent;
     Vibrator mZzz = new Vibrator();
     int mCount;
     final Handler mHandler = new Handler();

     Runnable mSuperLongPress = new Runnable() {
         public void run() {
             mCount++;
             mZzz.vibrate(50 * mCount);
             final float scale = 1f + 0.25f * mCount * mCount;
             mContent.setScaleX(scale);
             mContent.setScaleY(scale);

             if (mCount <= 3) {
                 mHandler.postDelayed(mSuperLongPress, ViewConfiguration.getLongPressTimeout());
             } else {
                 try {
                     startActivity(new Intent(Intent.ACTION_MAIN)
                         .setFlags(Intent.FLAG_ACTIVITY_NEW_TASK
                             | Intent.FLAG_ACTIVITY_CLEAR_TASK
                             | Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS)
                         .setClassName("com.android.systemui","com.android.systemui.Nyandroid"));
                 } catch (ActivityNotFoundException ex) {
                     android.util.Log.e("PlatLogoActivity", "Couldn't find platlogo screensaver.");
                 }
                 finish();
             }
         }
     };

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

         mToast = Toast.makeText(this, "Android 4.0: Ice Cream Sandwich", Toast.LENGTH_SHORT);

         mContent = new ImageView(this);
         mContent.setImageResource(com.android.internal.R.drawable.platlogo);
         mContent.setScaleType(ImageView.ScaleType.CENTER_INSIDE);

         mContent.setOnTouchListener(new View.OnTouchListener() {
             @Override
             public boolean onTouch(View v, MotionEvent event) {
                 final int action = event.getAction();
                 if (action == MotionEvent.ACTION_DOWN) {
                     mContent.setPressed(true);
                     mHandler.removeCallbacks(mSuperLongPress);
                     mCount = 0;
                     mHandler.postDelayed(mSuperLongPress, 2*ViewConfiguration.getLongPressTimeout());
                 } else if (action == MotionEvent.ACTION_UP) {
                     if (mContent.isPressed()) {
                         mContent.setPressed(false);
                         mHandler.removeCallbacks(mSuperLongPress);
                         mToast.show();
                     }
                 }
                 return true;
             }
         });

         setContentView(mContent);
     }
 }

这里对图片的触摸事件进行了处理，

mHandler.postDelayed(mSuperLongPress, 2*ViewConfiguration.getLongPressTimeout());

在图片按下开始，2倍长按超时时间后，执行mSuperLongPress，而在mSuperLongPress中会设置图片缩放比例，逐渐放大。图片连续放大超过三次后，启动com.android.systemui.Nyandroid，显示一堆机器人。

frameworks/base/packages/SystemUI/src/com/android/systemui/Nyandroid.java

 public class Nyandroid extends Activity {
     final static boolean DEBUG = false;

     public static class Board extends FrameLayout
     {
         public static final boolean FIXED_STARS = true;
         public static final int NUM_CATS = 20;

         static Random sRNG = new Random();

         static float lerp(float a, float b, float f) {
             return (b-a)*f + a;
         }

         static float randfrange(float a, float b) {
             return lerp(a, b, sRNG.nextFloat());
         }

         static int randsign() {
             return sRNG.nextBoolean() ? 1 : -1;
         }

         static <E> E pick(E[] array) {
             if (array.length == 0) return null;
             return array[sRNG.nextInt(array.length)];
         }

         public class FlyingCat extends ImageView {
             public static final float VMAX = 1000.0f;
             public static final float VMIN = 100.0f;

             public float v, vr;

             public float dist;
             public float z;

             public ComponentName component;

             public FlyingCat(Context context, AttributeSet as) {
                 super(context, as);
                 setImageResource(R.drawable.nyandroid_anim); // @@@

                 if (DEBUG) setBackgroundColor(0x80FF0000);
             }

             public String toString() {
                 return String.format("<cat (%.1f, %.1f) (%d x %d)>",
                     getX(), getY(), getWidth(), getHeight());
             }

             public void reset() {
                 final float scale = lerp(0.1f,2f,z);
                 setScaleX(scale); setScaleY(scale);

                 setX(-scale*getWidth()+1);
                 setY(randfrange(0, Board.this.getHeight()-scale*getHeight()));
                 v = lerp(VMIN, VMAX, z);

                 dist = 0;

 //                android.util.Log.d("Nyandroid", "reset cat: " + this);
             }

             public void update(float dt) {
                 dist += v * dt;
                 setX(getX() + v * dt);
             }
         }

         TimeAnimator mAnim;

         public Board(Context context, AttributeSet as) {
             super(context, as);

             setLayerType(View.LAYER_TYPE_HARDWARE, null);
             setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
             setBackgroundColor(0xFF003366);
         }

         private void reset() {
 //            android.util.Log.d("Nyandroid", "board reset");
             removeAllViews();

             final ViewGroup.LayoutParams wrap = new ViewGroup.LayoutParams(
                         ViewGroup.LayoutParams.WRAP_CONTENT,
                         ViewGroup.LayoutParams.WRAP_CONTENT);

             if (FIXED_STARS) {
                 for(int i=0; i<20; i++) {
                     ImageView fixedStar = new ImageView(getContext(), null);
                     if (DEBUG) fixedStar.setBackgroundColor(0x8000FF80);
                     fixedStar.setImageResource(R.drawable.star_anim); // @@@
                     addView(fixedStar, wrap);
                     final float scale = randfrange(0.1f, 1f);
                     fixedStar.setScaleX(scale); fixedStar.setScaleY(scale);
                     fixedStar.setX(randfrange(0, getWidth()));
                     fixedStar.setY(randfrange(0, getHeight()));
                     final AnimationDrawable anim = (AnimationDrawable) fixedStar.getDrawable();
                     postDelayed(new Runnable() {
                         public void run() {
                             anim.start();
                         }}, (int) randfrange(0, 1000));
                 }
             }

             for(int i=0; i<NUM_CATS; i++) {
                 FlyingCat nv = new FlyingCat(getContext(), null);
                 addView(nv, wrap);
                 nv.z = ((float)i/NUM_CATS);
                 nv.z *= nv.z;
                 nv.reset();
                 nv.setX(randfrange(0,Board.this.getWidth()));
                 final AnimationDrawable anim = (AnimationDrawable) nv.getDrawable();
                 postDelayed(new Runnable() {
                     public void run() {
                         anim.start();
                     }}, (int) randfrange(0, 1000));
             }

             if (mAnim != null) {
                 mAnim.cancel();
             }
             mAnim = new TimeAnimator();
             mAnim.setTimeListener(new TimeAnimator.TimeListener() {
                 public void onTimeUpdate(TimeAnimator animation, long totalTime, long deltaTime) {
                     // setRotation(totalTime * 0.01f); // not as cool as you would think
 //                    android.util.Log.d("Nyandroid", "t=" + totalTime);

                     for (int i=0; i<getChildCount(); i++) {
                         View v = getChildAt(i);
                         if (!(v instanceof FlyingCat)) continue;
                         FlyingCat nv = (FlyingCat) v;
                         nv.update(deltaTime / 1000f);
                         final float catWidth = nv.getWidth() * nv.getScaleX();
                         final float catHeight = nv.getHeight() * nv.getScaleY();
                         if (   nv.getX() + catWidth < -2
                             || nv.getX() > getWidth() + 2
                             || nv.getY() + catHeight < -2
                             || nv.getY() > getHeight() + 2)
                         {
                             nv.reset();
                         }
                     }
                 }
             });
         }

         @Override
         protected void onSizeChanged (int w, int h, int oldw, int oldh) {
             super.onSizeChanged(w,h,oldw,oldh);
 //            android.util.Log.d("Nyandroid", "resized: " + w + "x" + h);
             post(new Runnable() { public void run() {
                 reset();
                 mAnim.start();
             } });
         }


         @Override
         protected void onDetachedFromWindow() {
             super.onDetachedFromWindow();
             mAnim.cancel();
         }

         @Override
         public boolean isOpaque() {
             return true;
         }
     }

     private Board mBoard;

     @Override
     public void onStart() {
         super.onStart();

         getWindow().addFlags(
                   WindowManager.LayoutParams.FLAG_ALLOW_LOCK_WHILE_SCREEN_ON
                 | WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED
                 );
     }

     @Override
     public void onResume() {
         super.onResume();
         mBoard = new Board(this, null);
         setContentView(mBoard);

         mBoard.setOnSystemUiVisibilityChangeListener(new View.OnSystemUiVisibilityChangeListener() {
             @Override
             public void onSystemUiVisibilityChange(int vis) {
                 if (0 == (vis & View.SYSTEM_UI_FLAG_HIDE_NAVIGATION)) {
                     Nyandroid.this.finish();
                 }
             }
         });
     }

     @Override
     public void onUserInteraction() {
 //        android.util.Log.d("Nyandroid", "finishing on user interaction");
         finish();
     }
 }

这里面FlyingCat继承了ImageView，每次产生一个FlyingCat，生成的图片大小都是随机的。

Board继承了FrameLayout，所有的星星和机器人图片都添加到Board中。

Board使用TimeAnimator定时刷新每个机器人图片的位置，实现了移动。

星星和机器本身的变化是同过boolean postDelayed(Runnable r, long delayMillis)实现自身形状变化的。

                    postDelayed(new Runnable() {
                         public void run() {
                             anim.start();
                         }}, (int) randfrange(0, 1000));