通过WindowManager图片切换的效果

最近为这个事情焦头烂额，原因无他。原来打算是把ViewPager放在WindowManager中，再设定一个定时器，让图片自动切换，但是搞了很久，发现无论如何，这个图片只显示一张。虽然日志看得出来图片确实在切换，但是除了这初始化的这张图片之外，其他的都是黑窗口，也就是没有显示出来。

此路不通，另找出路。其实未必用得着PagerAdapter。安卓就是这点方便，反正View，不管咋整，都是可以往窗口里面放的，我对界面不懂，所以这里也说不出个所以然来。但是这种需求，估计也是有的（比如有些比较恶心的广告程序，就是想要独占最上层，那用windowManager就是比较合适的方式）。

废话不多说，直接上代码

 public class MainActivity extends Activity {
 private Runnable viewpagerRunnable;
 private Handler MainThreadhandler;
 private WindowManager mWndMgr;
 private ViewPager mViewPager;
 private ImageView mImgView;
 private WindowManager.LayoutParams mLayoutParams;
 private Context mContext;
 private List<ImageView> mImgViewList;
 private int[] picRes = {R.drawable.first,R.drawable.second,R.drawable.third};
 int CurrentIndex = 0;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 mContext = this.getApplicationContext();
 MainThreadhandler = new Handler();
 prepareImageView();
 initView();
 startAutomaticRoll();
 }

 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
 // Inflate the menu; this adds items to the action bar if it is present.
 getMenuInflater().inflate(R.menu.main, menu);
 return true;
 }

 @Override
 public boolean onOptionsItemSelected(MenuItem item) {
 // Handle action bar item clicks here. The action bar will
 // automatically handle clicks on the Home/Up button, so long
 // as you specify a parent activity in AndroidManifest.xml.
 int id = item.getItemId();
 if (id == R.id.action_settings) {
 return true;
 }
 return super.onOptionsItemSelected(item);
 }

 private void prepareImageView(){
 mViewPager = new ViewPager(mContext);
 mWndMgr = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
 DisplayMetrics outMetrics = new DisplayMetrics();
 mWndMgr.getDefaultDisplay().getMetrics(outMetrics);
 mLayoutParams = new WindowManager.LayoutParams();
 mLayoutParams.type = WindowManager.LayoutParams.TYPE_SYSTEM_ALERT;
 mLayoutParams.width = outMetrics.widthPixels;
 mLayoutParams.height = outMetrics.heightPixels - 150;
 //mViewPager.setLayoutParams(mLayoutParams);
 mImgViewList = new ArrayList<ImageView>();
 int len = picRes.length;
 for(int i = 0; i < len ;i++){
 ImageView view = new ImageView(mContext);
 view.setBackgroundResource(picRes[i]);
 mImgViewList.add(view);
 }
 //mViewPager.setAdapter(new ViewAdapha(mImgViewList));
 }

 public void initView(){
 //mWndMgr.addView(mViewPager, mLayoutParams);
 mImgView = mImgViewList.get(CurrentIndex);
 mImgView.setLayoutParams(mLayoutParams);
 mWndMgr.addView(mImgView, mLayoutParams);
 //mWndMgr.updateViewLayout(mImgView, mLayoutParams);
 }

 private void startAutomaticRoll() {
 viewpagerRunnable = new Runnable() {
 @Override
 public void run() {
 //int nowIndex = mViewPager.getCurrentItem();
 //int count = mViewPager.getAdapter().getCount();
 if (CurrentIndex + 1 >= 3) {
 //mViewPager.setCurrentItem(0);
 CurrentIndex = 0;
 } else {
 CurrentIndex = CurrentIndex + 1;
 }
 mWndMgr.removeView(mImgView);
 mImgView = mImgViewList.get(CurrentIndex);
 mImgView.setLayoutParams(mLayoutParams);
 //mViewPager.removeAllViews();
 Log.i("index", "index="+CurrentIndex);
 //mViewPager.removeAllViews();
 //mViewPager.addView(mImgViewList.get(CurrentIndex));
 mWndMgr.addView(mImgView, mLayoutParams);
 //mWndMgr.updateViewLayout(mImgView, mLayoutParams);
 MainThreadhandler.postDelayed(viewpagerRunnable, 3000);
 }
 };
 MainThreadhandler.postDelayed(viewpagerRunnable, 3000);
 }
 }

这种方式比较戳，在图片切换之间，会有闪断的现象，也就是切换的不平滑。如果有知道的朋友，还请指点下是什么情况。或者是如何才能做到在我这种方式下，把ViewPager放到WindowManager里面，再把ImageView数组放在ViewPager里面，然后还能实现正常的切换的效果。

===========================================

又修改了下，效果更好了。哈哈～～～

public class MainActivity extends Activity {
	private Runnable viewpagerRunnable;
	private Handler MainThreadhandler;
	private WindowManager mWndMgr;
	private ImageView mImgView;
	private WindowManager.LayoutParams mLayoutParams;
	private Context mContext;
	private List<ImageView> mImgViewList;
	private int[] picRes = {R.drawable.first,R.drawable.second,R.drawable.third};
	int CurrentIndex = 0;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mContext = this.getApplicationContext();
        MainThreadhandler = new Handler();
        prepareView();
        initView();
        startAutomaticRoll();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    private void prepareView(){
    	new ViewPager(mContext);
		mWndMgr = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
		DisplayMetrics outMetrics = new DisplayMetrics();
		mWndMgr.getDefaultDisplay().getMetrics(outMetrics);
		mLayoutParams = new WindowManager.LayoutParams();
		mLayoutParams.type = WindowManager.LayoutParams.TYPE_SYSTEM_ALERT;
		mLayoutParams.width = outMetrics.widthPixels;
		mLayoutParams.height = outMetrics.heightPixels - 150;
    	mImgViewList = new ArrayList<ImageView>();
    	int len = picRes.length;
    	for(int i = 0; i < len ;i++){
    		ImageView view = new ImageView(mContext);
    		view.setBackgroundResource(picRes[i]);
    		mImgViewList.add(view);
    	}
    }

    public void initView(){
		mImgView = mImgViewList.get(CurrentIndex);
		mImgView.setLayoutParams(mLayoutParams);
		mWndMgr.addView(mImgView, mLayoutParams);
	}

    private void startAutomaticRoll() {
		viewpagerRunnable = new Runnable() {
			@Override
			public void run() {
				if (CurrentIndex + 1 >= 3) {
					CurrentIndex = 0;
				} else {
					CurrentIndex = CurrentIndex + 1;
				}
				mImgView.setBackgroundResource(picRes[CurrentIndex]);
				Log.i("index", "index="+CurrentIndex);
				MainThreadhandler.postDelayed(viewpagerRunnable, 3000);
			}
		};
		MainThreadhandler.postDelayed(viewpagerRunnable, 3000);
	}
}