Android实现多任务高斯模糊

/***
 * 截取当前activity
 * @param activity
 * @return
 */
public static Bitmap activityShot(Activity activity) {
    /*获取windows中最顶层的view*/
    View view = activity.getWindow().getDecorView();

    //允许当前窗口保存缓存信息
    view.setDrawingCacheEnabled(true);
    view.buildDrawingCache();

    //获取状态栏高度
    Rect rect = new Rect();
    view.getWindowVisibleDisplayFrame(rect);
    int statusBarHeight = rect.top;

    WindowManager windowManager = activity.getWindowManager();

    //获取屏幕宽和高
    DisplayMetrics outMetrics = new DisplayMetrics();
    windowManager.getDefaultDisplay().getMetrics(outMetrics);
    int width = outMetrics.widthPixels;
    int height = outMetrics.heightPixels;

    //去掉状态栏
    Bitmap bitmap = Bitmap.createBitmap(view.getDrawingCache(), 0, statusBarHeight, width,
            height - statusBarHeight);

    //销毁缓存信息
    view.destroyDrawingCache();
    view.setDrawingCacheEnabled(false);


    return bitmap;
}

public static Bitmap rsBlur(Context context, Bitmap source, int radius){
        Bitmap inputBmp = source;
        //(1)
        //初始化一个RenderScript Context
        RenderScript renderScript =  RenderScript.create(context);
 
        // Allocate memory for Renderscript to work with
        //(2)
        //创建输入输出的allocation
        final Allocation input = Allocation.createFromBitmap(renderScript,inputBmp);
        final Allocation output = Allocation.createTyped(renderScript,input.getType());
        //(3)
        // Load up an instance of the specific script that we want to use.
        //创建ScriptIntrinsic
        ScriptIntrinsicBlur scriptIntrinsicBlur = ScriptIntrinsicBlur.create(renderScript, Element.U8_4(renderScript));
        //(4)
        //填充数据
        scriptIntrinsicBlur.setInput(input);
        //(5)
        // Set the blur radius
        //设置模糊半径
        scriptIntrinsicBlur.setRadius(radius);
        //(6)
        // Start the ScriptIntrinisicBlur
        //启动内核
        scriptIntrinsicBlur.forEach(output);
        //(7)
        // Copy the output to the blurred bitmap
        //copy数据
        output.copyTo(inputBmp);
        //(8)
        //销毁renderScript
        renderScript.destroy();
        return inputBmp;
 
    }

public class DeviceKeyMonitor {

    /**
     * 参数
     */
    private static final String SYSTEM_REASON = "reason";
    private static final String SYSTEM_HOME_RECENT_APPS = "recentapps";

    private Context mContext;
    private BroadcastReceiver mDeviceKeyReceiver = null;
    private OnKeyListener mListener;


    public DeviceKeyMonitor (Context context, final OnKeyListener listener) {
        mContext = context;
        mListener = listener;
        mDeviceKeyReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                String action=intent.getAction();
                if(!TextUtils.isEmpty(action)){

                    if (intent.getAction().equals(Intent.ACTION_CLOSE_SYSTEM_DIALOGS)) {
                        String reason = intent.getStringExtra(SYSTEM_REASON);

                        if (reason == null)
                            return;

                        // 最近任务列表键
                        if (reason.equals(SYSTEM_HOME_RECENT_APPS)) {
                            mListener.onRecentClick();

                        }
                    }
                }
            }
        };
        mContext.registerReceiver(mDeviceKeyReceiver, new IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS));
    }

    public interface OnKeyListener{
        void onRecentClick();//多任务键监听
    }

    public void unregister(){
        if (mDeviceKeyReceiver != null){
            mContext.unregisterReceiver(mDeviceKeyReceiver);
            mDeviceKeyReceiver = null;

        }
    }

}

@Override
public void onRecentClick() {
    Toast.makeText(this,"按了多任务键",Toast.LENGTH_LONG).show();
  group = (ViewGroup) this.getWindow().getDecorView();
    group.removeView(imageView);
//      创建imageview
    imageView = new ImageView(this);
    FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
    imageView.setLayoutParams(params);

//      截图，并将图片高斯模糊处理
    Bitmap bitmap=PicUtil.rsBlur(GaussianBlurActivity.this,PicUtil.activityShot(GaussianBlurActivity.this),20);
//      将处理后的图片填充到imageview
    imageView.setImageBitmap(bitmap);
    group.addView(imageView);

}