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

        //方案一
        Paint paint = new Paint();
        ColorMatrix cm = new ColorMatrix();
        cm.setSaturation(0);//灰度效果
        paint.setColorFilter(new ColorMatrixColorFilter(cm));
        getWindow().getDecorView().setLayerType(View.LAYER_TYPE_HARDWARE,paint);
    }

public class GrayFrameLayout extends FrameLayout {
    private Paint mPaint = new Paint();

    public GrayFrameLayout(@NonNull Context context) {
        super(context);
    }

    public GrayFrameLayout(@NonNull Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        ColorMatrix cm = new ColorMatrix();
        cm.setSaturation(0);
        mPaint.setColorFilter(new ColorMatrixColorFilter(cm));
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.saveLayer(null, mPaint, Canvas.ALL_SAVE_FLAG);
        super.onDraw(canvas);
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        canvas.saveLayer(null, mPaint, Canvas.ALL_SAVE_FLAG);
        super.dispatchDraw(canvas);
    }
}

 	@Override
    public View onCreateView(View parent, String name, Context context, AttributeSet attrs) {
        
        //方案二
        if("FrameLayout".equals(name)){
            int attributeCount = attrs.getAttributeCount();
            for (int i = 0; i < attributeCount; i++) {
                String attributeName = attrs.getAttributeName(i);
                String attributeValue = attrs.getAttributeValue(i);
                if(attributeName.equals("id")){
                    int id = Integer.parseInt(attributeValue.substring(1));
                    String resourceName = getResources().getResourceName(id);
                    if("android:id/content".equals(resourceName)){
                        GrayFrameLayout frameLayout  = new GrayFrameLayout(this,attrs);
                        return frameLayout;
                    }
                }
            }
        }

        return super.onCreateView(parent, name, context, attrs);
    }

public class GrayManager {

    private static GrayManager mInstance;
    private Paint mGrayPaint;
    private ColorMatrix mGrayMatrix;

    public static GrayManager getInstance() {
        if (mInstance == null) {
            synchronized (GrayManager.class) {
                if (mInstance == null) {
                    mInstance = new GrayManager();
                }
            }
        }
        return mInstance;
    }

    //初始化
    public void init() {
        mGrayMatrix = new ColorMatrix();
        mGrayPaint = new Paint();
        mGrayMatrix.setSaturation(0);
        mGrayPaint.setColorFilter(new ColorMatrixColorFilter(mGrayMatrix));
    }


    //硬件加速置灰方法
    public void setLayerGrayType(View view) {
        if (mGrayMatrix == null || mGrayPaint == null) {
            init();
        }

        view.setLayerType(View.LAYER_TYPE_HARDWARE, mGrayPaint);
    }
}

GrayManager.getInstance().setLayerGrayType(getWindow().getDecorView());