Android实现灰度模式

App快速实现“哀悼主题”方案
全局设置灰白模式：

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

        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);
    }

创建一个置灰的管理类

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);
        //view.setLayerType(View.LAYER_TYPE_SOFTWARE, mGrayPaint); 不能用硬件加速的方法
    }
}

特殊控件需要置灰的话直接调用setLayerGrayType()方法将view传进去，比如demo中让某个Activity置灰，那就在Activity里面调用

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