默哀色0.0
在onCreate方法中調(diào)用
Paint paint = new Paint();
ColorMatrix cm = new ColorMatrix();
//設置色彩飽和度，當飽和度為0，即黑白色
cm.setSaturation(0);
//將飽和度為0的顏色過濾器設置在畫筆
paint.setColorFilter(new ColorMatrixColorFilter(cm));
//getWindow().getDecorView() is the top-level window decor view；
//View.LAYER_TYPE_HARDWARE 硬件加速
getWindow().getDecorView().setLayerType(View.LAYER_TYPE_HARDWARE, paint);
