window

window.setBackgroundDrawable(ColorDrawable(0))

phoneWindow源码 ：

private DecorView mDecor;

@Override

    public final void setBackgroundDrawable(Drawable drawable) {

        if (drawable != mBackgroundDrawable || mBackgroundResource != 0) {

            mBackgroundResource = 0;

            mBackgroundDrawable = drawable;

            if (mDecor != null) {

                mDecor.setWindowBackground(drawable);

            }

        }

    }

：可知：

window.setBackgroundDrawable(ColorDrawable(0))

window.decorView.setBackgroundColor(Color.RED) 都是 改变decorview的背景色