view在屏幕中是否可见的一些工具方法

//view被遮住
    private fun isCover(): Boolean {
        val rect: Rect = Rect()
        val cover = getGlobalVisibleRect(rect)
        if (cover) {
            if (rect.width() >= measuredWidth && rect.height() >= measuredHeight) {
                return !cover
            }
        }
        return true
    }

    //当 View 有一点点不可见时立即返回false
    private fun isVisibleLocal(): Boolean {
        val rect = Rect()
        getLocalVisibleRect(Rect())
        return rect.top == 0
    }

//view显示在屏幕大于一半返回true
fun checkIsMajorityVisible(view: View?): Boolean {
        if (view == null) return false
        val rect = Rect()
        val location = IntArray(2)
        view.getLocationInWindow(location)
        view.getLocalVisibleRect(rect)
        val showHeight = rect.bottom - rect.top
        val height = view.height.orZero()
        return showHeight.toFloat() > height.toFloat() / 2
    }

其中在view往上滑动时，头部慢慢被遮住了，
此时rect.bottom = height, 而rect.top由0开始变大
当view处于屏幕中，完全可见时，
rect.bottom = height ， rect.top = 0
当view向下滑动时，底部慢慢被遮住了，
此时rect.bottom由height慢慢变小， 而rect.top一直为0
当view有一点可见rect.top总是为0的

//在view内部检测是否屏幕可见，不太可靠
override fun onWindowVisibilityChanged(visibility: Int) {
        super.onWindowVisibilityChanged(visibility)
        if (visibility == View.VISIBLE) {
            if (isVisibleLocal()) {
                //todo
            }
        }
    }