Android：Toolbar標題欄顏色漸變

僅僅調用RecyclerView中的api即可

mRv.setOnScrollListener(new RecyclerView.OnScrollListener() {
    int titleHeight;
    @Override
    public void onScrolled(RecyclerView rv, int dx, int dy) {
        super.onScrolled(rv, dx, dy);
        titleHeight = titleHeight == 0 ? titleView.getMeasuredHeight() : titleHeight;
        if (rv.computeVerticalScrollOffset() <= titleHeight) {
            float rate = (float) rv.computeVerticalScrollOffset() / (float) titleHeight;
            titleView.setAlpha(rate);
        }
    }
});

這個titleHeight是標題欄的高度，然後這裡的邏輯是垂直下滑的位移除以標題欄的高度就是比例

非常簡單

效果圖