各位早上好,话不多说,先上效果图:

注意顶部:首页textview的变化(显示和隐藏)!

首先分析下:ui状态,其是由recyclerview添加头部组成+recyclerview

头部添加和recyclerview分别引用如下:具体的分装数据的过程这里就不在说明,下篇博客会更加深入的写关于

recyclerview总添加多种不同type类型

compile 'com.bartoszlipinski.recyclerviewheader:library:1.2.1'

compile 'com.android.support:recyclerview-v7:25.3.1'

第一步:生成布局视图

xmlns:tools="http://schemas.android.com/tools"

android:background="#f2f2f2"

android:layout_width="match_parent"

android:layout_height="match_parent">

android:id="@+id/recycler"

android:layout_width="match_parent"

android:layout_height="match_parent"/>

android:background="#ffffff"

android:paddingtop="5dp"

android:paddingbottom="5dp"

android:gravity="center_horizontal"

tools:visibility="visible"

android:textcolor="#000000"

android:textsize="20sp"

android:id="@+id/home_text"

android:visibility="invisible"

android:text="首页"

android:layout_width="match_parent"

android:layout_height="wrap_content"/>

第二步:直接上其他主要的代码,其注释很详细,不多说

public class mainactivity extends appcompatactivity {

private textview mtextview;

private int mtextviewheight;

private recyclerview mrecyclerview;

private recyclerviewheader mrecyclerviewheader;

//头部图片(轮播图的高度)

private int mrecyclerheaderbannerheight;

//头部的高度

private int mrecyclerheaderheight;

@override

protected void oncreate(bundle savedinstancestate) {

super.oncreate(savedinstancestate);

setcontentview(r.layout.activity_main);

mtextview = (textview) findviewbyid(r.id.home_text);

//recyclerview填充数据(忽略不计)

initdata();

mrecyclerview = (recyclerview) findviewbyid(r.id.recycler);

mrecyclerview.setlayoutmanager(new linearlayoutmanager(this));

mrecyclerview.setadapter(madapter);

//获取到文本的高度

mtextviewheight = mtextview.getheight();

//轮播图片的高度--和xml图片的高度是一样的

mrecyclerheaderbannerheight = (int) getresources().getdimension(r.dimen.home_page_banner_height);

//recyclerview每个item之间的距离,和adapter中设置的距离一样

final int recycleritemheight = (int) getresources().getdimension(r.dimen.home_page_list_item_margin_top);

//添加头部视图,其布局文件就忽略

mrecyclerviewheader = recyclerviewheader.fromxml(this, r.layout.list_item_prime_product_header);

//设置其滑动事件

mrecyclerview.addonscrolllistener(new recyclerview.onscrolllistener() {

@override

public void onscrolled(recyclerview recyclerview, int dx, int dy) {

//设置其透明度

float alpha = 0;

int scollyheight = getscollyheight(true, mrecyclerheaderheight);

//起始截止变化高度,如可以变化高度为mrecyclerheaderheight

int baseheight = mrecyclerheaderbannerheight - recycleritemheight - mtextviewheight;

if(scollyheight >= baseheight) {

//完全不透明

alpha = 1;

}else {

//产生渐变效果

alpha = scollyheight / (baseheight*1.0f);

}

mtextview.setalpha(alpha);

super.onscrolled(recyclerview, dx, dy);

}

});

//将头部视图添加到recyclerview中

mrecyclerviewheader.attachto(mrecyclerview);

//第一次进来其状态显示

mrecyclerviewheader.post(new runnable() {

@override

public void run() {

mrecyclerheaderheight = mrecyclerviewheader.getheight();

mtextviewheight = mtextview.getheight();

mtextview.setvisibility(view.visible);

mtextview.setalpha(0);

}

});

}

第三步:获取其滑动的距离

/**

* 计算recyclerview滑动的距离

* @param hashead 是否有头部

* @param headerheight recyclerview的头部高度

* @return 滑动的距离

*/

private int getscollyheight(boolean hashead, int headerheight) {

linearlayoutmanager layoutmanager = (linearlayoutmanager) mrecyclerview.getlayoutmanager();

//获取到第一个可见的position,其添加的头部不算其position当中

int position = layoutmanager.findfirstvisibleitemposition();

//通过position获取其管理器中的视图

view firstvisiablechildview = layoutmanager.findviewbyposition(position);

//获取自身的高度

int itemheight = firstvisiablechildview.getheight();

//有头部

if(hashead) {

return headerheight + itemheight*position - firstvisiablechildview.gettop();

}else {

return itemheight*position - firstvisiablechildview.gettop();

}

}

以上:就可以实现其效果!

以上所述是小编给大家介绍的android 顶部标题栏随滑动时的渐变隐藏和渐变显示效果，希望对大家有所帮助