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="/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
