微信朋友圈上面的图片封面,qq空间说说上面的图片封面都有下拉反弹的效果,这些都是使用滚动条实现的。下拉,当松开时候,反弹至原来的位置。下拉时候能看到背景图片。那么这里简单介绍一下这种效果的实现。
1、效果图
这部手机显示的分辨率有限,很老的手机调试。
2、具有反弹效果bouncescrollview
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package com.org.scroll; import android.content.context; import android.graphics.rect; import android.util.attributeset; import android.view.motionevent; import android.view.view; import android.view.animation.translateanimation; import android.widget.scrollview; /** * scrollview反弹效果的实现 */ public class bouncescrollview extends scrollview { private view inner; // 孩子view private float y; // 点击时y坐标 // 矩形(这里只是个形式,只是用于判断是否需要动画.) private rect normal = new rect(); private boolean iscount = false ; // 是否开始计算 public bouncescrollview(context context, attributeset attrs) { super (context, attrs); } /*** * 根据 xml 生成视图工作完成.该函数在生成视图的最后调用,在所有子视图添加完之后. 即使子类覆盖了 onfinishinflate * 方法,也应该调用父类的方法,使该方法得以执行. */ @override protected void onfinishinflate() { if (getchildcount() > 0 ) { inner = getchildat( 0 ); } } /*** * 监听touch */ @override public boolean ontouchevent(motionevent ev) { if (inner != null ) { commontouchevent(ev); } return super .ontouchevent(ev); } /*** * 触摸事件 * * @param ev */ public void commontouchevent(motionevent ev) { int action = ev.getaction(); switch (action) { case motionevent.action_down: break ; case motionevent.action_up: // 手指松开. if (isneedanimation()) { animation(); iscount = false ; } break ; /*** * 排除出第一次移动计算,因为第一次无法得知y坐标, 在motionevent.action_down中获取不到, * 因为此时是myscrollview的touch事件传递到到了listview的孩子item上面.所以从第二次计算开始. * 然而我们也要进行初始化,就是第一次移动的时候让滑动距离归0. 之后记录准确了就正常执行. */ case motionevent.action_move: final float prey = y; // 按下时的y坐标 float nowy = ev.gety(); // 时时y坐标 int deltay = ( int ) (prey - nowy); // 滑动距离 if (!iscount) { deltay = 0 ; // 在这里要归0. } y = nowy; // 当滚动到最上或者最下时就不会再滚动,这时移动布局 if (isneedmove()) { // 初始化头部矩形 if (normal.isempty()) { // 保存正常的布局位置 normal.set(inner.getleft(), inner.gettop(), inner.getright(), inner.getbottom()); } // log.e("jj", "矩形:" + inner.getleft() + "," + inner.gettop() // + "," + inner.getright() + "," + inner.getbottom()); // 移动布局 inner.layout(inner.getleft(), inner.gettop() - deltay / 2 , inner.getright(), inner.getbottom() - deltay / 2 ); } iscount = true ; break ; default : break ; } } /*** * 回缩动画 */ public void animation() { // 开启移动动画 translateanimation ta = new translateanimation( 0 , 0 , inner.gettop(), normal.top); ta.setduration( 200 ); inner.startanimation(ta); // 设置回到正常的布局位置 inner.layout(normal.left, normal.top, normal.right, normal.bottom); // log.e("jj", "回归:" + normal.left + "," + normal.top + "," + normal.right // + "," + normal.bottom); normal.setempty(); } // 是否需要开启动画 public boolean isneedanimation() { return !normal.isempty(); } /*** * 是否需要移动布局 inner.getmeasuredheight():获取的是控件的总高度 * * getheight():获取的是屏幕的高度 * * @return */ public boolean isneedmove() { int offset = inner.getmeasuredheight() - getheight(); int scrolly = getscrolly(); // log.e("jj", "scrolly=" + scrolly); // 0是顶部,后面那个是底部 if (scrolly == 0 || scrolly == offset) { return true ; } return false ; } } |
3、mainactivity
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package com.org.activity; import android.os.bundle; import android.app.activity; import android.view.menu; import android.view.window; public class mainactivity extends activity { @override protected void oncreate(bundle savedinstancestate) { super .oncreate(savedinstancestate); requestwindowfeature(window.feature_no_title); setcontentview(r.layout.activity_main); } @override public boolean oncreateoptionsmenu(menu menu) { // inflate the menu; this adds items to the action bar if it is present. getmenuinflater().inflate(r.menu.activity_main, menu); return true ; } } |
这个没做什么,主要看布局,以及bouncescrollview类。
4、activity_main布局
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<linearlayout xmlns:android= "http://schemas.android.com/apk/res/android" xmlns:tools= "http://schemas.android.com/tools" android:layout_width= "match_parent" android:layout_height= "match_parent" android:orientation= "vertical" > <include layout= "@layout/common_title_bg" /> <com.org.scroll.bouncescrollview android:layout_width= "match_parent" android:layout_height= "wrap_content" android:background= "@drawable/coversation_bg" android:focusable= "true" android:focusableintouchmode= "true" > <linearlayout android:layout_width= "match_parent" android:layout_height= "match_parent" android:orientation= "vertical" android:paddingtop= "10.0dip" > <relativelayout android:id= "@+id/accountsetting" android:layout_width= "fill_parent" android:layout_height= "63.0dip" android:background= "#80ffffff" android:focusable= "true" > <framelayout android:id= "@+id/framelayout1" android:layout_width= "54.0dip" android:layout_height= "54.0dip" android:layout_centervertical= "true" android:layout_marginleft= "10.0dip" > <imageview android:id= "@+id/face" android:layout_width= "50.0dip" android:layout_height= "50.0dip" android:layout_gravity= "center" android:contentdescription= "@null" android:src= "@drawable/h0" /> <imageview android:id= "@+id/statusicon" android:layout_width= "18.0dip" android:layout_height= "18.0dip" android:layout_gravity= "bottom|right|center" android:contentdescription= "@null" /> </framelayout> <imageview android:id= "@+id/imageview1" android:layout_width= "wrap_content" android:layout_height= "wrap_content" android:layout_alignparentright= "true" android:layout_centervertical= "true" android:layout_marginright= "10.0dip" android:contentdescription= "@null" android:duplicateparentstate= "true" /> <textview android:id= "@+id/status" android:layout_width= "wrap_content" android:layout_height= "wrap_content" android:layout_alignbottom= "@+id/nick" android:layout_marginright= "10.0dip" android:layout_toleftof= "@id/imageview1" android:duplicateparentstate= "true" android:text= "在线" /> <textview android:id= "@+id/nick" android:layout_width= "wrap_content" android:layout_height= "wrap_content" android:layout_centervertical= "true" android:layout_marginleft= "10.0dip" android:layout_marginright= "69.0dip" android:layout_torightof= "@id/framelayout1" android:duplicateparentstate= "true" android:ellipsize= "end" android:singleline= "true" /> </relativelayout> <linearlayout android:layout_width= "match_parent" android:layout_height= "600dp" android:layout_margintop= "16.0dip" android:layout_weight= "2.13" android:background= "#ffffffff" android:orientation= "vertical" > <textview android:id= "@+id/my_profile" android:layout_width= "fill_parent" android:layout_height= "44.0dip" android:background= "#800000ff" android:clickable= "true" android:gravity= "center_vertical" android:paddingleft= "10.0dip" android:paddingright= "10.0dip" android:text= "标题一" /> <linearlayout android:layout_width= "fill_parent" android:layout_height= "wrap_content" android:layout_margintop= "16.0dip" android:orientation= "vertical" > <relativelayout android:id= "@+id/set_feedback" android:layout_width= "fill_parent" android:layout_height= "44.0dip" android:background= "#8000ffff" android:clickable= "true" android:focusable= "true" > <textview android:layout_width= "wrap_content" android:layout_height= "wrap_content" android:layout_centervertical= "true" android:layout_marginleft= "12.0dip" android:duplicateparentstate= "true" android:gravity= "center_vertical" android:text= "反馈" /> </relativelayout> </linearlayout> </linearlayout> </linearlayout> </com.org.scroll.bouncescrollview> </linearlayout> |
源码下载:android实现滚动条下拉反弹效果
希望本文对大家学习android软件编程有所帮助。