ViewPager是一个可以用来滑动内部View的组件，他有一个老搭档PagerAdapter，我们这次就来看看他们这两位拍档的本事。
我们要使用ViewPager与PagerAdapter结合
首先布局文件
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent">
然后实现自己的adapter继承PagerAdapter。实现PagerAdapter的方法
1、public int getCount()；//获取总View的数量
2、public void startUpdate(ViewGroup container) ；3、public Object instantiateItem(ViewGroup container, int position) ； //实例化当前的View,添加到contrainer中,然后返回生成的View或关联的Object (用于在isViewFromObject中检查)
4、public void destroyItem(ViewGroup container, int position, Object object)； //从container中移除指定的View (释放内存)5、public void finishUpdate(ViewGroup container) ；
6、 public boolean isViewFromObject(View view, Object object) ；// 检查View是否与一个Object关联,
下面展示一下demo
package com.example.communityfunction.myView;import java.util.List;import android.animation.Animator;import android.animation.Animator.AnimatorListener;import android.animation.AnimatorSet;import android.animation.ObjectAnimator;import android.app.ActionBar.LayoutParams;import android.content.Context;import android.graphics.Bitmap;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.view.View;import android.view.View.OnClickListener;import android.view.ViewGroup;import android.widget.ImageView;publicclassImgViewPagerAdapterextends PagerAdapter
{
privateList imgBm;
private Context mContext;
private ViewPager pager;
publicImgViewPagerAdapter(Context context,ListimgBm,ViewPager pager)
{
this.imgBm=imgBm;
this.mContext=context;
this.pager=pager;
}
@Override
publicint getCount()
{
return imgBm.size();
}
@Override
publicObject instantiateItem(finalViewGroup container,int position)
{
ImageView imageView=new ImageView(mContext);
imageView.setImageBitmap(imgBm.get(position));
container.addView(imageView,LayoutParams.MATCH_PARENT,LayoutParams.MATCH_PARENT);
imageView.setOnClickListener(new OnClickListener()
{
@Override
publicvoid onClick(View v)
{
startAnim();
}
});
returnimageView; }
// PagerAdapter只缓存三张要显示的图片，如果滑动的图片超出了缓存的范围，就会调用这个方法，将图片销毁
@Override publicvoiddestroyItem(ViewGroup container,intposition, Object object)
{ container.removeView((View)object); };
@Override
publicbooleanisViewFromObject(View arg0, Object arg1)
{
returnarg0==arg1;//官方提示写法}
/*
*动画效果
*/
publicvoid startAnim()
{
AnimatorSet animSet =new AnimatorSet();
animSet.play(ObjectAnimator.ofFloat(pager, "alpha", 1.0f,0f))
.with(ObjectAnimator.ofFloat(pager, "scaleX",1.0f,0f))
.with(ObjectAnimator.ofFloat(pager, "scaleY",1.0f,0f));
animSet.setDuration(400);
animSet.start();
animSet.addListener(new AnimatorListener() {
@Override
publicvoid onAnimationStart(Animator animation) {}
@Override
publicvoid onAnimationRepeat(Animator animation) {}
@Override
publicvoid onAnimationEnd(Animator animation)
{
pager.setVisibility(View.GONE);
}
@Override
publicvoid onAnimationCancel(Animator animation){}
});
}
}
注意：
在ViewPager 外面嵌套ScrollView 时,发现ViewPager中的元素显示不出来。
解决办法：
在ScrollView节点指定android:fillviewport="true"
转载于:https://www.jianshu.com/p/6c8a7e5d21f6