Android原生ViewPager控件实现卡片翻动效果

本文实例为大家分享了Android控件ViewPager实现卡片翻动效果的具体代码，供大家参考，具体内容如下

先放一张效果图：

想要实现这样的效果其实并不是太难，需要对ViewPager的一些细节属性更深入的了解和认识，下面介绍下一个小demo的实现过程：

第一步、创建卡片viewpager适配器的itemview的布局文件：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="@drawable/bitmap"
  android:gravity="center">

  <ImageView
    android:id="@+id/home_viewpage_item_img"
    android:paddingBottom="@dimen/dp_82"
    android:paddingTop="@dimen/dp_82"
    android:paddingLeft="@dimen/dp_44"
    android:paddingRight="@dimen/dp_44"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:src="@drawable/ic_launcher" />
</RelativeLayout>

第二步、创建适配器：

class CardAdapter(var context: Context) : PagerAdapter() {
  val horoscopestrImgs = intArrayOf(R.drawable.ic_launcher, R.drawable.ic_launcher, R.drawable.ic_launcher, R.drawable.ic_launcher, R.drawable.ic_launcher, R.drawable.ic_launcher,
      R.drawable.ic_launcher, R.drawable.ic_launcher, R.drawable.ic_launcher, R.drawable.ic_launcher, R.drawable.ic_launcher, R.drawable.ic_launcher)

  override fun isViewFromObject(view: View, `object`: Any): Boolean {
    return view === `object`
  }

  override fun getCount(): Int {
    return 12 * 30
  }

  override fun instantiateItem(container: ViewGroup, position: Int): Any {
    val view = LayoutInflater.from(context).inflate(R.layout.home_viewpage_item, null)

    view.home_viewpage_item_img.setImageResource(horoscopestrImgs.get(position%12))

    container.addView(view)
    return view
  }

  override fun destroyItem(container: ViewGroup, position: Int, `object`: Any) {
    container.removeView(`object` as View)

  }
}

第三步、创建放viewpager控件的布局文件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:background="#fff"
  android:layout_height="match_parent" >

  <android.support.v4.view.ViewPager
    android:id="@+id/viewpager"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:layout_centerInParent="true"
    android:overScrollMode="never"
    android:paddingBottom="@dimen/dp_240"
    android:paddingLeft="50dp"
    android:paddingRight="50dp"
    android:paddingTop="@dimen/dp_60" />

</RelativeLayout>

第四步、创建viewpager滑动切换动画效果：

class CardTransformer(var context: Context) :ViewPager.PageTransformer{
  val TAG = "CardTransformer"
  private val MAX_SCALE = 1.0f
  private val MIN_SCALE = 0.85f//0.85f
  var animator:ObjectAnimator?=null

  override fun transformPage(page: View, position: Float) {
    //设置了内间距  有0.15的偏差
     var pos=position -0.15.toFloat()

    if ( pos <= 1) {
      val scaleFactor = MIN_SCALE + (1 - Math.abs(pos)) * (MAX_SCALE - MIN_SCALE)

      page.scaleX = scaleFactor //缩放效果
      if (pos > 0) {
        page.translationX = -scaleFactor * 2
      } else if (pos < 0 && pos > -1) {
        page.translationX = scaleFactor * 2
      }
      page.scaleY = scaleFactor

    } else {
      page.scaleX = MIN_SCALE
      page.scaleY = MIN_SCALE
    }

  }
}

第五步、开始调用实现卡片效果的关键代码：

class MainActivity : Activity() {

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main7)

    //设置ViewPager中两页之间的距离
    // viewpager?.setPageMargin(80)

    //自定义ViewPager的页面切换动画
    viewpager?.setPageTransformer(false, CardTransformer(applicationContext))
    //设置viewpager预加载的页数
    viewpager?.offscreenPageLimit = 5
    viewpager?.currentItem = 12 * 15
    viewpager?.setAdapter(CardAdapter(this))
  }

}

到这里就基本实现了想要的卡片滑动切换和展示效果了！

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