- 默认3.0API,所以3.0API以下的要自定义实现。
- 下载github开源jar包(nineoldandroid.jar), 并添加到项目的libs中
MainActivity.java
public class MainActivity extends AppCompatActivity {
private ViewPager mViewPager;
private int[] mImgIds=new int[]{R.drawable.bg0,R.drawable.bg1,R.drawable.bg2};
private List<ImageView> mImages=new ArrayList<ImageView>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewPager= (ViewPager) findViewById(R.id.id_viewpager);
mViewPager.setPageTransformer(true,new RotateDownPageTransformer());
mViewPager.setAdapter(new PagerAdapter() {
@Override
public Object instantiateItem(ViewGroup container, int position) {
ImageView imageView=new ImageView(MainActivity.this);
imageView.setImageResource(mImgIds[position]);
//防止图片变形
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
container.addView(imageView);
mImages.add(imageView);
return imageView;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView(mImages.get(position));
}
@Override
public int getCount() {
return mImgIds.length;
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view==object;
}
});
}
}
RotateDownPageTransformer.java
public class RotateDownPageTransformer implements ViewPager.PageTransformer {
private static final float MAX_ROTATE =20f;
//A页角度变化从0~-20,B页角度从20~0;
//变化的角度
private float mRot;
@Override
public void transformPage(View view, float position)
{
if(position<-1)
ViewHelper.setRotation(view,0);
else if(position<=0)//A页
{
//0~ 20
mRot=position*MAX_ROTATE;
//设置旋转中心
ViewHelper.setPivotX(view,view.getMeasuredWidth()/2);
ViewHelper.setPivotY(view,view.getMeasuredHeight());
//实现动画效果
ViewHelper.setRotation(view,mRot);
}
else if(position<=1)//B页
{
//20~ 0
mRot=position*MAX_ROTATE;
ViewHelper.setPivotX(view,view.getMeasuredWidth()/2);
ViewHelper.setPivotY(view,view.getMeasuredHeight());
ViewHelper.setRotation(view,mRot);
}
else if(position>1)
ViewHelper.setRotation(view,0);
}
}
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.support.v4.view.ViewPager
android:id="@+id/id_viewpager"
android:layout_height="match_parent"
android:layout_width="match_parent">
</android.support.v4.view.ViewPager>
</RelativeLayout>
在3.0API可以直接用view实现动画效果
public class DepthPageTransformer implements ViewPager.PageTransformer
{
private static final float MIN_SCALE=0.75f;
@Override
public void transformPage(View view, float position)
{
int pageWidth=view.getWidth();
if(position<-1)
view.setAlpha(0);//完全透明看不到
else if(position<=0)//A页
{
view.setAlpha(1);//不透明
view.setTranslationX(0);
view.setScaleX(1);
view.setScaleY(1);
}
else if(position<=1)
{
view.setAlpha(1-position);
view.setTranslationX(pageWidth*-position);
//0.75~ 1
float scaleFactor=MIN_SCALE+(1-MIN_SCALE)*(1-Math.abs(position));
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor);
}
else
view.setAlpha(0);
}
}