ViewPager实现画廊效果[转]

/**
 * ViewPager实现画廊效果
 * 
 * @author Trinea 2013-04-03
 */
public class ViewPagerMulTiFragmentDemo extends FragmentActivity {

    private static int     TOTAL_COUNT = 10;

    private RelativeLayout viewPagerContainer;
    private ViewPager      viewPager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        viewPager = (ViewPager)findViewById(R.id.view_pager);
        viewPagerContainer = (RelativeLayout)findViewById(R.id.pager_layout);
        viewPager.setAdapter(new MyPagerAdapter());
        // to cache all page, or we will see the right item delayed
        viewPager.setOffscreenPageLimit(TOTAL_COUNT);
        viewPager.setPageMargin(10);
        MyOnPageChangeListener myOnPageChangeListener = new MyOnPageChangeListener();
        viewPager.setOnPageChangeListener(myOnPageChangeListener);

        viewPagerContainer.setOnTouchListener(new OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {
                // dispatch the events to the ViewPager, to solve the problem that we can swipe only the middle view.
                return viewPager.dispatchTouchEvent(event);
            }
        });
    }

    /**
     * this is a example fragment, just a imageview, u can replace it with your needs
     * 
     * @author Trinea 2013-04-03
     */
    class MyPagerAdapter extends PagerAdapter {

        @Override
        public int getCount() {
            return TOTAL_COUNT;
        }

        @Override
        public boolean isViewFromObject(View view, Object object) {
            return (view == object);
        }

        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            ImageView imageView = new ImageView(ViewPagerMulTiFragmentDemo.this);
            imageView.setImageResource(R.drawable.ic_launcher);
            ((ViewPager)container).addView(imageView, position);
            return imageView;

        }

        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            ((ViewPager)container).removeView((ImageView)object);
        }
    }

    public class MyOnPageChangeListener implements OnPageChangeListener {

        @Override
        public void onPageSelected(int position) {
        }

        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
            // to refresh frameLayout
            if (viewPagerContainer != null) {
                viewPagerContainer.invalidate();
            }
        }

        @Override
        public void onPageScrollStateChanged(int arg0) {
        }
    }
}




<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/pager_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:clipChildren="false"
    android:layerType="software"
    tools:context=".MainActivity" >

    <android.support.v4.view.ViewPager
        android:id="@+id/view_pager"
        android:layout_width="80dp"
        android:layout_height="200dp"
        android:layout_gravity="center"
        android:clipChildren="false" />

</RelativeLayout>

发现上面的RelativeLayout(可以用其它layout替换)和ViewPager的android:clipChildren都设置为了false。
android:clipChildren表示是否限制子View在其范围内，在animations动画以及本文的情况下可以发挥很大的作用。默认为true。

(1). ViewPager设置
需要setOnPageChangeListener，在onPageScrolled(int position, float positionOffset, int positionOffsetPixels)函数中不断刷新layout。
还可以
viewPager.setOffscreenPageLimit(TOTAL_COUNT);
viewPager.setPageMargin(getResources().getDimensionPixelSize(R.dimen.page_margin));
setOffscreenPageLimit表示设置缓存，这样左右拖动即可看见后面的Fragment。setPageMargin表示设置Fragment之间的间距

(2)
需要setOnTouchListener函数中将滑动滑动事件传递给viewPager，否则只有viewPager中间的view可以滑动，设置后整个viewPager都可以滑动。

可能运行后出现viewpager的部分Fragment无法看见或是突然消失的问题，请确保RelativeLayout和ViewPager的android:clipChildren都设置为了false并且viewPager.setOffscreenPageLimit(TOTAL_COUNT);其中TOTAL_COUNT大于0. 当然子Fragment本身不能是match_parent的。viewpager设置了paddingTop也会导致无法实现画廊而只是显示一屏。

[转]http://www.trinea.cn/android/viewpager实现画廊一屏多个fragment效果/