学习ViewPage实现无限左右滑动

xtdhwl 2012-12-13 03:46:23

在项目中有需求展示图片，可以左右滑动
一开始使用Gallery实现

public class ZMGallery extends Gallery {



	public ZMGallery(Context context) {

		super(context);

		// TODO Auto-generated constructor stub

	}



	public ZMGallery(Context context, AttributeSet attrs, int defStyle) {

		super(context, attrs, defStyle);

		// TODO Auto-generated constructor stub

	}



	public ZMGallery(Context context, AttributeSet attrs) {

		super(context, attrs);

		// TODO Auto-generated constructor stub

	}

	

	@Override

	public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {

		// TODO Auto-generated method stub

		return false;

	}

	

	

}

在xml中设置属性

 <net.shenru.common.view.ZMGallery

                        android:id="@+id/gal_album"

                        android:layout_width="fill_parent"

                        android:layout_height="fill_parent"

                        android:fadingEdgeLength="0dp"

                        android:spacing="10dp" >

                    </net.shenru.ui.common.view.ZMGallery>

但这样是有弊端的体验不好，在滑动时必须滑动超过一半才能翻页
一开始想重写Gallery方法经过一番周折我认输了。
不要紧我们使用ViewPager实现

public class MainActivity extends Activity {



	public static final String TAG = MainActivity.class.getSimpleName();

	ViewPager pager = null;



	@Override

	public void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState);

		setContentView(R.layout.activity_main);

		//学习ViewPage

		//ViewPage可以实现滑动 使用PageAdatper

		pager = (ViewPager) this.findViewById(R.id.pager);

		pager.setAdapter(new MyPagerAdatper(this));

		pager.setCurrentItem(Integer.MAX_VALUE /2);

	}



	private class MyPagerAdatper extends PagerAdapter {



		private List<Drawable> lists = null;

		private Context mContext;



		public MyPagerAdatper(Context context) {

			super();

			mContext = context;

			lists = new ArrayList<Drawable>();

			lists.add(mContext.getResources().getDrawable(R.drawable.ic_launcher));

			lists.add(mContext.getResources().getDrawable(R.drawable.ic_launcher));

			lists.add(mContext.getResources().getDrawable(R.drawable.ic_launcher));

			lists.add(mContext.getResources().getDrawable(R.drawable.ic_launcher));

		}



		//得到adapter的个数

		@Override

		public int getCount() {

			Log.i(TAG, "getCount");

			return Integer.MAX_VALUE;

		}

                //是否把对象作为view

		@Override

		public boolean isViewFromObject(View view, Object obj) {

			Log.i(TAG, "isViewFromObject");

			return view == (View) obj;

		}



		@Override

		public void startUpdate(ViewGroup container) {

			// TODO Auto-generated method stub

			Log.i(TAG, "startUpdate");

			super.startUpdate(container);

		}

                //初始化一个item

		@Override

		public Object instantiateItem(ViewGroup container, int position) {

			Log.i(TAG, "instantiateItem");

			View view = View.inflate(mContext, R.layout.img, null);

			ImageView iv = (ImageView) view.findViewById(R.id.img);

			

			int size = lists.size();

			int location = Integer.MAX_VALUE % size;

			iv.setImageDrawable(lists.get(location));

			((ViewPager) container).addView(view);

			return view;

		}

                

                 //pageAdatper与BaseAdapter有很大区别，现在我理解为ViewPager释放有adapter处理

		@Override

		public void destroyItem(View container, int position, Object object) {

			// TODO Auto-generated method stub

			Log.i(TAG, "destroyItem");

			((ViewPager) container).removeView((View) object);

		}



		@Override

		public void destroyItem(ViewGroup container, int position, Object object) {

			// TODO Auto-generated method stub

			Log.i(TAG, "destroyItem");

			super.destroyItem(container, position, object);

		}



		@Override

		public void setPrimaryItem(ViewGroup container, int position, Object object) {

			// TODO Auto-generated method stub

			Log.i(TAG, "setPrimaryItem");

			super.setPrimaryItem(container, position, object);

		}



		@Override

		public void finishUpdate(ViewGroup container) {

			// TODO Auto-generated method stub

			Log.i(TAG, "finishUpdate");

			super.finishUpdate(container);

		}



		@Override

		public void startUpdate(View container) {

			// TODO Auto-generated method stub

			Log.i(TAG, "startUpdate");

			super.startUpdate(container);

		}



		@Override

		public Object instantiateItem(View container, int position) {

			// TODO Auto-generated method stub

			Log.i(TAG, "instantiateItem position:" + position);

			return super.instantiateItem(container, position);

		}



		@Override

		public void setPrimaryItem(View container, int position, Object object) {

			// TODO Auto-generated method stub

			Log.i(TAG, "setPrimaryItem position:" + position);

			super.setPrimaryItem(container, position, object);

		}



		@Override

		public void finishUpdate(View container) {

			// TODO Auto-generated method stub

			Log.i(TAG, "finishUpdate");

			super.finishUpdate(container);

		}



		@Override

		public Parcelable saveState() {

			// TODO Auto-generated method stub

			Log.i(TAG, "saveState");

			return super.saveState();

		}



		@Override

		public void restoreState(Parcelable state, ClassLoader loader) {

			// TODO Auto-generated method stub

			Log.i(TAG, "restoreState");

			super.restoreState(state, loader);

		}



		@Override

		public int getItemPosition(Object object) {

			// TODO Auto-generated method stub

			Log.i(TAG, "getItemPosition");

			return super.getItemPosition(object);

		}



		@Override

		public void notifyDataSetChanged() {

			// TODO Auto-generated method stub

			Log.i(TAG, "notifyDataSetChanged");

			super.notifyDataSetChanged();

		}



		@Override

		public CharSequence getPageTitle(int position) {

			// TODO Auto-generated method stub

			Log.i(TAG, "getPageTitle position:" + position);

			return super.getPageTitle(position);

		}

                //这个是一个很有用的方法默认返回1.0f，权重比例

		@Override

		public float getPageWidth(int position) {

			// TODO Auto-generated method stub

			Log.i(TAG, "getPageWidth position:" + position);

			return super.getPageWidth(position);

		}



	}

}

xml如下

<RelativeLayout 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.support.v4.view.ViewPager

        android:id="@+id/pager"

        android:layout_width="fill_parent"

        android:layout_height="fill_parent" >

    </android.support.v4.view.ViewPager>



</RelativeLayout>

一样可以实现左右无限滑动，体验还贲好

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liuzhi_cdsn 2015-07-07

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int size = lists.size(); int location = Integer.MAX_VALUE % size; iv.setImageDrawable(lists.get(location)); 要改成 int location = postion % size;

xtdhwl 2013-05-10

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引用 7 楼 hcy303563038 的回复:

如果滑到最后一页就让它跳到一个新的Activity去，请问怎么实现好？

ViewPage有监听接口 mViewPager.setOnPageChangeListener(new OnPageChangeListener())

引用 11 楼 b87936260 的回复:

这个内存会不会有问题？

我认为ViewPage需要PageAdapter去释放资源，Gallery内部来释放资源现在感觉项目中使用ViewPage要比Gallery要多 git上有一个开源的CirclePageIndicator ，配合ViewPage很不错

b87936260 2013-01-22

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这个内存会不会有问题？

叫我三三 2013-01-22

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这个区还真冷

wlcw16 2013-01-21

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mark 回家学习以下

kenny2471 2013-01-21

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Viewpager 的效果是挺好的

kaicheng21_ 2013-01-21

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如果滑到最后一页就让它跳到一个新的Activity去，请问怎么实现好？

jiaxin1029 2012-12-31

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好好研究一下

passself 2012-12-17

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如果是真是的图片会是怎样

xtdhwl 2012-12-17

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动态加载吗？不太理解什么意思

gavinkaihuang 2012-12-13

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动态加载吗？

xtdhwl 2012-12-13

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下面是log，可以看出viewPage还是很轻量级的调用instantiateItem3次

12-13 15:52:01.469: I/MainActivity(12066): getCount
12-13 15:52:01.469: I/MainActivity(12066): getCount
12-13 15:52:01.479: I/MainActivity(12066): startUpdate
12-13 15:52:01.479: I/MainActivity(12066): startUpdate
12-13 15:52:01.479: I/MainActivity(12066): getCount
12-13 15:52:01.479: I/MainActivity(12066): instantiateItem
12-13 15:52:01.479: I/MainActivity(12066): getPageWidth position:1073741823
12-13 15:52:01.479: I/MainActivity(12066): instantiateItem
12-13 15:52:01.479: I/MainActivity(12066): getPageWidth position:1073741822
12-13 15:52:01.479: I/MainActivity(12066): instantiateItem
12-13 15:52:01.479: I/MainActivity(12066): getPageWidth position:1073741824
12-13 15:52:01.479: I/MainActivity(12066): getCount
12-13 15:52:01.479: I/MainActivity(12066): setPrimaryItem
12-13 15:52:01.479: I/MainActivity(12066): setPrimaryItem position:1073741823
12-13 15:52:01.479: I/MainActivity(12066): finishUpdate
12-13 15:52:01.479: I/MainActivity(12066): finishUpdate
12-13 15:52:01.479: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.479: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.479: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.479: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.479: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.479: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.479: I/MainActivity(12066): startUpdate
12-13 15:52:01.479: I/MainActivity(12066): startUpdate
12-13 15:52:01.479: I/MainActivity(12066): getCount
12-13 15:52:01.479: I/MainActivity(12066): getCount
12-13 15:52:01.479: I/MainActivity(12066): setPrimaryItem
12-13 15:52:01.479: I/MainActivity(12066): setPrimaryItem position:1073741823
12-13 15:52:01.479: I/MainActivity(12066): finishUpdate
12-13 15:52:01.479: I/MainActivity(12066): finishUpdate
12-13 15:52:01.489: I/MainActivity(12066): startUpdate
12-13 15:52:01.489: I/MainActivity(12066): startUpdate
12-13 15:52:01.489: I/MainActivity(12066): getCount
12-13 15:52:01.489: I/MainActivity(12066): getCount
12-13 15:52:01.489: I/MainActivity(12066): setPrimaryItem
12-13 15:52:01.499: I/MainActivity(12066): setPrimaryItem position:1073741823
12-13 15:52:01.499: I/MainActivity(12066): finishUpdate
12-13 15:52:01.499: I/MainActivity(12066): finishUpdate
12-13 15:52:01.499: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.499: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.499: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.499: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.499: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.499: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.499: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.499: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.499: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.499: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.499: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.499: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.509: I/MainActivity(12066): startUpdate
12-13 15:52:01.509: I/MainActivity(12066): startUpdate
12-13 15:52:01.509: I/MainActivity(12066): getCount
12-13 15:52:01.509: I/MainActivity(12066): getCount
12-13 15:52:01.509: I/MainActivity(12066): setPrimaryItem
12-13 15:52:01.509: I/MainActivity(12066): setPrimaryItem position:1073741823
12-13 15:52:01.509: I/MainActivity(12066): finishUpdate
12-13 15:52:01.509: I/MainActivity(12066): finishUpdate
12-13 15:52:01.509: I/MainActivity(12066): startUpdate
12-13 15:52:01.509: I/MainActivity(12066): startUpdate
12-13 15:52:01.509: I/MainActivity(12066): getCount
12-13 15:52:01.509: I/MainActivity(12066): getCount
12-13 15:52:01.509: I/MainActivity(12066): setPrimaryItem
12-13 15:52:01.509: I/MainActivity(12066): setPrimaryItem position:1073741823
12-13 15:52:01.509: I/MainActivity(12066): finishUpdate
12-13 15:52:01.509: I/MainActivity(12066): finishUpdate
12-13 15:52:01.509: I/MainActivity(12066): startUpdate
12-13 15:52:01.509: I/MainActivity(12066): startUpdate
12-13 15:52:01.509: I/MainActivity(12066): getCount
12-13 15:52:01.509: I/MainActivity(12066): getCount
12-13 15:52:01.509: I/MainActivity(12066): setPrimaryItem
12-13 15:52:01.509: I/MainActivity(12066): setPrimaryItem position:1073741823
12-13 15:52:01.509: I/MainActivity(12066): finishUpdate
12-13 15:52:01.509: I/MainActivity(12066): finishUpdate
12-13 15:52:01.509: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.509: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.509: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.509: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.509: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.509: I/MainActivity(12066): isViewFromObject
12-13 15:52:01.539: I/MainActivity(12066): getCount

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