有没有办法在android中创建预览滑块 [英] Is there a way to create preview slider in android

问题描述

我正在尝试创建像

这样的界面

.

中心元素是带有全尺寸图像的 ViewPager，顶部元素是带有预览图像的 RecyclerView.但是我找不到将元素吸引到中心的方法.有没有办法覆盖 RecyclerView 的行为?

解决方案

我找到了正是您需要的解决方案.我在 github.com 上创建了一个小例子:

问题是顶视图是 ViewPager 而中心视图也是 ViewPager.详细代码如下:

顶部预览适配器

public class PhotoPreviewAdapter extends FragmentPagerAdapter {私有静态最终 int DEFAULT_SIDE_PREVIEW_COUNT = 3;私人最终 int sidePreviewCount;私人最终名单<PhotoInfo>照片信息；公共 PhotoPreviewAdapter(FragmentManager fm, List photoInfos) {这(FM，DEFAULT_SIDE_PREVIEW_COUNT，photoInfos)；}public PhotoPreviewAdapter(FragmentManager fm, int sidePreviewCount, List photoInfos) {超级(调频)；this.sidePreviewCount = sidePreviewCount;this.photoInfos = photoInfos;}公共 int getSidePreviewCount() {返回 sidePreviewCount;}@覆盖公共片段 getItem(int position) {如果(isDummy(位置)){返回 DummyPreviewFragment.newInstance();} 别的 {返回 PhotoPreviewFragment.newInstance(photoInfos.get(getRealPosition(position)));}}私有布尔值 isDummy(int position) {返回位置＜sidePreviewCount ||位置 >photoInfos.size() - 1 + sidePreviewCount;}私人 int getRealPosition(int position) {返回位置 - sidePreviewCount;}@覆盖公共 int getCount() {返回 photoInfos.size() + (sidePreviewCount * 2);}@覆盖公共浮动 getPageWidth(int position) {返回 1.0f/getElementsPerPage();}私有 int getElementsPerPage() {返回 (sidePreviewCount * 2) + 1;}}

中央视图适配器很简单

public class PhotoViewAdapter extends FragmentPagerAdapter {私人最终名单<PhotoInfo>照片信息；公共 PhotoViewAdapter(FragmentManager fm, List photoInfos) {超级(调频)；this.photoInfos = photoInfos;}@覆盖公共片段 getItem(int position) {返回 PhotoViewFragment.newInstance(photoInfos.get(position));}@覆盖公共 int getCount() {返回 photoInfos.size();}}

其中一个主要是同步监听器

公共类 OnSyncPageChangeListener 实现 ViewPager.OnPageChangeListener {private int scrollState = ViewPager.SCROLL_STATE_IDLE;私有最终 ViewPager syncToViewPager；私有最终 ViewPager syncWithViewPager；公共 OnSyncPageChangeListener(ViewPager syncToViewPager, ViewPager syncWithViewPager) {this.syncToViewPager = syncToViewPager;this.syncWithViewPager = syncWithViewPager;}@覆盖public void onPageScrolled(final int position, final float positionOffset, final int positionOffsetPixels) {如果(滚动状态！= ViewPager.SCROLL_STATE_IDLE){最终浮动比率 = calculateRatioForPosition(position);final float scrollX = syncWithViewPager.getScrollX();final float scrollY = syncWithViewPager.getScrollY();syncToViewPager.scrollTo((int) (scrollX * ratio), (int) scrollY);}}私人浮点计算RatioForPosition(整数位置){最终浮动 syncToViewPagerWidth = syncToViewPager.getWidth();最终浮动 syncWithViewPagerWidth = syncWithViewPager.getWidth();最终浮动 syncToViewPagerElementWeight = syncToViewPager.getAdapter().getPageWidth(position);最终浮动 syncWithViewPagerElementWeight = syncWithViewPager.getAdapter().getPageWidth(position);最终浮动 syncToViewPagerElementsCount = (1.0f/syncToViewPagerElementWeight);最终浮动 syncWithViewPagerElementsCount = (1.0f/syncWithViewPagerElementWeight);最终浮动 syncToViewPagerElementWidth = syncToViewPagerWidth/syncToViewPagerElementsCount;最终浮动 syncWithViewPagerElementWidth = syncWithViewPagerWidth/syncWithViewPagerElementsCount;返回 syncToViewPagerElementWidth/syncWithViewPagerElementWidth;}@覆盖公共无效 onPageSelected(最终 int 位置){}@覆盖public void onPageScrollStateChanged(final int state) {滚动状态 = 状态；如果(状态== ViewPager.SCROLL_STATE_IDLE){syncToViewPager.setCurrentItem(syncWithViewPager.getCurrentItem(), false);}}}

最后init ViewPager的

@Bind(R.id.photoPreviewPager)ViewPager photoPreviewPager;@Bind(R.id.photoViewPager)ViewPager photoViewPager;@覆盖protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);ButterKnife.bind(this);最终名单<PhotoInfo>photoInfos = PhotoInfosProvider.generate();final PhotoPreviewAdapter photoPreviewAdapter = new PhotoPreviewAdapter(getSupportFragmentManager(), photoInfos);final PhotoViewAdapter photoViewAdapter = new PhotoViewAdapter(getSupportFragmentManager(), photoInfos);photoPreviewPager.setAdapter(photoPreviewAdapter);photoPreviewPager.addOnPageChangeListener(new OnSyncPageChangeListener(photoViewPager, photoPreviewPager));photoViewPager.setAdapter(photoViewAdapter);photoViewPager.setOffscreenPageLimit(photoPreviewAdapter.getSidePreviewCount() * 2 + 1);photoViewPager.addOnPageChangeListener(new OnSyncPageChangeListener(photoPreviewPager, photoViewPager));}

更详细的代码在repo

I'm trying to create interface like

.

Central element is ViewPager with full-size image, top element is RecyclerView with preview images. But I couldn't find the way to magnet elements to center. Is there way to override behavior of RecyclerView?

解决方案

I found the solution exactly what you need. I created a small example on github.com: AndroidPreviewSlider

The thing is that top view is ViewPager and center view is ViewPager too. Detailed code is below:

Adapter for top preview

public class PhotoPreviewAdapter extends FragmentPagerAdapter {

    private static final int DEFAULT_SIDE_PREVIEW_COUNT = 3;

    private final int sidePreviewCount;

    private final List<PhotoInfo> photoInfos;

    public PhotoPreviewAdapter(FragmentManager fm, List<PhotoInfo> photoInfos) {
        this(fm, DEFAULT_SIDE_PREVIEW_COUNT, photoInfos);
    }

    public PhotoPreviewAdapter(FragmentManager fm, int sidePreviewCount, List<PhotoInfo> photoInfos) {
        super(fm);
        this.sidePreviewCount = sidePreviewCount;
        this.photoInfos = photoInfos;
    }

    public int getSidePreviewCount() {
        return sidePreviewCount;
    }

    @Override
    public Fragment getItem(int position) {
        if (isDummy(position)) {
            return DummyPreviewFragment.newInstance();
        } else {
            return PhotoPreviewFragment.newInstance(photoInfos.get(getRealPosition(position)));
        }
    }

    private boolean isDummy(int position) {
        return position < sidePreviewCount || position > photoInfos.size() - 1 + sidePreviewCount;
    }

    private int getRealPosition(int position) {
        return position - sidePreviewCount;
    }

    @Override
    public int getCount() {
        return photoInfos.size() + (sidePreviewCount * 2);
    }

    @Override
    public float getPageWidth(int position) {
        return 1.0f / getElementsPerPage();
    }

    private int getElementsPerPage() {
        return (sidePreviewCount * 2) + 1;
    }
}

Adapter for central view is simple

public class PhotoViewAdapter extends FragmentPagerAdapter {

    private final List<PhotoInfo> photoInfos;

    public PhotoViewAdapter(FragmentManager fm, List<PhotoInfo> photoInfos) {
        super(fm);
        this.photoInfos = photoInfos;
    }

    @Override
    public Fragment getItem(int position) {
        return PhotoViewFragment.newInstance(photoInfos.get(position));
    }

    @Override
    public int getCount() {
        return photoInfos.size();
    }
}

And one of the main is sync listener

public class OnSyncPageChangeListener implements ViewPager.OnPageChangeListener {

    private int scrollState = ViewPager.SCROLL_STATE_IDLE;

    private final ViewPager syncToViewPager;
    private final ViewPager syncWithViewPager;

    public OnSyncPageChangeListener(ViewPager syncToViewPager, ViewPager syncWithViewPager) {
        this.syncToViewPager = syncToViewPager;
        this.syncWithViewPager = syncWithViewPager;
    }

    @Override
    public void onPageScrolled(final int position, final float positionOffset, final int positionOffsetPixels) {
        if (scrollState != ViewPager.SCROLL_STATE_IDLE) {
            final float ratio = calculateRatioForPosition(position);
            final float scrollX = syncWithViewPager.getScrollX();
            final float scrollY = syncWithViewPager.getScrollY();
            syncToViewPager.scrollTo((int) (scrollX * ratio), (int) scrollY);
        }
    }

    private float calculateRatioForPosition(int position) {
        final float syncToViewPagerWidth = syncToViewPager.getWidth();
        final float syncWithViewPagerWidth = syncWithViewPager.getWidth();

        final float syncToViewPagerElementWeight = syncToViewPager.getAdapter().getPageWidth(position);
        final float syncWithViewPagerElementWeight = syncWithViewPager.getAdapter().getPageWidth(position);

        final float syncToViewPagerElementsCount = (1.0f / syncToViewPagerElementWeight);
        final float syncWithViewPagerElementsCount = (1.0f / syncWithViewPagerElementWeight);

        final float syncToViewPagerElementWidth = syncToViewPagerWidth / syncToViewPagerElementsCount;
        final float syncWithViewPagerElementWidth = syncWithViewPagerWidth / syncWithViewPagerElementsCount;

        return syncToViewPagerElementWidth / syncWithViewPagerElementWidth;
    }

    @Override
    public void onPageSelected(final int position) {

    }

    @Override
    public void onPageScrollStateChanged(final int state) {
        scrollState = state;
        if (state == ViewPager.SCROLL_STATE_IDLE) {
            syncToViewPager.setCurrentItem(syncWithViewPager.getCurrentItem(), false);
        }
    }
}

And finally init ViewPager's

@Bind(R.id.photoPreviewPager)
ViewPager photoPreviewPager;

@Bind(R.id.photoViewPager)
ViewPager photoViewPager;

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

    final List<PhotoInfo> photoInfos = PhotoInfosProvider.generate();

    final PhotoPreviewAdapter photoPreviewAdapter = new PhotoPreviewAdapter(getSupportFragmentManager(), photoInfos);
    final PhotoViewAdapter photoViewAdapter = new PhotoViewAdapter(getSupportFragmentManager(), photoInfos);

    photoPreviewPager.setAdapter(photoPreviewAdapter);
    photoPreviewPager.addOnPageChangeListener(new OnSyncPageChangeListener(photoViewPager, photoPreviewPager));

    photoViewPager.setAdapter(photoViewAdapter);
    photoViewPager.setOffscreenPageLimit(photoPreviewAdapter.getSidePreviewCount() * 2 + 1);
    photoViewPager.addOnPageChangeListener(new OnSyncPageChangeListener(photoPreviewPager, photoViewPager));
}

More detailed code is in repo

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