有没有办法在 android 中创建预览滑块
Is there a way to create preview slider in android
我正在尝试创建类似
的界面
.
中心元素是 ViewPager
全尺寸图片,顶部元素是 RecyclerView
预览图片。但是我找不到让磁铁元素居中的方法。有没有办法覆盖 RecyclerView
的行为?
LinearLayoutManager 有一个 scrollToPositionWithOffset 方法,它获取项目开始位置和 RecyclerView 开始位置的偏移量,这似乎可以满足您的需要。
您可以使用此图像滑块 (https://github.com/jjhesk/LoyalNativeSlider) 而不是 ViewPager 。
首先,您可以使用此google official example创建将此视图拉到中心的视觉效果。您将在 ViewPager 上使用 ImageView 来显示动画外观。动画完成后,使您的 ImageView 消失并在 ViewPager 中显示请求的图像。
我找到了您所需要的解决方案。我在 github.com 上创建了一个小例子:AndroidPreviewSlider
问题是顶视图是 ViewPager
,中心视图也是 ViewPager
。
详细代码如下:
顶级预览适配器
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;
}
}
中心视图适配器很简单
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();
}
}
其中一个主要的是 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);
}
}
}
最后 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));
}
更详细的代码在repo
我正在尝试创建类似
的界面中心元素是 ViewPager
全尺寸图片,顶部元素是 RecyclerView
预览图片。但是我找不到让磁铁元素居中的方法。有没有办法覆盖 RecyclerView
的行为?
LinearLayoutManager 有一个 scrollToPositionWithOffset 方法,它获取项目开始位置和 RecyclerView 开始位置的偏移量,这似乎可以满足您的需要。
您可以使用此图像滑块 (https://github.com/jjhesk/LoyalNativeSlider) 而不是 ViewPager 。
首先,您可以使用此google official example创建将此视图拉到中心的视觉效果。您将在 ViewPager 上使用 ImageView 来显示动画外观。动画完成后,使您的 ImageView 消失并在 ViewPager 中显示请求的图像。
我找到了您所需要的解决方案。我在 github.com 上创建了一个小例子:AndroidPreviewSlider
问题是顶视图是 ViewPager
,中心视图也是 ViewPager
。
详细代码如下:
顶级预览适配器
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;
}
}
中心视图适配器很简单
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();
}
}
其中一个主要的是 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);
}
}
}
最后 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));
}
更详细的代码在repo