/*
|
* Copyright (C) 2013 Leszek Mzyk
|
*
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
* you may not use this file except in compliance with the License.
|
* You may obtain a copy of the License at
|
*
|
* http://www.apache.org/licenses/LICENSE-2.0
|
*
|
* Unless required by applicable law or agreed to in writing, software
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
* See the License for the specific language governing permissions and
|
* limitations under the License.
|
*/
|
|
package cn.sinata.xldutils.widget.autoscoll;
|
|
import android.content.Context;
|
import android.util.AttributeSet;
|
|
import androidx.viewpager.widget.PagerAdapter;
|
import androidx.viewpager.widget.ViewPager;
|
|
import java.util.ArrayList;
|
import java.util.List;
|
|
/**
|
* A ViewPager subclass enabling infinte scrolling of the viewPager elements
|
* <p/>
|
* When used for paginating views (in opposite to fragments), no code changes
|
* should be needed only change xml's from <android.support.v4.view.ViewPager>
|
* to <com.imbryk.viewPager.LoopViewPager>
|
* <p/>
|
* If "blinking" can be seen when paginating to first or last view, simply call
|
* seBoundaryCaching( true ), or change DEFAULT_BOUNDARY_CASHING to true
|
* <p/>
|
* When using a FragmentPagerAdapter or FragmentStatePagerAdapter,
|
* additional changes in the adapter must be done.
|
* The adapter must be prepared to create 2 extra items e.g.:
|
* <p/>
|
* The original adapter creates 4 items: [0,1,2,3]
|
* The modified adapter will have to create 6 items [0,1,2,3,4,5]
|
* with mapping realPosition=(position-1)%count
|
* [0->3, 1->0, 2->1, 3->2, 4->3, 5->0]
|
*/
|
public class LoopViewPager extends ViewPager {
|
|
private static final boolean DEFAULT_BOUNDARY_CASHING = false;
|
private static final boolean DEFAULT_BOUNDARY_LOOPING = true;
|
|
// OnPageChangeListener mOuterPageChangeListener;
|
private LoopPagerAdapterWrapper mAdapter;
|
private boolean mBoundaryCaching = DEFAULT_BOUNDARY_CASHING;
|
private boolean mBoundaryLooping = DEFAULT_BOUNDARY_LOOPING;
|
private List<OnPageChangeListener> mOnPageChangeListeners;
|
|
/**
|
* helper function which may be used when implementing FragmentPagerAdapter
|
*
|
* @param position
|
* @param count
|
* @return (position-1)%count
|
*/
|
public static int toRealPosition(int position, int count) {
|
position = position - 1;
|
if (position < 0) {
|
position += count;
|
} else {
|
position = position % count;
|
}
|
return position;
|
}
|
|
/**
|
* If set to true, the boundary views (i.e. first and last) will never be
|
* destroyed This may help to prevent "blinking" of some views
|
*
|
* @param flag
|
*/
|
public void setBoundaryCaching(boolean flag) {
|
mBoundaryCaching = flag;
|
if (mAdapter != null) {
|
mAdapter.setBoundaryCaching(flag);
|
}
|
}
|
|
public void setBoundaryLooping(boolean flag) {
|
mBoundaryLooping = flag;
|
if (mAdapter != null) {
|
mAdapter.setBoundaryLooping(flag);
|
}
|
}
|
|
@Override
|
public void setAdapter(PagerAdapter adapter) {
|
mAdapter = new LoopPagerAdapterWrapper(adapter);
|
super.setAdapter(mAdapter);
|
setCurrentItem(0, false);
|
}
|
|
public void notifyDataSetChanged(){
|
mAdapter.notifyDataSetChanged();
|
setCurrentItem(getCurrentItem());
|
}
|
|
@Override
|
public PagerAdapter getAdapter() {
|
return mAdapter != null ? mAdapter.getRealAdapter() : mAdapter;
|
}
|
|
@Override
|
public int getCurrentItem() {
|
return mAdapter != null ? mAdapter.toRealPosition(super.getCurrentItem()) : 0;
|
}
|
|
public void setCurrentItem(int item, boolean smoothScroll) {
|
|
int realItem = mAdapter.toInnerPosition(item);
|
super.setCurrentItem(realItem, smoothScroll);
|
}
|
|
@Override
|
public void setCurrentItem(int item) {
|
if (getCurrentItem() != item) {
|
setCurrentItem(item, true);
|
}
|
}
|
|
@Override
|
public void setOnPageChangeListener(OnPageChangeListener listener) {
|
addOnPageChangeListener(listener);
|
}
|
|
@Override
|
public void addOnPageChangeListener(OnPageChangeListener listener) {
|
if (mOnPageChangeListeners == null) {
|
mOnPageChangeListeners = new ArrayList<>();
|
}
|
mOnPageChangeListeners.add(listener);
|
}
|
|
@Override
|
public void removeOnPageChangeListener(OnPageChangeListener listener) {
|
if (mOnPageChangeListeners != null) {
|
mOnPageChangeListeners.remove(listener);
|
}
|
}
|
|
@Override
|
public void clearOnPageChangeListeners() {
|
if (mOnPageChangeListeners != null) {
|
mOnPageChangeListeners.clear();
|
}
|
}
|
|
public LoopViewPager(Context context) {
|
super(context);
|
init(context);
|
}
|
|
public LoopViewPager(Context context, AttributeSet attrs) {
|
super(context, attrs);
|
init(context);
|
}
|
|
private void init(Context context) {
|
if (onPageChangeListener != null) {
|
super.removeOnPageChangeListener(onPageChangeListener);
|
}
|
super.addOnPageChangeListener(onPageChangeListener);
|
}
|
|
private OnPageChangeListener onPageChangeListener = new OnPageChangeListener() {
|
private float mPreviousOffset = -1;
|
private float mPreviousPosition = -1;
|
|
@Override
|
public void onPageSelected(int position) {
|
|
int realPosition = mAdapter.toRealPosition(position);
|
if (mPreviousPosition != realPosition) {
|
mPreviousPosition = realPosition;
|
// if (mOuterPageChangeListener != null) {
|
// mOuterPageChangeListener.onPageSelected(realPosition);
|
// }
|
|
if (mOnPageChangeListeners != null) {
|
for (int i = 0; i < mOnPageChangeListeners.size(); i++) {
|
OnPageChangeListener listener = mOnPageChangeListeners.get(i);
|
if (listener != null) {
|
listener.onPageSelected(realPosition);
|
}
|
}
|
}
|
}
|
}
|
|
@Override
|
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
|
int realPosition = position;
|
if (mAdapter != null) {
|
realPosition = mAdapter.toRealPosition(position);
|
|
if (positionOffset == 0 && mPreviousOffset == 0 && (position == 0 || position == mAdapter.getCount() - 1)) {
|
setCurrentItem(realPosition, false);
|
}
|
}
|
|
mPreviousOffset = positionOffset;
|
|
if (mOnPageChangeListeners != null) {
|
for (int i = 0; i < mOnPageChangeListeners.size(); i++) {
|
OnPageChangeListener listener = mOnPageChangeListeners.get(i);
|
if (listener != null) {
|
if (realPosition != mAdapter.getRealCount() - 1) {
|
listener.onPageScrolled(realPosition, positionOffset, positionOffsetPixels);
|
} else {
|
if (positionOffset > .5) {
|
listener.onPageScrolled(0, 0, 0);
|
} else {
|
listener.onPageScrolled(realPosition, 0, 0);
|
}
|
}
|
}
|
}
|
}
|
/*
|
if (mOuterPageChangeListener != null) {
|
if (realPosition != mAdapter.getRealCount() - 1) {
|
mOuterPageChangeListener.onPageScrolled(realPosition, positionOffset, positionOffsetPixels);
|
} else {
|
if (positionOffset > .5) {
|
mOuterPageChangeListener.onPageScrolled(0, 0, 0);
|
} else {
|
mOuterPageChangeListener.onPageScrolled(realPosition, 0, 0);
|
}
|
}
|
}*/
|
}
|
|
@Override
|
public void onPageScrollStateChanged(int state) {
|
if (mAdapter != null) {
|
int position = LoopViewPager.super.getCurrentItem();
|
int realPosition = mAdapter.toRealPosition(position);
|
if (state == ViewPager.SCROLL_STATE_IDLE && (position == 0 || position == mAdapter.getCount() - 1)) {
|
setCurrentItem(realPosition, false);
|
}
|
}
|
// if (mOuterPageChangeListener != null) {
|
// mOuterPageChangeListener.onPageScrollStateChanged(state);
|
// }
|
|
if (mOnPageChangeListeners != null) {
|
for (int i = 0; i < mOnPageChangeListeners.size(); i++) {
|
OnPageChangeListener listener = mOnPageChangeListeners.get(i);
|
if (listener != null) {
|
listener.onPageScrollStateChanged(state);
|
}
|
}
|
}
|
}
|
};
|
|
}
|
