【发布时间】：2011-11-23 08:23:19
【问题描述】：
我正在使用 PagerAdapter 进行水平滑动以在我的应用中显示报纸页面。
目前我想在这个应用程序中实现循环滚动。现在我所做的是whenever I am getting on last page I try to set the currentItem to first pagei.e 该功能适用于最后一页到第一页，但问题是我如何才能从第一页转到最后一页页。
在这里，我粘贴与 pagerAdapter 和 onPageChangeListener 相关的代码：-
awesomeAdapter = new AwesomePagerAdapter(awesomePager);
awesomePager.setAdapter(awesomeAdapter);
awesomePager.setPageMargin(10);
awesomePager.setOnPageChangeListener(new OnPageChangeListener() {
int lastPosition;
float posOffset = 0;
@Override
public void onPageSelected(int position) {
viewerPage = position;
CommonLogic.logMessage("Viewer Page:- "+ viewerPage, TAG, Log.VERBOSE);
posOffset = 0;
}
@Override
public void onPageScrolled(int position,float positionOffset,int positionOffsetPixels) {
if (positionOffset == 0 && positionOffsetPixels == 0 && position != 0) {
lastPosition = position;
}
posOffset -= positionOffset;
CommonLogic.logMessage(" Position:- "
+ position + " Position Offset:- " + positionOffset
+ " Position Offset Variable:- "
+ posOffset
+ " Position Offset Pixels:- "
+ positionOffsetPixels
+ " Last Position " + lastPosition,
TAG, Log.VERBOSE);
CommonLogic.logMessage(" Last Position "
+ lastPosition, TAG, Log.VERBOSE);
}
@Override
public void onPageScrollStateChanged(int state) {
// To Detect the Last Page & This Sets it to first page.This working fine.
if (state == ViewPager.SCROLL_STATE_DRAGGING && viewerPage == (uris.size() - 1)) {
CommonLogic.logMessage("Scroll State Changed ", TAG,Log.VERBOSE);
postDelayed(new Runnable() {
@Override
public void run() {
awesomePager.setCurrentItem(0, true);
}
}, 200);
}
// I have also used this to detect whether the user is on first & try to move on last page,but it is not working well.
else if (state == ViewPager.SCROLL_STATE_DRAGGING && (lastPosition == 0 || lastPosition == (uris.size() - 1)) && viewerPage == 0 && posOffset <= 0) {
CommonLogic.logMessage( "Scroll State Changed ", TAG,Log.VERBOSE);
postDelayed(new Runnable() {
@Override
public void run() {
awesomePager.setCurrentItem((uris.size() - 1), true);
}
}, 200);
}
}
}
});
PagerAdapter 也就是我的情况下的 AwesomweAdapter，如下所示：-
private class AwesomePagerAdapter extends PagerAdapter {
ViewPager pdfContainer;
DocumentNewView documentNewView;
CustomViewPager customViewPager;
public AwesomePagerAdapter(CustomViewPager awesomePager) {
this.customViewPager = awesomePager;
}
@Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
@Override
public int getCount() {
return uris.size();
}
public DocumentNewView addViewAt(int position, DocumentNewView mainView) {
CommonLogic.logMessage("Position of View:- " + position, TAG,
Log.VERBOSE);
pdfContainer.addView(mainView);
return mainView;
}
/**
* Create the page for the given position. The adapter is responsible
* for adding the view to the container given here, although it only
* must ensure this is done by the time it returns from
* {@link #finishUpdate()}.
*
* @param container
* The containing View in which the page will be shown.
* @param position
* The page position to be instantiated.
* @return Returns an Object representing the new page. This does not
* need to be a View, but can be some other container of the
* page.
*/
@Override
public Object instantiateItem(View collection, int position) {
CommonLogic
.logMessage("Instantiate Item Called ", TAG, Log.VERBOSE);
documentNewView = new DocumentNewView(cxt, display, customViewPager);
documentNewView.setPdfContext(new PdfContext());
CodecDocument codecDocument = documentNewView.open(uris
.get(position));
documentNewView.renderDocument(codecDocument);
documentNewView.setMaxZoom(4f);
documentNewView.setVerticalScrollBarEnabled(true);
codecDocument = null;
this.pdfContainer = (ViewPager) collection;
return addViewAt(position, documentNewView);
}
/**
* Remove a page for the given position. The adapter is responsible for
* removing the view from its container, although it only must ensure
* this is done by the time it returns from {@link #finishUpdate()}.
*
* @param container
* The containing View from which the page will be removed.
* @param position
* The page position to be removed.
* @param object
* The same object that was returned by
* {@link #instantiateItem(View, int)}.
*/
@Override
public void destroyItem(View collection, int position, Object view) {
pdfContainer.removeView((DocumentNewView) view);
}
/**
* Called when the a change in the shown pages has been completed. At
* this point you must ensure that all of the pages have actually been
* added or removed from the container as appropriate.
*
* @param container
* The containing View which is displaying this adapter's
* page views.
*/
@Override
public void finishUpdate(View arg0) {
CommonLogic.logMessage("Finish Update Called ", TAG, Log.VERBOSE);
}
@Override
public void restoreState(Parcelable arg0, ClassLoader arg1) {
}
@Override
public Parcelable saveState() {
return null;
}
@Override
public void startUpdate(View arg0) {
CommonLogic.logMessage("State Update Called ", TAG, Log.VERBOSE);
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view == ((DocumentNewView) object);
}
请给我任何建议/更改我的代码（如果适用）。 提前致谢。
【问题讨论】：
-
我在文档中看到了一些循环列表适配器 ....
-
你在说哪个文档是 Android 文档还是其他文档。
标签： android adapter android-viewpager