package com.qhm123.slide;
import android.os.Parcelable;
import android.view.View;
/**
* Base class providing the adapter to populate pages inside of a
* {@link ViewPager}. You will most likely want to use a more specific
* implementation of this, such as
* {@link android.support.v4.app.FragmentPagerAdapter} or
* {@link android.support.v4.app.FragmentStatePagerAdapter}.
*/
public abstract class PagerAdapter {
private DataSetObserver mObserver;
public static final int POSITION_UNCHANGED = -1;
public static final int POSITION_NONE = -2;
/**
* Used to watch for changes within the adapter.
*/
interface DataSetObserver {
public void onDataSetChanged();
}
/**
* Return the number of views available.
*/
public abstract int getCount();
/**
* Called when a change in the shown pages is going to start being made.
*
* @param container
* The containing View which is displaying this adapter's page
* views.
*/
public abstract void startUpdate(View container);
/**
* 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.
*/
public abstract Object instantiateItem(View container, int position);
/**
* 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)}.
*/
public abstract void destroyItem(View container, int position, Object object);
/**
* Called to inform the adapter of which item is currently considered to be
* the "primary", that is the one show to the user as the current page.
*
* @param container
* The containing View from which the page will be removed.
* @param position
* The page position that is now the primary.
* @param object
* The same object that was returned by
* {@link #instantiateItem(View, int)}.
*/
public void setPrimaryItem(View container, int position, Object object) {
}
/**
* 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.
*/
public abstract void finishUpdate(View container);
public abstract boolean isViewFromObject(View view, Object object);
public abstract Parcelable saveState();
public abstract void restoreState(Parcelable state, ClassLoader loader);
/**
* Called when the host view is attempting to determine if an item's
* position has changed. Returns {@link #POSITION_UNCHANGED} if the position
* of the given item has not changed or {@link #POSITION_NONE} if the item
* is no longer present in the adapter.
*
* <p>
* The default implementation assumes that items will never change position
* and always returns {@link #POSITION_UNCHANGED}.
*
* @param object
* Object representing an item, previously returned by a call to
* {@link #instantiateItem(View, int)}.
* @return object's new position index from [0, {@link #getCount()}),
* {@link #POSITION_UNCHANGED} if the object's position has not
* changed, or {@link #POSITION_NONE} if the item is no longer
* present.
*/
public int getItemPosition(Object object) {
return POSITION_UNCHANGED;
}
/**
* This method should be called by the application if the data backing this
* adapter has changed and associated views should update.
*/
public void notifyDataSetChanged() {
if (mObserver != null) {
mObserver.onDataSetChanged();
}
}
void setDataSetObserver(DataSetObserver observer) {
mObserver = observer;
}
}