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March 8, 2015 23:41
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package org.sufficientlysecure.keychain.ui.adapter; | |
import android.content.Context; | |
import android.database.ContentObserver; | |
import android.database.Cursor; | |
import android.database.DataSetObserver; | |
import android.os.Handler; | |
import android.support.v7.widget.RecyclerView; | |
import android.widget.Filter; | |
import android.widget.FilterQueryProvider; | |
import android.widget.Filterable; | |
/** | |
* Reimplement and Rewrite CursorAdapter with RecycleView.ViewHolder and RecyclerView.Adapter | |
* from ASOP | |
* @param <VH> | |
*/ | |
public abstract class BaseAbstractRecycleCursorAdapter<VH extends RecyclerView.ViewHolder> | |
extends RecyclerView.Adapter<VH> implements Filterable, | |
CursorFilter.CursorFilterClient { | |
/** | |
* Call when bind view with the cursor | |
* | |
* @param holder RecyclerView.ViewHolder | |
* @param cursor The cursor from which to get the data. The cursor is already | |
* moved to the correct position. | |
*/ | |
public abstract void onBindViewHolder(VH holder, Cursor cursor); | |
/** | |
* This field should be made private, so it is hidden from the SDK. | |
* {@hide} | |
*/ | |
protected boolean mDataValid; | |
/** | |
* This field should be made private, so it is hidden from the SDK. | |
* {@hide} | |
*/ | |
protected Cursor mCursor; | |
/** | |
* This field should be made private, so it is hidden from the SDK. | |
* {@hide} | |
*/ | |
protected Context mContext; | |
/** | |
* This field should be made private, so it is hidden from the SDK. | |
* {@hide} | |
*/ | |
protected int mRowIDColumn; | |
/** | |
* This field should be made private, so it is hidden from the SDK. | |
* {@hide} | |
*/ | |
protected ChangeObserver mChangeObserver; | |
/** | |
* This field should be made private, so it is hidden from the SDK. | |
* {@hide} | |
*/ | |
protected DataSetObserver mDataSetObserver; | |
/** | |
* This field should be made private, so it is hidden from the SDK. | |
* {@hide} | |
*/ | |
protected CursorFilter mCursorFilter; | |
/** | |
* This field should be made private, so it is hidden from the SDK. | |
* {@hide} | |
*/ | |
protected FilterQueryProvider mFilterQueryProvider; | |
/** | |
* If set the adapter will register a content observer on the cursor and will call | |
* {@link #onContentChanged()} when a notification comes in. Be careful when | |
* using this flag: you will need to unset the current Cursor from the adapter | |
* to avoid leaks due to its registered observers. This flag is not needed | |
* when using a CursorAdapter with a | |
* {@link android.content.CursorLoader}. | |
*/ | |
public static final int FLAG_REGISTER_CONTENT_OBSERVER = 0x02; | |
/** | |
* Constructor that flags always FLAG_REGISTER_CONTENT_OBSERVER. | |
* | |
* @param c The cursor from which to get the data. | |
* @param context The context | |
* This option is discouraged, as it results in Cursor queries | |
* being performed on the application's UI thread and thus can cause poor | |
* responsiveness or even Application Not Responding errors. As an alternative, | |
* use {@link android.app.LoaderManager} with a {@link android.content.CursorLoader}. | |
*/ | |
public BaseAbstractRecycleCursorAdapter(Context context, Cursor c) { | |
this(context, c, FLAG_REGISTER_CONTENT_OBSERVER); | |
} | |
/** | |
* Recommended constructor. | |
* | |
* @param c The cursor from which to get the data. | |
* @param context The context | |
* @param flags Flags used to determine the behavior of the adapter; | |
* Currently it accept {@link #FLAG_REGISTER_CONTENT_OBSERVER}. | |
*/ | |
public BaseAbstractRecycleCursorAdapter(Context context, Cursor c, int flags) { | |
init(context, c, flags); | |
} | |
void init(Context context, Cursor c, int flags) { | |
boolean cursorPresent = c != null; | |
mCursor = c; | |
mDataValid = cursorPresent; | |
mContext = context; | |
mRowIDColumn = cursorPresent ? c.getColumnIndexOrThrow("_id") : -1; | |
if ((flags & FLAG_REGISTER_CONTENT_OBSERVER) == FLAG_REGISTER_CONTENT_OBSERVER) { | |
mChangeObserver = new ChangeObserver(); | |
mDataSetObserver = new MyDataSetObserver(); | |
} else { | |
mChangeObserver = null; | |
mDataSetObserver = null; | |
} | |
if (cursorPresent) { | |
if (mChangeObserver != null) c.registerContentObserver(mChangeObserver); | |
if (mDataSetObserver != null) c.registerDataSetObserver(mDataSetObserver); | |
} | |
setHasStableIds(true); | |
} | |
/** | |
* Returns the cursor. | |
* | |
* @return the cursor. | |
*/ | |
public Cursor getCursor() { | |
return mCursor; | |
} | |
/** | |
* @see android.support.v7.widget.RecyclerView.Adapter#getItemCount() | |
*/ | |
@Override | |
public int getItemCount() { | |
if (mDataValid && mCursor != null) { | |
return mCursor.getCount(); | |
} else { | |
return 0; | |
} | |
} | |
public Object getItem(int position) { | |
if (mDataValid && mCursor != null) { | |
mCursor.moveToPosition(position); | |
return mCursor; | |
} else { | |
return null; | |
} | |
} | |
/** | |
* @param position Adapter position to query | |
* @see android.support.v7.widget.RecyclerView.Adapter#getItemId(int) | |
*/ | |
@Override | |
public long getItemId(int position) { | |
if (mDataValid && mCursor != null) { | |
if (mCursor.moveToPosition(position)) { | |
return mCursor.getLong(mRowIDColumn); | |
} else { | |
return 0; | |
} | |
} else { | |
return 0; | |
} | |
} | |
@Override | |
public void onBindViewHolder(VH holder, int position) { | |
if (!mDataValid) { | |
throw new IllegalStateException("this should only be called when the cursor is valid"); | |
} | |
if (!mCursor.moveToPosition(position)) { | |
throw new IllegalStateException("couldn't move cursor to position " + position); | |
} | |
onBindViewHolder(holder, mCursor); | |
} | |
/** | |
* Change the underlying cursor to a new cursor. If there is an existing cursor it will be | |
* closed. | |
* | |
* @param cursor The new cursor to be used | |
*/ | |
public void changeCursor(Cursor cursor) { | |
Cursor old = swapCursor(cursor); | |
if (old != null) { | |
old.close(); | |
} | |
} | |
/** | |
* Swap in a new Cursor, returning the old Cursor. Unlike | |
* {@link #changeCursor(Cursor)}, the returned old Cursor is <em>not</em> | |
* closed. | |
* | |
* @param newCursor The new cursor to be used. | |
* @return Returns the previously set Cursor, or null if there wasa not one. | |
* If the given new Cursor is the same instance is the previously set | |
* Cursor, null is also returned. | |
*/ | |
public Cursor swapCursor(Cursor newCursor) { | |
if (newCursor == mCursor) { | |
return null; | |
} | |
Cursor oldCursor = mCursor; | |
if (oldCursor != null) { | |
if (mChangeObserver != null) oldCursor.unregisterContentObserver(mChangeObserver); | |
if (mDataSetObserver != null) oldCursor.unregisterDataSetObserver(mDataSetObserver); | |
} | |
mCursor = newCursor; | |
if (newCursor != null) { | |
if (mChangeObserver != null) newCursor.registerContentObserver(mChangeObserver); | |
if (mDataSetObserver != null) newCursor.registerDataSetObserver(mDataSetObserver); | |
mRowIDColumn = newCursor.getColumnIndexOrThrow("_id"); | |
mDataValid = true; | |
// notify the observers about the new cursor | |
notifyDataSetChanged(); | |
} else { | |
mRowIDColumn = -1; | |
mDataValid = false; | |
// notify the observers about the lack of a data set | |
//There is no notifyDataSetInvalidated() method in RecyclerView.Adapter | |
notifyDataSetChanged(); | |
} | |
return oldCursor; | |
} | |
/** | |
* <p>Converts the cursor into a CharSequence. Subclasses should override this | |
* method to convert their results. The default implementation returns an | |
* empty String for null values or the default String representation of | |
* the value.</p> | |
* | |
* @param cursor the cursor to convert to a CharSequence | |
* @return a CharSequence representing the value | |
*/ | |
public CharSequence convertToString(Cursor cursor) { | |
return cursor == null ? "" : cursor.toString(); | |
} | |
/** | |
* Runs a query with the specified constraint. This query is requested | |
* by the filter attached to this adapter. | |
* <p/> | |
* The query is provided by a | |
* {@link android.widget.FilterQueryProvider}. | |
* If no provider is specified, the current cursor is not filtered and returned. | |
* <p/> | |
* After this method returns the resulting cursor is passed to {@link #changeCursor(Cursor)} | |
* and the previous cursor is closed. | |
* <p/> | |
* This method is always executed on a background thread, not on the | |
* application's main thread (or UI thread.) | |
* <p/> | |
* Contract: when constraint is null or empty, the original results, | |
* prior to any filtering, must be returned. | |
* | |
* @param constraint the constraint with which the query must be filtered | |
* @return a Cursor representing the results of the new query | |
* @see #getFilter() | |
* @see #getFilterQueryProvider() | |
* @see #setFilterQueryProvider(android.widget.FilterQueryProvider) | |
*/ | |
public Cursor runQueryOnBackgroundThread(CharSequence constraint) { | |
if (mFilterQueryProvider != null) { | |
return mFilterQueryProvider.runQuery(constraint); | |
} | |
return mCursor; | |
} | |
public Filter getFilter() { | |
if (mCursorFilter == null) { | |
mCursorFilter = new CursorFilter(this); | |
} | |
return mCursorFilter; | |
} | |
/** | |
* Returns the query filter provider used for filtering. When the | |
* provider is null, no filtering occurs. | |
* | |
* @return the current filter query provider or null if it does not exist | |
* @see #setFilterQueryProvider(android.widget.FilterQueryProvider) | |
* @see #runQueryOnBackgroundThread(CharSequence) | |
*/ | |
public FilterQueryProvider getFilterQueryProvider() { | |
return mFilterQueryProvider; | |
} | |
/** | |
* Sets the query filter provider used to filter the current Cursor. | |
* The provider's | |
* {@link android.widget.FilterQueryProvider#runQuery(CharSequence)} | |
* method is invoked when filtering is requested by a client of | |
* this adapter. | |
* | |
* @param filterQueryProvider the filter query provider or null to remove it | |
* @see #getFilterQueryProvider() | |
* @see #runQueryOnBackgroundThread(CharSequence) | |
*/ | |
public void setFilterQueryProvider(FilterQueryProvider filterQueryProvider) { | |
mFilterQueryProvider = filterQueryProvider; | |
} | |
/** | |
* Called when the {@link android.database.ContentObserver} on the cursor receives a change notification. | |
* The default implementation provides the auto-requery logic, but may be overridden by | |
* sub classes. | |
* | |
* @see android.database.ContentObserver#onChange(boolean) | |
*/ | |
protected void onContentChanged() { | |
} | |
private class ChangeObserver extends ContentObserver { | |
public ChangeObserver() { | |
super(new Handler()); | |
} | |
@Override | |
public boolean deliverSelfNotifications() { | |
return true; | |
} | |
@Override | |
public void onChange(boolean selfChange) { | |
onContentChanged(); | |
} | |
} | |
private class MyDataSetObserver extends DataSetObserver { | |
@Override | |
public void onChanged() { | |
mDataValid = true; | |
notifyDataSetChanged(); | |
} | |
@Override | |
public void onInvalidated() { | |
mDataValid = false; | |
//There is no notifyDataSetInvalidated() method in RecyclerView.Adapter | |
notifyDataSetChanged(); | |
} | |
} | |
} |
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package org.sufficientlysecure.keychain.ui.adapter; | |
import android.database.Cursor; | |
import android.widget.Filter; | |
public class CursorFilter extends Filter { | |
CursorFilterClient mClient; | |
interface CursorFilterClient { | |
CharSequence convertToString(Cursor cursor); | |
Cursor runQueryOnBackgroundThread(CharSequence constraint); | |
Cursor getCursor(); | |
void changeCursor(Cursor cursor); | |
} | |
CursorFilter(CursorFilterClient client) { | |
mClient = client; | |
} | |
@Override | |
public CharSequence convertResultToString(Object resultValue) { | |
return mClient.convertToString((Cursor) resultValue); | |
} | |
@Override | |
protected FilterResults performFiltering(CharSequence constraint) { | |
Cursor cursor = mClient.runQueryOnBackgroundThread(constraint); | |
FilterResults results = new FilterResults(); | |
if (cursor != null) { | |
results.count = cursor.getCount(); | |
results.values = cursor; | |
} else { | |
results.count = 0; | |
results.values = null; | |
} | |
return results; | |
} | |
@Override | |
protected void publishResults(CharSequence constraint, FilterResults results) { | |
Cursor oldCursor = mClient.getCursor(); | |
if (results.values != null && results.values != oldCursor) { | |
mClient.changeCursor((Cursor) results.values); | |
} | |
} | |
} |
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