Android Open Source - GridListViewAdapters Cursor Grid Adapter

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License

The source code is released under:

Apache License

Java Source Code

package com.birin.gridlistviewadapters;
/*from   w w  w  .  j  a  v  a 2  s.  c o m*/
import android.content.ContentProvider;
import android.content.Context;
import android.content.CursorLoader;
import android.database.Cursor;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Filter;
import android.widget.FilterQueryProvider;
import android.widget.Filterable;

/**
 * Adapter that exposes data from a {@link android.database.Cursor Cursor} to a
 * {@link android.widget.ListView ListView} widget to place data in Grid like
 * list-view.
 * 
 * <p>
 * Note : This class is extension of
 * {@link android.support.v4.widget.CursorAdapter} such that it places data
 * within grid, This {@link CursorGridAdapter} works well with
 * {@link ContentProvider} & {@link CursorLoader} mechanism, this class doesn't
 * provide support for any traditional auto-re-query method
 * {@link android.support.v4.widget.CursorAdapter} since query was performed on
 * UI-thread & its already deprecated from latest CursorAdapter source.
 * </p>
 * 
 * @param <CVH>
 *            The CardViewHolder class with which this adapter is operating
 * 
 * @see BaseGridAdapter parent class For Full features of this class
 */
public abstract class CursorGridAdapter<CVH> extends
    BaseGridAdapter<Cursor, CVH> implements Filterable,
    CursorFilter.CursorFilterClient {

  /*
   * Copyright (C) 2011 The Android Open Source Project
   * 
   * 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.
   */

  protected Cursor mCursor;
  protected CursorFilter mCursorFilter;
  protected FilterQueryProvider mFilterQueryProvider;

  public CursorGridAdapter(Context context, int totalCardsInRow, Cursor c) {
    super(context, totalCardsInRow);
    init(c);
  }

  void init(Cursor c) {
    boolean cursorPresent = c != null;
    mCursor = c;
    if (cursorPresent == true) {
      updateGridWithNewSize(c.getCount());
    }
  }

  /**
   * Returns the cursor.
   * 
   * @return the cursor.
   */
  public Cursor getCursor() {
    return mCursor;
  }

  @Override
  public View getDropDownView(int position, View convertView, ViewGroup parent) {
    return null;
  }

  /**
   * 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;
    mCursor = newCursor;
    invalidateStructure();
    if (newCursor != null) {
      updateGridWithNewSize(newCursor.getCount());
    } else {
      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.
   * 
   * The query is provided by a {@link android.widget.FilterQueryProvider}. If
   * no provider is specified, the current cursor is not filtered and
   * returned.
   * 
   * After this method returns the resulting cursor is passed to
   * {@link #changeCursor(Cursor)} and the previous cursor is closed.
   * 
   * This method is always executed on a background thread, not on the
   * application's main thread (or UI thread.)
   * 
   * 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;
  }

  /**
   * Copyright 2014-present Biraj Patel
   * 
   * 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.
   */

  public void validatePositionOrThrow(int position) {
    if (position < 0 || position >= getAbsoluteCardsCount()) {
      throw new IndexOutOfBoundsException("Position requested "
          + position + " Available Cursor size "
          + getAbsoluteCardsCount());
    }
  }

  @Override
  public int getAbsoluteCardsCount() {
    if (mCursor != null) {
      return mCursor.getCount();
    } else {
      return 0;
    }
  }

  @Override
  public Cursor getCardData(int absoluteCardPosition) {
    validatePositionOrThrow(absoluteCardPosition);
    if (mCursor == null) {
      throw new IllegalStateException(
          "this should only be called when the cursor is valid");
    }
    if (!mCursor.moveToPosition(absoluteCardPosition)) {
      throw new IllegalStateException("couldn't move cursor to position "
          + absoluteCardPosition);
    }
    return mCursor;
  }

}

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