Home | History | Annotate | Download | only in widget 
      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.widget;
     18 
     19 import android.database.DataSetObservable;
     20 import android.database.DataSetObserver;
     21 
     22 /**
     23  * Base class for a {@link ExpandableListAdapter} used to provide data and Views
     24  * from some data to an expandable list view.
     25  * <p>
     26  * Adapters inheriting this class should verify that the base implementations of
     27  * {@link #getCombinedChildId(long, long)} and {@link #getCombinedGroupId(long)}
     28  * are correct in generating unique IDs from the group/children IDs.
     29  * <p>
     30  * @see SimpleExpandableListAdapter
     31  * @see SimpleCursorTreeAdapter
     32  */
     33 public abstract class BaseExpandableListAdapter implements ExpandableListAdapter,
     34         HeterogeneousExpandableList {
     35     private final DataSetObservable mDataSetObservable = new DataSetObservable();
     36 
     37     public void registerDataSetObserver(DataSetObserver observer) {
     38         mDataSetObservable.registerObserver(observer);
     39     }
     40 
     41     public void unregisterDataSetObserver(DataSetObserver observer) {
     42         mDataSetObservable.unregisterObserver(observer);
     43     }
     44 
     45     /**
     46      * @see DataSetObservable#notifyInvalidated()
     47      */
     48     public void notifyDataSetInvalidated() {
     49         mDataSetObservable.notifyInvalidated();
     50     }
     51 
     52     /**
     53      * @see DataSetObservable#notifyChanged()
     54      */
     55     public void notifyDataSetChanged() {
     56         mDataSetObservable.notifyChanged();
     57     }
     58 
     59     public boolean areAllItemsEnabled() {
     60         return true;
     61     }
     62 
     63     public void onGroupCollapsed(int groupPosition) {
     64     }
     65 
     66     public void onGroupExpanded(int groupPosition) {
     67     }
     68 
     69     /**
     70      * Override this method if you foresee a clash in IDs based on this scheme:
     71      * <p>
     72      * Base implementation returns a long:
     73      * <li> bit 0: Whether this ID points to a child (unset) or group (set), so for this method
     74      *             this bit will be 1.
     75      * <li> bit 1-31: Lower 31 bits of the groupId
     76      * <li> bit 32-63: Lower 32 bits of the childId.
     77      * <p>
     78      * {@inheritDoc}
     79      */
     80     public long getCombinedChildId(long groupId, long childId) {
     81         return 0x8000000000000000L | ((groupId & 0x7FFFFFFF) << 32) | (childId & 0xFFFFFFFF);
     82     }
     83 
     84     /**
     85      * Override this method if you foresee a clash in IDs based on this scheme:
     86      * <p>
     87      * Base implementation returns a long:
     88      * <li> bit 0: Whether this ID points to a child (unset) or group (set), so for this method
     89      *             this bit will be 0.
     90      * <li> bit 1-31: Lower 31 bits of the groupId
     91      * <li> bit 32-63: Lower 32 bits of the childId.
     92      * <p>
     93      * {@inheritDoc}
     94      */
     95     public long getCombinedGroupId(long groupId) {
     96         return (groupId & 0x7FFFFFFF) << 32;
     97     }
     98 
     99     /**
    100      * {@inheritDoc}
    101      */
    102     public boolean isEmpty() {
    103         return getGroupCount() == 0;
    104     }
    105 
    106 
    107     /**
    108      * {@inheritDoc}
    109      * @return 0 for any group or child position, since only one child type count is declared.
    110      */
    111     public int getChildType(int groupPosition, int childPosition) {
    112         return 0;
    113     }
    114 
    115     /**
    116      * {@inheritDoc}
    117      * @return 1 as a default value in BaseExpandableListAdapter.
    118      */
    119     public int getChildTypeCount() {
    120         return 1;
    121     }
    122 
    123     /**
    124      * {@inheritDoc}
    125      * @return 0 for any groupPosition, since only one group type count is declared.
    126      */
    127     public int getGroupType(int groupPosition) {
    128         return 0;
    129     }
    130 
    131     /**
    132      * {@inheritDoc}
    133      * @return 1 as a default value in BaseExpandableListAdapter.
    134      */
    135     public int getGroupTypeCount() {
    136         return 1;
    137     }
    138 }
    139