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      1 /*
      2  * Copyright (C) 2013 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 com.android.documentsui;
     18 
     19 import android.database.DataSetObserver;
     20 import android.view.View;
     21 import android.view.ViewGroup;
     22 import android.widget.BaseAdapter;
     23 import android.widget.LinearLayout;
     24 import android.widget.ListAdapter;
     25 import android.widget.ListView;
     26 
     27 import com.android.internal.util.Preconditions;
     28 
     29 /**
     30  * Adapter that wraps an existing adapter, presenting its contents in multiple
     31  * equally-sized horizontal columns.
     32  */
     33 public class ColumnAdapter extends BaseAdapter {
     34     private final ListAdapter mWrapped;
     35     private final OnItemClickListener mListener;
     36 
     37     private int mColumns = 1;
     38 
     39     public interface OnItemClickListener {
     40         public void onItemClick(ListAdapter adapter, int position);
     41     }
     42 
     43     public ColumnAdapter(ListAdapter wrapped, OnItemClickListener listener) {
     44         mWrapped = Preconditions.checkNotNull(wrapped);
     45         mListener = Preconditions.checkNotNull(listener);
     46 
     47         if (!wrapped.areAllItemsEnabled()) {
     48             throw new IllegalStateException("All items must be enabled");
     49         }
     50         if (wrapped.getViewTypeCount() > 1) {
     51             throw new IllegalStateException("All items must be identical");
     52         }
     53     }
     54 
     55     public static void prepare(ListView list) {
     56         list.setItemsCanFocus(true);
     57     }
     58 
     59     public void setColumns(int columns) {
     60         mColumns = columns;
     61         notifyDataSetChanged();
     62     }
     63 
     64     private View.OnClickListener mItemListener = new View.OnClickListener() {
     65         @Override
     66         public void onClick(View v) {
     67             final int position = (Integer) v.getTag();
     68             mListener.onItemClick(mWrapped, position);
     69         }
     70     };
     71 
     72     @Override
     73     public int getCount() {
     74         return (mWrapped.getCount() + mColumns - 1) / mColumns;
     75     }
     76 
     77     @Override
     78     public Object getItem(int position) {
     79         return position;
     80     }
     81 
     82     @Override
     83     public long getItemId(int position) {
     84         return position;
     85     }
     86 
     87     @Override
     88     public View getView(int position, View convertView, ViewGroup parent) {
     89         if (convertView == null) {
     90             convertView = new LinearLayout(parent.getContext());
     91         }
     92 
     93         final LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
     94                 0, LinearLayout.LayoutParams.WRAP_CONTENT);
     95         params.weight = 1f / mColumns;
     96 
     97         final LinearLayout row = (LinearLayout) convertView;
     98         final int first = position * mColumns;
     99         final int last = mWrapped.getCount() - 1;
    100 
    101         for (int i = 0; i < mColumns; i++) {
    102             View convertItem = null;
    103             if (i < row.getChildCount()) {
    104                 convertItem = row.getChildAt(i);
    105             }
    106 
    107             final int pos = first + i;
    108             final int validPos = Math.min(pos, last);
    109             final View item = mWrapped.getView(validPos, convertItem, row);
    110             item.setTag(validPos);
    111             item.setOnClickListener(mItemListener);
    112             item.setFocusable(true);
    113 
    114             if (pos == validPos) {
    115                 item.setVisibility(View.VISIBLE);
    116             } else {
    117                 item.setVisibility(View.INVISIBLE);
    118             }
    119 
    120             if (convertItem == null) {
    121                 row.addView(item, params);
    122             }
    123         }
    124 
    125         return convertView;
    126     }
    127 
    128     @Override
    129     public void registerDataSetObserver(DataSetObserver observer) {
    130         super.registerDataSetObserver(observer);
    131         mWrapped.registerDataSetObserver(observer);
    132     }
    133 
    134     @Override
    135     public void unregisterDataSetObserver(DataSetObserver observer) {
    136         super.unregisterDataSetObserver(observer);
    137         mWrapped.unregisterDataSetObserver(observer);
    138     }
    139 }
    140