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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.gallery3d.filtershow.history;
     18 
     19 import android.graphics.drawable.Drawable;
     20 import android.view.MenuItem;
     21 
     22 import java.util.Vector;
     23 
     24 public class HistoryManager {
     25     private static final String LOGTAG = "HistoryManager";
     26 
     27     private Vector<HistoryItem> mHistoryItems = new Vector<HistoryItem>();
     28     private int mCurrentPresetPosition = 0;
     29     private MenuItem mUndoMenuItem = null;
     30     private MenuItem mRedoMenuItem = null;
     31     private MenuItem mResetMenuItem = null;
     32 
     33     public void setMenuItems(MenuItem undoItem, MenuItem redoItem, MenuItem resetItem) {
     34         mUndoMenuItem = undoItem;
     35         mRedoMenuItem = redoItem;
     36         mResetMenuItem = resetItem;
     37         updateMenuItems();
     38     }
     39 
     40     private int getCount() {
     41         return mHistoryItems.size();
     42     }
     43 
     44     public HistoryItem getItem(int position) {
     45         if (position > mHistoryItems.size() - 1) {
     46             return null;
     47         }
     48         return mHistoryItems.elementAt(position);
     49     }
     50 
     51     private void clear() {
     52         mHistoryItems.clear();
     53     }
     54 
     55     private void add(HistoryItem item) {
     56         mHistoryItems.add(item);
     57     }
     58 
     59     private void notifyDataSetChanged() {
     60         // TODO
     61     }
     62 
     63     public boolean canReset() {
     64         if (getCount() <= 0) {
     65             return false;
     66         }
     67         return true;
     68     }
     69 
     70     public boolean canUndo() {
     71         if (mCurrentPresetPosition == getCount() - 1) {
     72             return false;
     73         }
     74         return true;
     75     }
     76 
     77     public boolean canRedo() {
     78         if (mCurrentPresetPosition == 0) {
     79             return false;
     80         }
     81         return true;
     82     }
     83 
     84     public void updateMenuItems() {
     85         if (mUndoMenuItem != null) {
     86             setEnabled(mUndoMenuItem, canUndo());
     87         }
     88         if (mRedoMenuItem != null) {
     89             setEnabled(mRedoMenuItem, canRedo());
     90         }
     91         if (mResetMenuItem != null) {
     92             setEnabled(mResetMenuItem, canReset());
     93         }
     94     }
     95 
     96     private void setEnabled(MenuItem item, boolean enabled) {
     97         item.setEnabled(enabled);
     98         Drawable drawable = item.getIcon();
     99         if (drawable != null) {
    100             drawable.setAlpha(enabled ? 255 : 80);
    101         }
    102     }
    103 
    104     public void setCurrentPreset(int n) {
    105         mCurrentPresetPosition = n;
    106         updateMenuItems();
    107         notifyDataSetChanged();
    108     }
    109 
    110     public void reset() {
    111         if (getCount() == 0) {
    112             return;
    113         }
    114         clear();
    115         updateMenuItems();
    116     }
    117 
    118     public HistoryItem getLast() {
    119         if (getCount() == 0) {
    120             return null;
    121         }
    122         return getItem(0);
    123     }
    124 
    125     public HistoryItem getCurrent() {
    126         return getItem(mCurrentPresetPosition);
    127     }
    128 
    129     public void addHistoryItem(HistoryItem preset) {
    130         insert(preset, 0);
    131         updateMenuItems();
    132     }
    133 
    134     private void insert(HistoryItem preset, int position) {
    135         if (mCurrentPresetPosition != 0) {
    136             // in this case, let's discount the presets before the current one
    137             Vector<HistoryItem> oldItems = new Vector<HistoryItem>();
    138             for (int i = mCurrentPresetPosition; i < getCount(); i++) {
    139                 oldItems.add(getItem(i));
    140             }
    141             clear();
    142             for (int i = 0; i < oldItems.size(); i++) {
    143                 add(oldItems.elementAt(i));
    144             }
    145             mCurrentPresetPosition = position;
    146             notifyDataSetChanged();
    147         }
    148         mHistoryItems.insertElementAt(preset, position);
    149         mCurrentPresetPosition = position;
    150         notifyDataSetChanged();
    151     }
    152 
    153     public int redo() {
    154         mCurrentPresetPosition--;
    155         if (mCurrentPresetPosition < 0) {
    156             mCurrentPresetPosition = 0;
    157         }
    158         notifyDataSetChanged();
    159         updateMenuItems();
    160         return mCurrentPresetPosition;
    161     }
    162 
    163     public int undo() {
    164         mCurrentPresetPosition++;
    165         if (mCurrentPresetPosition >= getCount()) {
    166             mCurrentPresetPosition = getCount() - 1;
    167         }
    168         notifyDataSetChanged();
    169         updateMenuItems();
    170         return mCurrentPresetPosition;
    171     }
    172 
    173 }
    174