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      1 /*
      2  * Copyright (C) 2015 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.deskclock.uidata;
     18 
     19 import android.content.SharedPreferences;
     20 import android.text.TextUtils;
     21 
     22 import java.util.ArrayList;
     23 import java.util.Arrays;
     24 import java.util.List;
     25 import java.util.Locale;
     26 
     27 import static android.view.View.LAYOUT_DIRECTION_RTL;
     28 import static com.android.deskclock.uidata.UiDataModel.Tab;
     29 
     30 /**
     31  * All tab data is accessed via this model.
     32  */
     33 final class TabModel {
     34 
     35     private final SharedPreferences mPrefs;
     36 
     37     /** The listeners to notify when the selected tab is changed. */
     38     private final List<TabListener> mTabListeners = new ArrayList<>();
     39 
     40     /** The listeners to notify when the vertical scroll state of the selected tab is changed. */
     41     private final List<TabScrollListener> mTabScrollListeners = new ArrayList<>();
     42 
     43     /** The scrolled-to-top state of each tab. */
     44     private final boolean[] mTabScrolledToTop = new boolean[Tab.values().length];
     45 
     46     /** An enumerated value indicating the currently selected tab. */
     47     private Tab mSelectedTab;
     48 
     49     TabModel(SharedPreferences prefs) {
     50         mPrefs = prefs;
     51         Arrays.fill(mTabScrolledToTop, true);
     52     }
     53 
     54     //
     55     // Selected tab
     56     //
     57 
     58     /**
     59      * @param tabListener to be notified when the selected tab changes
     60      */
     61     void addTabListener(TabListener tabListener) {
     62         mTabListeners.add(tabListener);
     63     }
     64 
     65     /**
     66      * @param tabListener to no longer be notified when the selected tab changes
     67      */
     68     void removeTabListener(TabListener tabListener) {
     69         mTabListeners.remove(tabListener);
     70     }
     71 
     72     /**
     73      * @return the number of tabs
     74      */
     75     int getTabCount() {
     76         return Tab.values().length;
     77     }
     78 
     79     /**
     80      * @param ordinal the ordinal (left-to-right index) of the tab
     81      * @return the tab at the given {@code ordinal}
     82      */
     83     Tab getTab(int ordinal) {
     84         return Tab.values()[ordinal];
     85     }
     86 
     87     /**
     88      * @param position the position of the tab in the user interface
     89      * @return the tab at the given {@code ordinal}
     90      */
     91     Tab getTabAt(int position) {
     92         final int ordinal;
     93         if (TextUtils.getLayoutDirectionFromLocale(Locale.getDefault()) == LAYOUT_DIRECTION_RTL) {
     94             ordinal = getTabCount() - position - 1;
     95         } else {
     96             ordinal = position;
     97         }
     98         return getTab(ordinal);
     99     }
    100 
    101     /**
    102      * @return an enumerated value indicating the currently selected primary tab
    103      */
    104     Tab getSelectedTab() {
    105         if (mSelectedTab == null) {
    106             mSelectedTab = TabDAO.getSelectedTab(mPrefs);
    107         }
    108         return mSelectedTab;
    109     }
    110 
    111     /**
    112      * @param tab an enumerated value indicating the newly selected primary tab
    113      */
    114     void setSelectedTab(Tab tab) {
    115         final Tab oldSelectedTab = getSelectedTab();
    116         if (oldSelectedTab != tab) {
    117             mSelectedTab = tab;
    118             TabDAO.setSelectedTab(mPrefs, tab);
    119 
    120             // Notify of the tab change.
    121             for (TabListener tl : mTabListeners) {
    122                 tl.selectedTabChanged(oldSelectedTab, tab);
    123             }
    124 
    125             // Notify of the vertical scroll position change if there is one.
    126             final boolean tabScrolledToTop = isTabScrolledToTop(tab);
    127             if (isTabScrolledToTop(oldSelectedTab) != tabScrolledToTop) {
    128                 for (TabScrollListener tsl : mTabScrollListeners) {
    129                     tsl.selectedTabScrollToTopChanged(tab, tabScrolledToTop);
    130                 }
    131             }
    132         }
    133     }
    134 
    135     //
    136     // Tab scrolling
    137     //
    138 
    139     /**
    140      * @param tabScrollListener to be notified when the scroll position of the selected tab changes
    141      */
    142     void addTabScrollListener(TabScrollListener tabScrollListener) {
    143         mTabScrollListeners.add(tabScrollListener);
    144     }
    145 
    146     /**
    147      * @param tabScrollListener to be notified when the scroll position of the selected tab changes
    148      */
    149     void removeTabScrollListener(TabScrollListener tabScrollListener) {
    150         mTabScrollListeners.remove(tabScrollListener);
    151     }
    152 
    153     /**
    154      * Updates the scrolling state in the {@link UiDataModel} for this tab.
    155      *
    156      * @param tab an enumerated value indicating the tab reporting its vertical scroll position
    157      * @param scrolledToTop {@code true} iff the vertical scroll position of this tab is at the top
    158      */
    159     void setTabScrolledToTop(Tab tab, boolean scrolledToTop) {
    160         if (isTabScrolledToTop(tab) != scrolledToTop) {
    161             mTabScrolledToTop[tab.ordinal()] = scrolledToTop;
    162             if (tab == getSelectedTab()) {
    163                 for (TabScrollListener tsl : mTabScrollListeners) {
    164                     tsl.selectedTabScrollToTopChanged(tab, scrolledToTop);
    165                 }
    166             }
    167         }
    168     }
    169 
    170     /**
    171      * @param tab identifies the tab
    172      * @return {@code true} iff the content in the given {@code tab} is currently scrolled to top
    173      */
    174     boolean isTabScrolledToTop(Tab tab) {
    175         return mTabScrolledToTop[tab.ordinal()];
    176     }
    177 }