| /* |
| * Copyright 2018 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. |
| */ |
| |
| package androidx.preference; |
| |
| import android.content.Context; |
| import android.text.TextUtils; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| /** |
| * A controller to handle advanced children display logic with collapsible functionality. |
| */ |
| final class CollapsiblePreferenceGroupController { |
| |
| private final PreferenceGroupAdapter mPreferenceGroupAdapter; |
| private final Context mContext; |
| |
| /** |
| * Whether there is a child PreferenceGroup that has an expandable preference. This is used to |
| * avoid unnecessary preference tree rebuilds when no such group exists. |
| */ |
| private boolean mHasExpandablePreference = false; |
| |
| CollapsiblePreferenceGroupController(PreferenceGroup preferenceGroup, |
| PreferenceGroupAdapter preferenceGroupAdapter) { |
| mPreferenceGroupAdapter = preferenceGroupAdapter; |
| mContext = preferenceGroup.getContext(); |
| } |
| |
| /** |
| * Generates the visible section of the PreferenceGroup. |
| * |
| * @param group the root preference group to be processed |
| * @return the flattened and visible section of the PreferenceGroup |
| */ |
| public List<Preference> createVisiblePreferencesList(PreferenceGroup group) { |
| return createInnerVisiblePreferencesList(group); |
| } |
| |
| private List<Preference> createInnerVisiblePreferencesList(PreferenceGroup group) { |
| mHasExpandablePreference = false; |
| int visiblePreferenceCount = 0; |
| final boolean hasExpandablePreference = |
| group.getInitialExpandedChildrenCount() != Integer.MAX_VALUE; |
| final List<Preference> visiblePreferences = new ArrayList<>(); |
| final List<Preference> collapsedPreferences = new ArrayList<>(); |
| |
| final int groupSize = group.getPreferenceCount(); |
| for (int i = 0; i < groupSize; i++) { |
| final Preference preference = group.getPreference(i); |
| |
| if (!preference.isVisible()) { |
| continue; |
| } |
| |
| if (!hasExpandablePreference |
| || visiblePreferenceCount < group.getInitialExpandedChildrenCount()) { |
| visiblePreferences.add(preference); |
| } else { |
| collapsedPreferences.add(preference); |
| } |
| |
| // PreferenceGroups do not count towards the maximal number of preferences to show |
| if (!(preference instanceof PreferenceGroup)) { |
| visiblePreferenceCount++; |
| continue; |
| } |
| |
| PreferenceGroup innerGroup = (PreferenceGroup) preference; |
| if (!innerGroup.isOnSameScreenAsChildren()) { |
| continue; |
| } |
| |
| // Recursively generate nested list of visible preferences |
| final List<Preference> innerList = createInnerVisiblePreferencesList(innerGroup); |
| if (hasExpandablePreference && mHasExpandablePreference) { |
| throw new IllegalArgumentException("Nested expand buttons are not supported!"); |
| } |
| |
| for (Preference inner : innerList) { |
| if (!hasExpandablePreference |
| || visiblePreferenceCount < group.getInitialExpandedChildrenCount()) { |
| visiblePreferences.add(inner); |
| } else { |
| collapsedPreferences.add(inner); |
| } |
| visiblePreferenceCount++; |
| } |
| } |
| |
| // If there are any visible preferences being hidden, add an expand button to show the rest |
| // of the preferences. Clicking the expand button will show all the visible preferences. |
| if (hasExpandablePreference |
| && visiblePreferenceCount > group.getInitialExpandedChildrenCount()) { |
| final ExpandButton expandButton = createExpandButton(group, collapsedPreferences); |
| visiblePreferences.add(expandButton); |
| } |
| mHasExpandablePreference |= hasExpandablePreference; |
| return visiblePreferences; |
| } |
| |
| /** |
| * Called when a preference has changed its visibility. |
| * |
| * @param preference The preference whose visibility has changed. |
| * @return {@code true} if view update has been handled by this controller. |
| */ |
| public boolean onPreferenceVisibilityChange(Preference preference) { |
| if (mHasExpandablePreference) { |
| // We only want to show up to the maximal number of preferences. Preference visibility |
| // change can result in the expand button being added/removed, as well as changes to |
| // its summary. Rebuild to ensure that the correct data is shown. |
| mPreferenceGroupAdapter.onPreferenceHierarchyChange(preference); |
| return true; |
| } |
| return false; |
| } |
| |
| private ExpandButton createExpandButton(final PreferenceGroup group, |
| List<Preference> collapsedPreferences) { |
| final ExpandButton preference = new ExpandButton(mContext, collapsedPreferences, |
| group.getId()); |
| preference.setOnPreferenceClickListener(new Preference.OnPreferenceClickListener() { |
| @Override |
| public boolean onPreferenceClick(Preference preference) { |
| group.setInitialExpandedChildrenCount(Integer.MAX_VALUE); |
| mPreferenceGroupAdapter.onPreferenceHierarchyChange(preference); |
| return true; |
| } |
| }); |
| return preference; |
| } |
| |
| /** |
| * A {@link Preference} that provides capability to expand the collapsed items in the |
| * {@link PreferenceGroup}. |
| */ |
| static class ExpandButton extends Preference { |
| private long mId; |
| |
| ExpandButton(Context context, List<Preference> collapsedPreferences, long parentId) { |
| super(context); |
| initLayout(); |
| setSummary(collapsedPreferences); |
| // Since IDs are unique, using the parentId as a reference ensures that this expand |
| // button will have a unique ID and hence transitions will be correctly animated by |
| // RecyclerView when there are multiple ExpandButtons. |
| mId = parentId + 1000000; |
| } |
| |
| private void initLayout() { |
| setLayoutResource(R.layout.expand_button); |
| setIcon(R.drawable.ic_arrow_down_24dp); |
| setTitle(R.string.expand_button_title); |
| // Sets a high order so that the expand button will be placed at the bottom of the group |
| setOrder(999); |
| } |
| |
| /* |
| * The summary of this will be the list of title for collapsed preferences. Iterate through |
| * the preferences not in the visible list and add its title to the summary text. If |
| * there are any nested groups with titles, ignore their children. |
| */ |
| private void setSummary(List<Preference> collapsedPreferences) { |
| CharSequence summary = null; |
| final List<PreferenceGroup> parents = new ArrayList<>(); |
| |
| for (Preference preference : collapsedPreferences) { |
| final CharSequence title = preference.getTitle(); |
| if (preference instanceof PreferenceGroup && !TextUtils.isEmpty(title)) { |
| parents.add((PreferenceGroup) preference); |
| } |
| if (parents.contains(preference.getParent())) { |
| if (preference instanceof PreferenceGroup) { |
| parents.add((PreferenceGroup) preference); |
| } |
| continue; |
| } |
| if (!TextUtils.isEmpty(title)) { |
| if (summary == null) { |
| summary = title; |
| } else { |
| summary = getContext().getString( |
| R.string.summary_collapsed_preference_list, summary, title); |
| } |
| } |
| } |
| setSummary(summary); |
| } |
| |
| @Override |
| public void onBindViewHolder(PreferenceViewHolder holder) { |
| super.onBindViewHolder(holder); |
| holder.setDividerAllowedAbove(false); |
| } |
| |
| @Override |
| public long getId() { |
| return mId; |
| } |
| } |
| |
| } |