com.sagar.sunshine.ItemChoiceManager.java Source code

Introduction

Here is the source code for com.sagar.sunshine.ItemChoiceManager.java

Source

/*
 * Copyright (C) 2015 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 com.sagar.sunshine;

import android.os.Bundle;
import android.os.Parcel;
import android.support.v4.util.LongSparseArray;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.util.SparseBooleanArray;
import android.widget.AbsListView;
import android.widget.Checkable;

public class ItemChoiceManager {
    private final String LOG_TAG = MainActivity.class.getSimpleName();
    private final String SELECTED_ITEMS_KEY = "SIK";
    private int mChoiceMode;

    private RecyclerView.Adapter mAdapter;
    private RecyclerView.AdapterDataObserver mAdapterDataObserver = new RecyclerView.AdapterDataObserver() {
        @Override
        public void onChanged() {
            super.onChanged();
            if (mAdapter != null && mAdapter.hasStableIds())
                confirmCheckedPositionsById(mAdapter.getItemCount());
        }
    };

    private ItemChoiceManager() {
    }

    public ItemChoiceManager(RecyclerView.Adapter adapter) {
        mAdapter = adapter;
    }

    private static final int CHECK_POSITION_SEARCH_DISTANCE = 20;

    SparseBooleanArray mCheckStates = new SparseBooleanArray();

    LongSparseArray<Integer> mCheckedIdStates = new LongSparseArray<Integer>();

    public void onClick(RecyclerView.ViewHolder vh) {
        if (mChoiceMode == AbsListView.CHOICE_MODE_NONE)
            return;

        int checkedItemCount = mCheckStates.size();
        int position = vh.getAdapterPosition();

        if (position == RecyclerView.NO_POSITION) {
            Log.d(LOG_TAG, "Unable to Set Item State");
            return;
        }

        switch (mChoiceMode) {
        case AbsListView.CHOICE_MODE_NONE:
            break;
        case AbsListView.CHOICE_MODE_SINGLE: {
            boolean checked = mCheckStates.get(position, false);
            if (!checked) {
                for (int i = 0; i < checkedItemCount; i++) {
                    mAdapter.notifyItemChanged(mCheckStates.keyAt(i));
                }
                mCheckStates.clear();
                mCheckStates.put(position, true);
                mCheckedIdStates.clear();
                mCheckedIdStates.put(mAdapter.getItemId(position), position);
            }
            mAdapter.onBindViewHolder(vh, position);
            break;
        }
        case AbsListView.CHOICE_MODE_MULTIPLE: {
            boolean checked = mCheckStates.get(position, false);
            mCheckStates.put(position, !checked);
            mAdapter.onBindViewHolder(vh, position);
            break;
        }
        case AbsListView.CHOICE_MODE_MULTIPLE_MODAL: {
            throw new RuntimeException("Multiple Modal not implemented in ItemChoiceManager.");
        }
        }
    }

    public void setChoiceMode(int choiceMode) {
        if (mChoiceMode != choiceMode) {
            mChoiceMode = choiceMode;
            clearSelections();
        }
    }

    public boolean isItemChecked(int position) {
        return mCheckStates.get(position);
    }

    void clearSelections() {
        mCheckStates.clear();
        mCheckedIdStates.clear();
    }

    void confirmCheckedPositionsById(int oldItemCount) {
        mCheckStates.clear();

        for (int checkedIndex = 0; checkedIndex < mCheckedIdStates.size(); checkedIndex++) {
            final long id = mCheckedIdStates.keyAt(checkedIndex);
            final int lastPos = mCheckedIdStates.valueAt(checkedIndex);

            final long lastPosId = mAdapter.getItemId(lastPos);
            if (id != lastPosId) {
                final int start = Math.max(0, lastPos - CHECK_POSITION_SEARCH_DISTANCE);
                final int end = Math.min(lastPos + CHECK_POSITION_SEARCH_DISTANCE, oldItemCount);
                boolean found = false;
                for (int searchPos = start; searchPos < end; searchPos++) {
                    final long searchId = mAdapter.getItemId(searchPos);
                    if (id == searchId) {
                        found = true;
                        mCheckStates.put(searchPos, true);
                        mCheckedIdStates.setValueAt(checkedIndex, searchPos);
                        break;
                    }
                }

                if (!found) {
                    mCheckedIdStates.delete(id);
                    checkedIndex--;
                }
            } else {
                mCheckStates.put(lastPos, true);
            }
        }
    }

    public void onBindViewHolder(RecyclerView.ViewHolder vh, int position) {
        boolean checked = isItemChecked(position);
        if (vh.itemView instanceof Checkable) {
            ((Checkable) vh.itemView).setChecked(checked);
        }
        ViewCompat.setActivated(vh.itemView, checked);
    }

    public void onRestoreInstanceState(Bundle savedInstanceState) {
        byte[] states = savedInstanceState.getByteArray(SELECTED_ITEMS_KEY);
        if (null != states) {
            Parcel inParcel = Parcel.obtain();
            inParcel.unmarshall(states, 0, states.length);
            inParcel.setDataPosition(0);
            mCheckStates = inParcel.readSparseBooleanArray();
            final int numStates = inParcel.readInt();
            mCheckedIdStates.clear();
            for (int i = 0; i < numStates; i++) {
                final long key = inParcel.readLong();
                final int value = inParcel.readInt();
                mCheckedIdStates.put(key, value);
            }
        }
    }

    public void onSaveInstanceState(Bundle outState) {
        Parcel outParcel = Parcel.obtain();
        outParcel.writeSparseBooleanArray(mCheckStates);
        final int numStates = mCheckedIdStates.size();
        outParcel.writeInt(numStates);
        for (int i = 0; i < numStates; i++) {
            outParcel.writeLong(mCheckedIdStates.keyAt(i));
            outParcel.writeInt(mCheckedIdStates.valueAt(i));
        }
        byte[] states = outParcel.marshall();
        outState.putByteArray(SELECTED_ITEMS_KEY, states);
        outParcel.recycle();
    }

    public int getSelectedItemPosition() {
        if (mCheckStates.size() == 0) {
            return RecyclerView.NO_POSITION;
        } else {
            return mCheckStates.keyAt(0);
        }
    }
}