SearchViewNetworkQueryHelper.java

/*
 * Copyright (C) 2014 barter.li
 *
 * 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 li.barter.utils;

import android.os.Handler;
import android.widget.SearchView;
import android.widget.SearchView.OnQueryTextListener;

/**
 * Helper class for performing efficient network suggestions with SearchView
 * 
 * @author Vinay S Shenoy
 */
public class SearchViewNetworkQueryHelper implements OnQueryTextListener {

    /**
     * Callbacks to perform network queries
     * 
     * @author Vinay S Shenoy
     */
    public static interface NetworkCallbacks {
        public void performQuery(SearchView searchView, String query);
    }

    /**
     * SearchView to which this helper is set
     */
    private SearchView       mSearchView;

    /**
     * {@link NetworkCallbacks} implementation to perform the actual network
     * query
     */
    private NetworkCallbacks mNetworkCallbacks;

    private Handler          mHandler;

    private Runnable         mPerformSearchRunnable;

    /**
     * Minimum number of characters that need to be entered before the network
     * search is triggered
     */
    private int              mSuggestCountThreshold;

    /**
     * Minimum duration we need to wait after the user has stopped typing to
     * actually perform the search
     */
    private int              mSuggestWaitThreshold;

    /**
     * 
     */
    public SearchViewNetworkQueryHelper(SearchView searchView, NetworkCallbacks networkCallbacks) {
        mSearchView = searchView;
        mNetworkCallbacks = networkCallbacks;
        mHandler = new Handler();
        
        mSearchView.setOnQueryTextListener(this);
    }

    @Override
    public boolean onQueryTextSubmit(String query) {
        return true;
    }

    @Override
    public boolean onQueryTextChange(String newText) {

        removeAnyCallbacks();
        if (newText != null && newText.length() >= mSuggestCountThreshold) {

            mPerformSearchRunnable = makeSearchRunnable(newText);
            mHandler.postDelayed(mPerformSearchRunnable, mSuggestWaitThreshold);
        }
        return true;
    }

    public int getSuggestCountThreshold() {
        return mSuggestCountThreshold;
    }

    public void setSuggestCountThreshold(final int suggestCountThreshold) {
        mSuggestCountThreshold = suggestCountThreshold;
    }

    public int getSuggestWaitThreshold() {
        return mSuggestWaitThreshold;
    }

    public void setSuggestWaitThreshold(final int suggestWaitThreshold) {
        mSuggestWaitThreshold = suggestWaitThreshold;
    }

    /**
     * Removes any pending callbacks(if any) from the handler
     */
    private void removeAnyCallbacks() {
        if (mPerformSearchRunnable != null) {
            mHandler.removeCallbacks(mPerformSearchRunnable);
        }
    }

    /**
     * Creates a runnable for perfoming a search query
     * 
     * @param query The query to search for
     * @return a {@link Runnable} for performing a search request
     */
    private Runnable makeSearchRunnable(final String query) {
        return new Runnable() {

            @Override
            public void run() {
                if (mNetworkCallbacks != null) {
                    mNetworkCallbacks.performQuery(mSearchView, query);
                }
            }
        };
    }

}