chrome/android/java/src/org/chromium/chrome/browser/profiles/MostVisitedSites.java

// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package org.chromium.chrome.browser.profiles;

import android.graphics.Bitmap;

import org.chromium.base.CalledByNative;

/**
 * Methods to bridge into native history to provide most recent urls, titles and thumbnails.
 */
public class MostVisitedSites {

    private long mNativeMostVisitedSites;

    /**
     * Interface for receiving the list of most visited urls.
     */
    public interface MostVisitedURLsObserver {
        /**
         * This is called when the list of most visited URLs is initially available or updated.
         * Parameters guaranteed to be non-null.
         *
         * @param titles Array of most visited url page titles.
         * @param urls Array of most visited urls.
         */
        @CalledByNative("MostVisitedURLsObserver")
        public void onMostVisitedURLsAvailable(String[] titles, String[] urls);
    }

    /**
     * Interface for receiving a thumbnail for a most visited site.
     */
    public interface ThumbnailCallback {
        /**
         * Callback method for fetching thumbnail of a most visited URL.
         * Parameter may be null.
         *
         * @param thumbnail The bitmap thumbnail for the requested URL.
         */
        @CalledByNative("ThumbnailCallback")
        public void onMostVisitedURLsThumbnailAvailable(Bitmap thumbnail);
    }

    /**
     * MostVisitedSites constructor requires a valid user profile object.
     *
     * @param profile The profile for which to fetch most visited sites.
     */
    public MostVisitedSites(Profile profile) {
        mNativeMostVisitedSites = nativeInit(profile);
    }

    /**
     * Cleans up the C++ side of this class. This instance must not be used after calling destroy().
     */
    public void destroy() {
        assert mNativeMostVisitedSites != 0;
        nativeDestroy(mNativeMostVisitedSites);
        mNativeMostVisitedSites = 0;
    }

    @Override
    protected void finalize() {
        // Ensure that destroy() was called.
        assert mNativeMostVisitedSites == 0;
    }

    /**
     * Sets the MostVisitedURLsObserver to receive the list of most visited sites now or soon, and
     * after any changes to the list. Note: the observer may be notified synchronously or
     * asynchronously.
     * @param observer The MostVisitedURLsObserver to be called once when the most visited sites
     *            are initially available and again whenever the list of most visited sites changes.
     * @param numSites The maximum number of most visited sites to return.
     */
    public void setMostVisitedURLsObserver(final MostVisitedURLsObserver observer, int numSites) {
        MostVisitedURLsObserver wrappedObserver = new MostVisitedURLsObserver() {
            @Override
            public void onMostVisitedURLsAvailable(String[] titles, String[] urls) {
                // Don't notify observer if we've already been destroyed.
                if (mNativeMostVisitedSites != 0) {
                    observer.onMostVisitedURLsAvailable(titles, urls);
                }
            }
        };
        nativeSetMostVisitedURLsObserver(mNativeMostVisitedSites, wrappedObserver, numSites);
    }

    /**
     * Fetches thumbnail bitmap for a url returned by getMostVisitedURLs.
     *
     * @param url String representation of url.
     * @param callback Instance of a callback object.
     */
    public void getURLThumbnail(String url, final ThumbnailCallback callback) {
        ThumbnailCallback wrappedCallback = new ThumbnailCallback() {
            @Override
            public void onMostVisitedURLsThumbnailAvailable(Bitmap thumbnail) {
                // Don't notify callback if we've already been destroyed.
                if (mNativeMostVisitedSites != 0) {
                    callback.onMostVisitedURLsThumbnailAvailable(thumbnail);
                }
            }
        };
        nativeGetURLThumbnail(mNativeMostVisitedSites, url, wrappedCallback);
    }

    /**
     * Blacklist a URL from the most visited URLs list.
     * @param url The URL to be blacklisted.
     */
    public void blacklistUrl(String url) {
        nativeBlacklistUrl(mNativeMostVisitedSites, url);
    }

    private native long nativeInit(Profile profile);
    private native void nativeDestroy(long nativeMostVisitedSites);
    private native void nativeSetMostVisitedURLsObserver(long nativeMostVisitedSites,
            MostVisitedURLsObserver observer, int numSites);
    private native void nativeGetURLThumbnail(long nativeMostVisitedSites, String url,
            ThumbnailCallback callback);
    private native void nativeBlacklistUrl(long nativeMostVisitedSites, String url);
}