root/chrome/android/java/src/org/chromium/chrome/browser/NavigationPopup.java

DEFINITIONS

1. shouldBeShown
2. show
3. dismiss
4. initializeNative
5. onFaviconUpdated
6. onItemClick
7. updateBitmapForTextView
8. computeFadeDimensions
9. createListItem
10. getCount
11. getItem
12. getItemId
13. getView
14. nativeGetHistoryUrl
15. nativeInit
16. nativeDestroy
17. nativeFetchFaviconForUrl

// 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;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.text.TextUtils;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.HeaderViewListAdapter;
import android.widget.ListPopupWindow;
import android.widget.PopupWindow;
import android.widget.TextView;

import org.chromium.base.CalledByNative;
import org.chromium.base.ThreadUtils;
import org.chromium.content.browser.NavigationClient;
import org.chromium.content.browser.NavigationEntry;
import org.chromium.content.browser.NavigationHistory;
import org.chromium.ui.base.LocalizationUtils;

import java.util.HashSet;
import java.util.Set;

/**
 * A popup that handles displaying the navigation history for a given tab.
 */
public class NavigationPopup extends ListPopupWindow implements AdapterView.OnItemClickListener {

    private static final int FAVICON_SIZE_DP = 16;

    private static final int MAXIMUM_HISTORY_ITEMS = 8;

    private final Context mContext;
    private final NavigationClient mNavigationClient;
    private final NavigationHistory mHistory;
    private final NavigationAdapter mAdapter;
    private final ListItemFactory mListItemFactory;

    private final int mFaviconSize;

    private long mNativeNavigationPopup;

    /**
     * Constructs a new popup with the given history information.
     *
     * @param context The context used for building the popup.
     * @param navigationClient The owner of the history being displayed.
     * @param isForward Whether to request forward navigation entries.
     */
    public NavigationPopup(
            Context context, NavigationClient navigationClient, boolean isForward) {
        super(context, null, android.R.attr.popupMenuStyle);
        mContext = context;
        mNavigationClient = navigationClient;
        mHistory = mNavigationClient.getDirectedNavigationHistory(
                isForward, MAXIMUM_HISTORY_ITEMS);
        mAdapter = new NavigationAdapter();

        float density = mContext.getResources().getDisplayMetrics().density;
        mFaviconSize = (int) (density * FAVICON_SIZE_DP);

        setModal(true);
        setInputMethodMode(PopupWindow.INPUT_METHOD_NOT_NEEDED);
        setHeight(ViewGroup.LayoutParams.WRAP_CONTENT);
        setOnItemClickListener(this);

        setAdapter(new HeaderViewListAdapter(null, null, mAdapter));

        mListItemFactory = new ListItemFactory(context);
    }

    /**
     * @return Whether a navigation popup is valid for the given page.
     */
    public boolean shouldBeShown() {
        return mHistory.getEntryCount() > 0;
    }

    @Override
    public void show() {
        if (mNativeNavigationPopup == 0) initializeNative();
        super.show();
    }

    @Override
    public void dismiss() {
        if (mNativeNavigationPopup != 0) {
            nativeDestroy(mNativeNavigationPopup);
            mNativeNavigationPopup = 0;
        }
        super.dismiss();
    }

    private void initializeNative() {
        ThreadUtils.assertOnUiThread();
        mNativeNavigationPopup = nativeInit();

        Set<String> requestedUrls = new HashSet<String>();
        for (int i = 0; i < mHistory.getEntryCount(); i++) {
            NavigationEntry entry = mHistory.getEntryAtIndex(i);
            if (entry.getFavicon() != null) continue;
            String url = entry.getUrl();
            if (!requestedUrls.contains(url)) {
                nativeFetchFaviconForUrl(mNativeNavigationPopup, url);
                requestedUrls.add(url);
            }
        }
        nativeFetchFaviconForUrl(mNativeNavigationPopup, nativeGetHistoryUrl());
    }

    @CalledByNative
    private void onFaviconUpdated(String url, Object favicon) {
        for (int i = 0; i < mHistory.getEntryCount(); i++) {
            NavigationEntry entry = mHistory.getEntryAtIndex(i);
            if (TextUtils.equals(url, entry.getUrl())) entry.updateFavicon((Bitmap) favicon);
        }
        mAdapter.notifyDataSetChanged();
    }

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        NavigationEntry entry = (NavigationEntry) parent.getItemAtPosition(position);
        mNavigationClient.goToNavigationIndex(entry.getIndex());
        dismiss();
    }

    private void updateBitmapForTextView(TextView view, Bitmap bitmap) {
        Drawable faviconDrawable = null;
        if (bitmap != null) {
            faviconDrawable = new BitmapDrawable(mContext.getResources(), bitmap);
            ((BitmapDrawable) faviconDrawable).setGravity(Gravity.FILL);
        } else {
            faviconDrawable = new ColorDrawable(Color.TRANSPARENT);
        }
        faviconDrawable.setBounds(0, 0, mFaviconSize, mFaviconSize);
        view.setCompoundDrawables(faviconDrawable, null, null, null);
    }

    private static class ListItemFactory {
        private static final int LIST_ITEM_HEIGHT_DP = 48;
        private static final int PADDING_DP = 8;
        private static final int TEXT_SIZE_SP = 18;
        private static final float FADE_LENGTH_DP = 25.0f;
        private static final float FADE_STOP = 0.75f;

        int mFadeEdgeLength;
        int mFadePadding;
        int mListItemHeight;
        int mPadding;
        boolean mIsLayoutDirectionRTL;
        Context mContext;

        public ListItemFactory(Context context) {
            mContext = context;
            computeFadeDimensions();
        }

        private void computeFadeDimensions() {
            // Fade with linear gradient starting 25dp from right margin.
            // Reaches 0% opacity at 75% length. (Simulated with extra padding)
            float density = mContext.getResources().getDisplayMetrics().density;
            float fadeLength = (FADE_LENGTH_DP * density);
            mFadeEdgeLength = (int) (fadeLength * FADE_STOP);
            mFadePadding = (int) (fadeLength * (1 - FADE_STOP));
            mListItemHeight = (int) (density * LIST_ITEM_HEIGHT_DP);
            mPadding = (int) (density * PADDING_DP);
            mIsLayoutDirectionRTL = LocalizationUtils.isLayoutRtl();
        }

        public TextView createListItem() {
            TextView view = new TextView(mContext);
            view.setFadingEdgeLength(mFadeEdgeLength);
            view.setHorizontalFadingEdgeEnabled(true);
            view.setSingleLine();
            view.setTextSize(TEXT_SIZE_SP);
            view.setMinimumHeight(mListItemHeight);
            view.setGravity(Gravity.CENTER_VERTICAL);
            view.setCompoundDrawablePadding(mPadding);
            if (!mIsLayoutDirectionRTL) {
                view.setPadding(mPadding, 0, mPadding + mFadePadding , 0);
            } else {
                view.setPadding(mPadding + mFadePadding, 0, mPadding, 0);
            }
            return view;
        }
    }

    private class NavigationAdapter extends BaseAdapter {
        @Override
        public int getCount() {
            return mHistory.getEntryCount();
        }

        @Override
        public Object getItem(int position) {
            return mHistory.getEntryAtIndex(position);
        }

        @Override
        public long getItemId(int position) {
            return ((NavigationEntry) getItem(position)).getIndex();
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            TextView view;
            if (convertView != null && convertView instanceof TextView) {
                view = (TextView) convertView;
            } else {
                view = mListItemFactory.createListItem();
            }
            NavigationEntry entry = (NavigationEntry) getItem(position);

            String entryText = entry.getTitle();
            if (TextUtils.isEmpty(entryText)) entryText = entry.getVirtualUrl();
            if (TextUtils.isEmpty(entryText)) entryText = entry.getUrl();
            view.setText(entryText);
            updateBitmapForTextView(view, entry.getFavicon());

            return view;
        }
    }

    private static native String nativeGetHistoryUrl();

    private native long nativeInit();
    private native void nativeDestroy(long nativeNavigationPopup);
    private native void nativeFetchFaviconForUrl(long nativeNavigationPopup, String url);
}