home.java

android 例子中的Home。很有代表意义

/*
 * Copyright (C) 2007 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.example.android.home;

import android.app.Activity;
import android.app.ActivityManager;
import android.app.SearchManager;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.content.res.Resources;
import android.database.ContentObserver;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PaintFlagsDrawFilter;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.PaintDrawable;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.LayoutAnimationController;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.CheckBox;
import android.widget.GridView;
import android.widget.TextView;
import android.net.Uri;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

public class Home extends Activity {
    /**
     * Tag used for logging errors.
     */
    private static final String LOG_TAG = "Home";

    /**
     * Keys during freeze/thaw.
     */
    private static final String KEY_SAVE_GRID_OPENED = "grid.opened";

    // Identifiers for option menu items
    private static final int MENU_WALLPAPER_SETTINGS = Menu.FIRST + 1;
    private static final int MENU_SEARCH = MENU_WALLPAPER_SETTINGS + 1;
    private static final int MENU_SETTINGS = MENU_SEARCH + 1;

    /**
     * Maximum number of recent tasks to query.
     */
    private static final int MAX_RECENT_TASKS = 20;

    private static boolean mWallpaperChecked;
    private static ArrayList<ApplicationInfo> mApplications;
    private static LinkedList<ApplicationInfo> mFavorites;

    private Handler mHandler = new Handler();

    private final BroadcastReceiver mWallpaperReceiver = new WallpaperIntentReceiver();
    private final BroadcastReceiver mApplicationsReceiver = new ApplicationsIntentReceiver();
    private final ContentObserver mObserver = new FavoritesChangeObserver();

    private GridView mGrid;

    private LayoutAnimationController mShowLayoutAnimation;
    private LayoutAnimationController mHideLayoutAnimation;

    private boolean mBlockAnimation;

    private View mShowApplications;
    private CheckBox mShowApplicationsCheck;

    private ApplicationsStackLayout mApplicationsStack;

    private Animation mGridEntry;
    private Animation mGridExit;
    
    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);

        setDefaultKeyMode(DEFAULT_KEYS_SEARCH_LOCAL);

        setContentView(R.layout.home);

        registerIntentReceivers();
        registerContentObservers();

        setDefaultWallpaper();

        loadApplications(true);

        bindApplications();
        bindFavorites(true);
        bindRecents();
        bindButtons();

        mGridEntry = AnimationUtils.loadAnimation(this, R.anim.grid_entry);
        mGridExit = AnimationUtils.loadAnimation(this, R.anim.grid_exit);
    }

    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);

        // Close the menu
        if (Intent.ACTION_MAIN.equals(intent.getAction())) {
            getWindow().closeAllPanels();
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();

        // Remove the callback for the cached drawables or we leak
        // the previous Home screen on orientation change
        final int count = mApplications.size();
        for (int i = 0; i < count; i++) {
            mApplications.get(i).icon.setCallback(null);
        }

        getContentResolver().unregisterContentObserver(mObserver);
        unregisterReceiver(mWallpaperReceiver);
        unregisterReceiver(mApplicationsReceiver);
    }

    @Override
    protected void onResume() {
        super.onResume();
        bindRecents();
    }
    
    @Override
    protected void onRestoreInstanceState(Bundle state) {
        super.onRestoreInstanceState(state);
        final boolean opened = state.getBoolean(KEY_SAVE_GRID_OPENED, false);
        if (opened) {
            showApplications(false);
        }
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putBoolean(KEY_SAVE_GRID_OPENED, mGrid.getVisibility() == View.VISIBLE);
    }

    /**
     * Registers various intent receivers. The current implementation registers
     * only a wallpaper intent receiver to let other applications change the
     * wallpaper.
     */
    private void registerIntentReceivers() {
        IntentFilter filter = new IntentFilter(Intent.ACTION_WALLPAPER_CHANGED);
        registerReceiver(mWallpaperReceiver, filter);

        filter = new IntentFilter(Intent.ACTION_PACKAGE_ADDED);
        filter.addAction(Intent.ACTION_PACKAGE_REMOVED);
        filter.addAction(Intent.ACTION_PACKAGE_CHANGED);
        filter.addDataScheme("package");
        registerReceiver(mApplicationsReceiver, filter);
    }

    /**
     * Registers various content observers. The current implementation registers
     * only a favorites observer to keep track of the favorites applications.
     */
    private void registerContentObservers() {
        ContentResolver resolver = getContentResolver();
        resolver.registerContentObserver(Uri.parse("content://" +
                android.provider.Settings.AUTHORITY + "/favorites?notify=true"), true, mObserver);
    }

    /**
     * Creates a new appplications adapter for the grid view and registers it.
     */
    private void bindApplications() {
        if (mGrid == null) {
            mGrid = (GridView) findViewById(R.id.all_apps);
        }
        mGrid.setAdapter(new ApplicationsAdapter(this, mApplications));
        mGrid.setSelection(0);

        if (mApplicationsStack == null) {
            mApplicationsStack = (ApplicationsStackLayout) findViewById(R.id.faves_and_recents);
        }
    }

    /**
     * Binds actions to the various buttons.
     */
    private void bindButtons() {
        mShowApplications = findViewById(R.id.show_all_apps);
        mShowApplications.setOnClickListener(new ShowApplications());
        mShowApplicationsCheck = (CheckBox) findViewById(R.id.show_all_apps_check);

        mGrid.setOnItemClickListener(new ApplicationLauncher());
    }

    /**
     * When no wallpaper was manually set, a default wallpaper is used instead.
     */
    private void setDefaultWallpaper() {
        if (!mWallpaperChecked) {
            Drawable wallpaper = peekWallpaper();
            if (wallpaper == null) {
                try {
                    clearWallpaper();
                } catch (IOException e) {
                    Log.e(LOG_TAG, "Failed to clear wallpaper " + e);
                }
            } else {
                getWindow().setBackgroundDrawable(wallpaper);
            }
            mWallpaperChecked = true;
        }
    }

    /**
     * Refreshes the favorite applications stacked over the all apps button.
     * The number of favorites depends on the user.
     */
    private void bindFavorites(boolean isLaunching) {
        if (!isLaunching || mFavorites == null) {
            final Cursor c = getContentResolver().query(Uri.parse("content://" +
                android.provider.Settings.AUTHORITY + "/favorites?notify=true"),
                    null, null, null, "cellX");

            final int intentIndex = c.getColumnIndexOrThrow("intent");
            final int titleIndex = c.getColumnIndexOrThrow("title");
            final int typeIndex = c.getColumnIndexOrThrow("itemType");

            final PackageManager manager = getPackageManager();

            ApplicationInfo info;
            String intentDescription;

            if (mFavorites == null) {
                mFavorites = new LinkedList<ApplicationInfo>();
            } else {
                mFavorites.clear();
            }

            while (c.moveToNext()) {
                final int itemType = c.getInt(typeIndex);

                if (itemType == 0 || // 0 == application
                    itemType == 1) { // 1 == shortcut

                    intentDescription = c.getString(intentIndex);
                    if (intentDescription == null) {
                        continue;
                    }

                    Intent intent;
                    try {
                        intent = Intent.getIntent(intentDescription);
                    } catch (java.net.URISyntaxException e) {
                        continue;
                    }
                    info = getApplicationInfo(manager, intent);
                    if (info != null) {
                        info.title = c.getString(titleIndex);
                        info.intent = intent;
                        mFavorites.addFirst(info);
                    }
                }
            }

            c.close();
        }

        mApplicationsStack.setFavorites(mFavorites);
    }

    /**
     * Refreshes the recently launched applications stacked over the favorites. The number
     * of recents depends on how many favorites are present.
     */
    private void bindRecents() {
        final PackageManager manager = getPackageManager();
        final ActivityManager tasksManager = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
        final List<ActivityManager.RecentTaskInfo> recentTasks = tasksManager.getRecentTasks(
                MAX_RECENT_TASKS, 0);

        final int count = recentTasks.size();
        final ArrayList<ApplicationInfo> recents = new ArrayList<ApplicationInfo>();

        for (int i = count - 1; i >= 0; i--) {
            final Intent intent = recentTasks.get(i).baseIntent;

            if (Intent.ACTION_MAIN.equals(intent.getAction()) &&
                    !intent.hasCategory(Intent.CATEGORY_HOME)) {

                ApplicationInfo info = getApplicationInfo(manager, intent);
                if (info != null) {
                    info.intent = intent;
                    if (!mFavorites.contains(info)) {
                        recents.add(info);
                    }
                }
            }
        }

        mApplicationsStack.setRecents(recents);
    }

    private static ApplicationInfo getApplicationInfo(PackageManager manager, Intent intent) {
        final ResolveInfo resolveInfo = manager.resolveActivity(intent, 0);