Android 桌面載入圖示過程分析

摘要： 桌面應用圖示流程 前言 本人工作上碰到這麼一個需求，開發一款濾鏡引擎，將桌面上所有的圖示進行統一的濾鏡化，這就需要了解一下整個桌面去取圖示的過程，瞭解了整個過程，找到真正拿圖示的地方，在真正取圖示的地方將圖片進行替換，或者濾鏡化，之前分析情況，現在整理下，與大家分享。 本文所用的程式...

桌面應用圖示流程

前言

本人工作上碰到這麼一個需求，開發一款濾鏡引擎，將桌面上所有的圖示進行統一的濾鏡化，這就需要了解一下整個桌面去取圖示的過程，瞭解了整個過程，找到真正拿圖示的地方，在真正取圖示的地方將圖片進行替換，或者濾鏡化，之前分析情況，現在整理下，與大家分享。 本文所用的程式碼，是基於Android 5.1

桌面元件介紹

• 一級選單

  • WorkSpace：他是一個ViewGroup，要想在桌面上顯示東西，就得往這個ViewGroup裡新增自己的View

  • BubbleTextView：他是一個TextView，上方是圖示，下方是名稱，在桌面上的圖示都是由這個類表示

  • FolderIcon：他也是一個ViewGroup，用來表示桌面上的資料夾圖示，裡面添加了縮略處理過的bitmap，他的背景圖片就是資料夾的形狀

  • HotSeat： 他是個FrameLayout，是桌面下方的固定快捷區，包含了幾個常用的圖示，中間的AllApp按鈕是固定位置，也是一個TextView

• 抽屜頁面 元件

  • PagedView ：他是一個viewgroup，代表進入抽屜頁後的介面，應用圖示需要新增到這個viewgoup裡面才能顯示，一個或幾個PagedView 承載了手機上所有的應用圖示
  • PagedViewIcon ：他是一個TextView，和BubblTextView一樣，只是在抽屜容器裡換了個名字

桌面載入圖示流程

• 先來看一張流程圖

  

  桌面載入流程圖

• 桌面Activity 也就是Launcher.java 類，該類裡面維護了一個 LauncherModel,該物件會在onCreate 方法中去呼叫startLoader() 方法，

• 下面看一下startLoader() 方法的原始碼，

  public void startLoader(boolean isLaunching, int synchronousBindPage) {
  synchronized (mLock) {
  if (DEBUG_LOADERS) {
  Log.d(TAG, "startLoader isLaunching=" + isLaunching);
  }
  
  // Clear any deferred bind-runnables from the synchronized load process
  // We must do this before any loading/binding is scheduled below.
  mDeferredBindRunnables.clear();
  
  // Don't bother to start the thread if we know it's not going to do anything
  if (mCallbacks != null && mCallbacks.get() != null) {
  // If there is already one running, tell it to stop.
  // also, don't downgrade isLaunching if we're already running
  isLaunching = isLaunching || stopLoaderLocked();
  // 這搞了一個非同步任務去載入
  mLoaderTask = new LoaderTask(mApp.getContext(), isLaunching);
  if (synchronousBindPage > -1 && mAllAppsLoaded && mWorkspaceLoaded) {
  mLoaderTask.runBindSynchronousPage(synchronousBindPage);
  } else {
  sWorkerThread.setPriority(Thread.NORM_PRIORITY);
  sWorker.post(mLoaderTask);
  }
  }
  }
  }

  我們看到，這裡面有個關鍵的類，loaderTask,見名只義，可以猜到這裡面會起一個執行緒，去載入一些資源。看看裡面去載入什麼

• LoaderTask.java

  可以看到LoaderTask實現了Runnable介面，直接去看該類的run() 方法

  public void run() {
  boolean isUpgrade = false;
  
  synchronized (mLock) {
  mIsLoaderTaskRunning = true;
  }
  // Optimize for end-user experience: if the Launcher is up and // running with the
  // All Apps interface in the foreground, load All Apps first. Otherwise, load the
  // workspace first (default).
  keep_running: {
  // Elevate priority when Home launches for the first time to avoid
  // starving at boot time. Staring at a blank home is not cool.
  synchronized (mLock) {
  if (DEBUG_LOADERS) Log.d(TAG, "Setting thread priority to " +
  (mIsLaunching ? "DEFAULT" : "BACKGROUND"));
  android.os.Process.setThreadPriority(mIsLaunching
  ? Process.THREAD_PRIORITY_DEFAULT : Process.THREAD_PRIORITY_BACKGROUND);
  }
  if (DEBUG_LOADERS) Log.d(TAG, "step 1: loading workspace");
  
  //載入一級選單的方法
  isUpgrade = loadAndBindWorkspace();
  
  if (mStopped) {
  break keep_running;
  }
  
  // Whew! Hard work done.Slow us down, and wait until the UI thread has
  // settled down.
  synchronized (mLock) {
  if (mIsLaunching) {
  if (DEBUG_LOADERS) Log.d(TAG, "Setting thread priority to BACKGROUND");
  android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
  }
  }
  waitForIdle();
  
  // second step
  if (DEBUG_LOADERS) Log.d(TAG, "step 2: loading all apps");
  //載入二級選單裡面的方法
  loadAndBindAllApps();
  
  // Restore the default thread priority after we are done loading items
  synchronized (mLock) {
  android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_DEFAULT);
  }
  }
  
  // Update the saved icons if necessary
  if (DEBUG_LOADERS) Log.d(TAG, "Comparing loaded icons to database icons");
  synchronized (sBgLock) {
  for (Object key : sBgDbIconCache.keySet()) {
  updateSavedIcon(mContext, (ShortcutInfo) key, sBgDbIconCache.get(key));
  }
  sBgDbIconCache.clear();
  }
  
  if (AppsCustomizePagedView.DISABLE_ALL_APPS) {
  // Ensure that all the applications that are in the system are
  // represented on the home screen.
  if (!UPGRADE_USE_MORE_APPS_FOLDER || !isUpgrade) {
  verifyApplications();
  }
  }
  
  // Clear out this reference, otherwise we end up holding it until all of the
  // callback runnables are done.
  mContext = null;
  
  synchronized (mLock) {
  // If we are still the last one to be scheduled, remove ourselves.
  if (mLoaderTask == this) {
  mLoaderTask = null;
  }
  mIsLoaderTaskRunning = false;
  }
  }

  可以看到在該類中主要有兩個方法，

  • loadAndBindWorkSpace(), WorkSpace是一級選單裡面的容器類，該方法是載入一及選單的方法
  • loadAndBindAllapp() ,這是抽屜內二級選單的載入方法

  下面著重分析下這兩個方法的載入流程

loadAndBindWorkSpace()

• 這裡載入主要分為兩個流程一個是 loadWorkSpace 另一個是 bindWorkSpace,可以看下原始碼

  private boolean loadAndBindWorkspace() {
  mIsLoadingAndBindingWorkspace = true;
  
  // Load the workspace
  if (DEBUG_LOADERS) {
  Log.d(TAG, "loadAndBindWorkspace mWorkspaceLoaded=" + mWorkspaceLoaded);
  }
  
  boolean isUpgradePath = false;
  if (!mWorkspaceLoaded) {
  isUpgradePath = loadWorkspace();
  synchronized (LoaderTask.this) {
  if (mStopped) {
  return isUpgradePath;
  }
  mWorkspaceLoaded = true;
  }
  }
  
  // Bind the workspace
  bindWorkspace(-1, isUpgradePath);
  return isUpgradePath;
  }

  可以看到並沒有直接去載入，而是先判斷了一些條件，然後去載入

  • loadWorkSpace() 方法比較長大概分為三步，

    • 初始化後面要用到的物件例項

      final long t = DEBUG_LOADERS ? SystemClock.uptimeMillis() : 0;
      
      final Context context = mContext;
      final ContentResolver contentResolver = context.getContentResolver();
      final PackageManager manager = context.getPackageManager();
      final AppWidgetManager widgets = AppWidgetManager.getInstance(context);
      final boolean isSafeMode = manager.isSafeMode();
      
      LauncherAppState app = LauncherAppState.getInstance();
      DeviceProfile grid = app.getDynamicGrid().getDeviceProfile();
      int countX = (int) grid.numColumns;
      int countY = (int) grid.numRows;

    • 載入預設配置，並儲存資料庫中

      synchronized public void loadDefaultFavoritesIfNecessary(int origWorkspaceResId) {
      String spKey = LauncherAppState.getSharedPreferencesKey();
      SharedPreferences sp = getContext().getSharedPreferences(spKey, Context.MODE_PRIVATE);
      
      if (sp.getBoolean(EMPTY_DATABASE_CREATED, false)) {
      int workspaceResId = origWorkspaceResId;
      
      // Use default workspace resource if none provided
      //如果workspaceResId=0，就會載入預設的配置(default_workspace_xxx.xml)，並儲存到資料庫中
      if (workspaceResId == 0) {
      workspaceResId = sp.getInt(DEFAULT_WORKSPACE_RESOURCE_ID, R.xml.default_workspace);
      }
      
      // Populate favorites table with initial favorites
      SharedPreferences.Editor editor = sp.edit();
      editor.remove(EMPTY_DATABASE_CREATED);
      if (origWorkspaceResId != 0) {
      editor.putInt(DEFAULT_WORKSPACE_RESOURCE_ID, origWorkspaceResId);
      }
      
      mOpenHelper.loadFavorites(mOpenHelper.getWritableDatabase(), workspaceResId);
      mOpenHelper.setFlagJustLoadedOldDb();
      editor.commit();
      }
      }

    • 讀取資料庫，獲取需要載入的應用快捷方式

      此段程式碼較多，就是去讀取資料庫的一些操作，具體過程是根據一些不同的type 存到不同的list中。

  • bindWorkSpace()

    應用資訊讀取完之後，剛才的幾個變數中就儲存了該資訊，然後將其繫結到workspace中去，這個過程也是很複雜的

    • 建立區域性變數，將全域性變數的資訊複製過來，單獨進行操作

      ArrayList<iteminfo> workspaceItems = new ArrayList<iteminfo>();
      ArrayList<launcherappwidgetinfo> appWidgets = new ArrayList<launcherappwidgetinfo>();
      HashMap<long, folderinfo=""> folders = new HashMap<long, folderinfo="">();
      HashMap<long, iteminfo=""> itemsIdMap = new HashMap<long, iteminfo="">();
      ArrayList<long> orderedScreenIds = new ArrayList<long>();
      synchronized (sBgLock) {
      workspaceItems.addAll(sBgWorkspaceItems);
      appWidgets.addAll(sBgAppWidgets);
      folders.putAll(sBgFolders);
      itemsIdMap.putAll(sBgItemsIdMap);
      orderedScreenIds.addAll(sBgWorkspaceScreens);
      }
      
      final boolean isLoadingSynchronously = synchronizeBindPage != PagedView.INVALID_RESTORE_PAGE;
      int currScreen = isLoadingSynchronously ? synchronizeBindPage : oldCallbacks.getCurrentWorkspaceScreen();
      if (currScreen >= orderedScreenIds.size()) {
      // There may be no workspace screens (just hotseat items and an empty page).
      currScreen = PagedView.INVALID_RESTORE_PAGE;
      }
      final int currentScreen = currScreen;// 當前screen
      final long currentScreenId = currentScreen < 0 ? INVALID_SCREEN_ID : orderedScreenIds.get(currentScreen);// 當前screen id
      
      // Load all the items that are on the current page first (and in the process, unbind
      // all the existing workspace items before we call startBinding() below.
      unbindWorkspaceItemsOnMainThread();// 先解除繫結

    • 根據item中的screenID將items分成當前screen和其他screen，並進行排序

      // Separate the items that are on the current screen, and all the other remaining items
      ArrayList<iteminfo> currentWorkspaceItems = new ArrayList<iteminfo>();// 存放當前workspace上的items
      ArrayList<iteminfo> otherWorkspaceItems = new ArrayList<iteminfo>();// 存放除當前workspace之外的items
      ArrayList<launcherappwidgetinfo> currentAppWidgets = new ArrayList<launcherappwidgetinfo>();// 存放當前workspace上的appwidgets
      ArrayList<launcherappwidgetinfo> otherAppWidgets = new ArrayList<launcherappwidgetinfo>();// 存放除當前workspace之外的appwidgets
      HashMap<long, folderinfo=""> currentFolders = new HashMap<long, folderinfo="">();// 存放當前workspace上的folder
      HashMap<long, folderinfo=""> otherFolders = new HashMap<long, folderinfo="">();// 存放除當前workspace之外的folder
      
      filterCurrentWorkspaceItems(currentScreenId, workspaceItems, currentWorkspaceItems, otherWorkspaceItems);// 過濾items，區分當前screen和其他screen上的items
      filterCurrentAppWidgets(currentScreenId, appWidgets, currentAppWidgets, otherAppWidgets);// 同上
      filterCurrentFolders(currentScreenId, itemsIdMap, folders, currentFolders, otherFolders);// 同上
      sortWorkspaceItemsSpatially(currentWorkspaceItems);// 對workspace上的items進行排序，按照從上到下和從左到右的順序
      sortWorkspaceItemsSpatially(otherWorkspaceItems);// 同上

    • runnable執行塊，告訴workspace要開始繫結items了，startBinding方法在Launcher中實現，做一些清除工作

      // Tell the workspace that we're about to start binding items
      r = new Runnable() {
      public void run() {
      Callbacks callbacks = tryGetCallbacks(oldCallbacks);
      if (callbacks != null) {
      callbacks.startBinding();
      }
      }
      };
      runOnMainThread(r, MAIN_THREAD_BINDING_RUNNABLE);

      可以看一下實現類launcher中startBinding()方法

      public void startBinding() {
      // If we're starting binding all over again, clear any bind calls we'd postponed in
      // the past (see waitUntilResume) -- we don't need them since we're starting binding
      // from scratch again
      mBindOnResumeCallbacks.clear();
      
      // Clear the workspace because it's going to be rebound
      mWorkspace.clearDropTargets();
      mWorkspace.removeAllWorkspaceScreens();
      
      mWidgetsToAdvance.clear();
      if (mHotseat != null) {
      mHotseat.resetLayout();
      }
      }

      可以看到主要做的是清除和重置工作

    • 繫結workspace screen

      bindWorkspaceScreens(oldCallbacks, orderedScreenIds);
      具體實現在launcher中

    • Workspace繫結完成之後，就是將items、widgets和folders放到上面去

loadAndBindAllapp()

• 可以看到載入過程也是分為兩步：如果所有app已經載入過了，就只需要繫結就行了，否則的話，載入所有app，第一次啟動肯定是載入所有的，我們按照這種情況來分析

  • 1.獲取需要顯示到Launcher中的app列表，建立app圖示

    private void loadAndBindAllApps() {
    if (DEBUG_LOADERS) {
    Log.d(TAG, "loadAndBindAllApps mAllAppsLoaded=" + mAllAppsLoaded);
    }
    if (!mAllAppsLoaded) {
    loadAllApps();
    synchronized (LoaderTask.this) {
    if (mStopped) {
    return;
    }
    mAllAppsLoaded = true;
    }
    } else {
    onlyBindAllApps();
    }
    }

  • loadAllApps()

    final long loadTime = DEBUG_LOADERS ? SystemClock.uptimeMillis() : 0;
    
    final Callbacks oldCallbacks = mCallbacks.get();
    if (oldCallbacks == null) {
    // This launcher has exited and nobody bothered to tell us.Just bail.
    Log.w(TAG, "LoaderTask running with no launcher (loadAllApps)");
    return;
    }
    
    final Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
    mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);
    
    final List<userhandlecompat> profiles = mUserManager.getUserProfiles();
    
    // Clear the list of apps
    mBgAllAppsList.clear();// 清除所有app列表
    SharedPreferences prefs = mContext.getSharedPreferences(
    LauncherAppState.getSharedPreferencesKey(), Context.MODE_PRIVATE);
    for (UserHandleCompat user : profiles) {
    // Query for the set of apps
    final long qiaTime = DEBUG_LOADERS ? SystemClock.uptimeMillis() : 0;
    List<launcheractivityinfocompat> apps = mLauncherApps.getActivityList(null, user);// 獲取需要顯示在Launcher上的activity列表
    if (DEBUG_LOADERS) {
    Log.d(TAG, "getActivityList took "
    + (SystemClock.uptimeMillis()-qiaTime) + "ms for user " + user);
    Log.d(TAG, "getActivityList got " + apps.size() + " apps for user " + user);
    }
    // Fail if we don't have any apps
    // TODO: Fix this. Only fail for the current user.
    if (apps == null || apps.isEmpty()) {// 沒有需要顯示的，直接返回
    return;
    }
    // Sort the applications by name
    final long sortTime = DEBUG_LOADERS ? SystemClock.uptimeMillis() : 0;
    Collections.sort(apps, new LauncherModel.ShortcutNameComparator(mLabelCache));// 排序
    if (DEBUG_LOADERS) {
    Log.d(TAG, "sort took " + (SystemClock.uptimeMillis()-sortTime) + "ms");
    }
    
    // Create the ApplicationInfos
    for (int i = 0; i < apps.size(); i++) {
    LauncherActivityInfoCompat app = apps.get(i);
    // This builds the icon bitmaps.
    mBgAllAppsList.add(new AppInfo(mContext, app, user, mIconCache, mLabelCache));// 建立應用圖示物件，並新增到所有APP列表中
    
    }
    
    if (ADD_MANAGED_PROFILE_SHORTCUTS && !user.equals(UserHandleCompat.myUserHandle())) {
    // Add shortcuts for packages which were installed while launcher was dead.
    String shortcutsSetKey = INSTALLED_SHORTCUTS_SET_PREFIX + mUserManager.getSerialNumberForUser(user);
    Set<string> packagesAdded = prefs.getStringSet(shortcutsSetKey, Collections.EMPTY_SET);
    HashSet<string> newPackageSet = new HashSet<string>();
    
    for (LauncherActivityInfoCompat info : apps) {
    String packageName = info.getComponentName().getPackageName();
    if (!packagesAdded.contains(packageName)
    && !newPackageSet.contains(packageName)) {
    InstallShortcutReceiver.queueInstallShortcut(info, mContext);
    }
    newPackageSet.add(packageName);
    }
    
    prefs.edit().putStringSet(shortcutsSetKey, newPackageSet).commit();
    }
    }
    // Huh? Shouldn't this be inside the Runnable below?
    final ArrayList added = mBgAllAppsList.added;// 獲取自上次更新（notify()廣播）後新增加的應用清單，如果是開機初次啟動Launcher，那麼added就是mBgAllAppsList
    mBgAllAppsList.added = new ArrayList();// 將AllAppsList的added清空，不影響後續新增的app
    
    // Post callback on main thread
    mHandler.post(new Runnable() {
    public void run() {
    final long bindTime = SystemClock.uptimeMillis();
    final Callbacks callbacks = tryGetCallbacks(oldCallbacks);
    if (callbacks != null) {
    callbacks.bindAllApplications(added);
    if (DEBUG_LOADERS) {
    Log.d(TAG, "bound " + added.size() + " apps in "
    + (SystemClock.uptimeMillis() - bindTime) + "ms");
    }
    } else {
    Log.i(TAG, "not binding apps: no Launcher activity");
    }
    }
    });
    
    if (DEBUG_LOADERS) {
    Log.d(TAG, "Icons processed in "
    + (SystemClock.uptimeMillis() - loadTime) + "ms");
    }

  • 繫結app--bindAllApplications

    public void bindAllApplications(final ArrayList apps) {
    if (LauncherAppState.isDisableAllApps()) {// 判斷是否禁用所有app,就是所有應用都顯示在一級目錄
    if (mIntentsOnWorkspaceFromUpgradePath != null) {
    if (LauncherModel.UPGRADE_USE_MORE_APPS_FOLDER) {
    getHotseat().addAllAppsFolder(mIconCache, apps,
    mIntentsOnWorkspaceFromUpgradePath, Launcher.this, mWorkspace);
    }
    mIntentsOnWorkspaceFromUpgradePath = null;
    }
    if (mAppsCustomizeContent != null) {
    mAppsCustomizeContent.onPackagesUpdated(
    LauncherModel.getSortedWidgetsAndShortcuts(this));
    }
    } else {
    if (mAppsCustomizeContent != null) {
    mAppsCustomizeContent.setApps(apps);
    mAppsCustomizeContent.onPackagesUpdated(LauncherModel.getSortedWidgetsAndShortcuts(this));
    }
    }
    if (mLauncherCallbacks != null) {
    mLauncherCallbacks.bindAllApplications(apps);
    }
    }

  可以看到無論是一級桌面拿圖示，還是抽屜頁面拿圖示，都是去走，IconCache的getIcon()方法，

IconCache

• getIcon()

  public Bitmap getIcon(ComponentName component, ResolveInfo resolveInfo,
  HashMap<Object, CharSequence> labelCache) {
  synchronized (mCache) {
  if (resolveInfo == null || component == null) {
  return null;
  }
  
  CacheEntry entry = cacheLocked(component, resolveInfo, labelCache);
  return entry.icon;
  }
  }

  這裡判斷一下條件，會去走cacheLocked() 方法

• cacheLocked()

  private CacheEntry cacheLocked(ComponentName componentName, ResolveInfo info,
  HashMap<Object, CharSequence> labelCache) {
  CacheEntry entry = mCache.get(componentName);
  if (entry == null) {
  entry = new CacheEntry();
  
  mCache.put(componentName, entry);
  
  ComponentName key = LauncherModel.getComponentNameFromResolveInfo(info);
  if (labelCache != null && labelCache.containsKey(key)) {
  entry.title = labelCache.get(key).toString();
  } else {
  entry.title = info.loadLabel(mPackageManager).toString();
  if (labelCache != null) {
  labelCache.put(key, entry.title);
  }
  }
  if (entry.title == null) {
  entry.title = info.activityInfo.name;
  }
  
  entry.icon = Utilities.createIconBitmap(
  getFullResIcon(info), mContext);
  
  }
  return entry;
  }

  這個方法裡面。就是最終去拿圖示的方法，裡面去拿一些必要資訊，去給entry賦值

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