Android 桌面加载图标过程分析

桌面应用图标流程

前言

本人工作上碰到这么一个需求，开发一款滤镜引擎，将桌面上所有的图标进行统一的滤镜化，这就需要了解一下整个桌面去取图标的过程，了解了整个过程，找到真正拿图标的地方，在真正取图标的地方将图片进行替换，或者滤镜化，之前分析情况，现在整理下，与大家分享。本文所用的代码，是基于Android 5.1

桌面组件介绍

一级页面

• 一级菜单

  • WorkSpace：他是一个ViewGroup，要想在桌面上显示东西，就得往这个ViewGroup里添加自己的View

  • BubbleTextView：他是一个TextView，上方是图标，下方是名称，在桌面上的图标都是由这个类表示

  • FolderIcon：他也是一个ViewGroup，用来表示桌面上的文件夹图标，里面添加了缩略处理过的bitmap，他的背景图片就是文件夹的形状

  • HotSeat： 他是个FrameLayout，是桌面下方的固定快捷区，包含了几个常用的图标，中间的AllApp按钮是固定位置，也是一个TextView

抽屉桌面

• 抽屉页面 组件

  • PagedView：他是一个viewgroup，代表进入抽屉页后的界面，应用图标需要添加到这个viewgoup里面才能显示，一个或几个PagedView 承载了手机上所有的应用图标
  • PagedViewIcon：他是一个TextView，和BubblTextView一样，只是在抽屉容器里换了个名字

桌面加载图标流程

• 先来看一张流程图

  桌面加载流程图

• 桌面Activity 也就是Launcher.java 类，该类里面维护了一个 LauncherModel,该对象会在onCreate 方法中去调用startLoader() 方法，

• 下面看一下startLoader() 方法的源码，

    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();
              // 这搞了一个异步任务去加载
                mLoaderTask = new LoaderTask(mApp.getContext(), isLaunching);
                if (synchronousBindPage > -1 && mAllAppsLoaded && mWorkspaceLoaded) {
                    mLoaderTask.runBindSynchronousPage(synchronousBindPage);
                } else {
                    sWorkerThread.setPriority(Thread.NORM_PRIORITY);
                    sWorker.post(mLoaderTask);
                }
            }
        }
       }
  
  

  我们看到，这里面有个关键的类，loaderTask,见名只义，可以猜到这里面会起一个线程，去加载一些资源。看看里面去加载什么

• LoaderTask.java

  可以看到LoaderTask实现了Runnable接口，直接去看该类的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");
  
          //加载一级菜单的方法
          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");
            //加载二级菜单里面的方法
          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;
        }
    }
  
  

  可以看到在该类中主要有两个方法，

  • loadAndBindWorkSpace(), WorkSpace是一级菜单里面的容器类，该方法是加载一及菜单的方法
  • loadAndBindAllapp() ,这是抽屉内二级菜单的加载方法

  下面着重分析下这两个方法的加载流程

loadAndBindWorkSpace()

• 这里加载主要分为两个流程一个是 loadWorkSpace 另一个是 bindWorkSpace,可以看下源代码

    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;
    }
  
  

  可以看到并没有直接去加载，而是先判断了一些条件，然后去加载

  • loadWorkSpace() 方法比较长大概分为三步，

    • 初始化后面要用到的对象实例

        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;
      
      

    • 加载默认配置，并保存数据库中

        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，就会加载默认的配置(default_workspace_xxx.xml)，并保存到数据库中
                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();
            }
        }
      
      

    • 读取数据库，获取需要加载的应用快捷方式

      此段代码较多，就是去读取数据库的一些操作，具体过程是根据一些不同的type 存到不同的list中。

  • bindWorkSpace()

    应用信息读取完之后，刚才的几个变量中就存储了该信息，然后将其绑定到workspace中去，这个过程也是很复杂的

    • 创建局部变量，将全局变量的信息复制过来，单独进行操作

        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;// 当前screen
        final long currentScreenId = currentScreen < 0 ? INVALID_SCREEN_ID : orderedScreenIds.get(currentScreen);// 当前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();// 先解除绑定
      
      

    • 根据item中的screenID将items分成当前screen和其他screen，并进行排序

        // Separate the items that are on the current screen, and all the other remaining items
        ArrayList<iteminfo> currentWorkspaceItems = new ArrayList<iteminfo>();// 存放当前workspace上的items
        ArrayList<iteminfo> otherWorkspaceItems = new ArrayList<iteminfo>();// 存放除当前workspace之外的items
        ArrayList<launcherappwidgetinfo> currentAppWidgets = new ArrayList<launcherappwidgetinfo>();// 存放当前workspace上的appwidgets
        ArrayList<launcherappwidgetinfo> otherAppWidgets = new ArrayList<launcherappwidgetinfo>();// 存放除当前workspace之外的appwidgets
        HashMap<long, folderinfo=""> currentFolders = new HashMap<long, folderinfo="">();// 存放当前workspace上的folder
        HashMap<long, folderinfo=""> otherFolders = new HashMap<long, folderinfo="">();// 存放除当前workspace之外的folder
      
        filterCurrentWorkspaceItems(currentScreenId, workspaceItems, currentWorkspaceItems, otherWorkspaceItems);// 过滤items，区分当前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);// 对workspace上的items进行排序，按照从上到下和从左到右的顺序
        sortWorkspaceItemsSpatially(otherWorkspaceItems);// 同上
      
      

    • runnable执行块，告诉workspace要开始绑定items了，startBinding方法在Launcher中实现，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);
      
      

      可以看一下实现类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

    • 绑定workspace screen

         bindWorkspaceScreens(oldCallbacks, orderedScreenIds);
         具体实现在launcher中
      
      

    • Workspace绑定完成之后，就是将items、widgets和folders放到上面去

loadAndBindAllapp()

• 可以看到加载过程也是分为两步：如果所有app已经加载过了，就只需要绑定就行了，否则的话，加载所有app，第一次启动肯定是加载所有的，我们按照这种情况来分析

  • 1.获取需要显示到Launcher中的app列表，创建app图标

      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);// 获取需要显示在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()) {// 没有需要显示的，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));// 创建应用图标对象，并添加到所有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;// 获取自上次更新（notify()广播）后新增加的应用清单，如果是开机初次启动Launcher，那么added就是mBgAllAppsList
      mBgAllAppsList.added = new ArrayList();// 将AllAppsList的added清空，不影响后续新增的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");
      }
    
    

  • 绑定app--bindAllApplications

        public void bindAllApplications(final ArrayList apps) {
            if (LauncherAppState.isDisableAllApps()) {// 判断是否禁用所有app,就是所有应用都显示在一级目录
                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);
            }
            }
    
    

  可以看到无论是一级桌面拿图标，还是抽屉页面拿图标，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;
        }
    }
  
  

  这里判断一下条件，会去走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;
    }
  
  

  这个方法里面。就是最终去拿图标的方法，里面去拿一些必要信息，去给entry赋值

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