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，
下面着重分析下这两个方法的加载流程
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
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
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
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。
loadWorkSpace() 方法比较长大概分为三步，
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
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
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，
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); } }
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
作者：Android高级架构探索
链接：https://www.jianshu.com/p/c3d2e8cb196c