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