Launcher进程的启动到用户界面的呈现，揭示每个阶段的关键步骤

@TargetApi(两3)
public InvariantDeviceProfile(Context context) {
  WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
  Display display = wm.getDefaultDisplay();
  DisplayMetrics dm = new DisplayMetrics();
  display.getMetrics(dm);
  ...
  ArrayList<InvariantDeviceProfile> closestProfiles = findClosestDeviceProfiles(minWidthDps, minHeightDps, getPredefinedDeviceProfiles(context));
  ...
}

ArrayList<InvariantDeviceProfile> getPredefinedDeviceProfiles(Context context) {
  ArrayList<InvariantDeviceProfile> profiles = new ArrayList<>();
  try (XmlResourceParser parser = context.getResources().getXml(R.xml.device_profiles)) {
    final int depth = parser.getDepth();
    int type;
    while (((type = parser.next()) != XmlPullParser.END_TAG || parser.getDepth() > depth) && type != XmlPullParser.END_DOCUMENT) {
      if ((type == XmlPullParser.START_TAG) && "profile".equals(parser.getName())) {
        TypedArray a = context.obtainStyledAttributes(Xml.asAttributeSet(parser), R.styleable.InvariantDeviceProfile);
        int numRows = a.getInt(R.styleable.InvariantDeviceProfile_numRows, 0);
        int numColumns = a.getInt(R.styleable.InvariantDeviceProfile_numColumns, 0);
        float iconSize = a.getFloat(R.styleable.InvariantDeviceProfile_iconSize, 0);
        profiles.add(new InvariantDeviceProfile(
          a.getString(R.styleable.InvariantDeviceProfile_name),
          a.getFloat(R.styleable.InvariantDeviceProfile_minWidthDps, 0),
          a.getFloat(R.styleable.InvariantDeviceProfile_minHeightDps, 0),
          numRows,
          numColumns,
          a.getInt(R.styleable.InvariantDeviceProfile_numFolderRows, numRows),
          a.getInt(R.styleable.InvariantDeviceProfile_numFolderColumns, numColumns),
          iconSize,
          a.getFloat(R.styleable.InvariantDeviceProfile_landscapeIconSize, iconSize),
          a.getFloat(R.styleable.InvariantDeviceProfile_iconTextSize, 0),
          a.getInt(R.styleable.InvariantDeviceProfile_numHotseatIcons, numColumns),
          a.getResourceId(R.styleable.InvariantDeviceProfile_defaultLayoutId, 0),
          a.getResourceId(R.styleable.InvariantDeviceProfile_demoModeLayoutId, 0)));
        a.recycle();
      }
    }
  } catch (IOException|XmlPullParserException e) {
    throw new RuntimeException(e);
  }
  return profiles;
}

InvariantDeviceProfile器材首要是存储App的根基设置疑息，比如App图标的尺寸巨细，笔墨巨细，每一个任务空有时文件夹能透露表现若干App等。

正在LauncherModel的startLoader()法子外，新修了一个LoaderResults器械，经由过程startLoaderForResults()办法建立没一个LoaderTask的Runnable事情。

public boolean startLoader(int synchronousBindPage) {
  ...
  synchronized (mLock) {
    // Don't bother to start the thread if we know it's not going to do anything
    if (mCallbacks != null && mCallbacks.get() != null) {
      ...
      LoaderResults loaderResults = new LoaderResults(mApp, sBgDataModel, mBgAllAppsList, synchronousBindPage, mCallbacks);
      if (mModelLoaded && !mIsLoaderTaskRunning) {
        ...
        return true;
      } else {
        startLoaderForResults(loaderResults);
      }
    }
  }
  return false;
}

public void startLoaderForResults(LoaderResults results) {
  synchronized (mLock) {
    stopLoader();
    mLoaderTask = new LoaderTask(mApp, mBgAllAppsList, sBgDataModel, results);
    runOnWorkerThread(mLoaderTask);
  }
}

private static void runOnWorkerThread(Runnable r) {
  if (sWorkerThread.getThreadId() == Process.myTid()) {
    r.run();
  } else {
    // If we are not on the worker thread, then post to the worker handler
    sWorker.post(r);
  }
}

public void run() {
  ...
  try (LauncherModel.LoaderTransaction transaction = mApp.getModel().beginLoader(this)) {
    // 查问数据库整顿App疑息，转化为View绑定到界里
    loadWorkspace();
    mResults.bindWorkspace();
    loadAllApps();
    mResults.bindAllApps();
    loadDeepShortcuts();
    mResults.bindDeepShortcuts();
    mBgDataModel.widgetsModel.update(mApp, null);
    mResults.bindWidgets();
    transaction.co妹妹it();
  } catch (CancellationException e) {
    // Loader stopped, ignore
    TraceHelper.partitionSection(TAG, "Cancelled");
  }
  TraceHelper.endSection(TAG);
}