launcher in android

launcher in android
http://blog.csdn.net/liangshengyang/article/details/5905351

Laucher的UI组成

UI组件属性在layout-port/launcher.xml中定义，主要有Workspace和SlidingDrawer两大部分组成，盛放这两者的容器就是DragLayer。
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1. <com.android.launcher.DragLayer
2. xmlns:android="http://schemas.android.com/apk/res/android"
3. xmlns:launcher="http://schemas.android.com/apk/res/com.android.launcher"
5. android:id="@+id/drag_layer"
6. android:layout_width="fill_parent"
7. android:layout_height="fill_parent">
9. 
10. <com.android.launcher.Workspace
11. android:id="@+id/workspace"
12. android:layout_width="fill_parent"
13. android:layout_height="fill_parent"
15. launcher:defaultScreen="1">
17. <include android:id="@+id/cell1" layout="@layout/workspace_screen" />
18. <include android:id="@+id/cell2" layout="@layout/workspace_screen" />
19. <include android:id="@+id/cell3" layout="@layout/workspace_screen" />
21. </com.android.launcher.Workspace>
23. <SlidingDrawer
24. android:id="@+id/drawer"
25. android:layout_width="fill_parent"
26. android:layout_height="fill_parent"
28. android:topOffset="5dip"
29. android:bottomOffset="7dip"
30. android:handle="@+id/all_apps"
31. android:content="@+id/content">
33. <com.android.launcher.HandleView
34. android:id="@id/all_apps"
35. android:layout_width="fill_parent"
36. android:layout_height="56dip"
38. android:background="@drawable/handle"
40. android:focusable="true"
41. android:clickable="true"
43. android:scaleType="center"
44. android:src="@drawable/handle_icon"
46. launcher:direction="horizontal" />
48. <com.android.launcher.AllAppsGridView
49. android:id="@id/content"
50. android:layout_width="fill_parent"
51. android:layout_height="fill_parent"
53. launcher:texture="@drawable/pattern_carbon_fiber_dark"
55. android:scrollbarStyle="outsideInset"
56. android:drawSelectorOnTop="false"
57. android:listSelector="@drawable/grid_selector"
59. android:nextFocusLeft="@id/content"
60. android:nextFocusDown="@id/content"
61. android:nextFocusUp="@id/all_apps"
62. android:nextFocusRight="@id/content"
64. android:verticalSpacing="10dip"
65. android:numColumns="4" />
67. </SlidingDrawer>
69. <com.android.launcher.DeleteZone
70. android:id="@+id/delete_zone"
71. android:layout_width="wrap_content"
72. android:layout_height="49dip"
74. android:scaleType="center"
75. android:src="@drawable/ic_delete"
76. android:background="@drawable/delete_zone_selector"
78. android:layout_gravity="bottom|center_horizontal"
79. android:visibility="invisible"
81. launcher:direction="horizontal" />
83. </com.android.launcher.DragLayer>
Workspace就是启动后进入的桌面，可以左右滑动得到3个（默认值）画面，它可以有背景图片作为墙纸。

SlidingDrawer包括HandleView和AllAppsGridView两部分。在屏幕为竖直时（Portait），在layout-port/launcher.xml文件里定义的高度56dip，宽度则充满充满整个屏幕，其背景图片在文件drawable/handle.xml中指定，见上面的layout文件中的定义。文件drawable/handle.xml：
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1. <selector xmlns:android="http://schemas.android.com/apk/res/android">
2. <item android:state_window_focused="false" android:state_enabled="true" android:drawable="@drawable/tray_handle_normal" />
3. <item android:state_pressed="true" android:drawable="@drawable/tray_handle_pressed" />
4. <item android:state_focused="true" android:state_enabled="true" android:drawable="@drawable/tray_handle_selected" />
5. <item android:state_enabled="true" android:drawable="@drawable/tray_handle_normal" />
6. <item android:state_focused="true" android:drawable="@drawable/tray_handle_selected" />
7. </selector>
对于竖直方式来说则是诸如图片res/drawable-port/tray_handle_normal.png。前景图标源则是在

drawable/handle_icon.xml（见上面的layout文件），该文件为内容为：
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1. <transition xmlns:android="http://schemas.android.com/apk/res/android">
2. <item android:drawable="@drawable/ic_tray_expand" />
3. <item android:drawable="@drawable/ic_tray_collapse" />
4. </transition>
点击或滑动HandleView中的按钮图标，则可显示AllAppsGridView，它包含了系统中的应用程序。再点击或滑动按钮，则隐藏AllAppsGridView。

在Launcher的onCreate函数中会调用setupViews来初始化各个View类，初始化布局则是由上面的layout文件中定义。setupViews函数代码如下：
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1. /**
2. * Finds all the views we need and configure them properly.
3. */
4. private void setupViews() {
5. mDragLayer = (DragLayer) findViewById(R.id.drag_layer);
6. final DragLayer dragLayer = mDragLayer;
8. mWorkspace = (Workspace) dragLayer.findViewById(R.id.workspace);
9. final Workspace workspace = mWorkspace;
11. mDrawer = (SlidingDrawer) dragLayer.findViewById(R.id.drawer);
12. final SlidingDrawer drawer = mDrawer;
14. mAllAppsGrid = (AllAppsGridView) drawer.getContent();
15. final AllAppsGridView grid = mAllAppsGrid;
17. final DeleteZone deleteZone = (DeleteZone) dragLayer.findViewById(R.id.delete_zone);
19. mHandleView = (HandleView) drawer.findViewById(R.id.all_apps);
20. mHandleView.setLauncher(this);
21. mHandleIcon = (TransitionDrawable) mHandleView.getDrawable();
22. mHandleIcon.setCrossFadeEnabled(true);
24. drawer.lock();
25. final DrawerManager drawerManager = new DrawerManager();
26. drawer.setOnDrawerOpenListener(drawerManager);
27. drawer.setOnDrawerCloseListener(drawerManager);
28. drawer.setOnDrawerScrollListener(drawerManager);
30. grid.setTextFilterEnabled(false);
31. grid.setDragger(dragLayer);
32. grid.setLauncher(this);
34. workspace.setOnLongClickListener(this);
35. workspace.setDragger(dragLayer);
36. workspace.setLauncher(this);
37. loadWallpaper();
39. deleteZone.setLauncher(this);
40. deleteZone.setDragController(dragLayer);
41. deleteZone.setHandle(mHandleView);
43. dragLayer.setIgnoredDropTarget(grid);
44. dragLayer.setDragScoller(workspace);
45. dragLayer.setDragListener(deleteZone);
46. }
其中DeleteZone用于：当长按workspace中的图标时会进入拖拽功能，可以将它们托到HandleView中，将它们从workspace中删除。

App的装载

在onCreate函数中，有如下这2行代码，用于装载应用程序信息，
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1. if (!mRestoring) {
2. startLoaders();
3. }
startLoaders会调用LauncherModel的loadApplications函数：
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1. private void startLoaders() {
2. boolean loadApplications = sModel.loadApplications(true, this, mLocaleChanged);
3. sModel.loadUserItems(!mLocaleChanged, this, mLocaleChanged, loadApplications);
5. mRestoring = false;
6. }
第一行装载应用程序包，第二行的函数装载workspace中用户自定义添加到ShortCut,LiveFolder,WidgetApp等。

在loadApplications中，需要注意2个地方，一是创建ApplicationsAdapter，它将应用程序数组列表ArrayList<ApplicationInfo> mApplications和View关联起来。二是继续调用函数startApplicationsLoaderLocked：
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1. /**
2. * Loads the list of installed applications in mApplications.
3. *
4. * @return true if the applications loader must be started
5. * (see startApplicationsLoader()), false otherwise.
6. */
7. synchronized boolean loadApplications(boolean isLaunching, Launcher launcher,
8. boolean localeChanged) {
10. if (DEBUG_LOADERS) d(LOG_TAG, "load applications");
12. if (isLaunching && mApplicationsLoaded && !localeChanged) {
13. mApplicationsAdapter = new ApplicationsAdapter(launcher, mApplications);
14. if (DEBUG_LOADERS) d(LOG_TAG, " --> applications loaded, return");
15. return false;
16. }
18. stopAndWaitForApplicationsLoader();
20. if (localeChanged) {
21. dropApplicationCache();
22. }
24. if (mApplicationsAdapter == null || isLaunching || localeChanged) {
25. mApplications = new ArrayList<ApplicationInfo>(DEFAULT_APPLICATIONS_NUMBER);
26. mApplicationsAdapter = new ApplicationsAdapter(launcher, mApplications);
27. }
29. mApplicationsLoaded = false;
31. if (!isLaunching) {
32. startApplicationsLoaderLocked(launcher, false);
33. return false;
34. }
36. return true;
37. }
再来看看startApplicationsLoaderLocked，它实际上启动一个线程去装载应用程序信息：
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1. private void startApplicationsLoaderLocked(Launcher launcher, boolean isLaunching) {
2. if (DEBUG_LOADERS) d(LOG_TAG, " --> starting applications loader");
4. stopAndWaitForApplicationsLoader();
6. mApplicationsLoader = new ApplicationsLoader(launcher, isLaunching);
7. mApplicationsLoaderThread = new Thread(mApplicationsLoader, "Applications Loader");
8. mApplicationsLoaderThread.start();
9. }
它创建一个线程执行体Runnable对象mApplicationsLoader，然后在调用mApplicationsLoaderThread.start()时会执行ApplicationsLoader. run():
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1. public void run() {
2. if (DEBUG_LOADERS) d(LOG_TAG, " ----> running applications loader (" + mId + ")");
4. // Elevate priority when Home launches for the first time to avoid
5. // starving at boot time. Staring at a blank home is not cool.
6. android.os.Process.setThreadPriority(mIsLaunching ? Process.THREAD_PRIORITY_DEFAULT :
7. Process.THREAD_PRIORITY_BACKGROUND);
9. final Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
10. mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);
12. final Launcher launcher = mLauncher.get();
13. final PackageManager manager = launcher.getPackageManager();
14. final List<ResolveInfo> apps = manager.queryIntentActivities(mainIntent, 0);
16. if (apps != null && !mStopped) {
17. final int count = apps.size();
18. // Can be set to null on the UI thread by the unbind() method
19. // Do not access without checking for null first
20. final ApplicationsAdapter applicationList = mApplicationsAdapter;
22. ChangeNotifier action = new ChangeNotifier(applicationList, true);
23. final HashMap<ComponentName, ApplicationInfo> appInfoCache = mAppInfoCache;
25. for (int i = 0; i < count && !mStopped; i++) {
26. ResolveInfo info = apps.get(i);
27. ApplicationInfo application =
28. makeAndCacheApplicationInfo(manager, appInfoCache, info, launcher);
30. if (action.add(application) && !mStopped) {
31. launcher.runOnUiThread(action);
32. action = new ChangeNotifier(applicationList, false);
33. }
34. }
36. launcher.runOnUiThread(action);
37. }
39. if (!mStopped) {
40. mApplicationsLoaded = true;
41. } else {
42. if (DEBUG_LOADERS) d(LOG_TAG, " ----> applications loader stopped (" + mId + ")");
43. }
44. mRunning = false;
45. }
46. }
在该线程中，它使用PackageManager获取安装的应用程序。

在装载完workspace和AllGridView中的各项后，onDesktopItemsLoaded将被调用，它会绑定桌面的Shortcut及appWidgets：
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1. void onDesktopItemsLoaded(ArrayList<ItemInfo> shortcuts,
2. ArrayList<LauncherAppWidgetInfo> appWidgets) {
3. if (mDestroyed) {
4. if (LauncherModel.DEBUG_LOADERS) {
5. d(LauncherModel.LOG_TAG, " ------> destroyed, ignoring desktop items");
6. }
7. return;
8. }
9. bindDesktopItems(shortcuts, appWidgets);
10. }
绑定过程

绑定过程包括ApplicationAdapter（即ArrayAapter的子类）与AllGridView的绑定，实现数据到View的显示。
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1. private void bindDesktopItems(ArrayList<ItemInfo> shortcuts,
2. ArrayList<LauncherAppWidgetInfo> appWidgets) {
4. final ApplicationsAdapter drawerAdapter = sModel.getApplicationsAdapter();
5. if (shortcuts == null || appWidgets == null || drawerAdapter == null) {
6. if (LauncherModel.DEBUG_LOADERS) d(LauncherModel.LOG_TAG, " ------> a source is null");
7. return;
8. }
12. mBinder = new DesktopBinder(this, shortcuts, appWidgets, drawerAdapter);
13. mBinder.startBindingItems();
14. }
DesktopBinder的构造函数如下，指定了Adapter，实现了数据到view的绑定：
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1. DesktopBinder(Launcher launcher, ArrayList<ItemInfo> shortcuts,
2. ArrayList<LauncherAppWidgetInfo> appWidgets,
3. ApplicationsAdapter drawerAdapter) {
5. mLauncher = new
6. WeakReference<Launcher>(launcher);
7. mShortcuts = shortcuts;
8. mDrawerAdapter = drawerAdapter;
9. ...
在函数bindDrawer 中为view指定了adapter：
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1. private void bindDrawer(Launcher.DesktopBinder binder,
2. ApplicationsAdapter drawerAdapter) {
3. mAllAppsGrid.setAdapter(drawerAdapter);
4. binder.startBindingAppWidgetsWhenIdle();
5. }
其它

LauncherModel提供了添加/删除/更新应用程序包的功能。

Launcher还提供了对ShortCut 、AppWidget、LiveFolder和搜索框等的管理功能，墙纸管理功能。默认的墙纸也是存放在该程序包的资源中。
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原文地址：https://www.cnblogs.com/greywolf/p/2831239.html