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Android5.1 壁纸设置流程浅析
Ubuntu14.04 Android5.1 Source Insight3
源代码请参阅http://androidxref.com/
这里只是简单分析一下5.1里是如何设置壁纸的；这个流程和4.4有一些不同。但基本都是找个地方存放壁纸文件，需要的时候读取，设置的时候更新
这里只看设置的过程。权当参考。
机器使用launcher3，在桌面上长按，底部显示设置壁纸的入口。
进入设置壁纸界面，观察log可知，此界面属于Trebuchet。也是launcher3
点击设置壁纸按钮，发现整个标题栏都有响应。在以下文件中可以找到相关定义：
/*--- ↓ --- WallpaperPickerActivity.java *********/ // Action bar // Show the custom action bar view final ActionBar actionBar = getActionBar(); actionBar.setCustomView(R.layout.actionbar_set_wallpaper); actionBar.getCustomView().setOnClickListener( new View.OnClickListener() { @Override public void onClick(View v) { if (mSelectedTile != null) { WallpaperTileInfo info = (WallpaperTileInfo) mSelectedTile.getTag(); info.onSave(WallpaperPickerActivity.this); } else { // no tile was selected, so we just finish the activity and go back setResult(Activity.RESULT_OK); finish(); } } }); mSetWallpaperButton = findViewById(R.id.set_wallpaper_button); /*--- ↑ --- (packages/apps/Trebuchet/WallpaperPicker/src/com/android/launcher3/) *********/
整个 actionBar都拿来响应点击。info是 WallpaperTileInfo抽象类的对象，有5个子类。
这样系统能根据图片来选择使用哪一个子类。再调用 onSave方法。以FileWallpaperInfo类为例。
它复写了 onSave方法
/*--- ↓ --- WallpaperPickerActivity.java *********/ @Override public void onSave(WallpaperPickerActivity a) { a.setWallpaper(Uri.fromFile(mFile), true); } /*--- ↑ --- (packages/apps/Trebuchet/WallpaperPicker/src/com/android/launcher3/) *********/
因为WallpaperPickerActivity 继承自 WallpaperCropActivity
setWallpaper方法在 WallpaperCropActivity中找到；传入了Uri和一个boolean值
/*↓ --- WallpaperCropActivity.java *********/ protected void setWallpaper(Uri uri, final boolean finishActivityWhenDone) { int rotation = getRotationFromExif(this, uri); BitmapCropTask cropTask = new BitmapCropTask( this, uri, null, rotation, 0, 0, true, false, null); final Point bounds = cropTask.getImageBounds(); Runnable onEndCrop = new Runnable() { public void run() { updateWallpaperDimensions(bounds.x, bounds.y); if (finishActivityWhenDone) { setResult(Activity.RESULT_OK); finish(); } } }; cropTask.setOnEndRunnable(onEndCrop); cropTask.setNoCrop(true); cropTask.execute(); } /*↑ --- (packages/apps/trebuchet/wallpaperpicker/src/com/android/launcher3) *********/
以上代码可以看出，它启动了一个异步任务 BitmapCropTask extends AsyncTask ；把一些列参数都传入了cropTask
启动一个线程onEndCrop，等待任务结束
进入BitmapCropTask看，系统做了什么工作
这是setWallpaper使用的构造方法
/*↓ --- WallpaperCropActivity.java *********/ public BitmapCropTask(Context c, Uri inUri, RectF cropBounds, int rotation, int outWidth, int outHeight, boolean setWallpaper, boolean saveCroppedBitmap, Runnable onEndRunnable) { mContext = c; mInUri = inUri; init(cropBounds, rotation, outWidth, outHeight, setWallpaper, saveCroppedBitmap, onEndRunnable); } // ...... private void init(RectF cropBounds, int rotation, int outWidth, int outHeight, boolean setWallpaper, boolean saveCroppedBitmap, Runnable onEndRunnable) { Log.d("rust","init after bitmapcroptask"); mCropBounds = cropBounds; mRotation = rotation; // 传入各项参数 mOutWidth = outWidth; mOutHeight = outHeight; mSetWallpaper = setWallpaper; mSaveCroppedBitmap = saveCroppedBitmap; mOnEndRunnable = onEndRunnable; } // ...... 在这里处理任务，启动 cropBitmap() @Override protected Boolean doInBackground(Void... params) { return cropBitmap(); } // ...... public boolean cropBitmap() { boolean failure = false; WallpaperManager wallpaperManager = null; if (mSetWallpaper) { wallpaperManager = WallpaperManager.getInstance(mContext.getApplicationContext()); } if (mSetWallpaper && mNoCrop) { try { InputStream is = regenerateInputStream(); // 获得InputStream if (is != null) { wallpaperManager.setStream(is); // 把is写进去，从这里进入到wallpaperManager Utils.closeSilently(is); } } catch (IOException e) { Log.w(LOGTAG, "cannot write stream to wallpaper", e); failure = true; } return !failure; } else { // 顺利的话不会进入这里 // ...... // Helper to setup input stream private InputStream regenerateInputStream() { if (mInUri == null && mInResId == 0 && mInFilePath == null && mInImageBytes == null) { Log.w(LOGTAG, "cannot read original file, no input URI, resource ID, or " + "image byte array given"); } else { try { String filepath = mInFilePath; if(mInUri != null){ filepath = DrmHelper.getFilePath(mContext, mInUri); } if(DrmHelper.isDrmFile(filepath)){ byte[] bytes = DrmHelper.getDrmImageBytes(filepath); return new ByteArrayInputStream(bytes); // 返回一个ByteArray } /*↑ --- (packages/apps/trebuchet/wallpaperpicker/src/com/android/launcher3) *********/
调用了wallpaperManager.setStream(is);进入 WallpaperManager.java 看看
/*↓ --- WallpaperManager.java *********/ public void setStream(InputStream data) throws IOException { //luncher3 里直接调用了这个方法 if (sGlobals.mService == null) { //WallpaperCropActivity 调用 Log.w(TAG, "WallpaperService not running"); return; } try { ParcelFileDescriptor fd = sGlobals.mService.setWallpaper(null); // 利用service得到fd if (fd == null) { // 这里要去WallpaperManagerService里找到对应方法 return; } FileOutputStream fos = null; try { fos = new ParcelFileDescriptor.AutoCloseOutputStream(fd); setWallpaper(data, fos); // 写入壁纸数据 } finally { if (fos != null) { fos.close(); } } } catch (RemoteException e) { // Ignore } } // ...... 在这里写入壁纸，写入过程结束，Manager完成任务 private void setWallpaper(InputStream data, FileOutputStream fos) throws IOException { byte[] buffer = new byte[32768]; int amt; while ((amt=data.read(buffer)) > 0) { fos.write(buffer, 0, amt); } } /*↑ --- (framework/base/core/java/android/app) *********/
再来看Globals extends IWallpaperManagerCallback.Stub
包含成员变量 IWallpaperManager mService，通过
Globals(Looper looper) { IBinder b = ServiceManager.getService(Context.WALLPAPER_SERVICE); mService = IWallpaperManager.Stub.asInterface(b); }
调用 WallpaperManagerService.java 里的setWallpaper方法
Service的作用
进入WallpaperManagerService看看，是如何返回ParcelFileDescriptor值的
/*↓ --- WallpaperManagerService.java *********/ public ParcelFileDescriptor setWallpaper(String name) { // 供 WallpaperManager 调用 checkPermission(android.Manifest.permission.SET_WALLPAPER); synchronized (mLock) { if (DEBUG) Slog.v(TAG, "setWallpaper"); int userId = UserHandle.getCallingUserId(); WallpaperData wallpaper = mWallpaperMap.get(userId); if (wallpaper == null) { throw new IllegalStateException("Wallpaper not yet initialized for user " + userId); } final long ident = Binder.clearCallingIdentity(); try { ParcelFileDescriptor pfd = updateWallpaperBitmapLocked(name, wallpaper); if (pfd != null) {// 启动下面的方法 wallpaper.imageWallpaperPending = true; } return pfd; // 返回ParcelFileDescriptor值给WallpaperManager } finally { Binder.restoreCallingIdentity(ident); } } } ParcelFileDescriptor updateWallpaperBitmapLocked(String name, WallpaperData wallpaper) { if (name == null) name = ""; try { File dir = getWallpaperDir(wallpaper.userId); // 找到壁纸 if (!dir.exists()) { dir.mkdir(); FileUtils.setPermissions( dir.getPath(), FileUtils.S_IRWXU|FileUtils.S_IRWXG|FileUtils.S_IXOTH, -1, -1); } File file = new File(dir, WALLPAPER); //创建一个新的文件 ParcelFileDescriptor fd = ParcelFileDescriptor.open(file, MODE_CREATE|MODE_READ_WRITE|MODE_TRUNCATE); if (!SELinux.restorecon(file)) { return null; } wallpaper.name = name; return fd; // 返回ParcelFileDescriptor值 } catch (FileNotFoundException e) { Slog.w(TAG, "Error setting wallpaper", e); } return null; } private static File getWallpaperDir(int userId) { // 取得壁纸文件 return Environment.getUserSystemDirectory(userId); } /*↑ --- (framework/base/services/core/java/com/android/server/wallpaper/) *********/
至此一个简单的流程就结束了
我们可反过来看
壁纸文件是存在 Environment.getUserSystemDirectory(userId) 这个路径下
WallpaperManagerService取到这个文件后，将其打开为ParcelFileDescriptor形式，交给WallpaperManager
WallpaperManager把launcher传来的数据写入这个文件中
小结一下：
选定壁纸，点击按钮，launcher把壁纸信息给WallpaperManager；
WallpaperManagerService把存放壁纸的文件打开，交给WallpaperManager
WallpaperManager把壁纸信息写入；一次设置壁纸的动作就完成了
这里传输数据使用到engine，一个挺有意思的东西。
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原文地址：http://www.cnblogs.com/rustfisher/p/4820490.html
