Android Wallpaper之设置壁纸流程

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Android Wallpaper之设置壁纸流程

2023-10-20 19:25| 来源: 网络整理| 查看: 265

What?

什么是壁纸？

android wallpaper包括锁屏壁纸和桌面壁纸，壁纸又区分静态和动态两种。我们每天使用手机第一眼看到的就是壁纸，好看的壁纸对于手机的颜值也有大大的提升（滑稽），就让我们对壁纸一探究竟吧。

本文基于Android 8.1源码，相关文件如下：

1./frameworks/base/services/core/java/com/android/server/wallpaper/WallpaperManagerService.java

2./frameworks/base/services/core/java/android/app/WallpaperManager.java

3./frameworks/base/core/java/android/service/wallpaper/WallpaperService.java

4./frameworks/base/core/java/android/service/wallpaper/IwallpaperService.aidl

5./frameworks/base/packages/apps/SystemUI/src/com/android/systemui/statusbar/phone/LockscreenWallpaper.java

6./frameworks/base/packages/SystemUI/src/com/android/systemui/ImageWallpaper.java

7./frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBar.java

How?

1.作为开发者如何去设置壁纸？

2.壁纸是怎么显示的？

3.壁纸存储在什么位置？

如何设置壁纸？举个栗子。

咱们手机中一般有内置主题的应用，在这里可以下载使用非常多好看的壁纸，点击即可设置为锁屏或桌面壁纸。

设置方法很简单，look:

WallpaperManager wallpaperManager = WallpaperManager.getInstance(this); try { wallpaperManager.setStream(InputStream,null,true,WallpaperManager.FLAG_LOCK); } catch (IOException e) { e.printStackTrace(); } 三步骤：

1.添加设置壁纸的权限

2.获取WallpaperManager对象

3.设置壁纸，四个参数分别对应：

a.InputStream:图片对于的输入流

b.visibleCropHint:图片裁剪相关，一般默认为null

c.allowBack:是否允许回退

d.which:壁纸分为锁屏壁纸和桌面壁纸，所以需要设置FLGA:锁屏壁纸--WallpaperManager.FLAG_LOCK,桌面壁纸：WallpaperManager.FLAG_SYSTEM

壁纸是如何显示的？

下面就对如上图中的每个过程做一个简单的分析：

1.setStream try { //sGlobals.mService即WallpaperManagerService ParcelFileDescriptor fd = sGlobals.mService.setWallpaper(null, mContext.getOpPackageName(), visibleCropHint, allowBackup, result, which, completion, UserHandle.myUserId()); if (fd != null) { FileOutputStream fos = null; try { //将壁纸copy一份并存储到对应目录，默认是/data/system/users/0/wallpaper(或wallpaper_lock),其中0是主用户的userId，支持多用户 fos = new ParcelFileDescriptor.AutoCloseOutputStream(fd); copyStreamToWallpaperFile(bitmapData, fos); fos.close(); completion.waitForCompletion(); } finally { IoUtils.closeQuietly(fos); } } } catch (RemoteException e) { throw e.rethrowFromSystemServer(); } } 2.WallpaperManagerService.java#setWallpaper @Override public ParcelFileDescriptor setWallpaper(String name, String callingPackage, Rect cropHint, boolean allowBackup, Bundle extras, int which, IWallpaperManagerCallback completion, int userId) { //检查有没有设置壁纸的权限 checkPermission(android.Manifest.permission.SET_WALLPAPER); //调用setStream方法的时候参数which必须是正确的 if ((which & (FLAG_LOCK|FLAG_SYSTEM)) == 0) { final String msg = "Must specify a valid wallpaper category to set"; Slog.e(TAG, msg); throw new IllegalArgumentException(msg); } /* If we're setting system but not lock, and lock is currently sharing the system * wallpaper, we need to migrate that image over to being lock-only before * the caller here writes new bitmap data. */ //如果当前没有锁屏壁纸的话，并且是设置桌面壁纸即which == FLAG_SYSTEM，那么同时设置为锁屏壁纸 if (which == FLAG_SYSTEM && mLockWallpaperMap.get(userId) == null) { if (DEBUG) { Slog.i(TAG, "Migrating system->lock to preserve"); } migrateSystemToLockWallpaperLocked(userId); } ParcelFileDescriptor pfd = updateWallpaperBitmapLocked(name, wallpaper, extras); } 3.最主要的方法：WallpaperObserver#onEvent

WallpaperObserver是WallpaperManagerservice.java的内部类，它的主要职责是监听文件变化，也就是壁纸对应的文件更新,看下源码中关于它的注释：

/** * Observes the wallpaper for changes and notifies all IWallpaperServiceCallbacks * that the wallpaper has changed. The CREATE is triggered when there is no * wallpaper set and is created for the first time. The CLOSE_WRITE is triggered * every time the wallpaper is changed. */

监听wallpaper变化并通知IWallpaperServiceCallbacks,前文提到的LockscreenWallpaper就是继承了

IWallpaperServiceCallbacks，并重写了它的onWallppaerChanged方法，在这里更新锁屏壁纸的。

@Override public void onEvent(int event, String path) { //如果是锁屏壁纸更新 if (moved && lockWallpaperChanged) { notifyLockWallpaperChanged(); //android 8.0新增的一个变化，锁屏包括下拉快捷的主题会根据当前的壁纸来变化，避免壁纸和锁屏的图标颜色一致导致的显示不清问题，但是有一个缺陷就是： //获取的是当前壁纸的主色调，而不是某个区域的主色调，这样就会导致虽然主色调是白色，比如时间的区域是黑色，这一点小米做的比较好，它是根据当前区域的壁纸的主色调来进行反色的。 notifyWallpaperColorsChanged(wallpaper, FLAG_LOCK); return; } if (sysWallpaperChanged || lockWallpaperChanged) { notifyCallbacksLocked(wallpaper); } if (sysWallpaperChanged) { //桌面壁纸变化，那么bind ImageWallpaper，ImageWallpaper是负责显示静态桌面壁纸的 // If this was the system wallpaper, rebind... bindWallpaperComponentLocked(mImageWallpaper, true, false, wallpaper, null); notifyColorsWhich |= FLAG_SYSTEM; } if (lockWallpaperChanged || (wallpaper.whichPending & FLAG_LOCK) != 0) { if (DEBUG) { Slog.i(TAG, "Lock-relevant wallpaper changed"); } // either a lock-only wallpaper commit or a system+lock event. // if it's system-plus-lock we need to wipe the lock bookkeeping; // we're falling back to displaying the system wallpaper there. //如果参数which是system+lock，也就是同时设置锁屏和桌面壁纸，那么remove锁屏壁纸，因为已经是同一张壁纸了 if (!lockWallpaperChanged) { mLockWallpaperMap.remove(wallpaper.userId); } // and in any case, tell keyguard about it notifyLockWallpaperChanged(); notifyColorsWhich |= FLAG_LOCK; } } 先看锁屏壁纸更新这一部分： void notifyLockWallpaperChanged() { final IWallpaperManagerCallback cb = mKeyguardListener; if (cb != null) { try { cb.onWallpaperChanged(); } catch (RemoteException e) { // Oh well it went away; no big deal } } }

mKeyguardListener赋值的地方：

@Override public boolean setLockWallpaperCallback(IWallpaperManagerCallback cb) { checkPermission(android.Manifest.permission.INTERNAL_SYSTEM_WINDOW); synchronized (mLock) { mKeyguardListener = cb; } return true; }

前面我们说过LockscreenWallpaper.java是继承了IWallpaperManagerCallback的，那么setLockWallpaperCallback调用的地方应该是在这里：

public LockscreenWallpaper(Context ctx, PhoneStatusBar bar, Handler h) { mService = IWallpaperManager.Stub.asInterface( ServiceManager.getService(Context.WALLPAPER_SERVICE)); mWallpaperManager = (WallpaperManager) ctx.getSystemService(Context.WALLPAPER_SERVICE); try { //在这里给mKeyguardListener赋值的 mService.setLockWallpaperCallback(this); } catch (RemoteException e) { Log.e(TAG, "System dead?" + e); } } 4.LockscreenWallpaper.java#onWallpaperChanged： @Override public void onWallpaperChanged() { // Called on Binder thread. mH.removeCallbacks(this); mH.post(this); } LockscreenWallpaper实现了Runnable接口的，所以看下它的run方法： @Override public void run() { // Called in response to onWallpaperChanged on the main thread. mLoader = new AsyncTask() { @Override protected LoaderResult doInBackground(Void... params) { return loadBitmap(currentUser, selectedUser); } @Override protected void onPostExecute(LoaderResult result) { super.onPostExecute(result); if (isCancelled()) { return; } if (result.success) { mCached = true; mCache = result.bitmap; mUpdateMonitor.setHasLockscreenWallpaper(result.bitmap != null); //通知StatsuBar更新壁纸 mBar.updateMediaMetaData( true /* metaDataChanged */, true /* allowEnterAnimation */); } mLoader = null; } }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR); }异步获取壁纸，并通知StatusBar去更新壁纸。 5.StatusBar.java#updateMediaMetaData:

这里主要就是对锁屏壁纸所在的View做最基本的setImageBitmap。

6.再看桌面壁纸部分：

6.1 bindWallpaperComponentLocked if (sysWallpaperChanged) { // If this was the system wallpaper, rebind... bindWallpaperComponentLocked(mImageWallpaper, true, false, wallpaper, null); notifyColorsWhich |= FLAG_SYSTEM; } mImageWallpaper = ComponentName.unflattenFromString( context.getResources().getString(R.string.image_wallpaper_component));

也就是一开始提到的：

/frameworks/base/packages/SystemUI/src/com/android/systemui/ImageWallpaper.java

boolean bindWallpaperComponentLocked(ComponentName componentName, boolean force, boolean fromUser, WallpaperData wallpaper, IRemoteCallback reply) { Intent intent = new Intent(WallpaperService.SERVICE_INTERFACE); WallpaperConnection newConn = new WallpaperConnection(wi, wallpaper); //componentName就是ImageWallpaper intent.setComponent(componentName); intent.putExtra(Intent.EXTRA_CLIENT_LABEL, com.android.internal.R.string.wallpaper_binding_label); intent.putExtra(Intent.EXTRA_CLIENT_INTENT, PendingIntent.getActivityAsUser( mContext, 0, Intent.createChooser(new Intent(Intent.ACTION_SET_WALLPAPER), mContext.getText(com.android.internal.R.string.chooser_wallpaper)), 0, null, new UserHandle(serviceUserId))); } ImageWallpaper继承了Service，既然是bindService，那么主要看下conn,也就是WallpaperConnection。它的onServiceConnected方法： @Override public void onServiceConnected(ComponentName name, IBinder service) { synchronized (mLock) { if (mWallpaper.connection == this) { mService = IWallpaperService.Stub.asInterface(service); attachServiceLocked(this, mWallpaper); // XXX should probably do saveSettingsLocked() later // when we have an engine, but I'm not sure about // locking there and anyway we always need to be able to // recover if there is something wrong. saveSettingsLocked(mWallpaper.userId); FgThread.getHandler().removeCallbacks(mResetRunnable); } } } 6.2 继续看attachServcieLocked方法： void attachServiceLocked(WallpaperConnection conn, WallpaperData wallpaper) { try { conn.mService.attach(conn, conn.mToken, TYPE_WALLPAPER, false, wallpaper.width, wallpaper.height, wallpaper.padding); } catch (RemoteException e) { Slog.w(TAG, "Failed attaching wallpaper; clearing", e); if (!wallpaper.wallpaperUpdating) { bindWallpaperComponentLocked(null, false, false, wallpaper, null); } } }conn.mService.attach是调用了IWallpaperServiceWrapper 的attach方法，IWallpaperServiceWrapper 继承了 IWallpaperService.Stub。 @Override public void attach(IWallpaperConnection conn, IBinder windowToken, int windowType, boolean isPreview, int reqWidth, int reqHeight, Rect padding) { new IWallpaperEngineWrapper(mTarget, conn, windowToken, windowType, isPreview, reqWidth, reqHeight, padding); }

在看它的构造方法，发送了一个DO_ATTACH的消息：

Message msg = mCaller.obtainMessage(DO_ATTACH); mCaller.sendMessage(msg); case DO_ATTACH: { try { mConnection.attachEngine(this); } catch (RemoteException e) { Log.w(TAG, "Wallpaper host disappeared", e); return; } Engine engine = onCreateEngine(); mEngine = engine; mActiveEngines.add(engine); engine.attach(this); return; }

onCreateEngine也是一个抽象的方法：

/** * Must be implemented to return a new instance of the wallpaper's engine. * Note that multiple instances may be active at the same time, such as * when the wallpaper is currently set as the active wallpaper and the user * is in the wallpaper picker viewing a preview of it as well. */ public abstract Engine onCreateEngine();

实现的地方仍然是在ImageWallpaper.java里

@Override public Engine onCreateEngine() { mEngine = new DrawableEngine(); return mEngine; }

DrawableEngine是自定义的继承Engine的内部类

最后调用engine.attach方法。

WallpaperService.java的attach方法：

void attach(IWallpaperEngineWrapper wrapper) { onCreate(mSurfaceHolder); mInitializing = false; mReportedVisible = false; updateSurface(false, false, false); } 6.3 onCreate(mSurfaceHolder)

它是一个抽象方法

/** * Called once to initialize the engine. After returning, the * engine's surface will be created by the framework. */ public void onCreate(SurfaceHolder surfaceHolder) { }它是一个抽象方法，那么真正的实现是在它的子类，也就是ImageWallpaper.java里 @Override public void onCreate(SurfaceHolder surfaceHolder) { if (DEBUG) { Log.d(TAG, "onCreate"); } super.onCreate(surfaceHolder); mDefaultDisplay = getSystemService(WindowManager.class).getDefaultDisplay(); setOffsetNotificationsEnabled(false); updateSurfaceSize(surfaceHolder, getDefaultDisplayInfo(), false /* forDraw */); } surfaceHolder是在父类里初始化的，surfaceHolder = new BaseSurfaceHolder(); 6.4 updateSurfaceSize 在这里主要是继续调用loadWallpaper方法去解析壁纸并最终绘制到surfaceHolder上。 6.5 drawFrame

对壁纸进行一些裁剪操作，根据是否支持硬件加速来决定绘制的方法：

//支持硬件加速 if (mIsHwAccelerated) { if (!drawWallpaperWithOpenGL(sh, availw, availh, xPixels, yPixels)) { drawWallpaperWithCanvas(sh, availw, availh, xPixels, yPixels); } } else { drawWallpaperWithCanvas(sh, availw, availh, xPixels, yPixels); if (FIXED_SIZED_SURFACE) { // If the surface is fixed-size, we should only need to // draw it once and then we'll let the window manager // position it appropriately. As such, we no longer needed // the loaded bitmap. Yay! // hw-accelerated renderer retains bitmap for faster rotation unloadWallpaper(false /* forgetSize */); } }

到这里，把壁纸的设置的简单过程基本上就讲完了，作为笔记做一个记录。

如有错误的地方，欢迎指正。

【本文地址】

Android Wallpaper之设置壁纸流程

Android Wallpaper之设置壁纸流程

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