问题描述

设置壁纸A为桌面和锁屏壁纸，设置默认壁纸为桌面壁纸，锁屏壁纸也变为默认壁纸A。

问题分析

设置默认壁纸为桌面壁纸时
vendor/mediatek/proprietary/packages/apps/WallpaperPicker/src/com/android/wallpaperpicker/tileinfo/DefaultWallpaperInfo.java

@Overridepublic void onSave(final WallpaperPickerActivity a) {CropAndSetWallpaperTask.OnEndCropHandler onEndCropHandler= new CropAndSetWallpaperTask.OnEndCropHandler() {@Overridepublic void run(boolean cropSucceeded) {if (cropSucceeded) {a.setResult(Activity.RESULT_OK);}a.finish();}};CropAndSetWallpaperTask setWallpaperTask = new CropAndSetWallpaperTask(null, a, null, -1, -1, -1, onEndCropHandler) {@Overrideprotected Boolean doInBackground(Integer... params) {int whichWallpaper = params[0];boolean succeeded;//当设置默认壁纸为锁屏壁纸时，走setDefaultOnLock//设置默认壁纸为桌面壁纸或者桌面和锁屏壁纸都走的是clearWallpaper，传入whichWallpaper参数if (whichWallpaper == WallpaperManagerCompat.FLAG_SET_LOCK) {succeeded = setDefaultOnLock(a);} else {succeeded = clearWallpaper(a, whichWallpaper);}return succeeded;}};DialogUtils.executeCropTaskAfterPrompt(a, setWallpaperTask, a.getOnDialogCancelListener());}

思路1

修改wallpaperPick应用，细分默认壁纸设置。
优势：只需要修改app，不需要修改framework层逻辑。
缺点：单独设置默认壁纸为桌面或者锁屏壁纸时，耗时严重

@Override
protected Boolean doInBackground(Integer... params) {int whichWallpaper = params[0];boolean succeeded;if (whichWallpaper == WallpaperManagerCompat.FLAG_SET_LOCK || whichWallpaper == WallpaperManagerCompat.FLAG_SET_SYSTEM) {succeeded = setDefaultOnLockOrHome(a,whichWallpaper);} else {succeeded = clearWallpaper(a, whichWallpaper);}return succeeded;
}

//这里设置默认壁纸为锁屏壁纸，操作的时候界面会卡很久
//如果我们把FLAG_SET_LOCK换为FLAG_SET_SYSTEM，就是设置主屏幕壁纸
//我们可以添加一个int whichWallpaper参数，决定设置为哪一个
private boolean setDefaultOnLock(WallpaperPickerActivity a) {boolean succeeded = true;try {Bitmap defaultWallpaper = ((BitmapDrawable) WallpaperManager.getInstance(a.getApplicationContext()).getBuiltInDrawable()).getBitmap();ByteArrayOutputStream tmpOut = new ByteArrayOutputStream(2048);if (defaultWallpaper.compress(Bitmap.CompressFormat.PNG, 100, tmpOut)) {byte[] outByteArray = tmpOut.toByteArray();WallpaperManagerCompat.getInstance(a.getApplicationContext()).setStream(new ByteArrayInputStream(outByteArray), null,true, WallpaperManagerCompat.FLAG_SET_LOCK);}} catch (IOException e) {Log.w(TAG, "Setting wallpaper to default threw exception", e);succeeded = false;}return succeeded;}

对setDefaultOnLock方法进行改造，修改后

private boolean setDefaultOnLockOrHome(WallpaperPickerActivity a，int whichWallpaper) {boolean succeeded = true;try {Bitmap defaultWallpaper = ((BitmapDrawable) WallpaperManager.getInstance(a.getApplicationContext()).getBuiltInDrawable()).getBitmap();ByteArrayOutputStream tmpOut = new ByteArrayOutputStream(2048);if (defaultWallpaper.compress(Bitmap.CompressFormat.PNG, 100, tmpOut)) {byte[] outByteArray = tmpOut.toByteArray();WallpaperManagerCompat.getInstance(a.getApplicationContext()).setStream(new ByteArrayInputStream(outByteArray), null,true, whichWallpaper);}} catch (IOException e) {Log.w(TAG, "Setting wallpaper to default threw exception", e);succeeded = false;}return succeeded;}

思路2

我们注意到，clearWallpaper(a, whichWallpaper);其实是有传入参数的，那么按照这个逻辑，应该是可以分别对锁屏或者桌面壁纸进行清除，使它显示默认壁纸，而不影响另一个。

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

//可以看到，判断当clear参数为FLAG_SYSTEM的时候走了clear，而不是clearWallpaper
public void clear(@SetWallpaperFlags int which) throws IOException {if ((which & FLAG_SYSTEM) != 0) {clear();}if ((which & FLAG_LOCK) != 0) {clearWallpaper(FLAG_LOCK, mContext.getUserId());}
}

修改为：

public void clear(@SetWallpaperFlags int which) throws IOException {//如果清除桌面和锁屏壁纸if ((which & FLAG_SYSTEM) != 0 && (which & FLAG_LOCK) != 0){clear();}//如果只清除桌面if ((which & FLAG_SYSTEM) != 0) {clearWallpaper(FLAG_SYSTEM, mContext.getUserId());}//如果只清除锁屏壁纸if ((which & FLAG_LOCK) != 0) {clearWallpaper(FLAG_LOCK, mContext.getUserId());}
}

按照理解，这样就可以了。但是实际上测下来还是没有效果。
原因
1、桌面壁纸显示为：vendor/mediatek/proprietary/packages/apps/SystemUI/src/com/android/systemui/ImageWallpaper.java
当桌面和锁屏显示不同的壁纸，锁屏壁纸显示为：
vendor/mediatek/proprietary/packages/apps/SystemUI/src/com/android/systemui/statusbar/NotificationMediaManager.java中的private ImageView mBackdropFront;

2、桌面和锁屏显示同一张壁纸的时候，锁屏其实不显示壁纸，透明过去显示桌面壁纸。
直接清除桌面壁纸，从效果上来说，锁屏不显示壁纸，透过去看到桌面壁纸，所以看上去桌面壁纸和锁屏壁纸都变了。

我们需要在清除壁纸之前，把桌面壁纸设置为锁屏壁纸，再去清除桌面壁纸。

这个思想来自于WallpaperManagerService的setWallpaper。见下文↓

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

//桌面壁纸
private final SparseArray<WallpaperData> mWallpaperMap = new SparseArray<WallpaperData>();
//锁屏壁纸
private final SparseArray<WallpaperData> mLockWallpaperMap = new SparseArray<WallpaperData>();//当我们设置壁纸时，如果上一次桌面和锁屏壁纸相同，如果直接设置下一张壁纸为桌面壁纸，那么锁屏壁纸会跟着变。
//这时候有一个特殊处理：：：
//判断是设置桌面壁纸并且锁屏没有单独设置，先把当前壁纸设置为锁屏壁纸。
//migrateSystemToLockWallpaperLocked
//再把要设置的壁纸设置为桌面壁纸
public ParcelFileDescriptor setWallpaper(String name, String callingPackage,Rect cropHint, boolean allowBackup, Bundle extras, int which,IWallpaperManagerCallback completion, int userId) {...synchronized (mLock) {if (DEBUG) Slog.v(TAG, "setWallpaper which=0x" + Integer.toHexString(which));WallpaperData wallpaper;/* 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.*/if (which == FLAG_SYSTEM && mLockWallpaperMap.get(userId) == null) {Slog.i(TAG, "Migrating current wallpaper to be lock-only before"+ "updating system wallpaper");migrateSystemToLockWallpaperLocked(userId);}...wallpaper = getWallpaperSafeLocked(userId, which); }
}//那么，clearWallpaper的时候，我们也这样设计一下
@Override
public void clearWallpaper(String callingPackage, int which, int userId) {if (DEBUG) Slog.v(TAG, "clearWallpaper");...synchronized (mLock) {//add start如果清除的是桌面壁纸，并且之前锁屏没有壁纸，先把桌面壁纸复制到锁屏壁纸if (which == FLAG_SYSTEM && mLockWallpaperMap.get(userId) == null) {Slog.i(TAG, "Migrating current wallpaper to be lock-only before"+ "clear system wallpaper");migrateSystemToLockWallpaperLocked(userId);}//add end再进行清除系统壁纸clearWallpaperLocked(false, which, userId, null);if (which == FLAG_LOCK) {data = mLockWallpaperMap.get(userId);}if (which == FLAG_SYSTEM || data == null) {data = mWallpaperMap.get(userId);}}...
}