调用后动态壁纸其实是显示在Activity的后面，而Activity则是透明显示，这样就可以看到下面的动态壁纸，如果Activity不是透明的则什么也看不到。
代码中有用到两个接口
IWallpaperService mService;
IWallpaperEngine mEngine;
我们可以看到该目录下面有三个aidl接口，分别是
interface IWallpaperConnection {
void attachEngine(IWallpaperEngine engine);
ParcelFileDescriptor setWallpaper(String name);
}
oneway interface IWallpaperService {
void attach(IWallpaperConnection connection,
IBinder windowToken, int windowType, boolean isPreview,
int reqWidth, int reqHeight);
}
oneway interface IWallpaperEngine {
void setDesiredSize(int width, int height);
void setVisibility(boolean visible);
void dispatchPointer(in MotionEvent event);
void dispatchWallpaperCommand(String action, int x, int y, int z, in Bundle extras);
void destroy();
}
定义壁纸管理和壁纸信息变量
private WallpaperManager mWallpaperManager = null;
private WallpaperInfo mWallpaperInfo = null;
private WallpaperConnection mWallpaperConnection = null;
private Intent mWallpaperIntent;
初始化这些变量
mWallpaperManager = WallpaperManager.getInstance(this);
mWallpaperInfo = mWallpaperManager.getWallpaperInfo();//如果返回null则说明当前不是动态壁纸
mWallpaperIntent = new Intent(WallpaperService.SERVICE_INTERFACE);
mWallpaperIntent.setClassName(mWallpaperInfo.getPackageName(), mWallpaperInfo.getServiceName());
绑定动态壁纸服务
bindService(mIntent, this, Context.BIND_AUTO_CREATE);
IWallpaperService mService;//这里有一个adil接口
在连接监听中试着attach
public void onServiceConnected(ComponentName name, IBinder service) {
mService = IWallpaperService.Stub.asInterface(service);
try {
mService.attach(this, view.getWindowToken(),
// WindowManager.LayoutParams.TYPE_APPLICATION_MEDIA_OVERLAY,
WindowManager.LayoutParams.TYPE_APPLICATION_MEDIA,
true, root.getWidth(), root.getHeight());
} catch (RemoteException e) {
Log.w("", "Failed attaching wallpaper; clearing", e);
}
}
在bindService的时候发现总是失败，后来发现是权限问题，只有拥有系统权限的apk才可以使用WallpaperService.SERVICE_INTERFACE服务，所以问题就变成了怎么获取系统权限。
