How to get android lock screen wallpaper?

Question

I use the code below to retrieve the android lock screen wallpaper on an android 8.1 phone:

WallpaperManager manager = WallpaperManager.getInstance(getActivi         


        

Answer 1

If no lock-specific wallpaper has been configured for the given user, then this method will return null when requesting FLAG_LOCK rather than returning the system wallpaper's image file.

Are you sure you have a valid lock screen wallpaper set for the current user?

 /**
     * Get an open, readable file descriptor to the given wallpaper image file.
     * The caller is responsible for closing the file descriptor when done ingesting the file.
     *
     * 
If no lock-specific wallpaper has been configured for the given user, then
     * this method will return {@code null} when requesting {@link #FLAG_LOCK} rather than
     * returning the system wallpaper's image file.
     *
     * @param which The wallpaper whose image file is to be retrieved.  Must be a single
     *     defined kind of wallpaper, either {@link #FLAG_SYSTEM} or
     *     {@link #FLAG_LOCK}.
     *
     * @see #FLAG_LOCK
     * @see #FLAG_SYSTEM
     */
    public ParcelFileDescriptor getWallpaperFile(@SetWallpaperFlags int which) {
        return getWallpaperFile(which, mContext.getUserId());
    }

There is a similar function in WallpaperManager openDefaultWallpaper in that if you want LOCK-SCREEN wallpaper you get null, always, as According to the code Factory-default lock wallpapers are not yet supported.

So in your case maybe you haven't set the Lock-Screen wallpaper. Just to test, Download any wallpaper app, and try to set a wallpaper, then use your earlier code, to get it.

/**
     * Open stream representing the default static image wallpaper.
     *
     * If the device defines no default wallpaper of the requested kind,
     * {@code null} is returned.
     *
     * @hide
     */
    public static InputStream openDefaultWallpaper(Context context, @SetWallpaperFlags int which) {
        final String whichProp;
        final int defaultResId;
        if (which == FLAG_LOCK) {
            /* Factory-default lock wallpapers are not yet supported
            whichProp = PROP_LOCK_WALLPAPER;
            defaultResId = com.android.internal.R.drawable.default_lock_wallpaper;
            */
            return null;
        }

You can check the code at : http://androidxref.com/8.1.0_r33/xref/frameworks/base/core/java/android/app/WallpaperManager.java#openDefaultWallpaper