Schlagwort: Thumbnail

The standard way on Android to get a thumbnail is to use MediaStore.Images.Thumbnails.getThumbnail or MediaStore.Video.Thumbnails.getThumbnail dependent if you want a thumbnail from an image or an video. Both of these methods return a Bitmap ready to use.

However, sometimes you may want to have the path to the thumbnail, e.g. because your own ContentProvider also need to provide thumbnails for files. The documentation of the thumbnail functionality is not that clear currently, but to build this functionality you can query the standard thumbnail content provider similiar to querying the media store for the real file.

To get the path of a mini thumbnail (MINI_KIND) for the image on the external storage you could do the following:

String getThumbnailPathForLocalFile(long fileId)
{
    Cursor thumbCursor = null;
    try
    {
        thumbCursor = getContext().getContentResolver().
                query(MediaStore.Images.Thumbnails.EXTERNAL_CONTENT_URI
                , null
                , MediaStore.Images.Thumbnails.IMAGE_ID + " = " + fileId+ " AND "
                  + MediaStore.Images.Thumbnails.KIND + " = "
                  + MediaStore.Images.Thumbnails.MINI_KIND , null, null);

        if(thumbCursor.moveToFirst())
        {
            // the path is stored in the DATA column
            int dataIndex = thumbCursor.getColumnIndexOrThrow( MediaStore.MediaColumns.DATA );
            String thumbnailPath = thumbCursor.getString(dataIndex);
            return thumbnailPath;
        }
    }
    finally
    {
        if(thumbCursor != null)
        {
            thumbCursor.close();
        }
    }

    return null;
}

Things to consider:

• Querying the thumbnail content provider does not trigger the creation of the thumbnail. If the query does not return anything, you should trigger the creation of the thumbnail by calling the appropriate getThumbnail method and then querying the thumbnail content provider again.
• Getting the path to the thumbnail only works for mini thumbnails (MINI_KIND) because only for these the Android system creates files to store the thumbnail. Micro thumbnails (MICRO_KIND) are stored in the database only. But at least you can get the raw data also by querying the thumbnail content provider as described above.