/**
 * Abstract base class for thumbnail generators.
 * Provides common functionality for thumbnail generation implementations.
 */
public abstract class BaseThumbnailGenerator implements ThumbnailGenerator {
    private static final Logger logger = LogManager.getLogger(BaseThumbnailGenerator.class);

    /** Map of conditions for thumbnail generation. */
    protected final Map<String, String> conditionMap = new HashMap<>();

 * This class is used as a no-op thumbnail generator when thumbnail generation is disabled
 * or when no specific thumbnail generator is configured.
 */
public class EmptyGenerator extends BaseThumbnailGenerator {

    /**
     * Default constructor.
     */
    public EmptyGenerator() {
        super();
    }

    /**
     * Generates a thumbnail for the specified ID and output file.

 * ImageIO operations, and applies scaling and cropping to generate thumbnails
 * that meet the specified size requirements.</p>
 *
 */
public class HtmlTagBasedGenerator extends BaseThumbnailGenerator {

    private static final Logger logger = LogManager.getLogger(HtmlTagBasedGenerator.class);

    /**
     * Default constructor for HtmlTagBasedGenerator.
     */
    public HtmlTagBasedGenerator() {

 * Command-based thumbnail generator that executes external commands to create thumbnails.
 * Uses external tools through command execution to generate thumbnail images from documents.
 */
public class CommandGenerator extends BaseThumbnailGenerator {
    private static final Logger logger = LogManager.getLogger(CommandGenerator.class);

    /** List of command strings to execute for thumbnail generation. */
    protected List<String> commandList;