feat(cbr-to-pdf,pdf-to-cbr): add PDF to/from CBR conversion with ebook optimization option (#4581)

# Description of Changes This pull request adds support for converting CBR (Comic Book RAR) files to PDF, optimizes CBZ/CBR-to-PDF conversion for e-readers using Ghostscript, and improves file type detection and image file handling. It introduces the `CbrUtils` and `PdfToCbrUtils` utility classes, refactors CBZ conversion logic, and integrates these features into the API controller. The most important changes are grouped below. ### CBR Support and Conversion: - Added the `com.github.junrar:junrar` dependency to support RAR/CBR archive extraction in `build.gradle`. (https://github.com/junrar/junrar and https://github.com/junrar/junrar?tab=License-1-ov-file#readme for repo and license) - Introduced the new utility class `CbrUtils` for converting CBR files to PDF, including image extraction, sorting, and error handling. - Added the `PdfToCbrUtils` utility class to convert PDF files into CBR archives by rendering each page as an image and packaging them. ### CBZ/CBR Conversion Optimization: - Refactored `CbzUtils.convertCbzToPdf` to support optional Ghostscript optimization for e-reader compatibility and added a new method for this. - Added `GeneralUtils.optimizePdfWithGhostscript`, which uses Ghostscript to optimize PDFs for e-readers, and integrated error handling. ### API Controller Integration: - Updated `ConvertImgPDFController` to support CBR conversion, CBZ/CBR optimization toggling, and Ghostscript availability checks. ### Endpoints <img width="1298" height="522" alt="image" src="https://github.com/user-attachments/assets/144d3e03-a637-451a-9c35-f784b2a66dc1" /> <img width="1279" height="472" alt="image" src="https://github.com/user-attachments/assets/879f221d-b775-4224-8edb-a23dbea6a0ca" /> ### UI <img width="384" height="105" alt="image" src="https://github.com/user-attachments/assets/5f861943-0706-4fad-8775-c40a9c1f3170" /> ### File Type and Image Detection Improvements: - Improved file extension detection for comic book files and image files in `CbzUtils` and added a shared regex pattern utility for image files. ### Additional notes: - Please keep in mind new the dependency, this is not dependency-free implementation (as opposed to CBZ converter) - RAR 5 currently not supported. (because JUNRAR does not support it) - Added the new ebook optimization func to GeneralUtils since we'll soon (hopefully) at least 3 book/ebook formats (EPUB, CBZ, CBR) all of which can use it. - Once again this has been thoroughly tested but can't share actual "real life" file due to copyright. Closes: #775  --- ## Checklist ### General - [x] I have read the [Contribution Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md) - [x] I have read the [Stirling-PDF Developer Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md) (if applicable) - [ ] I have read the [How to add new languages to Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md) (if applicable) - [x] I have performed a self-review of my own code - [x] My changes generate no new warnings ### Documentation - [x] I have updated relevant docs on [Stirling-PDF's doc repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/) (if functionality has heavily changed) - [ ] I have read the section [Add New Translation Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags) (for new translation tags only) ### UI Changes (if applicable) - [x] Screenshots or videos demonstrating the UI changes are attached (e.g., as comments or direct attachments in the PR) ### Testing (if applicable) - [x] I have tested my changes locally. Refer to the [Testing Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing) for more details. --------- Signed-off-by: Balázs Szücs <[email protected]>
2026-07-14 18:44:05 +02:00 · 2025-10-04 11:15:23 +01:00
parent fd95876d8f
commit ec1ac4cb2d
19 changed files with 856 additions and 18 deletions
@@ -0,0 +1,258 @@
+package stirling.software.common.util;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+
+import org.apache.commons.io.FilenameUtils;
+import org.apache.pdfbox.pdmodel.PDDocument;
+import org.apache.pdfbox.pdmodel.PDPage;
+import org.apache.pdfbox.pdmodel.PDPageContentStream;
+import org.apache.pdfbox.pdmodel.common.PDRectangle;
+import org.apache.pdfbox.pdmodel.graphics.image.PDImageXObject;
+import org.springframework.web.multipart.MultipartFile;
+
+import com.github.junrar.Archive;
+import com.github.junrar.exception.CorruptHeaderException;
+import com.github.junrar.exception.RarException;
+import com.github.junrar.rarfile.FileHeader;
+
+import lombok.experimental.UtilityClass;
+import lombok.extern.slf4j.Slf4j;
+
+import stirling.software.common.service.CustomPDFDocumentFactory;
+
+@Slf4j
+@UtilityClass
+public class CbrUtils {
+
+    public byte[] convertCbrToPdf(
+            MultipartFile cbrFile,
+            CustomPDFDocumentFactory pdfDocumentFactory,
+            TempFileManager tempFileManager)
+            throws IOException {
+        return convertCbrToPdf(cbrFile, pdfDocumentFactory, tempFileManager, false);
+    }
+
+    public byte[] convertCbrToPdf(
+            MultipartFile cbrFile,
+            CustomPDFDocumentFactory pdfDocumentFactory,
+            TempFileManager tempFileManager,
+            boolean optimizeForEbook)
+            throws IOException {
+
+        validateCbrFile(cbrFile);
+
+        try (TempFile tempFile = new TempFile(tempFileManager, ".cbr")) {
+            cbrFile.transferTo(tempFile.getFile());
+
+            try (PDDocument document = pdfDocumentFactory.createNewDocument()) {
+
+                Archive archive;
+                try {
+                    archive = new Archive(tempFile.getFile());
+                } catch (CorruptHeaderException e) {
+                    log.warn(
+                            "Failed to open CBR/RAR archive due to corrupt header: {}",
+                            e.getMessage());
+                    throw ExceptionUtils.createIllegalArgumentException(
+                            "error.invalidFormat",
+                            "Invalid or corrupted CBR/RAR archive. "
+                                    + "The file may be corrupted, use an unsupported RAR format (RAR5+), "
+                                    + "or may not be a valid RAR archive. "
+                                    + "Please ensure the file is a valid RAR archive.");
+                } catch (RarException e) {
+                    log.warn("Failed to open CBR/RAR archive: {}", e.getMessage());
+                    String errorMessage;
+                    String exMessage = e.getMessage() != null ? e.getMessage() : "";
+
+                    if (exMessage.contains("encrypted")) {
+                        errorMessage = "Encrypted CBR/RAR archives are not supported.";
+                    } else if (exMessage.isEmpty()) {
+                        errorMessage =
+                                "Invalid CBR/RAR archive. "
+                                        + "The file may be encrypted, corrupted, or use an unsupported format.";
+                    } else {
+                        errorMessage =
+                                "Invalid CBR/RAR archive: "
+                                        + exMessage
+                                        + ". The file may be encrypted, corrupted, or use an unsupported format.";
+                    }
+                    throw ExceptionUtils.createIllegalArgumentException(
+                            "error.invalidFormat", errorMessage);
+                } catch (IOException e) {
+                    log.warn("IO error reading CBR/RAR archive: {}", e.getMessage());
+                    throw ExceptionUtils.createFileProcessingException("CBR extraction", e);
+                }
+
+                List<ImageEntryData> imageEntries = new ArrayList<>();
+
+                try {
+                    for (FileHeader fileHeader : archive) {
+                        if (!fileHeader.isDirectory() && isImageFile(fileHeader.getFileName())) {
+                            try (InputStream is = archive.getInputStream(fileHeader)) {
+                                ByteArrayOutputStream baos = new ByteArrayOutputStream();
+                                is.transferTo(baos);
+                                imageEntries.add(
+                                        new ImageEntryData(
+                                                fileHeader.getFileName(), baos.toByteArray()));
+                            } catch (Exception e) {
+                                log.warn(
+                                        "Error reading image {}: {}",
+                                        fileHeader.getFileName(),
+                                        e.getMessage());
+                            }
+                        }
+                    }
+                } finally {
+                    try {
+                        archive.close();
+                    } catch (IOException e) {
+                        log.warn("Error closing CBR/RAR archive: {}", e.getMessage());
+                    }
+                }
+
+                imageEntries.sort(
+                        Comparator.comparing(ImageEntryData::name, new NaturalOrderComparator()));
+
+                if (imageEntries.isEmpty()) {
+                    throw ExceptionUtils.createIllegalArgumentException(
+                            "error.fileProcessing",
+                            "No valid images found in the CBR file. The archive may be empty or contain no supported image formats.");
+                }
+
+                for (ImageEntryData imageEntry : imageEntries) {
+                    try {
+                        PDImageXObject pdImage =
+                                PDImageXObject.createFromByteArray(
+                                        document, imageEntry.data(), imageEntry.name());
+                        PDPage page =
+                                new PDPage(
+                                        new PDRectangle(pdImage.getWidth(), pdImage.getHeight()));
+                        document.addPage(page);
+                        try (PDPageContentStream contentStream =
+                                new PDPageContentStream(document, page)) {
+                            contentStream.drawImage(pdImage, 0, 0);
+                        }
+                    } catch (IOException e) {
+                        log.warn(
+                                "Error processing image {}: {}", imageEntry.name(), e.getMessage());
+                    }
+                }
+
+                if (document.getNumberOfPages() == 0) {
+                    throw ExceptionUtils.createIllegalArgumentException(
+                            "error.fileProcessing",
+                            "No images could be processed from the CBR file. All images may be corrupted or in unsupported formats.");
+                }
+
+                ByteArrayOutputStream baos = new ByteArrayOutputStream();
+                document.save(baos);
+                byte[] pdfBytes = baos.toByteArray();
+
+                // Apply Ghostscript optimization if requested
+                if (optimizeForEbook) {
+                    try {
+                        return GeneralUtils.optimizePdfWithGhostscript(pdfBytes);
+                    } catch (IOException e) {
+                        log.warn("Ghostscript optimization failed, returning unoptimized PDF", e);
+                        return pdfBytes;
+                    }
+                }
+
+                return pdfBytes;
+            }
+        }
+    }
+
+    private void validateCbrFile(MultipartFile file) {
+        if (file == null || file.isEmpty()) {
+            throw new IllegalArgumentException("File cannot be null or empty");
+        }
+
+        String filename = file.getOriginalFilename();
+        if (filename == null) {
+            throw new IllegalArgumentException("File must have a name");
+        }
+
+        String extension = FilenameUtils.getExtension(filename).toLowerCase();
+        if (!"cbr".equals(extension) && !"rar".equals(extension)) {
+            throw new IllegalArgumentException("File must be a CBR or RAR archive");
+        }
+    }
+
+    public boolean isCbrFile(MultipartFile file) {
+        String filename = file.getOriginalFilename();
+        if (filename == null) {
+            return false;
+        }
+
+        String extension = FilenameUtils.getExtension(filename).toLowerCase();
+        return "cbr".equals(extension) || "rar".equals(extension);
+    }
+
+    private boolean isImageFile(String filename) {
+        return RegexPatternUtils.getInstance().getImageFilePattern().matcher(filename).matches();
+    }
+
+    private record ImageEntryData(String name, byte[] data) {}
+
+    private class NaturalOrderComparator implements Comparator<String> {
+        private static String getChunk(String s, int length, int marker) {
+            StringBuilder chunk = new StringBuilder();
+            char c = s.charAt(marker);
+            chunk.append(c);
+            marker++;
+
+            if (isDigit(c)) {
+                while (marker < length && isDigit(s.charAt(marker))) {
+                    chunk.append(s.charAt(marker));
+                    marker++;
+                }
+            } else {
+                while (marker < length && !isDigit(s.charAt(marker))) {
+                    chunk.append(s.charAt(marker));
+                    marker++;
+                }
+            }
+            return chunk.toString();
+        }
+
+        private static boolean isDigit(char ch) {
+            return ch >= '0' && ch <= '9';
+        }
+
+        @Override
+        public int compare(String s1, String s2) {
+            int len1 = s1.length();
+            int len2 = s2.length();
+            int marker1 = 0, marker2 = 0;
+
+            while (marker1 < len1 && marker2 < len2) {
+                String chunk1 = getChunk(s1, len1, marker1);
+                marker1 += chunk1.length();
+
+                String chunk2 = getChunk(s2, len2, marker2);
+                marker2 += chunk2.length();
+
+                int result;
+                if (isDigit(chunk1.charAt(0)) && isDigit(chunk2.charAt(0))) {
+                    int thisNumericValue = Integer.parseInt(chunk1);
+                    int thatNumericValue = Integer.parseInt(chunk2);
+                    result = Integer.compare(thisNumericValue, thatNumericValue);
+                } else {
+                    result = chunk1.compareTo(chunk2);
+                }
+
+                if (result != 0) {
+                    return result;
+                }
+            }
+
+            return Integer.compare(len1, len2);
+        }
+    }
+}
@@ -8,7 +8,6 @@ import java.util.ArrayList;
 import java.util.Comparator;
 import java.util.Enumeration;
 import java.util.List;
-import java.util.regex.Pattern;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
 import java.util.zip.ZipInputStream;
@@ -30,14 +29,20 @@ import stirling.software.common.service.CustomPDFDocumentFactory;
@UtilityClass
 public class CbzUtils {

-    private final Pattern IMAGE_PATTERN =
-            Pattern.compile(".*\\.(jpg|jpeg|png|gif|bmp|webp)$", Pattern.CASE_INSENSITIVE);
-
    public byte[] convertCbzToPdf(
            MultipartFile cbzFile,
            CustomPDFDocumentFactory pdfDocumentFactory,
            TempFileManager tempFileManager)
            throws IOException {
+        return convertCbzToPdf(cbzFile, pdfDocumentFactory, tempFileManager, false);
+    }
+
+    public byte[] convertCbzToPdf(
+            MultipartFile cbzFile,
+            CustomPDFDocumentFactory pdfDocumentFactory,
+            TempFileManager tempFileManager,
+            boolean optimizeForEbook)
+            throws IOException {

        validateCbzFile(cbzFile);

@@ -106,7 +111,19 @@ public class CbzUtils {
                }
                ByteArrayOutputStream baos = new ByteArrayOutputStream();
                document.save(baos);
-                return baos.toByteArray();
+                byte[] pdfBytes = baos.toByteArray();
+
+                // Apply Ghostscript optimization if requested
+                if (optimizeForEbook) {
+                    try {
+                        return GeneralUtils.optimizePdfWithGhostscript(pdfBytes);
+                    } catch (IOException e) {
+                        log.warn("Ghostscript optimization failed, returning unoptimized PDF", e);
+                        return pdfBytes;
+                    }
+                }
+
+                return pdfBytes;
            }
        }
    }
@@ -137,8 +154,21 @@ public class CbzUtils {
        return "cbz".equals(extension) || "zip".equals(extension);
    }

+    public static boolean isComicBookFile(MultipartFile file) {
+        String filename = file.getOriginalFilename();
+        if (filename == null) {
+            return false;
+        }
+
+        String extension = FilenameUtils.getExtension(filename).toLowerCase();
+        return "cbz".equals(extension)
+                || "zip".equals(extension)
+                || "cbr".equals(extension)
+                || "rar".equals(extension);
+    }
+
    private boolean isImageFile(String filename) {
-        return IMAGE_PATTERN.matcher(filename).matches();
+        return RegexPatternUtils.getInstance().getImageFilePattern().matcher(filename).matches();
    }

    private record ImageEntryData(String name, byte[] data) {}
@@ -905,4 +905,67 @@ public class GeneralUtils {
        // If all components so far are equal, the longer version is considered higher
        return current.length > compare.length;
    }
+
+    /**
+     * Optimizes a PDF using Ghostscript with ebook settings for better e-reader compatibility. Uses
+     * -dPDFSETTINGS=/ebook -dFastWebView=true settings to create an optimized PDF.
+     *
+     * @param inputPdfBytes Original PDF as byte array
+     * @return Optimized PDF as byte array
+     * @throws IOException if Ghostscript optimization fails
+     */
+    public byte[] optimizePdfWithGhostscript(byte[] inputPdfBytes) throws IOException {
+        Path tempInput = null;
+        Path tempOutput = null;
+
+        try {
+            tempInput = Files.createTempFile("gs_input_", ".pdf");
+            tempOutput = Files.createTempFile("gs_output_", ".pdf");
+
+            Files.write(tempInput, inputPdfBytes);
+
+            List<String> command = new ArrayList<>();
+            command.add("gs");
+            command.add("-sDEVICE=pdfwrite");
+            command.add("-dPDFSETTINGS=/ebook");
+            command.add("-dFastWebView=true");
+            command.add("-dNOPAUSE");
+            command.add("-dQUIET");
+            command.add("-dBATCH");
+            command.add("-sOutputFile=" + tempOutput.toString());
+            command.add(tempInput.toString());
+
+            ProcessExecutor.ProcessExecutorResult result =
+                    ProcessExecutor.getInstance(ProcessExecutor.Processes.GHOSTSCRIPT)
+                            .runCommandWithOutputHandling(command);
+
+            if (result.getRc() != 0) {
+                log.warn(
+                        "Ghostscript ebook optimization failed with return code: {}",
+                        result.getRc());
+                throw ExceptionUtils.createGhostscriptCompressionException();
+            }
+
+            return Files.readAllBytes(tempOutput);
+
+        } catch (Exception e) {
+            log.warn("Ghostscript ebook optimization failed", e);
+            throw ExceptionUtils.createGhostscriptCompressionException(e);
+        } finally {
+            if (tempInput != null) {
+                try {
+                    Files.deleteIfExists(tempInput);
+                } catch (IOException e) {
+                    log.warn("Failed to delete temp input file: {}", tempInput, e);
+                }
+            }
+            if (tempOutput != null) {
+                try {
+                    Files.deleteIfExists(tempOutput);
+                } catch (IOException e) {
+                    log.warn("Failed to delete temp output file: {}", tempOutput, e);
+                }
+            }
+        }
+    }
 }
@@ -0,0 +1,99 @@
+package stirling.software.common.util;
+
+import java.awt.image.BufferedImage;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipOutputStream;
+
+import javax.imageio.ImageIO;
+
+import org.apache.commons.io.FilenameUtils;
+import org.apache.pdfbox.pdmodel.PDDocument;
+import org.apache.pdfbox.rendering.ImageType;
+import org.apache.pdfbox.rendering.PDFRenderer;
+import org.springframework.web.multipart.MultipartFile;
+
+import lombok.extern.slf4j.Slf4j;
+
+import stirling.software.common.service.CustomPDFDocumentFactory;
+
+@Slf4j
+public class PdfToCbrUtils {
+
+    public static byte[] convertPdfToCbr(
+            MultipartFile pdfFile, int dpi, CustomPDFDocumentFactory pdfDocumentFactory)
+            throws IOException {
+
+        validatePdfFile(pdfFile);
+
+        try (PDDocument document = pdfDocumentFactory.load(pdfFile)) {
+            if (document.getNumberOfPages() == 0) {
+                throw new IllegalArgumentException("PDF file contains no pages");
+            }
+
+            return createCbrFromPdf(document, dpi);
+        }
+    }
+
+    private static void validatePdfFile(MultipartFile file) {
+        if (file == null || file.isEmpty()) {
+            throw new IllegalArgumentException("File cannot be null or empty");
+        }
+
+        String filename = file.getOriginalFilename();
+        if (filename == null) {
+            throw new IllegalArgumentException("File must have a name");
+        }
+
+        String extension = FilenameUtils.getExtension(filename).toLowerCase();
+        if (!"pdf".equals(extension)) {
+            throw new IllegalArgumentException("File must be a PDF");
+        }
+    }
+
+    private static byte[] createCbrFromPdf(PDDocument document, int dpi) throws IOException {
+        PDFRenderer pdfRenderer = new PDFRenderer(document);
+
+        try (ByteArrayOutputStream cbrOutputStream = new ByteArrayOutputStream();
+                ZipOutputStream zipOut = new ZipOutputStream(cbrOutputStream)) {
+
+            int totalPages = document.getNumberOfPages();
+
+            for (int pageIndex = 0; pageIndex < totalPages; pageIndex++) {
+                try {
+                    BufferedImage image =
+                            pdfRenderer.renderImageWithDPI(pageIndex, dpi, ImageType.RGB);
+
+                    String imageFilename = String.format("page_%03d.png", pageIndex + 1);
+
+                    ZipEntry zipEntry = new ZipEntry(imageFilename);
+                    zipOut.putNextEntry(zipEntry);
+
+                    ImageIO.write(image, "PNG", zipOut);
+                    zipOut.closeEntry();
+
+                } catch (IOException e) {
+                    log.warn("Error processing page {}: {}", pageIndex + 1, e.getMessage());
+                } catch (OutOfMemoryError e) {
+                    throw ExceptionUtils.createOutOfMemoryDpiException(pageIndex + 1, dpi, e);
+                } catch (NegativeArraySizeException e) {
+                    throw ExceptionUtils.createOutOfMemoryDpiException(pageIndex + 1, dpi, e);
+                }
+            }
+
+            zipOut.finish();
+            return cbrOutputStream.toByteArray();
+        }
+    }
+
+    public static boolean isPdfFile(MultipartFile file) {
+        String filename = file.getOriginalFilename();
+        if (filename == null) {
+            return false;
+        }
+
+        String extension = FilenameUtils.getExtension(filename).toLowerCase();
+        return "pdf".equals(extension);
+    }
+}
@@ -437,6 +437,11 @@ public final class RegexPatternUtils {
                Pattern.CASE_INSENSITIVE);
    }

+    /** Pattern for matching image file extensions (case-insensitive) */
+    public Pattern getImageFilePattern() {
+        return getPattern(".*\\.(jpg|jpeg|png|gif|bmp|webp)$", Pattern.CASE_INSENSITIVE);
+    }
+
    /** Pattern for matching attachment section headers (case-insensitive) */
    public Pattern getAttachmentSectionPattern() {
        return getPattern("attachments\\s*\\(\\d+\\)", Pattern.CASE_INSENSITIVE);