Mirrors/Stirling-PDF
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Compression fix

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This commit is contained in:
Anthony Stirling 2025-03-19 00:19:02 +00:00
parent 0fb76a1f4c
commit 853744864b
2 changed files with 138 additions and 32 deletions
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2
build.gradle
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@ -25,7 +25,7 @@ ext {
} }
group = "stirling.software" group = "stirling.software"
version = "0.44.2" version = "0.44.3"
java { java {
// 17 is lowest but we support and recommend 21 // 17 is lowest but we support and recommend 21

162
src/main/java/stirling/software/SPDF/controller/api/misc/CompressController.java
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@ -25,12 +25,23 @@ import javax.imageio.ImageWriter;
import javax.imageio.plugins.jpeg.JPEGImageWriteParam; import javax.imageio.plugins.jpeg.JPEGImageWriteParam;
import javax.imageio.stream.ImageOutputStream; import javax.imageio.stream.ImageOutputStream;
import org.apache.pdfbox.contentstream.PDFStreamEngine;
import org.apache.pdfbox.contentstream.operator.Operator;
import org.apache.pdfbox.cos.COSArray;
import org.apache.pdfbox.cos.COSBase;
import org.apache.pdfbox.cos.COSDictionary;
import org.apache.pdfbox.cos.COSName; import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.cos.COSStream;
import org.apache.pdfbox.pdmodel.PDDocument; import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDDocumentCatalog;
import org.apache.pdfbox.pdmodel.PDPage; import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDResources; import org.apache.pdfbox.pdmodel.PDResources;
import org.apache.pdfbox.pdmodel.graphics.PDXObject; import org.apache.pdfbox.pdmodel.graphics.PDXObject;
import org.apache.pdfbox.pdmodel.graphics.image.PDImageXObject; import org.apache.pdfbox.pdmodel.graphics.image.PDImageXObject;
import org.apache.pdfbox.pdmodel.graphics.image.PDInlineImage;
import org.apache.pdfbox.pdmodel.graphics.pattern.PDAbstractPattern;
import org.apache.pdfbox.pdmodel.graphics.pattern.PDTilingPattern;
import org.apache.pdfbox.pdmodel.graphics.shading.PDShading;
import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity; import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ModelAttribute; import org.springframework.web.bind.annotation.ModelAttribute;
@ -78,11 +89,19 @@ public class CompressController {
int pageNum; // Page number where the image appears int pageNum; // Page number where the image appears
COSName name; // The name used to reference this image COSName name; // The name used to reference this image
} }
@Data
@AllArgsConstructor
@NoArgsConstructor
private static class NestedImageReference extends ImageReference {
COSName formName; // Name of the form XObject containing the image
COSName imageName; // Name of the image within the form
}
public Path compressImagesInPDF( public Path compressImagesInPDF(
Path pdfFile, double scaleFactor, float jpegQuality, boolean convertToGrayscale) Path pdfFile, double scaleFactor, float jpegQuality, boolean convertToGrayscale)
throws Exception { throws Exception {
Path newCompressedPDF = Files.createTempFile("compressedPDF", ".pdf"); Path newCompressedPDF = Files.createTempFile("compressedPDF", ".pdf");
long originalFileSize = Files.size(pdfFile); long originalFileSize = Files.size(pdfFile);
log.info( log.info(
"Starting image compression with scale factor: {}, JPEG quality: {}, grayscale: {} on file size: {}", "Starting image compression with scale factor: {}, JPEG quality: {}, grayscale: {} on file size: {}",
@ -92,42 +111,84 @@ public class CompressController {
GeneralUtils.formatBytes(originalFileSize)); GeneralUtils.formatBytes(originalFileSize));
try (PDDocument doc = pdfDocumentFactory.load(pdfFile)) { try (PDDocument doc = pdfDocumentFactory.load(pdfFile)) {
// Collect all unique images by content hash // Collect all unique images by content hash
Map<String, List<ImageReference>> uniqueImages = new HashMap<>(); Map<String, List<ImageReference>> uniqueImages = new HashMap<>();
Map<String, PDImageXObject> compressedVersions = new HashMap<>(); Map<String, PDImageXObject> compressedVersions = new HashMap<>();
int totalImages = 0; int totalImages = 0;
int nestedImages = 0;
// FIRST PASS: Collect all images (direct and nested)
for (int pageNum = 0; pageNum < doc.getNumberOfPages(); pageNum++) { for (int pageNum = 0; pageNum < doc.getNumberOfPages(); pageNum++) {
PDPage page = doc.getPage(pageNum); PDPage page = doc.getPage(pageNum);
PDResources res = page.getResources(); PDResources res = page.getResources();
if (res == null || res.getXObjectNames() == null) continue; if (res == null || res.getXObjectNames() == null) continue;
// Process direct XObjects on page
for (COSName name : res.getXObjectNames()) { for (COSName name : res.getXObjectNames()) {
PDXObject xobj = res.getXObject(name); PDXObject xobj = res.getXObject(name);
if (!(xobj instanceof PDImageXObject)) continue;
totalImages++; // Direct image
PDImageXObject image = (PDImageXObject) xobj; if (xobj instanceof PDImageXObject) {
String imageHash = generateImageHash(image); totalImages++;
PDImageXObject image = (PDImageXObject) xobj;
String imageHash = generateImageHash(image);
// Store only page number and name reference ImageReference ref = new ImageReference();
ImageReference ref = new ImageReference(); ref.pageNum = pageNum;
ref.pageNum = pageNum; ref.name = name;
ref.name = name;
uniqueImages.computeIfAbsent(imageHash, k -> new ArrayList<>()).add(ref); log.info("Found direct image '{}' on page {} - {}x{}",
name.getName(), pageNum + 1, image.getWidth(), image.getHeight());
uniqueImages.computeIfAbsent(imageHash, k -> new ArrayList<>()).add(ref);
}
// Form XObject may contain nested images
else if (xobj instanceof org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject) {
org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject formXObj =
(org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject) xobj;
PDResources formResources = formXObj.getResources();
if (formResources != null && formResources.getXObjectNames() != null) {
// Process nested XObjects within the form
log.info("Checking form XObject '{}' on page {} for nested images",
name.getName(), pageNum + 1);
for (COSName nestedName : formResources.getXObjectNames()) {
PDXObject nestedXobj = formResources.getXObject(nestedName);
if (nestedXobj instanceof PDImageXObject) {
nestedImages++;
totalImages++;
PDImageXObject nestedImage = (PDImageXObject) nestedXobj;
log.info("Found nested image '{}' in form '{}' on page {} - {}x{}",
nestedName.getName(), name.getName(), pageNum + 1,
nestedImage.getWidth(), nestedImage.getHeight());
// Create a specialized reference for the nested image
NestedImageReference nestedRef = new NestedImageReference();
nestedRef.pageNum = pageNum;
nestedRef.formName = name;
nestedRef.imageName = nestedName;
String imageHash = generateImageHash(nestedImage);
uniqueImages.computeIfAbsent(imageHash, k -> new ArrayList<>()).add(nestedRef);
}
}
}
}
} }
} }
int uniqueImagesCount = uniqueImages.size(); int uniqueImagesCount = uniqueImages.size();
int duplicatedImages = totalImages - uniqueImagesCount; int duplicatedImages = totalImages - uniqueImagesCount;
log.info( log.info(
"Found {} unique images and {} duplicated instances across {} pages", "Found {} unique images and {} duplicated instances across {} pages ({} nested images in form XObjects)",
uniqueImagesCount, uniqueImagesCount,
duplicatedImages, duplicatedImages,
doc.getNumberOfPages()); doc.getNumberOfPages(),
nestedImages);
// SECOND PASS: Process each unique image exactly once // SECOND PASS: Process each unique image exactly once
int compressedImages = 0; int compressedImages = 0;
@ -143,10 +204,33 @@ public class CompressController {
// Get the first instance of this image // Get the first instance of this image
ImageReference firstRef = references.get(0); ImageReference firstRef = references.get(0);
PDPage firstPage = doc.getPage(firstRef.pageNum); PDImageXObject originalImage;
PDResources firstPageResources = firstPage.getResources();
PDImageXObject originalImage = // Handle differently based on whether it's a direct or nested image
(PDImageXObject) firstPageResources.getXObject(firstRef.name); if (firstRef instanceof NestedImageReference) {
// Get the nested image from within a form XObject
NestedImageReference nestedRef = (NestedImageReference) firstRef;
PDPage firstPage = doc.getPage(nestedRef.pageNum);
PDResources pageResources = firstPage.getResources();
// Get the form XObject
org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject formXObj =
(org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject) pageResources.getXObject(nestedRef.formName);
// Get the nested image from the form's resources
PDResources formResources = formXObj.getResources();
originalImage = (PDImageXObject) formResources.getXObject(nestedRef.imageName);
log.info("Processing nested image '{}' from form '{}'",
nestedRef.imageName.getName(), nestedRef.formName.getName());
} else {
// Get direct image from page resources
PDPage firstPage = doc.getPage(firstRef.pageNum);
PDResources firstPageResources = firstPage.getResources();
originalImage = (PDImageXObject) firstPageResources.getXObject(firstRef.name);
log.debug("Processing direct image '{}'", firstRef.name.getName());
}
// Track original size // Track original size
int originalSize = (int) originalImage.getCOSObject().getLength(); int originalSize = (int) originalImage.getCOSObject().getLength();
@ -185,14 +269,36 @@ public class CompressController {
// Replace ALL instances with the compressed version // Replace ALL instances with the compressed version
for (ImageReference ref : references) { for (ImageReference ref : references) {
// Get the page and resources when needed if (ref instanceof NestedImageReference) {
PDPage page = doc.getPage(ref.pageNum); // Replace nested image within form XObject
PDResources resources = page.getResources(); NestedImageReference nestedRef = (NestedImageReference) ref;
resources.put(ref.name, compressedImage); PDPage page = doc.getPage(nestedRef.pageNum);
PDResources pageResources = page.getResources();
log.info( // Get the form XObject
"Replaced image on page {} with compressed version", org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject formXObj =
ref.pageNum + 1); (org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject)
pageResources.getXObject(nestedRef.formName);
// Replace the nested image in the form's resources
PDResources formResources = formXObj.getResources();
formResources.put(nestedRef.imageName, compressedImage);
log.info(
"Replaced nested image '{}' in form '{}' on page {} with compressed version",
nestedRef.imageName.getName(),
nestedRef.formName.getName(),
nestedRef.pageNum + 1);
} else {
// Replace direct image in page resources
PDPage page = doc.getPage(ref.pageNum);
PDResources resources = page.getResources();
resources.put(ref.name, compressedImage);
log.info(
"Replaced direct image on page {} with compressed version",
ref.pageNum + 1);
}
} }
totalCompressedBytes += compressedData.length * references.size(); totalCompressedBytes += compressedData.length * references.size();
@ -216,11 +322,12 @@ public class CompressController {
: 0; : 0;
log.info( log.info(
"Image compression summary - Total unique: {}, Compressed: {}, Skipped: {}, Duplicates: {}", "Image compression summary - Total unique: {}, Compressed: {}, Skipped: {}, Duplicates: {}, Nested: {}",
uniqueImagesCount, uniqueImagesCount,
compressedImages, compressedImages,
skippedImages, skippedImages,
duplicatedImages); duplicatedImages,
nestedImages);
log.info( log.info(
"Total original image size: {}, compressed: {} (reduced by {}%)", "Total original image size: {}, compressed: {} (reduced by {}%)",
GeneralUtils.formatBytes(totalOriginalBytes), GeneralUtils.formatBytes(totalOriginalBytes),
@ -245,7 +352,6 @@ public class CompressController {
String.format("%.1f", overallReduction)); String.format("%.1f", overallReduction));
return newCompressedPDF; return newCompressedPDF;
} }
} }
private BufferedImage convertToGrayscale(BufferedImage image) { private BufferedImage convertToGrayscale(BufferedImage image) {
@ -611,7 +717,7 @@ public class CompressController {
// Check if optimized file is larger than the original // Check if optimized file is larger than the original
long finalFileSize = Files.size(currentFile); long finalFileSize = Files.size(currentFile);
if (finalFileSize > inputFileSize) { if (finalFileSize >= inputFileSize) {
log.warn("Optimized file is larger than the original. Using the original file instead."); log.warn("Optimized file is larger than the original. Using the original file instead.");
// Use the stored reference to the original file // Use the stored reference to the original file
currentFile = originalFile; currentFile = originalFile;