From 27c704951d9b440dc9c7a2dedafe854de520650d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bal=C3=A1zs=20Sz=C3=BCcs?= <bszucs1209@gmail.com>
Date: Sat, 15 Nov 2025 18:17:06 +0100
Subject: [PATCH] feat(compress): add PDF linearization option using QPDF
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Signed-off-by: Balázs Szücs <bszucs1209@gmail.com>
---
 .../api/misc/CompressController.java          | 40 +++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/app/core/src/main/java/stirling/software/SPDF/controller/api/misc/CompressController.java b/app/core/src/main/java/stirling/software/SPDF/controller/api/misc/CompressController.java
index 865a95c5c..1fecc1aef 100644
--- a/app/core/src/main/java/stirling/software/SPDF/controller/api/misc/CompressController.java
+++ b/app/core/src/main/java/stirling/software/SPDF/controller/api/misc/CompressController.java
@@ -791,6 +791,16 @@ public class CompressController {
                 currentFile = originalFile;
             }
 
+            // Apply linearization as final step if requested
+            if (Boolean.TRUE.equals(request.getLinearize()) && isQpdfEnabled()) {
+                try {
+                    applyLinearization(currentFile, tempFiles);
+                    log.info("PDF linearization applied successfully");
+                } catch (IOException e) {
+                    log.warn("PDF linearization failed, continuing without linearization", e);
+                }
+            }
+
             String outputFilename =
                     GeneralUtils.generateFilename(
                             inputFile.getOriginalFilename(), "_Optimized.pdf");
@@ -810,6 +820,36 @@ public class CompressController {
         }
     }
 
+    // Apply PDF linearization using QPDF
+    private void applyLinearization(Path currentFile, List<Path> tempFiles) throws IOException {
+        log.info("Applying PDF linearization to: {}", currentFile);
+
+        // Create output file for linearization
+        Path linearizedOutputFile = Files.createTempFile("linearized_output_", ".pdf");
+        tempFiles.add(linearizedOutputFile);
+
+        // Build QPDF command for linearization only
+        List<String> command = new ArrayList<>();
+        command.add("qpdf");
+        command.add("--linearize");
+        command.add(currentFile.toString());
+        command.add(linearizedOutputFile.toString());
+
+        try {
+            ProcessExecutorResult returnCode =
+                    ProcessExecutor.getInstance(ProcessExecutor.Processes.QPDF)
+                            .runCommandWithOutputHandling(command);
+
+            // Update current file to the linearized output
+            Files.copy(linearizedOutputFile, currentFile, StandardCopyOption.REPLACE_EXISTING);
+
+            log.info("PDF linearization completed successfully");
+        } catch (Exception e) {
+            log.warn("PDF linearization failed", e);
+            throw new IOException("PDF linearization failed", e);
+        }
+    }
+
     // Run Ghostscript compression
     private void applyGhostscriptCompression(
             OptimizePdfRequest request, int optimizeLevel, Path currentFile, List<Path> tempFiles)