From 1f10693eafdd60c34443a44c22641773496e77ee Mon Sep 17 00:00:00 2001
From: sbplat <71648843+sbplat@users.noreply.github.com>
Date: Thu, 28 Dec 2023 03:23:55 +0000
Subject: [PATCH] fix: sequentially convert each pdf page into a BufferedImage
 to avoid getting MLE for large pdf files

---
 .../stirling/software/SPDF/utils/PdfUtils.java | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/src/main/java/stirling/software/SPDF/utils/PdfUtils.java b/src/main/java/stirling/software/SPDF/utils/PdfUtils.java
index 22e09d6a..000a8294 100644
--- a/src/main/java/stirling/software/SPDF/utils/PdfUtils.java
+++ b/src/main/java/stirling/software/SPDF/utils/PdfUtils.java
@@ -205,11 +205,6 @@ public class PdfUtils {
             int pageCount = document.getNumberOfPages();
             List<BufferedImage> images = new ArrayList<>();
 
-            // Create images of all pages
-            for (int i = 0; i < pageCount; i++) {
-                images.add(pdfRenderer.renderImageWithDPI(i, DPI, colorType));
-            }
-
             // Create a ByteArrayOutputStream to save the image(s) to
             ByteArrayOutputStream baos = new ByteArrayOutputStream();
 
@@ -226,8 +221,8 @@ public class PdfUtils {
                         writer.setOutput(ios);
                         writer.prepareWriteSequence(null);
 
-                        for (int i = 0; i < images.size(); ++i) {
-                            BufferedImage image = images.get(i);
+                        for (int i = 0; i < pageCount; ++i) {
+                            BufferedImage image = pdfRenderer.renderImageWithDPI(i, DPI, colorType);
                             writer.writeToSequence(new IIOImage(image, null, null), param);
                         }
 
@@ -240,8 +235,9 @@ public class PdfUtils {
                     BufferedImage combined = new BufferedImage(images.get(0).getWidth(), images.get(0).getHeight() * pageCount, BufferedImage.TYPE_INT_RGB);
                     Graphics g = combined.getGraphics();
 
-                    for (int i = 0; i < images.size(); i++) {
-                        g.drawImage(images.get(i), 0, i * images.get(0).getHeight(), null);
+                    for (int i = 0; i < pageCount; ++i) {
+                        BufferedImage image = pdfRenderer.renderImageWithDPI(i, DPI, colorType);
+                        g.drawImage(image, 0, i * image.getHeight(), null);
                     }
 
                     // Write the image to the output stream
@@ -253,8 +249,8 @@ public class PdfUtils {
             } else {
                 // Zip the images and return as byte array
                 try (ZipOutputStream zos = new ZipOutputStream(baos)) {
-                    for (int i = 0; i < images.size(); i++) {
-                        BufferedImage image = images.get(i);
+                    for (int i = 0; i < pageCount; ++i) {
+                        BufferedImage image = pdfRenderer.renderImageWithDPI(i, DPI, colorType);
                         try (ByteArrayOutputStream baosImage = new ByteArrayOutputStream()) {
                             ImageIO.write(image, imageType, baosImage);