From 04511c607b43d89b72f21adcbb078119e93b75bd Mon Sep 17 00:00:00 2001
From: ritwic <ritwic@gmail.com>
Date: Thu, 19 Jun 2025 07:51:05 +0800
Subject: [PATCH] Parse the group blend mode from ExtGState in Form XObject
 Resources

---
 src/core/evaluator.js | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/src/core/evaluator.js b/src/core/evaluator.js
index edf02c2c0..0dfd1a5e8 100644
--- a/src/core/evaluator.js
+++ b/src/core/evaluator.js
@@ -510,6 +510,27 @@ class PartialEvaluator {
         smask.backdrop = colorSpace.getRgbHex(smask.backdrop, 0);
       }
 
+      // Parse group blend mode from ExtGState if it's in FormX Resources
+      const localResources = dict.get("Resources");
+      if (localResources instanceof Dict) {
+        const extGState = localResources.get("ExtGState");
+        if (extGState instanceof Dict) {
+          for (const val of extGState.getRawValues()) { 
+            if (val instanceof Dict && val.has("BM")) {
+              const blendMode = val.get("BM");
+              if (blendMode != null) {
+                try {
+                  groupOptions.blendMode = normalizeBlendMode(blendMode);
+                  break;
+                } catch (ex) {
+                  console.error(`Invalid blend mode in ExtGState: ${blendMode}`, ex);
+                }
+              }
+            }
+          }
+        }
+      }
+
       operatorList.addOp(OPS.beginGroup, [groupOptions]);
     }