From 1737b8f6d794f90ff90c9603f57ee119da314ad0 Mon Sep 17 00:00:00 2001
From: Andrew <andrew@digerati.co.nz>
Date: Thu, 20 Jun 2024 09:58:50 +1200
Subject: [PATCH] Keep fcTL after PLTE

---
 src/png/mod.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/png/mod.rs b/src/png/mod.rs
index a2135c47..f71846e6 100644
--- a/src/png/mod.rs
+++ b/src/png/mod.rs
@@ -186,9 +186,11 @@ impl PngData {
         // Ancillary chunks - split into those that come before IDAT and those that come after
         let mut aux_split = self.aux_chunks.split(|c| &c.name == b"IDAT");
         let aux_pre = aux_split.next().unwrap();
+        // Many chunks need to be before PLTE, so write all except those that explicitly need to be after
+        // Note: fcTL does not strictly need to be after PLTE but some software may expect it
         for chunk in aux_pre
             .iter()
-            .filter(|c| !(&c.name == b"bKGD" || &c.name == b"hIST" || &c.name == b"tRNS"))
+            .filter(|c| !matches!(&c.name, b"bKGD" | b"hIST" | b"tRNS" | b"fcTL"))
         {
             write_png_block(&chunk.name, &chunk.data, &mut output);
         }
@@ -223,7 +225,7 @@ impl PngData {
         // Special ancillary chunks that need to come after PLTE but before IDAT
         for chunk in aux_pre
             .iter()
-            .filter(|c| &c.name == b"bKGD" || &c.name == b"hIST" || &c.name == b"tRNS")
+            .filter(|c| matches!(&c.name, b"bKGD" | b"hIST" | b"tRNS" | b"fcTL"))
         {
             write_png_block(&chunk.name, &chunk.data, &mut output);
         }