From 945064d709707298dbc9d7a2112d6ef815b132bc Mon Sep 17 00:00:00 2001
From: Andrew <andrew@digerati.co.nz>
Date: Sat, 27 May 2023 00:10:06 +1200
Subject: [PATCH] Fix tRNS size calc

---
 src/png/mod.rs | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/png/mod.rs b/src/png/mod.rs
index 46ccc04a..6502d05e 100644
--- a/src/png/mod.rs
+++ b/src/png/mod.rs
@@ -279,9 +279,8 @@ impl PngImage {
         match &self.ihdr.color_type {
             ColorType::Indexed { palette } => {
                 let plte = 12 + palette.len() * 3;
-                let trns = palette.iter().filter(|p| p.a != 255).count();
-                if trns != 0 {
-                    plte + 12 + trns
+                if let Some(trns) = palette.iter().rposition(|p| p.a != 255) {
+                    plte + 12 + trns + 1
                 } else {
                     plte
                 }