From 89fa56241dd43aeec59807976c83e6d58bc54011 Mon Sep 17 00:00:00 2001
From: Benign X <1341398182@qq.com>
Date: Wed, 1 May 2024 15:40:02 +0800
Subject: [PATCH] =?UTF-8?q?=F0=9F=98=81(NewQuant):=20add=20color=5Fmap=5Fa?=
 =?UTF-8?q?lpha=20for=20the=20tRNS=20trunc=20in=20the=20PNG=20format?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: Benign X <1341398182@qq.com>
---
 src/lib.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index 2bb408b..136ac50 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -235,6 +235,16 @@ impl NeuQuant {
         map
     }
 
+    /// Return the Alpha channel of the color map calculated from the sample.
+    /// It's useful for transparency used in the tRNS chunk of the PNG format.
+    pub fn color_map_alpha(&self) -> Vec<u8> {
+        let mut map = Vec::with_capacity(self.netsize);
+        for entry in &self.colormap {
+            map.push(entry.a as u8);
+        }
+        map
+    }
+
     /// Move neuron i towards biased (a,b,g,r) by factor alpha
     fn salter_single(&mut self, alpha: f64, i: i32, quad: Quad<f64>) {
         let n = &mut self.network[i as usize];