From 097f7d0f56baecf35a63e29960666def35fb5925 Mon Sep 17 00:00:00 2001
From: Jan Solanti <jhs@psonet.com>
Date: Wed, 16 Oct 2019 00:21:15 +0300
Subject: [PATCH] Stop decoding BC1 punchthrough alpha in BC2&3

---
 src/libImaging/BcnDecode.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/libImaging/BcnDecode.c b/src/libImaging/BcnDecode.c
index b6a4cbadc..611daba57 100644
--- a/src/libImaging/BcnDecode.c
+++ b/src/libImaging/BcnDecode.c
@@ -69,7 +69,7 @@ decode_565(UINT16 x) {
 }
 
 static void
-decode_bc1_color(rgba *dst, const UINT8 *src) {
+decode_bc1_color(rgba *dst, const UINT8 *src, int separate_alpha) {
     bc1_color col;
     rgba p[4];
     int n, cw;
@@ -150,13 +150,13 @@ decode_bc3_alpha(char *dst, const UINT8 *src, int stride, int o) {
 
 static void
 decode_bc1_block(rgba *col, const UINT8 *src) {
-    decode_bc1_color(col, src);
+    decode_bc1_color(col, src, 0);
 }
 
 static void
 decode_bc2_block(rgba *col, const UINT8 *src) {
     int n, bitI, byI, av;
-    decode_bc1_color(col, src + 8);
+    decode_bc1_color(col, src + 8, 1);
     for (n = 0; n < 16; n++) {
         bitI = n * 4;
         byI = bitI >> 3;
@@ -168,7 +168,7 @@ decode_bc2_block(rgba *col, const UINT8 *src) {
 
 static void
 decode_bc3_block(rgba *col, const UINT8 *src) {
-    decode_bc1_color(col, src + 8);
+    decode_bc1_color(col, src + 8, 1);
     decode_bc3_alpha((char *)col, src, sizeof(col[0]), 3);
 }