From 3e553d1efe2183cb67256c64f9142be27d9c108a Mon Sep 17 00:00:00 2001
From: DreamPiggy <lizhuoli1126@126.com>
Date: Fri, 23 Feb 2024 16:05:18 +0800
Subject: [PATCH] Fix the issue that iOS 17 indexed PNG workaround breaks the
 16bit RGBA PNG

---
 SDWebImage/Core/SDImageIOAnimatedCoder.m | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/SDWebImage/Core/SDImageIOAnimatedCoder.m b/SDWebImage/Core/SDImageIOAnimatedCoder.m
index dca44f18..b529efbc 100644
--- a/SDWebImage/Core/SDImageIOAnimatedCoder.m
+++ b/SDWebImage/Core/SDImageIOAnimatedCoder.m
@@ -48,6 +48,10 @@ static CGImageRef __nullable SDCGImageCreateMutableCopy(CGImageRef cg_nullable i
     return newImage;
 }
 
+static inline BOOL SDCGImageIs8Bit(CGImageRef cg_nullable image) {
+    return CGImageGetBitsPerComponent(image) == 8;
+}
+
 static inline CGImageRef __nullable SDCGImageCreateCopy(CGImageRef cg_nullable image) {
     if (!image) return nil;
     return SDCGImageCreateMutableCopy(image, CGImageGetBitmapInfo(image));
@@ -209,6 +213,7 @@ static BOOL SDImageIOPNGPluginBuggyNeedWorkaround(void) {
     // See: #3605 FB13322459
     // ImageIO on iOS 17 (17.0~17.2), there is one serious problem on ImageIO PNG plugin. The decode result for indexed color PNG use the wrong CGImageAlphaInfo
     // The returned CGImageAlphaInfo is alpha last, but the actual bitmap data is premultiplied alpha last, which cause many runtime render bug.
+    // The bug only exists on 8-bits indexed color, not about 16-bits
     // So, we do a hack workaround:
     // 1. Decode a indexed color PNG in runtime
     // 2. If the bitmap is premultiplied alpha, then assume it's buggy
@@ -527,7 +532,7 @@ static BOOL SDImageIOPNGPluginBuggyNeedWorkaround(void) {
     // :)
     CFStringRef uttype = CGImageSourceGetType(source);
     SDImageFormat imageFormat = [NSData sd_imageFormatFromUTType:uttype];
-    if (imageFormat == SDImageFormatPNG && SDImageIOPNGPluginBuggyNeedWorkaround()) {
+    if (imageFormat == SDImageFormatPNG && SDCGImageIs8Bit(imageRef) && SDImageIOPNGPluginBuggyNeedWorkaround()) {
         CGImageRef newImageRef = SDImageIOPNGPluginBuggyCreateWorkaround(imageRef);
         CGImageRelease(imageRef);
         imageRef = newImageRef;