From 4350bccf8e8c2c6151bc665d3553236eab626c29 Mon Sep 17 00:00:00 2001
From: Andreas Kling <andreas@ladybird.org>
Date: Wed, 20 Aug 2025 22:01:30 +0200
Subject: [PATCH] LibWeb: Use Accelerate framework on macOS to premultiply
 bitmap data

This leverages hardware acceleration to speed things up considerably,
shaving ~500ms of load time off of https://cloudflare.com/
---
 Libraries/LibGfx/Bitmap.cpp     | 41 +++++++++++++++++++++++++++++++--
 Libraries/LibGfx/CMakeLists.txt |  1 +
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/Libraries/LibGfx/Bitmap.cpp b/Libraries/LibGfx/Bitmap.cpp
index 5434ba8b1fe..8f0a2a4aea6 100644
--- a/Libraries/LibGfx/Bitmap.cpp
+++ b/Libraries/LibGfx/Bitmap.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2024, Andreas Kling <andreas@ladybird.org>
+ * Copyright (c) 2018-2025, Andreas Kling <andreas@ladybird.org>
  * Copyright (c) 2022, Timothy Slater <tslater2006@gmail.com>
  * Copyright (c) 2024, Jelle Raaijmakers <jelle@ladybird.org>
  *
@@ -12,6 +12,10 @@
 #include <LibGfx/ShareableBitmap.h>
 #include <errno.h>
 
+#ifdef AK_OS_MACOS
+#    include <Accelerate/Accelerate.h>
+#endif
+
 namespace Gfx {
 
 struct BackingStore {
@@ -280,6 +284,39 @@ void Bitmap::set_alpha_type_destructive(AlphaType alpha_type)
     if (alpha_type == m_alpha_type)
         return;
 
+#ifdef AK_OS_MACOS
+    vImage_Buffer buf { .data = m_data, .height = vImagePixelCount(height()), .width = vImagePixelCount(width()), .rowBytes = pitch() };
+    vImage_Error err;
+    if (m_alpha_type == AlphaType::Unpremultiplied) {
+        switch (m_format) {
+        case BitmapFormat::BGRA8888:
+        case BitmapFormat::BGRx8888:
+            err = vImagePremultiplyData_BGRA8888(&buf, &buf, kvImageNoFlags);
+            break;
+        case BitmapFormat::RGBA8888:
+        case BitmapFormat::RGBx8888:
+            err = vImagePremultiplyData_RGBA8888(&buf, &buf, kvImageNoFlags);
+            break;
+        default:
+            VERIFY_NOT_REACHED();
+        }
+    } else {
+        switch (m_format) {
+        case BitmapFormat::BGRA8888:
+        case BitmapFormat::BGRx8888:
+            err = vImageUnpremultiplyData_BGRA8888(&buf, &buf, kvImageNoFlags);
+            break;
+        case BitmapFormat::RGBA8888:
+        case BitmapFormat::RGBx8888:
+            err = vImageUnpremultiplyData_RGBA8888(&buf, &buf, kvImageNoFlags);
+            break;
+        default:
+            VERIFY_NOT_REACHED();
+        }
+    }
+    VERIFY(err == kvImageNoError);
+#else
+    // FIXME: Make this fast on other platforms too.
     if (m_alpha_type == AlphaType::Unpremultiplied) {
         for (auto y = 0; y < height(); ++y) {
             for (auto x = 0; x < width(); ++x)
@@ -293,7 +330,7 @@ void Bitmap::set_alpha_type_destructive(AlphaType alpha_type)
     } else {
         VERIFY_NOT_REACHED();
     }
-
+#endif
     m_alpha_type = alpha_type;
 }
 
diff --git a/Libraries/LibGfx/CMakeLists.txt b/Libraries/LibGfx/CMakeLists.txt
index 7868393080d..59e702a1cba 100644
--- a/Libraries/LibGfx/CMakeLists.txt
+++ b/Libraries/LibGfx/CMakeLists.txt
@@ -168,6 +168,7 @@ endif()
 
 if (APPLE)
     target_link_libraries(LibCore PUBLIC "-framework Metal")
+    target_link_libraries(LibCore PUBLIC "-framework Accelerate")
 endif()
 
 if (HAS_VULKAN)