From 09b2b3539bf779d88827d0df3c7e9cad2fd15845 Mon Sep 17 00:00:00 2001
From: Lucas CHOLLET <lucas.chollet@free.fr>
Date: Thu, 18 Jan 2024 16:59:42 -0500
Subject: [PATCH] LibGfx/JPEG+CMYKBitmap: Extract the CMYK to RGB conversion
 code

Right now, the JPEG decoder is the only one supporting CMYK, but that
won't last for long. So, let's move the conversion to CMYKBitmap.
---
 Userland/Libraries/LibGfx/CMYKBitmap.cpp      | 17 ++++++++++++++++
 Userland/Libraries/LibGfx/CMYKBitmap.h        |  5 +++++
 .../LibGfx/ImageFormats/JPEGLoader.cpp        | 20 +------------------
 3 files changed, 23 insertions(+), 19 deletions(-)

diff --git a/Userland/Libraries/LibGfx/CMYKBitmap.cpp b/Userland/Libraries/LibGfx/CMYKBitmap.cpp
index b587bc570e..bc1822035b 100644
--- a/Userland/Libraries/LibGfx/CMYKBitmap.cpp
+++ b/Userland/Libraries/LibGfx/CMYKBitmap.cpp
@@ -15,4 +15,21 @@ ErrorOr<NonnullRefPtr<CMYKBitmap>> CMYKBitmap::create_with_size(IntSize const& s
     return adopt_ref(*new CMYKBitmap(size, move(data)));
 }
 
+ErrorOr<RefPtr<Bitmap>> CMYKBitmap::to_low_quality_rgb() const
+{
+    if (!m_rgb_bitmap) {
+        m_rgb_bitmap = TRY(Bitmap::create(BitmapFormat::BGRx8888, { m_size.width(), m_size.height() }));
+
+        for (int y = 0; y < m_size.height(); ++y) {
+            for (int x = 0; x < m_size.width(); ++x) {
+                auto const& cmyk = scanline(y)[x];
+                u8 k = 255 - cmyk.k;
+                m_rgb_bitmap->scanline(y)[x] = Color((255 - cmyk.c) * k / 255, (255 - cmyk.m) * k / 255, (255 - cmyk.y) * k / 255).value();
+            }
+        }
+    }
+
+    return m_rgb_bitmap;
+}
+
 }
diff --git a/Userland/Libraries/LibGfx/CMYKBitmap.h b/Userland/Libraries/LibGfx/CMYKBitmap.h
index e24bb2913e..497e864616 100644
--- a/Userland/Libraries/LibGfx/CMYKBitmap.h
+++ b/Userland/Libraries/LibGfx/CMYKBitmap.h
@@ -9,6 +9,7 @@
 #include <AK/ByteBuffer.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/RefCounted.h>
+#include <LibGfx/Bitmap.h>
 #include <LibGfx/Size.h>
 
 namespace Gfx {
@@ -32,6 +33,8 @@ public:
     [[nodiscard]] CMYK* begin();
     [[nodiscard]] CMYK* end();
 
+    ErrorOr<RefPtr<Bitmap>> to_low_quality_rgb() const;
+
 private:
     CMYKBitmap(IntSize const& size, ByteBuffer data)
         : m_size(size)
@@ -41,6 +44,8 @@ private:
 
     IntSize m_size;
     ByteBuffer m_data;
+
+    mutable RefPtr<Bitmap> m_rgb_bitmap;
 };
 
 inline CMYK* CMYKBitmap::scanline(int y)
diff --git a/Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.cpp b/Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.cpp
index 470f6d4ee8..7147e040a7 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.cpp
@@ -1694,24 +1694,6 @@ static void invert_colors_for_adobe_images(JPEGLoadingContext const& context, Ve
     }
 }
 
-static ErrorOr<void> cmyk_to_rgb(JPEGLoadingContext& context)
-{
-    VERIFY(context.cmyk_bitmap);
-    VERIFY(!context.bitmap);
-
-    context.bitmap = TRY(Bitmap::create(BitmapFormat::BGRx8888, { context.frame.width, context.frame.height }));
-
-    for (int y = 0; y < context.frame.height; ++y) {
-        for (int x = 0; x < context.frame.width; ++x) {
-            auto const& cmyk = context.cmyk_bitmap->scanline(y)[x];
-            u8 k = 255 - cmyk.k;
-            context.bitmap->scanline(y)[x] = Color((255 - cmyk.c) * k / 255, (255 - cmyk.m) * k / 255, (255 - cmyk.y) * k / 255).value();
-        }
-    }
-
-    return {};
-}
-
 static void ycck_to_cmyk(Vector<Macroblock>& macroblocks)
 {
     // 7 - Conversions between colour encodings
@@ -2026,7 +2008,7 @@ ErrorOr<ImageFrameDescriptor> JPEGImageDecoderPlugin::frame(size_t index, Option
     }
 
     if (m_context->cmyk_bitmap && !m_context->bitmap)
-        TRY(cmyk_to_rgb(*m_context));
+        return ImageFrameDescriptor { TRY(m_context->cmyk_bitmap->to_low_quality_rgb()), 0 };
 
     return ImageFrameDescriptor { m_context->bitmap, 0 };
 }