From 9cbed7b359139f89e1a1d879c3273217f0d4b5a8 Mon Sep 17 00:00:00 2001
From: Lucas CHOLLET <lucas.chollet@free.fr>
Date: Tue, 21 Mar 2023 18:23:47 -0400
Subject: [PATCH] LibGfx/JPEG: Support for images with four components

This patch adds support for properly read images with four components,
basically CMYK or YCCK. However, we still lack color spaces
transformations for this type of image. So, it just postpones failure.
---
 .../Libraries/LibGfx/ImageFormats/JPEGLoader.cpp | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.cpp b/Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.cpp
index 85afc901d8..05dd008c6c 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.cpp
@@ -115,6 +115,8 @@ struct Macroblock {
         i32 cr[64] = { 0 };
         i32 b[64];
     };
+
+    i32 k[64] = { 0 };
 };
 
 struct MacroblockMeta {
@@ -197,7 +199,7 @@ struct ICCMultiChunkState {
 
 struct Scan {
     // B.2.3 - Scan header syntax
-    Vector<ScanComponent, 3> components;
+    Vector<ScanComponent, 4> components;
 
     u8 spectral_selection_start {};      // Ss
     u8 spectral_selection_end {};        // Se
@@ -242,12 +244,12 @@ struct JPEGLoadingContext {
 
     Scan current_scan;
 
-    Vector<Component, 3> components;
+    Vector<Component, 4> components;
     RefPtr<Gfx::Bitmap> bitmap;
     u16 dc_restart_interval { 0 };
     HashMap<u8, HuffmanTableSpec> dc_tables;
     HashMap<u8, HuffmanTableSpec> ac_tables;
-    Array<i32, 3> previous_dc_values {};
+    Array<i32, 4> previous_dc_values {};
     MacroblockMeta mblock_meta;
     OwnPtr<FixedMemoryStream> stream;
 
@@ -316,8 +318,12 @@ static inline i32* get_component(Macroblock& block, unsigned component)
         return block.y;
     case 1:
         return block.cb;
-    default:
+    case 2:
         return block.cr;
+    case 3:
+        return block.k;
+    default:
+        VERIFY_NOT_REACHED();
     }
 }
 
@@ -1020,7 +1026,7 @@ static ErrorOr<void> read_start_of_frame(Stream& stream, JPEGLoadingContext& con
     set_macroblock_metadata(context);
 
     auto component_count = TRY(stream.read_value<u8>());
-    if (component_count != 1 && component_count != 3) {
+    if (component_count != 1 && component_count != 3 && component_count != 4) {
         dbgln_if(JPEG_DEBUG, "Unsupported number of components in SOF: {}!", component_count);
         return Error::from_string_literal("Unsupported number of components in SOF");
     }