From dbe12662b8ff4e45ff9931357c8a5e927152d1bf Mon Sep 17 00:00:00 2001
From: Luke Wilde <lukew@serenityos.org>
Date: Sat, 1 Oct 2022 01:57:54 +0100
Subject: [PATCH] LibWeb: Implement matrix3d transform function from
 css-transforms-2

---
 .../Libraries/LibWeb/CSS/ResolvedCSSStyleDeclaration.cpp   | 3 +++
 Userland/Libraries/LibWeb/CSS/TransformFunctions.json      | 3 +++
 Userland/Libraries/LibWeb/Painting/StackingContext.cpp     | 7 +++++++
 3 files changed, 13 insertions(+)

diff --git a/Userland/Libraries/LibWeb/CSS/ResolvedCSSStyleDeclaration.cpp b/Userland/Libraries/LibWeb/CSS/ResolvedCSSStyleDeclaration.cpp
index db3bd4f4fa..1b80fd7811 100644
--- a/Userland/Libraries/LibWeb/CSS/ResolvedCSSStyleDeclaration.cpp
+++ b/Userland/Libraries/LibWeb/CSS/ResolvedCSSStyleDeclaration.cpp
@@ -458,6 +458,9 @@ RefPtr<StyleValue> ResolvedCSSStyleDeclaration::style_value_for_property(Layout:
         VERIFY(layout_node.paintable());
         auto const& paintable_box = verify_cast<Painting::PaintableBox const>(layout_node.paintable());
         VERIFY(paintable_box->stacking_context());
+
+        // FIXME: This needs to serialize to matrix3d if the transformation matrix is a 3D matrix.
+        //        https://w3c.github.io/csswg-drafts/css-transforms-2/#serialization-of-the-computed-value
         auto affine_matrix = paintable_box->stacking_context()->affine_transform_matrix();
 
         NonnullRefPtrVector<StyleValue> parameters;
diff --git a/Userland/Libraries/LibWeb/CSS/TransformFunctions.json b/Userland/Libraries/LibWeb/CSS/TransformFunctions.json
index f0dbe7022f..510f73bcdb 100644
--- a/Userland/Libraries/LibWeb/CSS/TransformFunctions.json
+++ b/Userland/Libraries/LibWeb/CSS/TransformFunctions.json
@@ -2,6 +2,9 @@
     "matrix": {
         "parameters": "<number>{6}"
     },
+    "matrix3d": {
+        "parameters": "<number>{16}"
+    },
     "translate": {
         "parameters": "<length-percentage>{1,2}"
     },
diff --git a/Userland/Libraries/LibWeb/Painting/StackingContext.cpp b/Userland/Libraries/LibWeb/Painting/StackingContext.cpp
index 53f1ce8c60..524cad258c 100644
--- a/Userland/Libraries/LibWeb/Painting/StackingContext.cpp
+++ b/Userland/Libraries/LibWeb/Painting/StackingContext.cpp
@@ -199,6 +199,13 @@ Gfx::FloatMatrix4x4 StackingContext::get_transformation_matrix(CSS::Transformati
                 0, 0, 1, 0,
                 0, 0, 0, 1);
         break;
+    case CSS::TransformFunction::Matrix3d:
+        if (count == 16)
+            return Gfx::FloatMatrix4x4(value(0), value(4), value(8), value(12),
+                value(1), value(5), value(9), value(13),
+                value(2), value(6), value(10), value(14),
+                value(3), value(7), value(11), value(15));
+        break;
     case CSS::TransformFunction::Translate:
         if (count == 1)
             return Gfx::FloatMatrix4x4(1, 0, 0, value(0, width),