From 71bd54891acbe2d92bab6910391abd3d4c3460c5 Mon Sep 17 00:00:00 2001
From: Moonchild <moonchild@palemoon.org>
Date: Fri, 16 Aug 2024 11:02:07 +0200
Subject: [PATCH] Issue #1810 - Implement {get|set}Transform with DOMMatrix
 arguments.

We already had part of the plumbing for other canvas manipulations, so
this is somewhat simplified.

This excludes the interface as that is breaking the build at this stage.
Some more research is required.
---
 dom/base/DOMMatrix.cpp                  |  9 ++------
 dom/base/DOMMatrix.h                    | 11 +++++++++-
 dom/canvas/CanvasRenderingContext2D.cpp | 28 +++++++++++++++++++++++++
 dom/canvas/CanvasRenderingContext2D.h   |  6 ++++++
 4 files changed, 46 insertions(+), 8 deletions(-)

diff --git a/dom/base/DOMMatrix.cpp b/dom/base/DOMMatrix.cpp
index 56cf6f1b17..f2dbe2a2a7 100644
--- a/dom/base/DOMMatrix.cpp
+++ b/dom/base/DOMMatrix.cpp
@@ -129,17 +129,12 @@ DOMMatrixReadOnly::SetDataFromMatrix2DInit(const DOMMatrix2DInit& aMatrixInit) {
 }
 
 void
-DOMMatrixReadOnly::SetDataFromMatrixInit(DOMMatrixInit& aMatrixInit)
+DOMMatrixReadOnly::SetDataFromMatrixInit(const DOMMatrixInit& aMatrixInit)
 {
   const bool is2D = aMatrixInit.mIs2D.Value();
   MOZ_ASSERT(is2D == Is2D());
   if (is2D) {
-    mMatrix2D->_11 = aMatrixInit.mM11.Value();
-    mMatrix2D->_12 = aMatrixInit.mM12.Value();
-    mMatrix2D->_21 = aMatrixInit.mM21.Value();
-    mMatrix2D->_22 = aMatrixInit.mM22.Value();
-    mMatrix2D->_31 = aMatrixInit.mM41.Value();
-    mMatrix2D->_32 = aMatrixInit.mM42.Value();
+    SetDataFromMatrix2DInit(aMatrixInit);
   } else {
     mMatrix3D->_11 = aMatrixInit.mM11.Value();
     mMatrix3D->_12 = aMatrixInit.mM12.Value();
diff --git a/dom/base/DOMMatrix.h b/dom/base/DOMMatrix.h
index 423580e2c4..9e961de7b4 100644
--- a/dom/base/DOMMatrix.h
+++ b/dom/base/DOMMatrix.h
@@ -52,6 +52,11 @@ public:
     mMatrix3D = new gfx::Matrix4x4(aMatrix);
   }
 
+  DOMMatrixReadOnly(nsISupports* aParent, const gfx::Matrix& aMatrix)
+    : mParent(aParent) {
+    mMatrix2D = new gfx::Matrix(aMatrix);
+  }
+
   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(DOMMatrixReadOnly)
   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(DOMMatrixReadOnly)
 
@@ -234,7 +239,7 @@ protected:
    * The init dictionary's dimension must match the matrix one.
    */
   void SetDataFromMatrix2DInit(const DOMMatrix2DInit& aMatrixInit);
-  void SetDataFromMatrixInit(DOMMatrixInit& aMatrixInit);
+  void SetDataFromMatrixInit(const DOMMatrixInit& aMatrixInit);
 
   DOMMatrixReadOnly* SetMatrixValue(const nsAString& aTransformList, ErrorResult& aRv);
   void Ensure3DMatrix();
@@ -268,6 +273,10 @@ public:
     : DOMMatrixReadOnly(aParent, aMatrix)
   {}
 
+  DOMMatrix(nsISupports* aParent, const gfx::Matrix& aMatrix)
+    : DOMMatrixReadOnly(aParent, aMatrix)
+  {}
+
   static already_AddRefed<DOMMatrix>
   FromMatrix(nsISupports* aParent, const DOMMatrixInit& aMatrixInit, ErrorResult& aRv);
   static already_AddRefed<DOMMatrix>
diff --git a/dom/canvas/CanvasRenderingContext2D.cpp b/dom/canvas/CanvasRenderingContext2D.cpp
index 60078a8fcb..d134cfade1 100644
--- a/dom/canvas/CanvasRenderingContext2D.cpp
+++ b/dom/canvas/CanvasRenderingContext2D.cpp
@@ -2229,6 +2229,18 @@ CanvasRenderingContext2D::Transform(double aM11, double aM12, double aM21,
   SetTransformInternal(newMatrix);
 }
 
+already_AddRefed<DOMMatrix>
+CanvasRenderingContext2D::GetTransform(ErrorResult& aError) {
+  EnsureTarget();
+  if (!IsTargetValid()) {
+    aError.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+  RefPtr<DOMMatrix> matrix =
+      new DOMMatrix(GetParentObject(), mTarget->GetTransform());
+  return matrix.forget();
+}
+
 void
 CanvasRenderingContext2D::SetTransform(double aM11, double aM12,
                                        double aM21, double aM22,
@@ -2244,6 +2256,22 @@ CanvasRenderingContext2D::SetTransform(double aM11, double aM12,
   SetTransformInternal(Matrix(aM11, aM12, aM21, aM22, aDx, aDy));
 }
 
+void
+CanvasRenderingContext2D::SetTransform(const DOMMatrix2DInit& aInit,
+                                       ErrorResult& aError) {
+  TransformWillUpdate();
+  if (!IsTargetValid()) {
+    aError.Throw(NS_ERROR_FAILURE);
+    return;
+  }
+
+  RefPtr<DOMMatrixReadOnly> matrix =
+      DOMMatrixReadOnly::FromMatrix(GetParentObject(), aInit, aError);
+  if (!aError.Failed()) {
+    SetTransformInternal(Matrix(*(matrix->GetInternal2D())));
+  }
+}
+
 void
 CanvasRenderingContext2D::SetTransformInternal(const Matrix& aTransform)
 {
diff --git a/dom/canvas/CanvasRenderingContext2D.h b/dom/canvas/CanvasRenderingContext2D.h
index d4f295a03f..81637e8eb6 100644
--- a/dom/canvas/CanvasRenderingContext2D.h
+++ b/dom/canvas/CanvasRenderingContext2D.h
@@ -57,6 +57,10 @@ class CanvasRenderingContext2DUserData;
 class CanvasDrawObserver;
 class CanvasShutdownObserver;
 
+class DOMMatrix;
+class DOMMatrixReadOnly;
+struct DOMMatrix2DInit;
+
 /**
  ** CanvasRenderingContext2D
  **/
@@ -88,8 +92,10 @@ public:
   void Translate(double aX, double aY, mozilla::ErrorResult& aError);
   void Transform(double aM11, double aM12, double aM21, double aM22, double aDx,
                  double aDy, mozilla::ErrorResult& aError);
+  already_AddRefed<DOMMatrix> GetTransform(mozilla::ErrorResult& aError);
   void SetTransform(double aM11, double aM12, double aM21, double aM22, double aDx,
                     double aDy, mozilla::ErrorResult& aError);
+  void SetTransform(const DOMMatrix2DInit& aInit, mozilla::ErrorResult& aError);
   void ResetTransform(mozilla::ErrorResult& aError);
 
   double GlobalAlpha()