Merge pull request #8256 from kaminova/master

Fix calculation of inverted matrix

src/Avalonia.Base/Matrix.cs

@@ -450,13 +450,13 @@ namespace Avalonia
             
             inverted = new Matrix(
                 (_m22 * _m33 - _m32 * _m23) * invdet,
-                (_m13 * _m31 - _m12 * _m33) * invdet,
+                (_m13 * _m32 - _m12 * _m33) * invdet,
                 (_m12 * _m23 - _m13 * _m22) * invdet,
                 (_m23 * _m31 - _m21 * _m33) * invdet,
                 (_m11 * _m33 - _m13 * _m31) * invdet,
                 (_m21 * _m13 - _m11 * _m23) * invdet,
                 (_m21 * _m32 - _m31 * _m22) * invdet,
-                (_m21 * _m12 - _m11 * _m32) * invdet,
+                (_m31 * _m12 - _m11 * _m32) * invdet,
                 (_m11 * _m22 - _m21 * _m12) * invdet
                 );
             

tests/Avalonia.Base.UnitTests/Media/MatrixTests.cs

@@ -30,6 +30,16 @@ namespace Avalonia.Base.UnitTests.Media
             Assert.True(matrix.HasInverse);
         }
 
+        [Fact]
+        public void Invert_Should_Work()
+        {
+            var matrix = new Matrix(1, 2, 3, 0, 1, 4, 5, 6, 0);
+            var inverted = matrix.Invert();
+
+            Assert.Equal(matrix * inverted, Matrix.Identity);
+            Assert.Equal(inverted * matrix, Matrix.Identity);
+        }
+
         [Fact]
         public void Can_Decompose_Translation()
         {