Merge pull request #5109 from MarchingCube/fix-non-invertible-matrix

Fix TransformToVisual not dealing with non-invertible transforms.

src/Avalonia.Visuals/Matrix.cs

@@ -282,25 +282,44 @@ namespace Avalonia
         }
 
         /// <summary>
-        /// Inverts the Matrix.
+        /// Attempts to invert the Matrix.
         /// </summary>
-        /// <returns>The inverted matrix.</returns>
-        public Matrix Invert()
+        /// <returns>The inverted matrix or <see langword="null"/> when matrix is not invertible.</returns>
+        public bool TryInvert(out Matrix inverted)
         {
             double d = GetDeterminant();
 
             if (MathUtilities.IsZero(d))
             {
-                throw new InvalidOperationException("Transform is not invertible.");
+                inverted = default;
+                
+                return false;
             }
 
-            return new Matrix(
+            inverted = new Matrix(
                 _m22 / d,
                 -_m12 / d,
                 -_m21 / d,
                 _m11 / d,
                 ((_m21 * _m32) - (_m22 * _m31)) / d,
                 ((_m12 * _m31) - (_m11 * _m32)) / d);
+
+            return true;
+        }
+
+        /// <summary>
+        /// Inverts the Matrix.
+        /// </summary>
+        /// <exception cref="InvalidOperationException">Matrix is not invertible.</exception>
+        /// <returns>The inverted matrix.</returns>
+        public Matrix Invert()
+        {
+            if (!TryInvert(out Matrix inverted))
+            {
+                throw new InvalidOperationException("Transform is not invertible.");
+            }
+
+            return inverted;
         }
 
         /// <summary>

src/Avalonia.Visuals/VisualExtensions.cs

@@ -50,7 +50,13 @@ namespace Avalonia
             {
                 var thisOffset = GetOffsetFrom(common, from);
                 var thatOffset = GetOffsetFrom(common, to);
-                return -thatOffset * thisOffset;
+
+                if (!thatOffset.TryInvert(out var thatOffsetInverted))
+                {
+                    return null;
+                }
+
+                return thatOffsetInverted * thisOffset;
             }
 
             return null;

tests/Avalonia.Visuals.UnitTests/VisualTests.cs

@@ -235,6 +235,25 @@ namespace Avalonia.Visuals.UnitTests
             Assert.Equal(new Point(100, 100), point);
         }
 
+        [Fact]
+        public void TransformToVisual_With_NonInvertible_RenderTransform_Should_Work()
+        {
+            var child = new Decorator
+            {
+                Width = 100,
+                Height = 100,
+                RenderTransform = new ScaleTransform() { ScaleX = 0, ScaleY = 0 }
+            };
+            var root = new TestRoot() { Child = child, Width = 400, Height = 400 };
+
+            root.Measure(Size.Infinity);
+            root.Arrange(new Rect(new Point(), root.DesiredSize));
+
+            var tr = root.TransformToVisual(child);
+
+            Assert.Null(tr);
+        }
+
         [Fact]
         public void Should_Not_Log_Binding_Error_When_Not_Attached_To_Logical_Tree()
         {