Fixed the matrix interop

binding/Binding/SKMatrix.cs

@@ -346,7 +346,7 @@ typeMask = Mask.Scale | Mask.RectStaysRect
 
 		public bool TryInvert (out SKMatrix inverse)
 		{
-			return SkiaApi.sk_matrix_try_invert (ref this, out inverse) != 0;
+			return SkiaApi.sk_matrix_try_invert (ref this, out inverse);
 		}
 
 		public static void Concat (ref SKMatrix target, SKMatrix first, SKMatrix second)

binding/Binding/SkiaApi.cs

@@ -1510,7 +1510,8 @@ namespace SkiaSharp
 
 		// matrix
 		[DllImport (SKIA, CallingConvention = CallingConvention.Cdecl)]
-		public extern static int sk_matrix_try_invert (ref SKMatrix matrix, out SKMatrix result);
+		[return: MarshalAs (UnmanagedType.I1)]
+		public extern static bool sk_matrix_try_invert (ref SKMatrix matrix, out SKMatrix result);
 		[DllImport (SKIA, CallingConvention = CallingConvention.Cdecl)]
 		public extern static void sk_matrix_concat (ref SKMatrix target, ref SKMatrix first, ref SKMatrix second);
 		[DllImport (SKIA, CallingConvention = CallingConvention.Cdecl)]

externals/skia

@@ -1 +1 @@
-Subproject commit ae5b160550244321c26510b6520270de275bbdcf
+Subproject commit 1cd54720ac6d215cd9086b18ef7582a4a85dd42f

tests/Tests/SKCanvasTest.cs

@@ -156,6 +156,20 @@ namespace SkiaSharp.Tests
 			}
 		}
 
+		[SkippableFact]
+		public void TotalMatrixIsCorrect()
+		{
+			using (var bitmap = new SKBitmap(new SKImageInfo(100, 100)))
+			using (var canvas = new SKCanvas(bitmap))
+			{
+				canvas.Translate(10, 20);
+				Assert.Equal(SKMatrix.MakeTranslation(10, 20).Values, canvas.TotalMatrix.Values);
+
+				canvas.Translate(10, 20);
+				Assert.Equal(SKMatrix.MakeTranslation(20, 40).Values, canvas.TotalMatrix.Values);
+			}
+		}
+
 		[SkippableFact]
 		public void SvgCanvasSavesFile()
 		{

tests/Tests/SKMatrixTests.cs

@@ -145,6 +145,48 @@ namespace SkiaSharp.Tests
 			Assert.Equal(results, actualResults);
 		}
 
+		[SkippableFact]
+		public void MatrixCanInvert()
+		{
+			var m = SKMatrix.MakeTranslation(10, 20);
+			Assert.True(m.TryInvert(out var inverse));
+			Assert.Equal(SKMatrix.MakeTranslation(-10, -20).Values, inverse.Values);
+		}
+
+		[SkippableFact]
+		public void MatrixCanConcat()
+		{
+			var a = SKMatrix.MakeTranslation(10, 20);
+			var b = SKMatrix.MakeTranslation(5, 7);
+			var c = new SKMatrix();
+
+			SKMatrix.Concat(ref c, ref a, ref b);
+			
+			Assert.Equal(SKMatrix.MakeTranslation(15, 27).Values, c.Values);
+		}
+
+		[SkippableFact]
+		public void MatrixCanPreConcat()
+		{
+			var a = SKMatrix.MakeTranslation(10, 20);
+			var b = SKMatrix.MakeTranslation(5, 7);
+
+			SKMatrix.PreConcat(ref a, ref b);
+			
+			Assert.Equal(SKMatrix.MakeTranslation(15, 27).Values, a.Values);
+		}
+
+		[SkippableFact]
+		public void MatrixCanPostConcat()
+		{
+			var a = SKMatrix.MakeTranslation(10, 20);
+			var b = SKMatrix.MakeTranslation(5, 7);
+
+			SKMatrix.PostConcat(ref a, ref b);
+			
+			Assert.Equal(SKMatrix.MakeTranslation(15, 27).Values, a.Values);
+		}
+
 		[SkippableFact]
 		public void MatrixMapsPoints()
 		{