Fix negative-origin viewBox image dimensions

src/Svg.Model/Services/SvgService.cs

@@ -730,7 +730,7 @@ public static SKSize GetDimensions(SvgFragment svgFragment, SKRect skViewport =
         if (isWidthperc && svgFragment is SvgDocument)
         {
             var bounds = percentViewport;
-            w = (bounds.Width + bounds.Left) * (svgFragment.Width.Value * 0.01f);
+            w = bounds.Width * (svgFragment.Width.Value * 0.01f);
         }
         else
         {
@@ -740,7 +740,7 @@ public static SKSize GetDimensions(SvgFragment svgFragment, SKRect skViewport =
         if (isHeightperc && svgFragment is SvgDocument)
         {
             var bounds = percentViewport;
-            h = (bounds.Height + bounds.Top) * (svgFragment.Height.Value * 0.01f);
+            h = bounds.Height * (svgFragment.Height.Value * 0.01f);
         }
         else
         {

tests/Svg.Skia.UnitTests/SKSvgTests.cs

@@ -107,6 +107,35 @@ public void Save_StandaloneDocumentWithExplicitPercentSize_UsesViewBoxWithoutCon
         Assert.Equal(100, image.Height);
     }
 
+    [Fact]
+    public void Save_StandaloneDocumentWithNegativeViewBoxOrigin_UsesViewBoxSize()
+    {
+        const string svgMarkup = """
+            <svg xmlns="http://www.w3.org/2000/svg" width="100%" height="100%" viewBox="-10 -20 120 80">
+              <rect x="-10" y="-20" width="120" height="80" fill="red" />
+            </svg>
+            """;
+
+        var document = SvgService.FromSvg(svgMarkup);
+        Assert.NotNull(document);
+
+        var size = SvgService.GetDimensions(document);
+        Assert.Equal(120f, size.Width);
+        Assert.Equal(80f, size.Height);
+
+        var svg = new SKSvg();
+        using var input = new MemoryStream(Encoding.UTF8.GetBytes(svgMarkup));
+        using var _ = svg.Load(input);
+        using var output = new MemoryStream();
+
+        Assert.True(svg.Save(output, SkiaSharp.SKColors.Transparent));
+
+        output.Position = 0;
+        using var image = Image.Load<Rgba32>(output);
+        Assert.Equal(120, image.Width);
+        Assert.Equal(80, image.Height);
+    }
+
     [Fact]
     public void Save_StandaloneDocumentWithExplicitPercentSize_UsesConfiguredStandaloneViewport()
     {

tests/Svg.Skia.UnitTests/SvgAnimationControllerTests.cs

@@ -330,7 +330,7 @@ public void SetAnimationTime_RebuildsRootViewBoxAnimations()
         Assert.Equal(50f, renderedDocument.ViewBox.Width, 3);
         Assert.Equal(50f, renderedDocument.ViewBox.Height, 3);
         Assert.Null(svg.HitTestTopmostElement(new SKPoint(65, 65)));
-        Assert.Equal("target", svg.HitTestTopmostElement(new SKPoint(25, 25))?.ID);
+        Assert.Equal("target", svg.HitTestTopmostElement(new SKPoint(15, 15))?.ID);
     }
 
     [Fact]