- fix letter's PointSize computation by applying the transform to a rectangle of height fontSize

- add test with rotated letters

src/UglyToad.PdfPig.Tests/Fonts/PointSizeTests.cs

@@ -0,0 +1,22 @@
+namespace UglyToad.PdfPig.Tests.Fonts
+{
+    using UglyToad.PdfPig.Tests.Dla;
+    using Xunit;
+
+    public class PointSizeTests
+    {
+        [Fact]
+        public void RotatedText()
+        {
+            using (var document = PdfDocument.Open(DlaHelper.GetDocumentPath("complex rotated")))
+            {
+                var page = document.GetPage(1);
+
+                foreach (var letter in page.Letters)
+                {
+                    Assert.Equal(12, letter.PointSize);
+                }
+            }
+        }
+    }
+}

src/UglyToad.PdfPig/Graphics/ContentStreamProcessor.cs

@@ -241,20 +241,7 @@
             var renderingMatrix =
                 TransformationMatrix.FromValues(fontSize * horizontalScaling, 0, 0, fontSize, 0, rise);
 
-            // TODO: this does not seem correct, produces the correct result for now but we need to revisit.
+            var pointSize = Math.Round(transformationMatrix.Multiply(TextMatrices.TextMatrix).Transform(new PdfRectangle(0, 0, 1, fontSize)).Height, 2);
-            // see: https://stackoverflow.com/questions/48010235/pdf-specification-get-font-size-in-points
-            var fontSizeMatrix = transformationMatrix.Multiply(TextMatrices.TextMatrix).Multiply(fontSize);
-            var pointSize = Math.Round(fontSizeMatrix.A, 2);
-            // Assume a rotated letter
-            if (pointSize == 0)
-            {
-                pointSize = Math.Round(fontSizeMatrix.B, 2);
-            }
-
-            if (pointSize < 0)
-            {
-                pointSize *= -1;
-            }
 
             while (bytes.MoveNext())
             {