#75 support vertical writing mode fonts

src/UglyToad.PdfPig.Tests/Fonts/CidFonts/VerticalWritingMetricsTests.cs

@@ -0,0 +1,62 @@
+namespace UglyToad.PdfPig.Tests.Fonts.CidFonts
+{
+    using System.Collections.Generic;
+    using PdfPig.Fonts.CidFonts;
+    using PdfPig.Geometry;
+    using Xunit;
+
+    public class VerticalWritingMetricsTests
+    {
+        private readonly VerticalVectorComponents defaults = new VerticalVectorComponents(250, 600);
+
+        [Fact]
+        public void UsesDefaultWhenOverridesNull()
+        {
+            var data = new VerticalWritingMetrics(defaults, null, null);
+
+            Assert.Empty(data.IndividualVerticalWritingDisplacements);
+            Assert.Empty(data.IndividualVerticalWritingPositions);
+
+            var position = data.GetPositionVector(60, 250);
+            Assert.Equal(defaults.Position, position.Y);
+
+            var displacement = data.GetDisplacementVector(32);
+            Assert.Equal(defaults.Displacement, displacement.Y);
+        }
+
+        [Fact]
+        public void DefaultXComponentsOfVectorsAreCorrect()
+        {
+            var data = new VerticalWritingMetrics(defaults, null, null);
+
+            var position = data.GetPositionVector(9, 120);
+            Assert.Equal(120 / 2m, position.X);
+
+            var displacement = data.GetDisplacementVector(10);
+            Assert.Equal(0m, displacement.X);
+        }
+
+        [Fact]
+        public void UsesVectorOverridesWhenPresent()
+        {
+            var data = new VerticalWritingMetrics(defaults, new Dictionary<int, decimal> {{7, 120}},
+                new Dictionary<int, PdfVector> {{7, new PdfVector(25, 250)}});
+
+            var position = data.GetPositionVector(7, 360);
+            Assert.Equal(25, position.X);
+            Assert.Equal(250, position.Y);
+
+            var displacement = data.GetDisplacementVector(7);
+            Assert.Equal(0, displacement.X);
+            Assert.Equal(120, displacement.Y);
+
+            var defaultPosition = data.GetPositionVector(6, 100);
+            Assert.Equal(50, defaultPosition.X);
+            Assert.Equal(defaults.Position, defaultPosition.Y);
+
+            var defaultDisplacement = data.GetDisplacementVector(6);
+            Assert.Equal(0, defaultDisplacement.X);
+            Assert.Equal(defaults.Displacement, defaultDisplacement.Y);
+        }
+    }
+}

src/UglyToad.PdfPig/Fonts/CidFonts/ICidFont.cs

@@ -45,5 +45,9 @@
         decimal GetWidthFromFont(int characterIdentifier);
 
         PdfRectangle GetBoundingBox(int characterIdentifier);
+
+        PdfVector GetPositionVector(int characterIdentifier);
+
+        PdfVector GetDisplacementVector(int characterIdentifier);
     }
 }

src/UglyToad.PdfPig/Fonts/CidFonts/Type0CidFont.cs

@@ -14,20 +14,30 @@
     internal class Type0CidFont : ICidFont
     {
         private readonly ICidFontProgram fontProgram;
+        private readonly VerticalWritingMetrics verticalWritingMetrics;
+
         public NameToken Type { get; }
+
         public NameToken SubType { get; }
+
         public NameToken BaseFont { get; }
+
         public CharacterIdentifierSystemInfo SystemInfo { get; }
+
         public TransformationMatrix FontMatrix { get; }
+
         public CidFontType CidFontType => CidFontType.Type0;
+
         public FontDescriptor Descriptor { get; }
+
         public IReadOnlyDictionary<int, decimal> Widths { get; }
 
         public Type0CidFont(ICidFontProgram fontProgram, NameToken type, NameToken subType, NameToken baseFont,
             CharacterIdentifierSystemInfo systemInfo,
-            FontDescriptor descriptor, IReadOnlyDictionary<int, decimal> widths)
+            FontDescriptor descriptor, VerticalWritingMetrics verticalWritingMetrics, IReadOnlyDictionary<int, decimal> widths)
         {
             this.fontProgram = fontProgram;
+            this.verticalWritingMetrics = verticalWritingMetrics;
             Type = type;
             SubType = subType;
             BaseFont = baseFont;
@@ -56,9 +66,14 @@
             }
 
             // TODO: correct values
+            if (Descriptor == null)
+            {
                 return 250;
             }
 
+            return Descriptor.MissingWidth;
+        }
+
         public PdfRectangle GetBoundingBox(int characterIdentifier)
         {
             // TODO: correct values
@@ -79,5 +94,17 @@
 
             return new PdfRectangle(0, 0, 250, 0);
         }
+
+        public PdfVector GetPositionVector(int characterIdentifier)
+        {
+            var width = GetWidthFromFont(characterIdentifier);
+
+            return verticalWritingMetrics.GetPositionVector(characterIdentifier, width);
+        }
+
+        public PdfVector GetDisplacementVector(int characterIdentifier)
+        {
+            return verticalWritingMetrics.GetDisplacementVector(characterIdentifier);
+        }
     }
 }

src/UglyToad.PdfPig/Fonts/CidFonts/Type2CidFont.cs

@@ -18,11 +18,17 @@
         private readonly CharacterIdentifierToGlyphIndexMap cidToGid;
 
         public NameToken Type { get; }
+
         public NameToken SubType { get; }
+
         public NameToken BaseFont { get; }
+
         public CharacterIdentifierSystemInfo SystemInfo { get; }
+
         public TransformationMatrix FontMatrix { get; }
+
         public CidFontType CidFontType => CidFontType.Type2;
+
         public FontDescriptor Descriptor { get; }
 
         public Type2CidFont(NameToken type, NameToken subType, NameToken baseFont, CharacterIdentifierSystemInfo systemInfo,
@@ -85,5 +91,17 @@
 
             return Descriptor.BoundingBox;
         }
+
+        public PdfVector GetPositionVector(int characterIdentifier)
+        {
+            var width = GetWidthFromFont(characterIdentifier);
+
+            return verticalWritingMetrics.GetPositionVector(characterIdentifier, width);
+        }
+
+        public PdfVector GetDisplacementVector(int characterIdentifier)
+        {
+            return verticalWritingMetrics.GetDisplacementVector(characterIdentifier);
+        }
     }
 }

src/UglyToad.PdfPig/Fonts/CidFonts/VerticalVectorComponents.cs

@@ -1,20 +1,60 @@
 namespace UglyToad.PdfPig.Fonts.CidFonts
 {
+    using Geometry;
+
     /// <summary>
-    /// Equivalent to the DW2 array in the font dictionary for vertical fonts.
+    /// Defines the default position and displacement vector vertical components
+    /// for fonts which have vertical writing modes.
     /// </summary>
     internal struct VerticalVectorComponents
     {
+        /// <summary>
+        /// The default value of <see cref="VerticalVectorComponents"/> if not defined by a font.
+        /// </summary>
+        public static readonly VerticalVectorComponents Default = new VerticalVectorComponents(800, -1000);
+
+        /// <summary>
+        /// The vertical component of the position vector.
+        /// </summary>
+        /// <remarks>
+        /// The full position vector unless overridden by the W2 array is:
+        /// (w0/2, Position)
+        /// Where w0 is the width of the given glyph.
+        /// </remarks>
         public decimal Position { get; }
         
+        /// <summary>
+        /// The vertical component of the displacement vector.
+        /// </summary>
+        /// <remarks>
+        /// The full displacement vector is:
+        /// (0, Displacement)
+        /// </remarks>
         public decimal Displacement { get; }
 
+        /// <summary>
+        /// Create a new <see cref="VerticalVectorComponents"/>.
+        /// </summary>
         public VerticalVectorComponents(decimal position, decimal displacement)
         {
             Position = position;
             Displacement = displacement;
         }
 
-        public static VerticalVectorComponents Default = new VerticalVectorComponents(800, -1000);
+        /// <summary>
+        /// Get the full position vector for a given glyph.
+        /// </summary>
+        public PdfVector GetPositionVector(decimal glyphWidth) => new PdfVector(glyphWidth / 2m, Position);
+
+        /// <summary>
+        /// Get the full displacement vector.
+        /// </summary>
+        public PdfVector GetDisplacementVector() => new PdfVector(0, Displacement);
+
+        /// <inheritdoc />
+        public override string ToString()
+        {
+            return $"Position: {Position}, Displacement: {Displacement}.";
+        }
     }
 }

src/UglyToad.PdfPig/Fonts/CidFonts/VerticalWritingMetrics.cs

@@ -2,20 +2,70 @@
 {
     using System.Collections.Generic;
     using Geometry;
+    using Util.JetBrains.Annotations;
 
+    /// <summary>
+    /// Glyphs from fonts which support vertical writing mode define displacement and position vectors.
+    /// The position vector specifies how the horizontal writing origin is transformed into the vertical writing origin.
+    /// The displacement vector specifies how far to move vertically before drawing the next glyph.
+    /// </summary>
     internal class VerticalWritingMetrics
     {
+        /// <summary>
+        /// The default position and displacement vectors where not overridden.
+        /// </summary>
         public VerticalVectorComponents DefaultVerticalWritingMetrics { get; }
 
+        /// <summary>
+        /// Overrides displacement vector y components for glyphs specified by CID code.
+        /// </summary>
+        [NotNull]
         public IReadOnlyDictionary<int, decimal> IndividualVerticalWritingDisplacements { get; }
 
+        /// <summary>
+        /// Overrides position vector (x and y) components for glyphs specified by CID code.
+        /// </summary>
+        [NotNull]
         public IReadOnlyDictionary<int, PdfVector> IndividualVerticalWritingPositions { get; }
 
-        public VerticalWritingMetrics(VerticalVectorComponents defaultVerticalWritingMetrics, IReadOnlyDictionary<int, decimal> individualVerticalWritingDisplacements, IReadOnlyDictionary<int, PdfVector> individualVerticalWritingPositions)
+        /// <summary>
+        /// Create new <see cref="VerticalWritingMetrics"/>.
+        /// </summary>
+        public VerticalWritingMetrics(VerticalVectorComponents defaultVerticalWritingMetrics, 
+            [CanBeNull] IReadOnlyDictionary<int, decimal> individualVerticalWritingDisplacements, 
+            [CanBeNull] IReadOnlyDictionary<int, PdfVector> individualVerticalWritingPositions)
         {
             DefaultVerticalWritingMetrics = defaultVerticalWritingMetrics;
-            IndividualVerticalWritingDisplacements = individualVerticalWritingDisplacements;
-            IndividualVerticalWritingPositions = individualVerticalWritingPositions;
+            IndividualVerticalWritingDisplacements = individualVerticalWritingDisplacements
+                                                     ?? new Dictionary<int, decimal>(0);
+            IndividualVerticalWritingPositions = individualVerticalWritingPositions
+                                                 ?? new Dictionary<int, PdfVector>(0);
+        }
+
+        /// <summary>
+        /// Get the position vector used to convert horizontal glyph origin to vertical origin.
+        /// </summary>
+        public PdfVector GetPositionVector(int characterIdentifier, decimal glyphWidth)
+        {
+            if (IndividualVerticalWritingPositions.TryGetValue(characterIdentifier, out var vector))
+            {
+                return vector;
+            }
+
+            return DefaultVerticalWritingMetrics.GetPositionVector(glyphWidth);
+        }
+
+        /// <summary>
+        /// Get the displacement vector used to move the origin to the next glyph location after drawing.
+        /// </summary>
+        public PdfVector GetDisplacementVector(int characterIdentifier)
+        {
+            if (IndividualVerticalWritingDisplacements.TryGetValue(characterIdentifier, out var displacementY))
+            {
+                return new PdfVector(0, displacementY);
+            }
+
+            return DefaultVerticalWritingMetrics.GetDisplacementVector();
         }
     }
 }

src/UglyToad.PdfPig/Fonts/Composite/Type0Font.cs

@@ -12,7 +12,7 @@
     /// <summary>
     /// Defines glyphs using a CIDFont
     /// </summary>
-    internal class Type0Font : IFont
+    internal class Type0Font : IFont, IVerticalWritingSupported
     {
         public NameToken Name => BaseFont;
 
@@ -97,5 +97,19 @@
         {
             return CidFont.FontMatrix;
         }
+
+        public PdfVector GetPositionVector(int characterCode)
+        {
+            var characterIdentifier = CMap.ConvertToCid(characterCode);
+
+            return CidFont.GetPositionVector(characterIdentifier).Scale(-1 / 1000m);
+        }
+
+        public PdfVector GetDisplacementVector(int characterCode)
+        {
+            var characterIdentifier = CMap.ConvertToCid(characterCode);
+
+            return CidFont.GetDisplacementVector(characterIdentifier).Scale(1 / 1000m);
+        }
     }
 }

src/UglyToad.PdfPig/Fonts/IVerticalWritingSupported.cs

@@ -0,0 +1,18 @@
+namespace UglyToad.PdfPig.Fonts
+{
+    using Geometry;
+
+    /// <summary>
+    /// A font which supports a vertical writing mode in addition to the default horizontal writing mode.
+    /// </summary>
+    internal interface IVerticalWritingSupported
+    {
+        /// <summary>
+        /// In vertical fonts the glyph position is described by a position vector from the origin used for horizontal writing.
+        /// The position vector is applied to the horizontal writing origin to give a new vertical writing origin. 
+        /// </summary>
+        PdfVector GetPositionVector(int characterCode);
+
+        PdfVector GetDisplacementVector(int characterCode);
+    }
+}

src/UglyToad.PdfPig/Fonts/Parser/Parts/CidFontFactory.cs

@@ -62,7 +62,7 @@
             var subType = dictionary.GetNameOrDefault(NameToken.Subtype);
             if (NameToken.CidFontType0.Equals(subType))
             {
-                return new Type0CidFont(fontProgram, type, subType, baseFont, systemInfo, descriptor, widths);
+                return new Type0CidFont(fontProgram, type, subType, baseFont, systemInfo, descriptor, verticalWritingMetrics, widths);
             }
 
             if (NameToken.CidFontType2.Equals(subType))
@@ -160,18 +160,18 @@
                 return widths;
             }
 
-            int size = widthArray.Data.Count;
-            int counter = 0;
+            var size = widthArray.Data.Count;
+            var counter = 0;
             while (counter < size)
             {
                 var firstCode = (NumericToken)widthArray.Data[counter++];
                 var next = widthArray.Data[counter++];
                 if (DirectObjectFinder.TryGet(next, pdfScanner, out ArrayToken array))
                 {
-                    int startRange = firstCode.Int;
-                    int arraySize = array.Data.Count;
+                    var startRange = firstCode.Int;
+                    var arraySize = array.Data.Count;
 
-                    for (int i = 0; i < arraySize; i++)
+                    for (var i = 0; i < arraySize; i++)
                     {
                         var width = (NumericToken)array.Data[i];
                         widths[startRange + i] = width.Data;
@@ -181,8 +181,8 @@
                 {
                     var secondCode = (NumericToken)next;
                     var rangeWidth = (NumericToken)widthArray.Data[counter++];
-                    int startRange = firstCode.Int;
-                    int endRange = secondCode.Int;
+                    var startRange = firstCode.Int;
+                    var endRange = secondCode.Int;
                     var width = rangeWidth.Data;
                     for (var i = startRange; i <= endRange; i++)
                     {
@@ -199,10 +199,11 @@
             var verticalDisplacements = new Dictionary<int, decimal>();
             var positionVectors = new Dictionary<int, PdfVector>();
 
+            // The default position vector and displacement vector are specified by the DW2 entry.
             VerticalVectorComponents dw2;
             if (!dict.TryGet(NameToken.Dw2, out var dw2Token) || !(dw2Token is ArrayToken arrayVerticalComponents))
             {
-                dw2 = new VerticalVectorComponents(880, -1000);
+                dw2 = VerticalVectorComponents.Default;
             }
             else
             {
@@ -222,9 +223,10 @@
 
                     if (next is ArrayToken array)
                     {
-                        for (int j = 0; j < array.Data.Count; j++)
+                        for (var j = 0; j < array.Data.Count; j++)
                         {
-                            int cid = c.Int + j;
+                            var cid = c.Int + j;
+                            // ReSharper disable InconsistentNaming
                             var w1y = (NumericToken)array.Data[j];
                             var v1x = (NumericToken)array.Data[++j];
                             var v1y = (NumericToken)array.Data[++j];
@@ -236,11 +238,12 @@
                     }
                     else
                     {
-                        int first = c.Int;
-                        int last = ((NumericToken)next).Int;
+                        var first = c.Int;
+                        var last = ((NumericToken)next).Int;
                         var w1y = (NumericToken)w2.Data[++i];
                         var v1x = (NumericToken)w2.Data[++i];
                         var v1y = (NumericToken)w2.Data[++i];
+                        // ReSharper restore InconsistentNaming
 
                         for (var cid = first; cid <= last; cid++)
                         {

src/UglyToad.PdfPig/Graphics/ContentStreamProcessor.cs

@@ -181,21 +181,31 @@
                     wordSpacing += GetCurrentState().FontState.WordSpacing;
                 }
 
+                var textMatrix = TextMatrices.TextMatrix;
+
                 if (font.IsVertical)
                 {
-                    throw new NotImplementedException("Vertical fonts are currently unsupported, please submit a pull request or issue with an example file.");
+                    if (!(font is IVerticalWritingSupported verticalFont))
+                    {
+                        throw new InvalidOperationException($"Font {font.Name} was in vertical writing mode but did not implement {nameof(IVerticalWritingSupported)}.");
+                    }
+
+                    var positionVector = verticalFont.GetPositionVector(code);
+
+                    textMatrix = textMatrix.Translate(positionVector.X, positionVector.Y);
                 }
 
                 var boundingBox = font.GetBoundingBox(code);
 
                 var transformedGlyphBounds = rotation.Rotate(transformationMatrix)
-                    .Transform(TextMatrices.TextMatrix
+                    .Transform(textMatrix
                         .Transform(renderingMatrix
                             .Transform(boundingBox.GlyphBounds)));
 
                 var transformedPdfBounds = rotation.Rotate(transformationMatrix)
-                    .Transform(TextMatrices.TextMatrix
-                        .Transform(renderingMatrix.Transform(new PdfRectangle(0, 0, boundingBox.Width, 0))));
+                    .Transform(textMatrix
+                        .Transform(renderingMatrix
+                            .Transform(new PdfRectangle(0, 0, boundingBox.Width, 0))));
 
                 // If the text rendering mode calls for filling, the current nonstroking color in the graphics state is used; 
                 // if it calls for stroking, the current stroking color is used.
@@ -218,8 +228,10 @@
                 decimal tx, ty;
                 if (font.IsVertical)
                 {
+                    var verticalFont = (IVerticalWritingSupported) font;
+                    var displacement = verticalFont.GetDisplacementVector(code);
                     tx = 0;
-                    ty = boundingBox.GlyphBounds.Height * fontSize + characterSpacing + wordSpacing;
+                    ty = (displacement.Y * fontSize) + characterSpacing + wordSpacing;
                 }
                 else
                 {