Moved ExtGState dictionaries to indirect objects, fixed prefix, and added to example

Author: synercoder

samples/Synercoding.FileFormats.Pdf.ConsoleTester/Program.cs

@@ -216,6 +216,10 @@ public static void Main(string[] args)
 
                     page.Content.AddShapes(trimBox, static (trim, context) =>
                     {
+                        context.SetExtendedGraphicsState(new ExtendedGraphicsState()
+                        {
+                            Overprint = true
+                        });
                         context.SetStroke(new SpotColor(new Separation(LowLevel.PdfName.Get("CutContour"), PredefinedColors.Magenta), 1));
                         context.Rectangle(trim);
                         context.Stroke();

src/Synercoding.FileFormats.Pdf/LowLevel/Internal/PageResources.cs

@@ -15,7 +15,7 @@ internal sealed class PageResources : IDisposable
     private readonly Map<PdfName, Image> _images;
     private readonly Dictionary<Separation, (PdfName Name, PdfReference Id)> _separations;
     private readonly Dictionary<Type1StandardFont, PdfReference> _standardFonts;
-    private readonly Dictionary<ExtendedGraphicsState, PdfName> _extendedGraphicsStates;
+    private readonly Dictionary<ExtendedGraphicsState, (PdfName Name, PdfReference Id)> _extendedGraphicsStates;
 
     private int _stateCounter = 0;
     private int _separationCounter = 0;
@@ -27,13 +27,13 @@ internal PageResources(TableBuilder tableBuilder)
         _images = new Map<PdfName, Image>();
         _separations = new Dictionary<Separation, (PdfName Name, PdfReference Id)>();
         _standardFonts = new Dictionary<Type1StandardFont, PdfReference>();
-        _extendedGraphicsStates = new Dictionary<ExtendedGraphicsState, PdfName>();
+        _extendedGraphicsStates = new Dictionary<ExtendedGraphicsState, (PdfName Name, PdfReference Id)>();
     }
 
     public IReadOnlyDictionary<PdfName, Image> Images
         => _images.Forward;
 
-    public IReadOnlyDictionary<ExtendedGraphicsState, PdfName> ExtendedGraphicsStates
+    public IReadOnlyDictionary<ExtendedGraphicsState, (PdfName Name, PdfReference Id)> ExtendedGraphicsStates
         => _extendedGraphicsStates;
 
     internal IReadOnlyDictionary<Separation, (PdfName Name, PdfReference Id)> SeparationReferences
@@ -115,12 +115,12 @@ internal PdfName AddSeparation(Separation separation)
 
     internal PdfName AddExtendedGraphicsState(ExtendedGraphicsState extendedGraphicsState)
     {
-        if (_extendedGraphicsStates.TryGetValue(extendedGraphicsState, out var name))
-            return name;
+        if (_extendedGraphicsStates.TryGetValue(extendedGraphicsState, out var tuple))
+            return tuple.Name;
 
-        var key = PREFIX_SEPARATION + Interlocked.Increment(ref _stateCounter).ToString().PadLeft(6, '0');
-        name = PdfName.Get(key);
-        _extendedGraphicsStates[extendedGraphicsState] = name;
+        var key = PREFIX_EXTGSTATE + Interlocked.Increment(ref _stateCounter).ToString().PadLeft(6, '0');
+        var name = PdfName.Get(key);
+        _extendedGraphicsStates[extendedGraphicsState] = (name, _tableBuilder.ReserveId());
 
         return name;
     }

src/Synercoding.FileFormats.Pdf/LowLevel/ObjectStream.cs

@@ -162,20 +162,11 @@ public ObjectStream Write(PdfPage page)
 
                 if (resources.ExtendedGraphicsStates.Count != 0)
                 {
-                    stream.Write(PdfName.Get("ExtGState"), resources.ExtendedGraphicsStates, static (extGStates, stream) => stream.Dictionary(extGStates, static (extendedGStates, extgstateDictionary) =>
+                    stream.Write(PdfName.Get("ExtGState"), resources.ExtendedGraphicsStates.Values, static (extGStates, stream) => stream.Dictionary(extGStates, static (extendedGStates, dict) =>
                     {
-                        foreach(var (state, name) in extendedGStates)
+                        foreach (var (name, reference) in extendedGStates)
                         {
-                            extgstateDictionary.Write(name, state, static (state, raw) =>
-                            {
-                                raw.Dictionary(state, static (state, dict) =>
-                                {
-                                    if (state.Overprint.HasValue)
-                                        dict.Write(PdfName.Get("OP"), state.Overprint.Value);
-                                    if (state.OverprintNonStroking.HasValue)
-                                        dict.Write(PdfName.Get("op"), state.OverprintNonStroking.Value);
-                                });
-                            });
+                            dict.Write(name, reference);
                         }
                     }));
                 }
@@ -238,6 +229,22 @@ public ObjectStream Write(PdfReference reference, Separation separation)
         return this;
     }
 
+    public ObjectStream Write(PdfReference reference, ExtendedGraphicsState state)
+    {
+        if (!_tableBuilder.TrySetPosition(reference, InnerStream.Position))
+            return this;
+
+        _indirectDictionary(reference, state, static (state, dict) =>
+        {
+            if (state.Overprint.HasValue)
+                dict.Write(PdfName.Get("OP"), state.Overprint.Value);
+            if (state.OverprintNonStroking.HasValue)
+                dict.Write(PdfName.Get("op"), state.OverprintNonStroking.Value);
+        });
+
+        return this;
+    }
+
     private void _indirectDictionary<T>(PdfReference reference, T data, Action<T, PdfDictionary> dictionaryAction)
     {
         InnerStream

src/Synercoding.FileFormats.Pdf/PdfWriter.cs

@@ -233,6 +233,9 @@ private void _writePageAndResourcesToObjectStream(PdfPage page)
         foreach (var (separation, (_, refId)) in page.Resources.SeparationReferences)
             _objectStream.Write(refId, separation);
 
+        foreach (var (state, (_, refId)) in page.Resources.ExtendedGraphicsStates)
+            _objectStream.Write(refId, state);
+
         _objectStream.Write(page.Content.RawContentStream);
     }