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Merged
BobLd merged 1 commit into from
Jun 21, 2026
Merged

Support default colour spaces #1337

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259 changes: 259 additions & 0 deletions src/UglyToad.PdfPig.Tests/ContentTests/ResourceStoreDefaultColorSpaceTests.cs
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@@ -0,0 +1,259 @@
namespace UglyToad.PdfPig.Tests.ContentTests
{
using System.Collections.Generic;
using PdfPig.Content;
using PdfPig.Graphics.Colors;
using PdfPig.PdfFonts;
using PdfPig.Tokens;
using UglyToad.PdfPig.Tests.Tokens;
using Xunit;

public class ResourceStoreDefaultColorSpaceTests
{
private sealed class NoOpFontFactory : IFontFactory
{
public IFont Get(DictionaryToken dictionary) => null!;
}

private static ResourceStore BuildStore()
{
return new ResourceStore(
new TestPdfTokenScanner(),
new NoOpFontFactory(),
new TestFilterProvider(),
new ParsingOptions
{
UseLenientParsing = true,
SkipMissingFonts = true,
});
}

[Fact]
public void DeviceRgbRequest_WithDefaultRgbInResources_UsesDefaultRgb()
{
// Resources/ColorSpace/DefaultRGB -> [ /CalRGB << /WhitePoint [0.9505 1 1.089] >> ]
var calRgbDict = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{
NameToken.WhitePoint,
new ArrayToken(new IToken[]
{
new NumericToken(0.9505),
new NumericToken(1.0),
new NumericToken(1.089),
})
},
});
var defaultRgbArray = new ArrayToken(new IToken[] { NameToken.Calrgb, calRgbDict });

var resources = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{
NameToken.ColorSpace,
new DictionaryToken(new Dictionary<NameToken, IToken>
{
{ NameToken.DefaultRgb, defaultRgbArray },
})
},
});

var store = BuildStore();
store.LoadResourceDictionary(resources);

var details = store.GetColorSpaceDetails(
NameToken.Devicergb,
new DictionaryToken(new Dictionary<NameToken, IToken>()));

Assert.Equal(ColorSpace.CalRGB, details.Type);
}

[Fact]
public void GetDeviceColorSpaceDetails_WithDefaultRgbInResources_UsesDefaultRgb()
{
// The g/rg/k operators select a device colour space directly; per 8.6.5.6 the matching
// Default* substitution must still apply (it takes precedence over any output intent).
var calRgbDict = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{
NameToken.WhitePoint,
new ArrayToken(new IToken[]
{
new NumericToken(0.9505),
new NumericToken(1.0),
new NumericToken(1.089),
})
},
});
var defaultRgbArray = new ArrayToken(new IToken[] { NameToken.Calrgb, calRgbDict });

var resources = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{
NameToken.ColorSpace,
new DictionaryToken(new Dictionary<NameToken, IToken>
{
{ NameToken.DefaultRgb, defaultRgbArray },
})
},
});

var store = BuildStore();
store.LoadResourceDictionary(resources);

var details = store.GetDeviceColorSpaceDetails(ColorSpace.DeviceRGB);

Assert.Equal(ColorSpace.CalRGB, details.Type);
}

[Fact]
public void GetDeviceColorSpaceDetails_WithoutDefault_ReturnsDeviceColorSpace()
{
var store = BuildStore();
store.LoadResourceDictionary(new DictionaryToken(new Dictionary<NameToken, IToken>()));

Assert.Same(DeviceGrayColorSpaceDetails.Instance, store.GetDeviceColorSpaceDetails(ColorSpace.DeviceGray));
Assert.Same(DeviceRgbColorSpaceDetails.Instance, store.GetDeviceColorSpaceDetails(ColorSpace.DeviceRGB));
Assert.Same(DeviceCmykColorSpaceDetails.Instance, store.GetDeviceColorSpaceDetails(ColorSpace.DeviceCMYK));
}

[Fact]
public void IndexedBase_WithDefaultRgbInResources_UsesDefaultRgb()
{
// 8.6.5.6: the base colour space of an Indexed space, when it is a device colour space, must
// be replaced by the corresponding Default* colour space.
var calRgbDict = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{
NameToken.WhitePoint,
new ArrayToken(new IToken[]
{
new NumericToken(0.9505),
new NumericToken(1.0),
new NumericToken(1.089),
})
},
});
var defaultRgbArray = new ArrayToken(new IToken[] { NameToken.Calrgb, calRgbDict });

var resources = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{
NameToken.ColorSpace,
new DictionaryToken(new Dictionary<NameToken, IToken>
{
{ NameToken.DefaultRgb, defaultRgbArray },
})
},
});

var store = BuildStore();
store.LoadResourceDictionary(resources);

// [ /Indexed /DeviceRGB 1 <000000FFFFFF> ] : 2 entries of 3 RGB components.
var indexedArray = new ArrayToken(new IToken[]
{
NameToken.Indexed,
NameToken.Devicergb,
new NumericToken(1),
new StringToken("ÿÿÿ"),
});
var imageDictionary = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{ NameToken.ColorSpace, indexedArray },
});

var details = store.GetColorSpaceDetails(NameToken.Indexed, imageDictionary);

var indexed = Assert.IsType<IndexedColorSpaceDetails>(details);
Assert.Equal(ColorSpace.CalRGB, indexed.BaseColorSpace.Type);
}

[Fact]
public void GetDeviceColorSpaceDetails_WithIndexedDefaultRgb_ReturnsDeviceColorSpace()
{
// 8.6.5.6: any colour space other than a Lab, Indexed, or Pattern colour space may be used as a
// default colour space. An Indexed DefaultRGB is therefore invalid and must be ignored, leaving
// the device colour space in place.
// DefaultRGB -> [ /Indexed /DeviceGray 1 <00FF> ]
var defaultRgbArray = new ArrayToken(new IToken[]
{
NameToken.Indexed,
NameToken.Devicegray,
new NumericToken(1),
new StringToken("ÿ"),
});

var resources = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{
NameToken.ColorSpace,
new DictionaryToken(new Dictionary<NameToken, IToken>
{
{ NameToken.DefaultRgb, defaultRgbArray },
})
},
});

var store = BuildStore();
store.LoadResourceDictionary(resources);

Assert.Same(DeviceRgbColorSpaceDetails.Instance, store.GetDeviceColorSpaceDetails(ColorSpace.DeviceRGB));
}

[Fact]
public void GetDeviceColorSpaceDetails_WithSelfReferentialIndexedDefaultRgb_ReturnsDeviceColorSpace()
{
// Regression: a self-referential default - /DefaultRGB defined as an Indexed space whose base
// is /DeviceRGB - must not recurse forever. Resolving DeviceRGB resolves the Indexed default,
// whose base resolves DeviceRGB again; the re-entrancy guard breaks the loop and the Indexed
// default is rejected, leaving the device colour space.
// DefaultRGB -> [ /Indexed /DeviceRGB 1 <000000FFFFFF> ]
var defaultRgbArray = new ArrayToken(new IToken[]
{
NameToken.Indexed,
NameToken.Devicergb,
new NumericToken(1),
new StringToken("ÿÿÿ"),
});

var resources = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{
NameToken.ColorSpace,
new DictionaryToken(new Dictionary<NameToken, IToken>
{
{ NameToken.DefaultRgb, defaultRgbArray },
})
},
});

var store = BuildStore();
store.LoadResourceDictionary(resources);

Assert.Same(DeviceRgbColorSpaceDetails.Instance, store.GetDeviceColorSpaceDetails(ColorSpace.DeviceRGB));
}

[Fact]
public void GetDeviceColorSpaceDetails_WithPatternDefaultRgb_ReturnsDeviceColorSpace()
{
// 8.6.5.6: a Pattern colour space may not be used as a default colour space, so a Pattern
// DefaultRGB must be ignored, leaving the device colour space in place.
// DefaultRGB -> /Pattern
var resources = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{
NameToken.ColorSpace,
new DictionaryToken(new Dictionary<NameToken, IToken>
{
{ NameToken.DefaultRgb, NameToken.Pattern },
})
},
});

var store = BuildStore();
store.LoadResourceDictionary(resources);

Assert.Same(DeviceRgbColorSpaceDetails.Instance, store.GetDeviceColorSpaceDetails(ColorSpace.DeviceRGB));
}
}
}
9 changes: 9 additions & 0 deletions src/UglyToad.PdfPig/Content/IResourceStore.cs
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Expand Up @@ -52,6 +52,15 @@ public interface IResourceStore
/// </summary>
ColorSpaceDetails GetColorSpaceDetails(NameToken? name, DictionaryToken? dictionary);

/// <summary>
/// Get the colour space details for a device colour space selected directly (for example by the
/// <c>g</c> / <c>rg</c> / <c>k</c> operators), applying the <c>DefaultGray</c> / <c>DefaultRGB</c> /
/// <c>DefaultCMYK</c> substitution from the current resource dictionary when present (PDF 2.0,
/// 8.6.5.6 "Default colour spaces"). Returns the device colour space itself when no matching
/// default colour space is defined.
/// </summary>
ColorSpaceDetails GetDeviceColorSpaceDetails(ColorSpace deviceColorSpace);

/// <summary>
/// Get the marked content properties dictionary corresponding to the name.
/// </summary>
Expand Down
71 changes: 63 additions & 8 deletions src/UglyToad.PdfPig/Content/ResourceStore.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@
using Filters;
using Util;

internal class ResourceStore : IResourceStore
internal sealed class ResourceStore : IResourceStore
{
private readonly IPdfTokenScanner scanner;
private readonly IFontFactory fontFactory;
Expand Down Expand Up @@ -55,7 +55,7 @@ public void LoadResourceDictionary(DictionaryToken resourceDictionary)

namedColorSpaces.Push();
currentFontState.Push();
currentXObjectState.Push();
currentXObjectState.Push();
extendedGraphicsStates.Push();

if (resourceDictionary.TryGet(NameToken.Font, out var fontBase))
Expand Down Expand Up @@ -307,10 +307,14 @@ public ColorSpaceDetails GetColorSpaceDetails(NameToken? name, DictionaryToken?
return ColorSpaceDetailsParser.GetColorSpaceDetails(null, dictionary, scanner, this, filterProvider);
}

if (name.TryMapToColorSpace(out ColorSpace colorspaceActual))
if (name.TryMapToColorSpace(out ColorSpace colorSpaceActual))
{
// TODO - We need to find a way to store profile that have an actual dictionary, e.g. ICC profiles - without parsing them again
return ColorSpaceDetailsParser.GetColorSpaceDetails(colorspaceActual, dictionary, scanner, this, filterProvider);
if (TryGetDefaultSubstitute(colorSpaceActual, out NameToken? substituteName))
{
return GetColorSpaceDetails(substituteName, dictionary);
}

return ColorSpaceDetailsParser.GetColorSpaceDetails(colorSpaceActual, dictionary, scanner, this, filterProvider);
}

// Named color spaces
Expand All @@ -326,7 +330,8 @@ public ColorSpaceDetails GetColorSpaceDetails(NameToken? name, DictionaryToken?
{
return ColorSpaceDetailsParser.GetColorSpaceDetails(mapped, dictionary, scanner, this, filterProvider);
}
else if (namedColorSpace.Data is ArrayToken array)

if (namedColorSpace.Data is ArrayToken array)
{
var csd = ColorSpaceDetailsParser.GetColorSpaceDetails(mapped, dictionary.With(NameToken.ColorSpace, array), scanner, this, filterProvider);
loadedNamedColorSpaceDetails[name] = csd;
Expand All @@ -337,6 +342,56 @@ public ColorSpaceDetails GetColorSpaceDetails(NameToken? name, DictionaryToken?
throw new InvalidOperationException($"Could not find color space for token '{name}'.");
}

public ColorSpaceDetails GetDeviceColorSpaceDetails(ColorSpace deviceColorSpace)
{
// 8.6.5.6: a directly selected device colour space is remapped to its DefaultGray/RGB/CMYK
// substitute when one is present in the current resources. Otherwise return the device
// space singleton.
// Any colour space other than a Lab, Indexed, or Pattern colour space may be used as a default
// colour space and it should be compatible with the original device colour space.
// We reject those families up-front from the substitute's own definition, before resolving its
// details. Besides being cheaper, this prevents infinite recursion for a self-referential default
// such as /DefaultRGB defined as [ /Indexed /DeviceRGB ... ], whose base would otherwise resolve
// this same device colour space again.
if (TryGetDefaultSubstitute(deviceColorSpace, out NameToken? substituteName) &&
TryGetNamedColorSpace(substituteName, out ResourceColorSpace substitute) &&
substitute.Name.TryMapToColorSpace(out ColorSpace substituteColorSpace) &&
substituteColorSpace is not ColorSpace.Lab and not ColorSpace.Indexed and not ColorSpace.Pattern)
{
return GetColorSpaceDetails(substituteName, null);
}

return deviceColorSpace switch
{
ColorSpace.DeviceGray => DeviceGrayColorSpaceDetails.Instance,
ColorSpace.DeviceRGB => DeviceRgbColorSpaceDetails.Instance,
ColorSpace.DeviceCMYK => DeviceCmykColorSpaceDetails.Instance,
_ => throw new ArgumentOutOfRangeException(nameof(deviceColorSpace),
deviceColorSpace,
"Expected a device colour space (DeviceGray, DeviceRGB or DeviceCMYK).")
};
}

private bool TryGetDefaultSubstitute(ColorSpace requested, [NotNullWhen(true)] out NameToken? substituteName)
{
NameToken? candidate = requested switch
{
ColorSpace.DeviceGray => NameToken.DefaultGray,
ColorSpace.DeviceRGB => NameToken.DefaultRgb,
ColorSpace.DeviceCMYK => NameToken.DefaultCmyk,
_ => null
};

if (candidate is not null && namedColorSpaces.TryGetValue(candidate, out _))
{
substituteName = candidate;
return true;
}

substituteName = null;
return false;
}

public bool TryGetXObject(NameToken name, [NotNullWhen(true)] out StreamToken? stream)
{
stream = null;
Expand All @@ -351,11 +406,11 @@ public bool TryGetXObject(NameToken name, [NotNullWhen(true)] out StreamToken? s
public DictionaryToken? GetExtendedGraphicsStateDictionary(NameToken name)
{
if (parsingOptions.UseLenientParsing)
{
{
if (extendedGraphicsStates.TryGetValue(name, out var dictToken))
{
return dictToken;
}
}

parsingOptions.Logger.Error($"The graphic state dictionary does not contain the key '{name}'.");
return null;
Expand Down
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