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Add indexed color space for stencils

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This commit is contained in:
Kasper Frank 2021-05-07 11:51:41 +02:00
parent 8c6f705d2a
commit f8990a79b8
3 changed files with 22 additions and 7 deletions
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2
src/UglyToad.PdfPig.Tests/Images/PngFromPdfImageFactoryTests.cs
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@ -150,7 +150,7 @@
var decodedBytes = ImageHelpers.LoadFileBytes("ccittfax-decoded.bin"); var decodedBytes = ImageHelpers.LoadFileBytes("ccittfax-decoded.bin");
var image = new TestPdfImage var image = new TestPdfImage
{ {
ColorSpaceDetails = IndexedColorSpaceDetails.CCITTFaxColorSpaceDetails, ColorSpaceDetails = IndexedColorSpaceDetails.StencilBlackIs1,
DecodedBytes = decodedBytes, DecodedBytes = decodedBytes,
WidthInSamples = 1800, WidthInSamples = 1800,
HeightInSamples = 3113, HeightInSamples = 3113,

20
src/UglyToad.PdfPig/Graphics/Colors/ColorSpaceDetails.cs
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@ -85,13 +85,25 @@
public class IndexedColorSpaceDetails : ColorSpaceDetails public class IndexedColorSpaceDetails : ColorSpaceDetails
{ {
/// <summary> /// <summary>
/// The lossless CCITT compression schemes are used for bitonal black and white images. /// A color space useful for extracting stencil masks as black-and-white images.
/// This is equivalent to an IndexedColorSpaceDetails with a black and white palette. /// Index 0 is black and index 1 is white.
/// </summary>
internal static readonly IndexedColorSpaceDetails StencilBlackIs0
= new IndexedColorSpaceDetails(DeviceGrayColorSpaceDetails.Instance, 1, new byte[] { 0, 255 });
/// <summary>
/// A color space useful for extracting stencil masks as black-and-white images.
/// Index 0 is white and index 1 is black. /// Index 0 is white and index 1 is black.
/// </summary> /// </summary>
internal static readonly IndexedColorSpaceDetails CCITTFaxColorSpaceDetails internal static readonly IndexedColorSpaceDetails StencilBlackIs1
= new IndexedColorSpaceDetails(DeviceGrayColorSpaceDetails.Instance, 1, new byte[] { 255, 0 }); = new IndexedColorSpaceDetails(DeviceGrayColorSpaceDetails.Instance, 1, new byte[] { 255, 0 });
internal static ColorSpaceDetails Stencil(decimal[] decode)
{
return decode.Length >= 2 && decode[0] == 1 && decode[1] == 0 ?
StencilBlackIs1 : StencilBlackIs0 /* default */;
}
/// <summary> /// <summary>
/// The base color space in which the values in the color table are to be interpreted. /// The base color space in which the values in the color table are to be interpreted.
/// It can be any device or CIE-based color space or(in PDF 1.3) a Separation or DeviceN space, /// It can be any device or CIE-based color space or(in PDF 1.3) a Separation or DeviceN space,
@ -119,7 +131,7 @@
HiVal = hiVal; HiVal = hiVal;
ColorTable = colorTable; ColorTable = colorTable;
BaseType = baseColorSpaceDetails.BaseType; BaseType = baseColorSpaceDetails.BaseType;
} }
} }
/// <summary> /// <summary>

7
src/UglyToad.PdfPig/Util/ColorSpaceDetailsParser.cs
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@ -75,9 +75,12 @@
ILookupFilterProvider filterProvider, ILookupFilterProvider filterProvider,
bool cannotRecurse = false) bool cannotRecurse = false)
{ {
if (filterProvider.GetFilters(imageDictionary).OfType<CcittFaxDecodeFilter>().Any()) if (imageDictionary.GetDictionaryObject(NameToken.ImageMask, NameToken.Im) != null)
{ {
return IndexedColorSpaceDetails.CCITTFaxColorSpaceDetails; var decodeRaw = imageDictionary.GetDictionaryObject(NameToken.Decode, NameToken.D) as ArrayToken
?? new ArrayToken(EmptyArray<IToken>.Instance);
var decode = decodeRaw.Data.OfType<NumericToken>().Select(x => x.Data).ToArray();
return IndexedColorSpaceDetails.Stencil(decode);
} }
if (!colorSpace.HasValue) if (!colorSpace.HasValue)