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handle transparency when adding pdfs in builder #345 #346

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This commit is contained in:
Eliot Jones
2021-08-07 13:49:01 -04:00
parent dd95b38345
commit 2df5ec9b10
2 changed files with 843 additions and 801 deletions
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48
src/UglyToad.PdfPig/Writer/PdfPageBuilder.cs
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@@ -15,7 +15,6 @@
using Images;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using PdfFonts;
@@ -491,20 +490,63 @@
data = memoryStream.ToArray();
}
var widthToken = new NumericToken(png.Width);
var heightToken = new NumericToken(png.Height);
IndirectReferenceToken smaskReference = null;
if (png.HasAlphaChannel)
{
var smaskData = new byte[data.Length / 3];
for (var rowIndex = 0; rowIndex < png.Height; rowIndex++)
{
for (var colIndex = 0; colIndex < png.Width; colIndex++)
{
var pixel = png.GetPixel(colIndex, rowIndex);
var index = rowIndex * png.Width + colIndex;
smaskData[index] = pixel.A;
}
}
var compressedSmask = DataCompresser.CompressBytes(smaskData);
// Create a soft-mask.
var smaskDictionary = new Dictionary<NameToken, IToken>
{
{NameToken.Type, NameToken.Xobject},
{NameToken.Subtype, NameToken.Image},
{NameToken.Width, widthToken},
{NameToken.Height, heightToken},
{NameToken.ColorSpace, NameToken.Devicegray},
{NameToken.BitsPerComponent, new NumericToken(png.Header.BitDepth)},
{NameToken.Decode, new ArrayToken(new IToken[] { new NumericToken(0), new NumericToken(1) })},
{NameToken.Length, new NumericToken(compressedSmask.Length)},
{NameToken.Filter, NameToken.FlateDecode}
};
smaskReference = documentBuilder.AddImage(new DictionaryToken(smaskDictionary), compressedSmask);
}
var compressed = DataCompresser.CompressBytes(data);
var imgDictionary = new Dictionary<NameToken, IToken>
{
{NameToken.Type, NameToken.Xobject},
{NameToken.Subtype, NameToken.Image},
{NameToken.Width, new NumericToken(png.Width) },
{NameToken.Height, new NumericToken(png.Height) },
{NameToken.Width, widthToken},
{NameToken.Height, heightToken},
{NameToken.BitsPerComponent, new NumericToken(png.Header.BitDepth)},
{NameToken.ColorSpace, NameToken.Devicergb},
{NameToken.Filter, NameToken.FlateDecode},
{NameToken.Length, new NumericToken(compressed.Length)}
};
if (smaskReference != null)
{
imgDictionary.Add(NameToken.Smask, smaskReference);
}
var reference = documentBuilder.AddImage(new DictionaryToken(imgDictionary), compressed);
var resources = pageDictionary.GetOrCreateDict(NameToken.Resources);