private void WriteStitchingFunction(DocumentWriter writer)
{
const int stitchingFunctionType = 3;
var stops = _shadingColor.Stops;
writer.WriteDictionaryOpen();
{
writer.WriteName(NameFunctionTypeBytes);
writer.WriteNumber(stitchingFunctionType);
WriteDomain0To1NameAndArray(writer);
writer.WriteName(NameFunctionsBytes);
writer.WriteArrayOpen();
{
for (var i = 0; i < stops.Count - 1; i++)
{
var stop = stops[i];
var next = stops[i + 1];
WriteLinearColorInterpolationFunction(writer, stop.Color, next.Color);
}
}
writer.WriteArrayClose();
writer.WriteName(NameBoundsBytes);
writer.WriteArrayOpen();
{
for (var i = 1; i < stops.Count - 1; i++)
{
writer.WriteNumber(stops[i].Offset);
}
}
writer.WriteArrayClose();
writer.WriteName(NameEncodeBytes);
writer.WriteArrayOpen();
{
for (var i = 0; i < stops.Count - 1; i++)
{
writer.WriteNumber(0);
writer.WriteNumber(1);
}
}
writer.WriteArrayClose();
}
writer.WriteDictionaryClose();
}
private static void WriteLinearColorInterpolationFunction(DocumentWriter writer, PdfColor color1, PdfColor color2)
{
const int interpolationFunctionType = 2;
void WriteColorArray(PdfColor color)
{
writer.WriteArrayOpen();
switch (color)
{
case RgbColor rgb:
writer.WriteNumberColor(rgb.R);
writer.WriteNumberColor(rgb.G);
writer.WriteNumberColor(rgb.B);
break;
case CmykColor cmyk:
writer.WriteNumberColor(cmyk.C);
writer.WriteNumberColor(cmyk.M);
writer.WriteNumberColor(cmyk.Y);
writer.WriteNumberColor(cmyk.K);
break;
default:
throw new NotSupportedException();
}
writer.WriteArrayClose();
}
writer.WriteDictionaryOpen();
{
writer.WriteName(NameFunctionTypeBytes);
writer.WriteNumber(interpolationFunctionType);
writer.WriteName(NameNBytes);
writer.WriteNumber1();
WriteDomain0To1NameAndArray(writer);
writer.WriteName(NameC0Bytes);
WriteColorArray(color1);
writer.WriteName(NameC1Bytes);
WriteColorArray(color2);
}
writer.WriteDictionaryClose();
}
public override void Draw(DocumentWriter writer)
{
const int shadingPatternType = 2; // tiling pattern = 1
void WriteNumberHighPrecision(float v)
{
// WriteNumber isn't high precision enough, only supports 2 decimal places :(
var bytes = Encoding.ASCII.GetBytes($"{v} ");
writer.Write(bytes);
}
writer.WriteBeginObject();
writer.WriteDictionaryOpen();
{
writer.WriteName(NamePatternTypeBytes);
writer.WriteNumber(shadingPatternType);
writer.WriteName(NameMatrixBytes);
writer.WriteArrayOpen();
{
_shadingColor.DrawMatrix(WriteNumberHighPrecision);
}
writer.WriteArrayClose();
writer.WriteName(NameShadingBytes);
writer.WriteDictionaryOpen();
{
writer.WriteName(NameShadingTypeBytes);
writer.WriteNumber((int)_shadingColor.ShadingType);
writer.WriteName(NameColorSpaceBytes);
_shadingColor.Stops[0].Color.ColorSpace.DrawColorSpace(writer);
writer.WriteName(NameCoordsBytes);
writer.WriteArrayOpen();
{
_shadingColor.DrawCoordinates(WriteNumberHighPrecision);
}
writer.WriteArrayClose();
writer.WriteName(NameExtendBytes);
writer.WriteArrayOpen();
{
writer.WriteBoolean(true);
writer.WriteBoolean(true);
}
writer.WriteArrayClose();
writer.WriteName(NameFunctionBytes);
if (_shadingColor.Stops.Count > 2)
{
WriteStitchingFunction(writer);
}
else if (_shadingColor.Stops.Count == 2)
{
var stop1 = _shadingColor.Stops[0];
var stop2 = _shadingColor.Stops[1];
WriteLinearColorInterpolationFunction(writer, stop1.Color, stop2.Color);
}
else
{
throw new InvalidOperationException($"Expected two or more color stops");
}
}
writer.WriteDictionaryClose();
}
writer.WriteDictionaryClose();
writer.WriteEndObject();
}