PdfColor.fromRYB constructor

PdfColor.fromRYB(double red, double yellow, double blue, [ double alpha = 1.0, ])

Load an RGB color from a RYB color

Implementation

factory PdfColor.fromRYB(double red, double yellow, double blue,
    [double alpha = 1.0]) {
  assert(red >= 0 && red <= 1);
  assert(yellow >= 0 && yellow <= 1);
  assert(blue >= 0 && blue <= 1);
  assert(alpha >= 0 && alpha <= 1);

  const magic = <List<double>>[
    <double>[1, 1, 1],
    <double>[1, 1, 0],
    <double>[1, 0, 0],
    <double>[1, 0.5, 0],
    <double>[0.163, 0.373, 0.6],
    <double>[0.0, 0.66, 0.2],
    <double>[0.5, 0.0, 0.5],
    <double>[0.2, 0.094, 0.0]
  ];

  double cubicInt(double t, double A, double B) {
    final weight = t * t * (3 - 2 * t);
    return A + weight * (B - A);
  }

  double getRed(double iR, double iY, double iB) {
    final x0 = cubicInt(iB, magic[0][0], magic[4][0]);
    final x1 = cubicInt(iB, magic[1][0], magic[5][0]);
    final x2 = cubicInt(iB, magic[2][0], magic[6][0]);
    final x3 = cubicInt(iB, magic[3][0], magic[7][0]);
    final y0 = cubicInt(iY, x0, x1);
    final y1 = cubicInt(iY, x2, x3);
    return cubicInt(iR, y0, y1);
  }

  double getGreen(double iR, double iY, double iB) {
    final x0 = cubicInt(iB, magic[0][1], magic[4][1]);
    final x1 = cubicInt(iB, magic[1][1], magic[5][1]);
    final x2 = cubicInt(iB, magic[2][1], magic[6][1]);
    final x3 = cubicInt(iB, magic[3][1], magic[7][1]);
    final y0 = cubicInt(iY, x0, x1);
    final y1 = cubicInt(iY, x2, x3);
    return cubicInt(iR, y0, y1);
  }

  double getBlue(double iR, double iY, double iB) {
    final x0 = cubicInt(iB, magic[0][2], magic[4][2]);
    final x1 = cubicInt(iB, magic[1][2], magic[5][2]);
    final x2 = cubicInt(iB, magic[2][2], magic[6][2]);
    final x3 = cubicInt(iB, magic[3][2], magic[7][2]);
    final y0 = cubicInt(iY, x0, x1);
    final y1 = cubicInt(iY, x2, x3);
    return cubicInt(iR, y0, y1);
  }

  final redValue = getRed(red, yellow, blue);
  final greenValue = getGreen(red, yellow, blue);
  final blueValue = getBlue(red, yellow, blue);
  return PdfColor(redValue, greenValue, blueValue, alpha);
}