flatten method
Apply the color transparency by updating the color values according to a background color.
Implementation
PdfColor flatten({PdfColor background = const PdfColor(1, 1, 1)}) {
return PdfColor(
alpha * red + (1 - alpha) * background.red,
alpha * green + (1 - alpha) * background.green,
alpha * blue + (1 - alpha) * background.blue,
background.alpha,
);
}