colorType is ignored on macOS

[tresf]

Steps to reproduce:

1. Using a Mac on Apple Silicon or Intel
2. Load https://demo.qz.io
3. Search for a printer capable of printing in color
4. From the Pixel tab, next to "Color Type", select "Black & White"
5. Click "Print HTML" button
6. Observe that the document is still printed in color

tray/src/qz/printer/action/PrintHTML.java

Lines 195 to 197 in 94f02af

	if (pxlOpts.getColorType() != null) {
	settings.setPrintColor(getColor(pxlOpts));
	}

Upstream bug filed (private) as QZ-12.

[tresf]

It appears MacOS may be missing an API for this... here's how Firefox does it...

// There's no standard setting in Core Printing for monochrome. Or rather,
// there is (PMSetColorMode) but it does nothing. Similarly, the relevant gtk
// setting only works on Windows, yay.
//
// So on CUPS the right setting to use depends on the print driver. So we set /
// look for a variety of driver-specific keys that are known to work across
// printers.
//
// We set all the known settings, because the alternative to that is parsing ppd
// files from the printer and find the relevant known choices that can apply,
// and that is a lot more complex, similarly sketchy (requires the same amount
// of driver-specific knowledge), and requires using deprecated CUPS APIs.
#define CUPS_EACH_MONOCHROME_PRINTER_SETTING(macro_)                           \
  macro_("ColorModel", "Gray")                    /* Generic */                \
      macro_("BRMonoColor", "Mono")               /* Brother */                \
      macro_("BRPrintQuality", "Black")           /* Brother */                \
      macro_("CNIJGrayScale", "1")                /* Canon */                  \
      macro_("CNGrayscale", "True")               /* Canon */                  \
      macro_("INK", "MONO")                       /* Epson */                  \
      macro_("HPColorMode", "GrayscalePrint")     /* HP */                     \
      macro_("ColorMode", "Mono")                 /* Samsung */                \
      macro_("PrintoutMode", "Normal.Gray")       /* Foomatic */               \
      macro_("ProcessColorModel", "Mono")         /* Samsung */                \
      macro_("ARCMode", "CMBW")                   /* Sharp */                  \
      macro_("XRXColor", "BW")                    /* Xerox */                  \
      macro_("XROutputColor", "PrintAsGrayscale") /* Xerox, bug 1676191#c32 */ \
      macro_("SelectColor", "Grayscale")          /* Konica Minolta */         \
      macro_("OKControl", "Gray")                 /* Oki */                    \
      macro_("BLW", "TrueM")                      /* Lexmark */                \
      macro_("EPRendering", "None")               /* Epson */

[tresf]

Upstream bug report:

• https://bugs.openjdk.org/browse/JDK-8315113

Mailing list conversation:

• https://mail.openjdk.org/pipermail/client-libs-dev/2023-August/014497.html